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Really appreciated two things about this video: 1) Your clarification that SR treats inertial frames as given - something you’re likely to get pushback on from commenters (as we once did) but about which you’re absolutely correct. 2) Your noting that proper acceleration as a solution doesn’t generalize to GR - something almost everyone who treats on the topic of the twin paradox overlooks. In our long study of the twin paradox, we learned that, within the context of the current theories of relativity, there is only one “resolution” to who is younger - and that is whichever twin traveled the shorter spacetime path. In flat spacetime, this will always be the accelerating twin, while in curved spacetime considerations of the metric will determine who travels the shorter spacetime path. But of course, if one asks, what is the physical meaning of spacetime distance - the only answer the theory can give is that it is the amount of proper time which elapses on a co-moving clock. So the “resolution” to the twin paradox is precisely this: the twin who comes back younger is the twin who experiences less elapsed proper time. Quite tautological. The problem you may or may not be grasping is that Relativity is not a theory of causes, it is a mathematical description of correlations between measuring instruments/coordinate systems. And the paradox of the twins is essentially not asking what breaks the symmetry, but asking what causes time dilation in the first place. And as both we know, Relativity can’t answer that question. Indeed it seems you still have not grasped the full significance of the one-way-speed-of-light problem. If nothing requires observers to choose epsilon = 1/2, then the twins can choose appropriate epsilon values such that they both agree that it is the traveling twins clocks that are running slower - and so there is no paradox in the first place. Of course, everyone’s understanding progresses at its own pace, and there was a time when we too still believed relativity to be correct, and dismissed all those who told us that only an ether could explain time dilation as essentially crackpots. Sometimes one must taste the medicine they dish.
The one-way speed of light doesn't exit. Just like the one-way speed of a goat. You have a pair of clock world-lines so there's an arbitrary choice of synchronization.
Started well, ended like nonsense. Why the hell did you mention Ether? Every attempt to show that it exists has failed, suggesting it doesnt exist in the first place. Relativity is wrong? We believe that it is incomplete, yes, not wrong. As there exists many quantum gravity issues and einstein's relativity doesnt work to solve them, we believe it must be at least incomplete. However, i think you said that because you believe in some Mumbo Jumbo ether theory or any shit related, which is very funny.
SR doesn't say anything about acceleration. Each observer is given identical clocks and measuring rods. One moves at constant velocity, the other doesn't. In SR it doesn't matter who is A and who is B. They both measure the same values within their respective inertial frames, for example, they measure the same value for the speed of light. Time dilation and length contraction falls from a comparison of A to B or B to A. Without the comparison there is no time dilation nor length contraction. Both will experience time dilation and length contraction depending on the point of view. A says B is moving. But B says A is moving. Swap your perspective and you get the same answers. The twin paradox arises because we compare the twins (thru observation of clocks) and say one is older than the other (time dilation). We define a point of view and define 'who' is 'moving'. We interpret that time dilation to be persistent once both twins return to the same inertial frame. Is it real? Perhaps neutrino decay is the best evidence for this? But, isn't there a larger concern here? If it is real, then can't we claim there is a preferred inertial frame. Wouldn't such a preferred inertial frame justify the ether? Wouldn't an ether change physics completely? Suppose that the ether could be explained as a series of coupled mechanical pendula. Special Relativity Hidden in a Series of Coupled Mechanical Pendula ua-cam.com/video/e7nA5y497U4/v-deo.html
So when I think about measurements in internal frames and use the verb "see", I never think about light reaching the observer. I think about his infinite lattice of graduate students with synchronized clocks and calibrated rulers, and "see" means what does the grad student who is at the distant event "now", at the time of seeing, measure. Right before turn around, the space twins grad student (bob) sees a younger earth twin. Then bam, turn around happens. Bob still sees a younger twin on earth, but bob is no longer synchronized with his adviser space twin. Space twin needs a whole new lattice of grad students, and the one he needs on Earth is a much older bob (if bob waits). This new grad student is now standing next to a much older Earth twin, who ages more slowly on space twins return trip.
Great video. Just one minor thing to add. Those who argue that the Twin Paradox can be resolved by simply considering inertial frames and use the Triplet example to show this to be the case, miss the obvious; The ‘Triplet Paradox’ is not the ‘Twin Paradox'! The Twin Paradox requires the twin to return to Earth, and hence accelerate. The Triplet example leads to a different paradox; Namely, when B and C pass each other they both agree they are the same age. A also agrees that B and C are the same age. But B and C disagree on the age of A.
The relative ages of b and c never play a role. When they meet, they synchronize their clocks. C can be infinitely old before that, and it makes no difference. Sure, that's not the twin paradox, but it leads to the same conclusion. That all that matters for the end result is the spacetime length of the journey, which is well defined.
@@narfwhals7843 'Age' above is simply used to make reference to the elapsed time recorded by the clocks on A, B, and C. No matter how you choose to synchronize the clocks, given the particulars of the thought experiment, B and C will disagree on how much time has elapsed on A. So when C arrives at A, C will conclude that more time has elapsed on A, whilst B on the other hand will conclude that less time has elapsed on A. Or, if A, B and C synchronize their clocks when B and C pass each other, B and C will disagree on the time at which A synchronized its clock due to the Relativity of Simultaneity.
That B and C disagree on the age of A is the resolution of the paradox, so this example makes it very clear that B and C are at the exact same event in spacetime but cannot agree on the definition of "now" everywhere in the universe. A lot of ppl struggle with relativity because they fail to abstract, I mean just read comments "but earth is moving", "but earth is spinng", "but the sun is moving", "but there's gravity on earth"--they can't just say "F-that, I'm moving the problem to a deep space space station"...oh, and then you ppl invoking quantum and atomic structure in some of the classic paradoxes..., this problem crops up in the normal formulation because B has to accelerate at absurd gees (even infinite), and they just can't get past that in a thought experiment. keyword: thought. So the triplet version just abstracts that away, we see that A sees B and C age less, and B and C see A age less, so that A + A < B + C for B and C, while A + A > B + C for A...yet because B and C disagree on when now is at distant locations, all the proper time is accounted for. tl;dr the triplet formation zeroes in on the resolution in an entirely abstract manner.
@@DrDeuteron Thanks for the comment. I'm unclear what you meant in your last paragraph. But, let A, B and C choose to synchronize their clocks at the point where C and B pass each other according to each of their frame's of reference. C then travels onto A. At the point where C passes A, the time on A, B and C's clocks are recorded, once again according to when A, B and C determine C and A to be coincident in their frame of reference. The results are as follows; More time has elapsed on A’s clock than on C’s clock; And, more time has elapsed on B’s clock than on both A’s and C’s clocks. There’s no paradox, but it’s viewed as paradoxical if one solely considers the rate at which ‘clocks tick’ and ‘rulers contract’, and ignore that when and where events occur is relative to the observers frame of reference i.e. the two events in question here being when C is coincident with B and the clocks are synchronized and when C is coincident with A and the time on the clocks are recorded. This is the no agreement on the universal ‘now’ as you said.
They're both the "twin paradox" which is just a comparison of world-line arc lengths connecting a common pair of events. The gravitational field does not care about the names of triplets.
It's simpler than we all imagine, you don't always see things in slow motion when you move, sometimes you see things in fast motion, things in the direction of motion move in fast motion, if you hover above a gravitational field, the universe above you is in fast motion. If you were to move very fast in the direction of Proxima Centauri, you would see it in fast motion, because you are moving in relation to it. When you get there, your're younger. When you reach it, it's older than it would've been if its aging were only determined by the time light takes to reach you, and you catching the light rays faster as you get close to it. You don't need acceleration, you don't need to go back to "compare clocks" and you don't need to be close to it beforehand.
With "it moves in fast motion", I assume you mean "its apparent clock rate is higher." Otherwise, your text does not make much sense. Also, you seem to equate apparent clock rate with the Doppler shift of light arriving at the observer. But relativistic Doppler shift consists of two components: the normal Newtonian frequency shift between the light leaving the source and arriving at the observer, and relativist time dilation of the source. Using the relativistic Doppler shift as if it is the clock rate simply makes everything harder to calculate. There is also a fundamental flaw with it, because light can travel from the source to the observer via multiple paths. Each of these paths will have its own Doppler shift that differ from each other. That makes the measurements inconsistent.
@@DrDeuteron _"you lost me at multiple paths"_ - then I probably misinterpreted your original statements. You might want to clarify what exactly you mean with "move in fast/slow motion", "see it in fast motion" The term "motion" is usually used for something that has relative speed. You don't seem to use it in that manner, which makes your comments unclear.
@@renedekker9806, Thanks a lot for reading my comment and taking some time to talk to me about reality! I really love talking to smart people, and I loved your way of thinking. I have some stuff to add: ------------------ I am precisely saying that it is not just the Doppler effect. I am saying that it IS in fact time dilation, lenght contraction and simultaneity. Even if the relativistic doppler effect has an aditional relativistic factor. ------------------ What I am saying is: In a scenario in which there is a Traveler, Earth and Proxima Centauri, when you move fast towards Proxima, during the trip, if you look in the direction of Proxima out of the window, it is "moving in fast motion", its clock is "speeding up", things are literally moving faster, and if you look back to Earth, it is "moving in slow motion", it's "time dilated". From the perspective of people on Earth and Proxima, the Traveler would reach Proxima in 4 years, and the part of the rocket in the direction of motion "happens later" than the part of the rocket in the opposite direction of motion, which "happens first", like this you explain the Relativity of simultaneity from both perspectives. ------------------ TV imagination: Imagine a television system on which there is a movie being displayed, passing by you horizontally, extremelly fast. The movie would not pass normally in all the parts of the TV, the movie would "pass first" in the part of the TV opposite to the direction of motion, and the movie would "pass later" in the direction of motion. ------------------ Perspective of the traveler: - Distance between planets is contracted, therefore it gets there in less time. Traveler ages less. - Simultaneity: the universe in the direction of motion "happens first". The universe in the direction opposite to the motion "happens later", because of this, the forward region "happens in fast motion" and the other direction "happens in slow motion", this is simultaneity. Perspective of the Planets: - Distance between planets is not contracted, the traveler takes 4 years to reach it, the traveler is contracted, the region of the rocket in the direction of motion "happens later" and the region of the rocket in the direction opposite to the motion "happens first", simultaneity again. ----------- How I thought about this: Imagine two planets A, B and a Traveler, all share the same inertial frame of reference. Their clocks read the same time. The Traveler moves from A to B. When the Traveler reaches planet B, he has aged less than people on both planets, therefore, during the trip, if the Traveler were to look out the window, he would see planet B in "fast motion", and the planet A in "slow motion". ----------- At the speed of light example: If the Traveler moves at the speed of light, he reaches planet B instantaneously. Then, at the planet B, when he looks back to planet A, it is exactly at the moment when the Traveler left it. Planet A is as old as planet B, but its light still hasn't reached the Traveler. THIS explain the relativity of simultaneity as well. ----------- Conclusion: So, as I see it, you do not need general relativity to explain the Twin Paradox.
I've really enjoyed this video and the one about whether or not falling charges radiate. My opinion is that in the framework of Special Relativity we are allowed to make a measurement to decide if we are accelerating. It could be an accelerometer, or just letting go of a golf ball in front of our eyes and seeing whether it changes speed. I think we are allowed to interpret the result of such an experiment within the framework of SR and measure our acceleration that way. The falling charge is fascinating, and after looking into it for some time I have to agree with Feynman. It solves all the paradoxes and preserves the equivalence principle if only a charge whose acceleration is changing produces radiation.
Very clear, as usual. Interesting "fact": in a not so popularly known formulation of the paradox, one twin is on earth, subject to earth's gravitational acceleration (ok, the floor imparted acceleration upwards... of 9,81 m/s^2) while the travelling twin starts from a high tower. Bear with me; the final makes one reflect on the nature of 3D-space. Well: Since he's starting from a high tower, with lesser gravitational strength, he can "use" the difference (say he's subject to 9,80 m/s^2, not 9,81) of 0,1 m/s^2 to move further up. As he gets away, the gravitational strength diminishes, so, in order to maintain his acceleration equal to the other twin's (=9,81 m/s^2) more and more "moving" acceleration becomes available. When the earth's gravitation becomes negligible, due to the *inverse square law* , the 9,81 m/s^2 are used practically only to increase his velocity. Then, to invert the motion he takes on a speed higher than orbital velocity around the - now far away - earth, so that he must maintain himself centripetally accelerated at 9,81 m/s2 while turning around, and finally heads back home, where he then decelerates, always maintaining his "perceived weight" at 9,81 m/s^2 against the spaceshift's floor. And, when he returns, he's younger. But the difference is only one: earth's gravitational field is spatially limited, whereas the "apparent" gravitational field arising from the (absolute) acceleration is not. So when the "fictitious", spatially infinite gravitational field acts, the one making time go faster on earth (therefore making the earthbound twin age faster) *from the travelling twin's perspective* , it acts at the *distance* between "orbital" (not really) motion and the earth. We call it "Radius", obviously. Now: different journeys with combinations of parameters: acceleration, journey duration, distance reached, etc... will result in different experiences, and different age offsets between twins. For example: A- if you decide to "orbit" (not really: you have to maintain centripetal acceleration of around 9,81 m/s^2 = 1 g) *very far away* , you'll experience 1g centripetally only to sustain circular motion; but here, far from earth, the circle is very wide: much time is needed to complete at least 1 circle to head back home. The circumference is = 2*pi*Radius. B- decide for a lower "orbit"? but then you've got to accelerate less - and for a shorter duration, as you're not so far away and the circumference isn't big - to invert the motion, because there's still a non negligible earth's gravitational field _helping_ you turn without accelerating. Being - "nearby" means that the "fictitious" gravitational field that you feel acts at a lesser distance and makes the earthbound twin age faster (from your perspective) at a much much lesser rate during that phase of accelerated motion, than in the previous (earth far away) example! Also, your proper time offset from pure SR isn't big, because the whole experience takes less time, distance, etc... Now, maintaining the relation between radius and circumference (2*pi), suppose we ask for the *gravitational strength distance relation* that has to be in place for a traveller that stays in the loop for a certain fixed duration and ends up experiencing a certain *fixed* age offset between stationary and travelling twins. The result is NEWTON's INVERSE SQUARE law for the gravitational field!!!!!!!!!! (the initial "tower" is only a kickstarter, a "trick" and can be reduced to zero at the limit)
Newton's law of motion, F=ma, Force equals Acceleration. Acceleration equals Force. Acceleration equals Acceleration. The twin undergoing the most force on their frame of reference is the one that is 'older'. Zero gravity/equalized Acceleration = less force on the twin's body. The only way to accurately compute "age' differences is by heart rates. The hummingbirds lifespan is shortened by its accelerated heart rates. By the extra energy it uses. E=mc. C is not just the speed of light but also the speed of time. C is absolute motion in time or one's lifespan. C is acceleration and that acceleration comes from an energy source. The food you eat accelerates you in time. The food you eat also accelerates you in space. Example. Solar sails. The energy that is not reflected back goes into accelerating the sail in time - radioactive decay. Around .2c, the sail goes into catastrophic meltdown- bursts into flames. Numerous astronomers and astrophysicists have rebutted Lerner’s claim, accusing it of opportunism, being thin on proof and supported by inconsistent arguments. Sounds like relativity. Where is the proof that time slows down the faster one travels in space? Does it delay embryo development. Seed germination. Plant growth. Reaching physiological maturity? Relativity is what is wrong with physics. Relativity is rebranded Flat Earth science.
@@stewiesaidthat yeah this sounds like it has no relation whatsoever with what I wrote. Furthermore, mine is a physicists' try to explain something very deep. you know... nothing for laymen, with all my respect. One thing you've got right, though: generally, the twin feeling more "force" foe example through the feet touching the floor is the younger one. ONLY: why would the twin on earth, in my example, who is feeling the very same "force" through his feet during the whole experience as the earthbound twin, be any older than the travelling twin? BECAUSE .... well: re-read the comment ! 🙂 And no, "c" isn't the "speed of time" but the speed of CAUSALITY. That's why to me, "c" stands exactly for "causality" instead of like originally thought: "celeritas" = celerity = speed. The speed of something is the units of that something per second (meter/hour, dollars/month etc...); in the case of time it would be just a dimensionless 1. Its UNITS? [seconds per second], or [s]* [s^-1] = 1#.
@@diemme568 thought so. You are just as confused by acceleration as Newton and Einstein. (c) is absolute acceleration. Both in space and in time. Mass is what determines how much acceleration (time/distance) one can has already/achieved. The Cause is instantaneous. The effect is what travels at (c) the carrier wave. E=mc. The process of converting atomic energy to radiant energy and back via Acceleration. C is absolute acceleration in time (radioactive decay) as you run out of atomic energy to convert to radiant energy. (c) is the absolute acceleration point in space as you run out of mass to accelerate and energy to accelerate said mass. Acceleration in space equals Acceleration in time. Whether you are using an outside force, the F in F=ma or the inside stored energy (mass) of the spaceship. The (m) in F=ma is the ships fuel tanks. Once they run out, there is no more acceleration. The (c) in E=mc is the physiological maturity of plants. Once (c) absolute acceleration is reached, the plant dies. The (m) in E=mc is the photon's wavelength. Once the photon reaches its wavelength, it propagates a new photon. Now, what happens to your causality limit when (c) gets redefined. When tachyons are discover and information can be transmitted faster than light. You are thinking 2 dimensional. You are a blind man that doesn't know anything at all about light. You're universe is bounded/defined at the speed of sound. I'm not saying that tachyons exist. Just that you are a blind person who has no concept of light. As far as which twin is 'older', they both experienced the same amount of time as shown by the energy each clock used. One just experienced more space. Two cars going around the track turning identical laps. One speeds up. The lead car is experiencing more space, more laps, more force going around the corners. How can a person possibly be aging less when they are experiencing more force? Motion is absolute. Everything is an emergent property of acceleration. Time, temperature, gravity. All measurements of acceleration. (C) is bounded acceleration. Both in space and in time. (C) is your lifespan. How long you live. (M) determines how long you live (photon's wavelength for instance) (e) is what gets you there. The energy from the sun accelerates the plant to (c) its physiological maturity date. C isn't just how fast one can go in space but also how far one can go in time. The gas in your tank is stored energy. (c) is how far that tank of gas will get you. Not only in space but also in time. Comprende. 100 gallons of fuel (mass) at an acceleration rate of 10 gallons per hour equals a maximum acceleration time of 10 hours, (c). At a mile per gallon, you get 100 miles in space. That's the law of motion. Speed is distance/time. Two separate frames of reference. (C) is the absolute amount of motion you can have either in space or in time.
@@diemme568F=ma. Nothing is real. The universe is unbounded, undefined. Whatever you want it to be. Like walking into a dark room and imaging it's filled with all kinds of stuff. E=mc. The contents of the room are now being refined to you at the speed of light. Only Acceleration is defined. Acceleration defines mass. Water? Solid, liquid, gas. All defined by its acceleration value. F=ma to E=mc. Only Acceleration is defined. Motion is absolute. Have a nice day.
Changing the direction of travel of your spaceship, such as going in circles, is said to be "Acceleration", in the world of physics. That sounds a bit confusing. Meanwhile, if your spaceship travels in a straight spatial line, but constantly accelerates while in the process of doing so, it too in truth is also constantly changing its direction of travel. All this goes on, while the magnitude of the motion of the spaceship, NEVER actually changes. All that can be changed, is its direction of travel. Within the 4D space-time environment, the more your spaceships ongoing motion is directed to being across space, the less of your ongoing motion is now directed across the dimension of time. Taking this 4D perspective into account, throws the paradoxes out the window.
The answer is a firm NO. In SR, you can work in Minkowski space and integrate proper time along a world line and get the answer without contradiction. Thus SR is enough, because it is a self-consistent theory. The reason you get a paradox is when you leave Minkowski space and work in 3 + 1 frames. The paradox is not the asymmetry, its that each twin sees the other's clock tick less time on each leg, so the sum of elapsed times disagree, Ofc the paradox is resolved when you remember a line takes the form: y = mx + b, and we're just looking at "m" (time dilation), you need to include "b" (clock bias), and that changes at turn around. It's not time dilation---you can make b "run" forward or backward--it's just clock bias (see Andromeda paradox). Now you can invoke GR, and ofc it gives you the correct results, but it is absolutely not necessary. If you want to describe it in apparent physical terms, it really is paradoxical, in the limit of zero turns around (TA) time: Space twin ages zero TA, Earth Twin sees space twin age zero during TA, Earth twin sees Earth twin age zero during TA, but Space twin just picks a whole new "now" on Earth that is much later. It's not aging, it's just a new now. You know it's not aging, because if he turns around again, boom Earth twin is young again. This is the Andromeda paradox, where "now" at distant locations depended on which way you drive your car here on Earth, and ofc, the ppl living in Andromeda don't care.
I'm not trolling, from what you have said above does one of the twins end up being older than the other? I'll just accept it as your view without further discussion. > I haven't looked at the Andromeda paradox but it does appear to highlight an issue in "what is time?" in the 3D and 4D geometries. I personal have serious doubts about so called 3D and 4D geometries as they appear to work from an ambiguous concepts of time. This is a fundamental question for me around for relativity and Minkowski diagrams with regard to which version of time is used. We have global (persistent) time, and we have motion where time does not exist. The geometries may look similar, but can be abstracted to many different versions of our human interpretations. Which geometry do you feel is asserted with regard to time? Again, just your view, as I have no desire left for entering into debates.
The difference in age of the twins doesn't come from time dilation, time dilation is symmetrical. However, length contraction is not symmetrical. While the stationary twin sees the rocket shorter, the traveling twin sees the entire length of the trip shorter. So the traveler needs less time to complete the journey. What exactly happens during the acceleration phases doesn't really matter for the twin paradox. As Lukas said, it can be made arbitrarily short.
I think it is easy to proof that relative velocity difference does not necessarily cause relative time dilation. Instead of twins consider triplets. L travels to left, E remains on earth, R travels to right with exactly same, but exactly opposite acceleration as L. There will be no time dilation between L and R, despite the HUGE difference velocity, but both will have time dilation against E. Also, if we only use SRT with straight lines then infinite acceleration within zero time at the starting, ending and turning point must be assumed. This is impossible to calculate. When it is neglected, we get an error.
You have to take simultaneity into account with your scenario. Both, R and L, will see say there is time dilation on the other for the entire trip. But they will disagree when the turnarounds occurred, which will result in their clocks being synchronized in the end. The elapsed time on their clocks only depends on the length of the trip, which you can calculate with or without acceleration.
_"There will be no time dilation between L and R"_ - only when viewed from E. The clock rate of R will appear to be slow when viewed from L, and L's clock rate will appear to be slow when viewed from R. From L's point of view, both E and R are moving away from him, R with almost double the speed as E. So both E's and R's clocks will appear to run slower according to L. _"[infinite acceleration] is impossible to calculate"_ - it is possible to calculate if, instead of zero turnaround time, you take the limit for the turn around time approaching zero.
@@renedekker9806 When L and R meet again on earth, there is no time difference between them. It does not matter in which direction they travel. If both travel in the same direction parallel, then the result ist the same. Therefore the relative velocity between L and R has no influence on time difference between their clocks. In this special case. This proofs relative velocity alone does not cause actual clocktime difference. It only influences the time which will be observed by a remote observer.
8:40 There is a paradox, it's just not a contradiction. one definition of a paradox is an apparent contradiction, and that's the one we're talking about.
The twin paradox is rigorously solved in this tutorial, with a realistic acceleration, from both points of view of the traveler and the stay-at-home twin: ua-cam.com/video/QFWF90bch3c/v-deo.html
I am confused by something I thought you said: my clock will tick slower if I am moving at uniform velocity wrt another, external Observer. I thought that wrt to my own inertial frame of reference, there is NO time dilation. So my clock would APPEAR to tick slower to the Observer but not to ME. I hope you agree so far. In your example, my elapsed time would be 5.75 years, from my perspective, before I turned around, although to the Observer it would seem like 2.84 years. When Observer and I meet again, after I turned around, my clock would have recorded MY time, which would be 11.5 years, not the time (5.75 years) that Observer thought I had clocked. The Observer looking at my clock when we are “sitting across a table and wondering who is older”, is no longer the scenario where we were moving relative to each other at near-light speed. My point simply is: my clock recoded my time, not the time perceived by Observer. So the so called “paradox” may be a “red herring”. Am I missing something?
You have that wrong. The "proper time" is the time elapsed on the clock that takes that path. So if the proper time on your path is 2.84 years, then that is the time _you_ consider to have passed. An observer who sees you move will notice that your clock has recorded that much time, but they will also notice that their own clock has recorded _more_ time in that period, so they will conclude that yours is "ticking more slowly". In the duration it takes you to reach the turnaround point the observer on earth measures 5.75 years in the time it takes your clock to measure 2.84. The total time elapsed on your clock when you meet again is twice that, so ~5.75. The total time elapsed on the earth observers clock is 11.5. There is less time elapsed on your clock, than on earth's. Each observer's clock records their own proper time. There is no paradox.
@@narfwhals7843 Thanks for your explanation but I still don’t see how it hangs together. You say, “proper time is the time elapsed on the clock that takes that path”. How can that be different from the time experienced in MY inertial reference frame? After all, they are MY clocks, residing on my spaceship. Proper Time cannot be my time observed from an external reference frame, as it would immediately raise the question: which reference, and attack the very foundation of the concept of SR. Note further that clocks are made with springs or crystals, none of which have any awareness of the uniform speed of my reference frame relative to the speed of light and therefore couldn’t be influenced by the ratio of the two. Likewise for my beard, which would grow at the same rate regardless of my speed. Every assertion of SR is about the observations of someone in an EXTERNAL reference frame, not in the SAME reference frame as containing the subject clocks.
@@sdutta8 If you are traveling with the clock then the clock will measure your proper time. *All* observers agree on what that clock reads. They do not agree on how that compares to their own clocks, which measure their own proper times. I think you are conflating two different things. "Your time" is just the time on your clock. How that relates to some other observers time is what we use the Lorentz Transformations for. Clocks and beards operate by the laws of physics, regardless of their construction. If the Principle of Relativity is to hold and include the speed of light, then different observers will disagree on how fast clocks tick or beards grow. Is your disagreement that, even though different observers will disagree on the rate of clocks, this can not have physical consequences? What does "external" mean? Any inertial reference frame is equally valid.
@@narfwhals7843 I agree with you that if we were traveling in different spaceships at uniform speeds, each of our clocks would tick at 1 second/second for each of us but might appear to be ticking more slowly if we had a radio link between our spaceships, providing visibility of each other’s clock times. You can guess that from logic and intuition - you don’t need SR or Lorentz for that. My issue is with the way the Twin Paradox is posited. The usual story is that the twins reunite and cannot agree who is younger. If they were having this discussion while the were passing each other at quasi-light speeds, then yes, they would have this conundrum. On the other hand, if they both alighted on Earth and checked their clocks, they should both see the same elapsed time on their clocks and biological aging in their bodies. If that was not the case, I wouldn’t understand why.
@@sdutta8 If all we use is Newtonian logic and intuition, we might conclude that the ships will see each other's clocks slow down if they move away from each other, and speed up if they move toward each other, due to doppler effects. This will not result in a difference in elapsed time when they meet again. This is present in special relativity, as well, but that is not time dilation. Time dilation is irrespective of direction and a result of demanding that the speed of light must be the same for all observers. This does result in a physical difference in elapsed time when they meet again. Time is just a certain idea of distance in spacetime and a clock measures that distance. That distance is different along different paths. The paradox is posited that way to appear paradoxical. It only does so until you properly consider the situation and see that it is not symmetric. The situation is clear and and fully resolved when you realize that you can not treat both twins equally because only one of them is inertial the entire time. The one who wasn't is invariably younger. This has been verified experimentally.
I understand that the ship frame is not an inertial frame and I trust what you said, but I imagine a light clock on Earth. In the ship frame the light ray path is longer, so I think the twin on Earth is younger as it moves in the ship frame. (even though the ship accelerates and decelerates) Maybe the speed of light changes? I really enjoyed your video, you are number one! (and I'm proud to follow you since your first videos) 🙂🙃🙂
A few years ago, as an interested layperson, I came up with the following concept to better understand the twin paradox: shells of light. When Alice moves towards Bob, she breaks through Bob's light shells more frequently, causing her to see Bob in fast motion (imagine a periodic signal emitted by both and counted by both). The key idea is that these light shells contain all the information about the relative present. Accordingly, one travels into the relative future or past of the other. For example, if Alice is 4 light years away at Alpha Centauri and Bob waves to her from Earth, and Alice instantly travels to Bob at the speed of light, no time would have passed for Alice, and she would be the same age upon arrival as she was when Bob last saw her in his telescope - since Alice traveled with her own light shell. Conversely, Alice would have broken through many of Bob's light shells during her journey, causing her to see Bob in extreme fast motion and experience him as 4 years older upon her arrival, according to the number of light shells she passed through. Essentially, both would just need to count their relative light pulses. For the full picture, you must take into account the change in direction and acceleration, but the basic concept should hold. Edit: Also, the situations in the twin paradox are not symmetrical from the start. If Alice travels to Alpha Centauri, 4 light years away, at the speed of light, she experiences it as follows: She leaves Bob, arrives immediately, and sees him as he appeared to her "just now," because she has traveled with his light. Conversely, Bob sees Alice disappear. He sees her arrive at Alpha Centauri after 8 years, appearing as she did 8 years ago when she left him, since no further light from her reached him in the meantime. If Alice returns to him shortly after her arrival, she sees him again in the next moment, but suddenly 8 years older - in that one moment, she has received 8 years of his light. From his perspective, she returns and is immediately back with him, not having aged, because he received no further light from her in the intervening time.
Yeah, this explanation gets bundled up as "Relatavistic Doppler Shift". The peaks of an electromagnetic wave can be thought of as the ticks of an oscillating electric charge.
If you go through "shells of light "more frequently" under whose time--see one guy going through more shells than another is objective. As soon as you tank about more frequently you introduce time and thats relative--reminds me of people who say "everythigs vibrations-time is a vibration---but to talk about vibrations one uses time so this is circular logic.
@@whatitis4872 When we talk about one person moving through more shells of light than another, this is indeed an objective observation. The number of light shells intersected by each observer can be quantified without reference to a specific frame of time. The notion of "more frequently" does indeed introduce the concept of time, which is relative according to the theory of relativity. However, this relativity is exactly what the concept aims to illustrate. When Alice moves towards Bob, she intersects Bob's light shells at a rate that appears faster to her due to her relative motion. This is a direct consequence of time dilation. The idea of "everything being vibrations" or "time as a vibration" can indeed lead to circular reasoning if not carefully defined. In the context of the light shells, the "ticks" or intersections are not described as vibrations but as discrete events marked by the passage of light fronts. These intersections are used to illustrate the relative experience of time between moving observers. The light shells provide a visual and conceptual tool to understand how information travels and how the perception of events changes with relative motion. They help to show that what one observer perceives as a short duration can be experienced differently by another observer due to their relative velocities. The concept of light shells helps me better understand the interplay between space and time. I imagine Bob surrounded by onion-like, nested light shells. Each of these shells shows an image of him at a specific point in time. No matter how Alice moves through space, the light shell of Bob that she is on is uniquely defined by her distance from Bob. When Alice moves towards Bob, she breaks through these light shells in quicker succession, causing her to see Bob in fast motion. Conversely, when she moves away from Bob, she sees him in slow motion. These light shells contain all the information about the relative present and illustrate that Alice travels into Bob's relative future or past, depending on her relative motion.
@sorokan761 As a concrete example, you can imagine a flashing light bulb/LED on a clock. If the LED blinks on an off once every second (or whatever duty cycle you want to use) and moving observers will see the period of the blinking cycle be at a higher or lower frequency depending on direction and speed. It *is* exactly described by the Relatavistic Doppler Effect. Red-shifting and blue-shifting is exactly the same thing for exactly the same reason. I should note that this is a *_DIFFERENT_* effect from _kinematic_ time dilation. (Moving clocks running slower, twin paradox and all that stuff.) and different from _gravitational_ time dilation. With the Doppler shift alone, observers moving apart will see the each other slowed down "red-shifted", and when moving towards each other, they will see each other sped up "blue-shifted". But when they are both going the same speed and direction, there's no shift. Kinematic time dilation will slow moving clocks in *all* directions of travel. Two observers traveling towards each other will both be blue-shifted by the Doppler effect *_AND_* red-shifted by kinematic time dilation! It's the kinematic time dilation in the so-called "Twin Paradox" that results in the twins being different ages when reunited together. Just Doppler Shift alone doesn't change proper time (age).
@@juliavixen176 Thank you for this enlightening and detailed explanation. I was not aware of this difference between the Doppler effect and kinematic time dilation. However, if I understand correctly, the following must hold true: 1. The difference in the number of mutually crossed light shells corresponds to the aging difference. 2. The image that an observer sees of another corresponds to the light shell they are currently traversing, and this is defined solely by the spatial distance.
Didn't you mention in a previous video that you can rotate your accelerometer by 90° and know that if there's no change then you are in an inertial reference frame? (Proper acceleration will make your accelerometer different in each orientation.)
Yes, just amazing and what I expected. Special relativity can handle acceleration and even the time gradient of the gravitational field by hyperbolic geometry, or two frames, or worldlines arc length, but it is itself against its first postulate, that everyone can claim to be stationary. In a spacetime diagram, if the moving twin (the zigzag line) was chosen to be stationary (straight line), it would mean that the structure of the diagram must change in such a way that it keeps his worldline shorter, kind of like changing from Cartesian to polar coordinates doesn't affect the path, or making the earth flat on a map doesn't affect the path. But for this mathematical assumption to be known, we must have the information about who is inertial in the first place. If we don't provide this information, the twin doesn't even know what his spacetime geometry is. So, General Relativity fixed that by allowing him to claim himself to be stationary no matter how much he accelerated and how many times he experienced a gravitational field, which allowed both of them to claim to be stationary.
The first postulate says nothing about being stationary. It says all inertial observers can use the same laws of physics. The geometry of spacetime in this scenario is Minkowski Space. There is no curvature and this is not observer dependent. Since there is no curvature, we only need Special Relativity. All observers can consider themselves "stationary", because that is a meaningless statement. One is always stationary with respect to ones own coordinates. This, too, has nothing to do with General Relativity. What we need to do is identify which twin is accelerating, which we can do by giving them accelerometers. During the acceleration period, we must concede that the person experiencing acceleration can not use the same laws of physics as one who is not, which is perfectly in line with special relativity, and have to include what we may call fictitious forces. What General Relativity does for this is to _always_ include the possibility of fictitious forces in the formulation of the laws of physics, allowing _everyone_ to always use the same ones. This is useful but not necessary to get the right result.
@@narfwhals7843 Thanks for your reasoning! I see it in a way that pushing the twin paradox too far can lead to a philosophical argument instead of a physical one. The idea is that worldlines are invariant and honest whether they are closed, hyperbolic, zig-zag, or whatever. If we make one of these worldlines straight through time, it would mean the diagram has a different line element formula to conserve their length. This is because the Lorentz transformation can only handle one section of the zigzag, or you can cut it out by adding many time coordinates as given moments, like the Rindler coordinate if you know the law of physics you are experiencing as a twin. But our twins cannot see spacetime and, therefore, cannot know if their worldline is shorter or longer. They cannot come up with the Rindler coordinate. However, if there is any asymmetry, it would indicate the difference in a relative way. Suppose you give everyone an accelerometer, and these twins have learned special relativity and understand the worldline concept but haven't learned general relativity. One of them has experienced acceleration, and one of them is free-falling near a black hole. After they come back, all they know about computing worldlines is based on special relativity, and they will be confused because they don't know the true geometry of spacetime near a black hole. All their assumptions about their worldlines based on the forces they experienced are wrong because one is falling around a black hole, but that person is thinking of themselves in Minkowski space. How does he know that he was wrong? Because all we did is formulate spacetime, and what they experience is very subjective, they cannot see their own worldlines. If the twins don't understand anything about physics, and you tell them that A's worldline is shorter and B's worldline is longer, that is enough. But they will be confused.
@@narfwhals7843 I think the word "relativity" is what caused this suffering for people. We first came up with the idea that every inertial frame shares the same laws of physics, and the speed of light is the same for all inertial observers. Then we proposed that a moving clock ticks slower, relative just like kinetic energy. But now, the twin paradox requires the understanding of worldlines and metrics, which are far beyond the simple photon clock that people think is the basis of relativity. We showed that worldlines are invariant. However, worldlines aren't a single moment or small duration; they are entire journeys when we already know the beginning and the end. This creates an invariant that everyone agrees on. We then conclude that worldlines are absolute, and coordinate systems are relative, serving as a standard measurement to observe worldlines. We ignored the fact that time dilation is caused by relative motion and developed the idea of proper time and worldline intervals to explain the entire twin paradox. We must accept that the initial idea showing that a moving clock moves slower is just part of the entire journey. It has now become an invariant concept that is far more complex than relative motion. Ultimately, we learn that relativity is based on things that are not relative. It's kind of like we came up with the idea of relative kinetic energy and found ourselves with an absolute kinetic energy. I don't know how to describe this feeling.
@@eigenvector123 I like to think of it like this. We had the principle of relativity, telling us that the laws of physics should be the same in all inertial reference frames. This leads to some problems with electromagnetism. Lorentz and others tried to solve this, while preserving an aether model, by introducing a length contraction relative to the aether frame. This gives the illusion of a constant speed of light and makes the aether undetectable. Einstein said "well, lets make the speed of light a law of physics" (or a constant of nature). That isn't actually a new postulate, as much as an observation. Length contraction and time dilation are a consequence of this, because it demands that space and time by themselves are just coordinate definitions. I don't quite understand what you mean by "ignore the fact that time dilation is caused by relative motion". That's the premise of the paradox. Time dilation is a discrepancy between clock readings and coordinate time. The resolution is to realize that clocks measure proper time, not coordinate time. If you place one twin near a black hole, that is a completely different scenario. They can _locally_ think they are in Minkowski space, but then they can't be aware of the black hole, so they also shouldn't be allowed to look at the distant twin. They can draw conclusions about the geometry from the end result of the experiment. One of the conclusions must be that special relativity is not enough to describe the whole situation. But that is a very different situation from the traditional twin paradox, with different results. They are right to be confused. They have a whole new theory of gravity to figure out.
@@narfwhals7843 Thanks for the last part. When I read, "They are right to be confused. They have a whole new theory of gravity to figure out," I was laughing. It was nice to talk with you; you are really smart. The first part, where time dilation is caused by relative motion, is still a thing. The first postulate really makes sense because Einstein was so magically genius that he chose the speed of light to be the truth. It was a perfect choice by accident, even after general relativity came out. After all, we figured out the speed of light is not constant in curvilinear coordinates and curved spacetime manifolds, but we still give "c" as the truth and define the concept of local speed of light, proper speed, proper distance, and proper time in a sense independent of the coordinate system we choose. The first logic of special relativity, which Lorentz and Einstein did, is viewing a photon clock ticking in a zigzag pattern. Using Pythagoras' theorem, we have the most basic formula, which is t = t'/sqrt(1-v^2/c^2), with no Minkowski metric and worldlines at all. We say that time dilation is relative, as long as there is no coming back, no hyperbolas, or zigzag worldlines, just straight to infinity. But after we figure out that if time dilation means comparing clocks when they share the same event, in the right space and time, we will find that only one person is older. They found out some invariants. This means we say time dilation is absolute, in the sense that we are giving up the first idea, which comes purely from coordinates, and now we rely on worldlines and proper time instead. A simple photon clock is not able to explain it anymore. In Rindler coordinates or curved spacetime, we must assume that the global speed of light can vary, and the photon clock can tick faster as those photons tick faster. But not everyone wants to learn complex geometric things. They want an explanation like a photon clock, realistic and simple, which was also the first idea of time dilation. They stay attached to those ideas, which is why many crackpots cannot get relativity easily.
Einstein's 1905 paper establishes a unification of Galileo's Principle of Relativity with Electromagnetism - it is not a theory of spacetime. Relativity is just general relativity and the machinery of the special theory can be used in the special case of the ground state gravitational field (the gravitational field such that the Riemann curvature is zero on all components).
He wrote 4 papers that year. Read "Does the Inertia of a Body Depend Upon Its Energy Content?" That papers proves the one you are taking about also works in accelerating frames of reference, but it affect the kinetic energy of a Body and ergo a mass is equal to Energy divided by c squared
@@ExistenceUniversity No, the papers have nothing to do with acceleration. In the E=m paper the kinetic energy is zero, K=(γ-1)m=0, and hence why it's called the rest energy. The total energy γm is the p^0 component of the 4-momentum. Anyway the point is that in 1905 we don't have notion of "spacetime" which wouldn't even be introduced as a concept until years later.
@kylelochlann5053 "Does the Inertia of a Body Depend Upon Its Energy Content?" Is 100% about acceleration. It's where Einstein writes gravity is equivalent to acceleration in that paper. I have it right in front of my for my history Of General Relativity video I will be publishing in a week Where do you think GR comes from?
@@ExistenceUniversity Then you haven't read the 1905 paper and your video will be filled with incorrect information. GR is predicated upon precise measurements of WEP, LLI, and LPI and subsequent measurements of the structure on top of the metric field. You cannot arrive at GR from SR.
Leo Moser posed the problem of the largest sofa you can move down a hallway and around a 90 degree turn. I just wonder if you could use length contraction to move a very long object down this hallway and around the turn as along as it maintains its high speed in the straight portions of the hallway and accelerates around the turn maintaining its speed? I don't understand how to do the math and if it could actually make the turn in the hallway. I know the car that is too long for the garage can fit from the stationary observers frame but how would this apply to an object too long to make a turn in a hallway ? Could you look at this problem , it might make an interesting video. I already asked this question on the stack exchange and pretty well got brushed off. They told me length contraction was not real and was just apparent. Also got a bunch of other non answers that it was off topic.
If you think about time keeping (like a light clock) as an electric oscillation on the smallest possible scale in any object you will find that any movement will result in a slowing of this time keeping. Explanation: If you look at a particle as a circle and the time keeping as an electric signal going from one side to the other and then back again (oscillating) it will take longer to make a cycle if the whole thing is moving. Einstein's famous light clock in a train works as well if it is laying down as when it is perpendicular. Seeing at time dilation this way points to that there is an absolute "Zero speed" in the universe. Acceleration has nothing to do with it other than you must accelerate (or decelerate) to get a different speed. That people stay younger when traveling fast is really no different to that frozen meat stays good longer than fresh meat. This is my opinion as it all makes sense to me. Also why shouldn't there be a "Zero speed"? We have a zero temperature and we have a maximum speed. It is just very difficult to find "absolute speeds" as we can't measure Electro Magnetic Emission (like light) in one direction only. Not yet at least. Time itself is in my opinion a momentary thing. We have a past that we can't change and a future that we don't know. That is why I say "Time keeping" (or time counting it should be). Also how can a future be deterministic if radioactivity is random? Radio activity can influence every thing.
Energy can be neither created nor destroyed only transformed. What transforms it? E=mc. Acceleration is what transforms mass from a solid to a liquid to a gas to radiant energy. (c) is absolute acceleration of the mass. Once the mass has been accelerated to c, it's transformed into the next phase of matter. Now, you have two quandaries. What is energy at Absolute Zero and what is Energy at +c. Since scientists still think the earth is a stationary plan (mass as an actionable force) a century's worth of progress has been lost on account of flat earther Einstein and 400 years lost because Galileo's peers were flat earthers. Even today, the entire scientific community is made up of science deniers. E=mc. Everything is an emergent property of acceleration, including mass. Why are scientists stuck on stupid still using mass as the actionable force.
@@stewiesaidthat Actually I would say it a little different about energy and mass. I would say that light or any other Electro Magnetic Emission is the purest form of energy and mass is energy decelerated to near stand still. For that to be possible it must be some thing like a standing wave if you know what that is - in my current opinion at least. I change my mind if I learn some thing new and it makes sense. Basically EME, like light, is at speed c and mass is energy some how caught at near stand still as we observe it. I believe the problem for scientists today is that for firstly getting their degrees they must stick to the norm and for getting a job and later funding for research they must stick to it too. It is daring to through away your future if you are game enough to say any thing different. I am not a physicist. I am only a design engineer and I no longer need a job. The government pays me a pension and as long as I don't do anything criminal they don't care much what I do or say especially if it isn't too political.
@@leonhardtkristensen4093 I have no idea what the problem with academia is. Surely they don't subscribe to this relativity nonsense. I always thought that relativity was one of those fringe flat earth type groups that didn't understand nature. You didn't see or hear it mentioned much until UA-cam came around and everyone started making videos trying to explain, as Nicholas Tesla put it, mathematical nonsense. It was then I realized how deep down the rabbit hole academia had gone. What makes anyone think that space and time are one and the same? That's what I don't understand. Have they not heard of refrigeration? Do they not know that microwaves accelerate the cooking process? Do they not understand what makes grass grow? It's like all they know is how to manipulate mathematical equations to get the desired outcome. A universe that is defined by mass. When I started looking into the infamous twin paradox, I thought it was just a simple misunderstanding of not knowing what it is that clocks measure. The more I looked, the worse it got. The Earth's tides. Galileo already showed that mass does not attract mass and theorized that it's the Earth's motion I'm space thst causes the tides. And yet. The UA-cam community still thinks the moon is creating the tides. Why? Newton's and Kepler's law's of motion clearly explain the tides and yet they are still trying to shoehorn in gravitational attraction. Newton's gravitational attraction is clearly at odds with his laws of motion. Didn't he understand that. And what about the rest of the scientific community? Surely they have to understand that gravitational attraction is a flat earth tool to explain why objects fall to the ground on a stationary plane. And Einstein, he contradicts himself left and write. I guess that comes from being a plagiarist and not understanding what he is stealing. Not a single experiment has validated his relativity nonsense. Not a single one. In fact, Hafele-Keating proves its just mathematical BS once you add in the missing data. Clocks in motion using the same amount of energy. The atomic clock's cesium-133 atom being chilled to absolute zero while the observer's atoms are at room temperature. The fact that actual objects accelerated into space are clearly showing to be accelerated in time. Accelerated heart rates, the solar sail's molecules increasing in temperature. So why the fixation with mass being the actionable force? Because the alternative is Acceleration. And there is already a god of Acceleration in the Bible. F=ma. Force comes from Acceleration of the mass. Not the mass itself. E=mc. Energy comes from Acceleration of the mass. Not the mass itself. Everything is an emergent property of acceleration. Acceleration is the actionable force. Now, explain acceleration. You can't without invoking a god of Acceleration. F=ma. The universe is either an inertial frame (outside force acting on it) or a non-inertial frame (accelerating itself). One requires a god, they other means the universe is an infinite loop. E=mc depicts an infinite universe bounded by light. No beginning of space. Only a beginning and end to the structures contained within. The Information about universe is bounded by c. The distance EM waves can travel before they propagate themselves into the CMB - shorter wavelengths. With tools like the JWST, academia is running out of plausible excuses. It's just that they have so much invested in their flat earth tools and their master craftsman, that they have to keep building using those tools. Imagine having to tell the entire world that Einstein is a fraud. That Newton was a flat earther and didn't take into account Galileo's findings that mass does not attract mass. That it's the Earth's motion that curves space, not it's mass. Relativity is the biggest scandal in the scientific community. And experiments like Hafele-Keating proves it. Nicholas Tesla stood up to these charlatans. Called them out for what they are. Problem is, he never understood why Relativity is mathematical nonsense in order to shut them up. Just like Einstein never understood what clocks are measuring and why clocks in motion run slow. Even though it was he himself that said light travels in its own frame of reference independent of the source. The source's frame has been accelerated but not the photon's. Motion changes the force of light acting on your frame. No need for Special Relativity as all motion can be measured using light as the absolute reference marker. General relativity? As shown by Galileo, mass is not the actionable force. Acceleration is. Mars gravity is the same as Earth's because it has the same acceleration factor. 1480 minutes in a day vs 1440. Every frame is screaming acceleration but they insist upon using mass. The only reason is because it's impossible to explain what acceleration is. What infinity is. What absolute zero is. That's the only reason I can think of why the scientific community is still modeling the universe using mass as the actionable force.
For everyone who keeps saying that "we don't know the one-way speed of light" as someone kind of "gotcha!" (as if it actually matters in this case at all) (and, as if the Compton Edge Experiment hasn't measured the speed of light to be isotropic to within one part in 10⁻¹⁴) (and, you know, Maxwell's Equations, etc.) Here's a really good argument that the speed of light would violate the conservation of energy if it did not propagate at the same velocity in all directions: ua-cam.com/video/tVm2Cvy6UEY/v-deo.html
How is using GR in this case better than using SR? SR: Rindler coordinates--> solution. GR: metric-->geodesic equation-->Rindler coordinates--> solution. Identical results, SR faster. How does using GR help? Can someone please explain this to me?
What solution are you coming up with. That both twins are the same age having experienced the same amount of time. One just experiences more space. Space and Time are separate frames of reference. Light travels in it it's own frame. Independent of the source. The source's frame has been accelerated but not the photon's Example: two cars on a track turning identical laps. One car speeds up. One car is experiencing more space (additional laps) in the same amount of time. Newton's law of motion, F=ma, properly explains the twin paradox. Motion increases the distance the photon has to travel resulting in less force. Less force equals fewer clock cycles. Clocks are instruments that measure motion in space expressed in units of time. Just like rulers measure length expressed in units of inches. Relativity is flat earth science. As Tesla put it, mathematical nonsense. Google really needs to start flagging these content creators for peddling debunked science.
You don't use GR in the traditional TP setup as the Riemann curvature is zero on all components and reduces to the ground state gravitational field of SR.
@@kylelochlann5053 the problem with relativity is that motion is absolute Einstein said as much and then he took it back. Why? Newton's F=ma. Motion is relative because acceleration is not defined. It's unbounded and infinite. E=mc. Motion is absolute. Acceleration is defined, bounded, limited to the speed of light. What is wrong with Newton and Einstein. Newton says the actionable force is acceleration and then back peddled and said mass is the actionable force. Einstein? Said motion is absolute and the backtracked and said it's relative. Same with gravity. First it's an emergent property of acceleration and then says it caused by mass. No wonder you kids are confused and think the earth is a stationary plane. Gravity is the excuse given for why objects fall instead of rise like smoke. So tell us, where is your evidence for mass attraction? I'll go first. Galileo dropped balls of disproportionate mass proving that mass does not attract mass. Nasa followed up with a hammer&feather on the moon. When two objects objects of dissimilar mass fall at the same rate, where is the mass in the equation? It appears when they contact the ground. F=ma becomes ma=F. There is no such thing as gravitational attraction. It's flat earth science. Comprende. SR? Where to even begin. How about 1) light travels in its own frame of reference, independent of its source 2) the speed of light is constant 3) it's the same for all observers 4) is the fastest anything can travel. In space and in time. The laws of physics are equally applicable in ALL frames of reference. That includes the photon's frame. Force decreases with distance. You accelerated the source's frame but not the photon's frame. Why? Why don't you understand what happens when one object speeds up while the other maintains speed? What else do relativists not understand? The clock's cesium-133 atom is being chilled to absolute zero to prevent an acceleration in time event from occurring when a force is applied. Unless the observer is also in cryostasis, they aren't even in the same time frame of reference. There is no time-dilation because clocks are instruments that measure motion I'm space. Not motion in time. Space and Time are separate frames of reference. Relatively is so full of errors, it's impossible to find st least one that invalidates all of relativity. So what's the deal? Why the concerted effort to promote Einstein’s relativity nonsense even though it's been mathematically and experimently disproven exhaustively.
It does not make much sense to use GR. You can use GR if you wish but then you should use a solution to Einstein's eq. without matter that leads to zero curvature of empty space that reduces to SR anyway. Misner-Thorne-Wheeler clearly explain in their book that we construct GR by using SR through the equivalence principle (EP), so it really does not make sense to use GR to solve a special relativistic problem. Of course, if you get sophisticated, you can say the EP is wrong, but I am talking about the heuristic construction of the theory which is very important to understand the "physics" and not merely the math and the strict logical structure.
@@justopastorlambare2933 I don't understand you logic. It's just circular and goes no where. Which is why Nicholas Tesla labeled relativity mathematical nonsense. Galileo proved that the mass is not an actionable force. You flat earthers dismissed it as a thought experiment. Gravity/mass attraction is required to keep objects from floating off into space on a stationary plane. Fast forward to the moon landings and the hammer&feather drop tests. Same thing. Gravity/mass attraction is required to explain why objects don't float off into space on a stationary plane. Only this time you created the lame excuse that is EP. The equivalence principle. Really flat earther. Do you not understand Newton's simple equation, F=ma. Mass TIMES Acceleration? Acceleration is the actionable force. Not mass. How about I show you how even more ignorant you flat earthers are. F=ma. Mass AND Acceleration. Two SEPARATE frames of reference. Space AND TIME. So why do you think it's spacetime? Because your god Einstein told you so? Shall I continue? F=ma. Neither mass nor acceleration are defined. They are unbounded, infinite. Motion is therefore relative. E=mc. Acceleration is now defined, limited, bounded by the speed of light. Motion is Absolute. Didn't Einstein himself say the motion is absolute. That nothing could travel faster than light. That it travels in its own frame of reference, independent of its source. And is the same for all observers. Sounds like light is an absolute reference marker in which to measure all other motion against. So why the relativity nonsense Einstein. Newton says Force comes from Acceleration not mass. Why are you still stuck on stupid with your flat earth science? Light travels through space IN ITS OWN FRAME OF REFERENCE. What is the equation for motion, F=ma? So why aren't you using Newton's law of motion to explain the Twin Paradox flat earther? I'll help you along. Two cars on the track turning identical laps. One speeds up. The observation, the lead car is experiencing more space (laps) in the same amount of time. There. Resolved once and for all. Both twins are the same age. One just experienced more space is all. Have a nice day.
The twin paradox is rigorously solved in this tutorial, with a realistic acceleration, from both points of view of the traveler and the stay-at-home twin: ua-cam.com/video/QFWF90bch3c/v-deo.html
I don't get why people don't get this. If two people are going different velocities, then the one that will be younger is the one that decides to change to the other's velocity. The actual definition of how much time passes is based on reference frame.
The _actual_ "paradox" (it's not really a paradox) is determining _who turns around_ i.e. what breaks the symmetry if each twin can consider themselves to be (inertial) standing still... and the solution is that is that two straight lines will only intersect once in flat manifold, so at least one twin can not be in the same inertial reference frame forever, or the twins will never be reunited. Gravity throws a curve in this, because you can have straight lines intersect at more than one point, but that's another story.
The Twin Paradox with realistic acceleration is rigorously solved in this tutorial: ua-cam.com/video/QFWF90bch3c/v-deo.html General Relativity is not required, as Special Relativity is perfectly capable of dealing with accelerated frames of reference, as proven in the tutorial.
In special relativity time is simply added to the distance function with a negative sign. s²=-ct²+x²+y²+z². This calculates the "spacetime interval", which has to be the same for all observers. In _general_ relativity all these germs are multiplied by the "metric", which can be a function of time and space.
@@narfwhals7843 so, I'm guessing you have some kind of quaternion cubic polynomial, the function uses the roots of that and can be expressed with 'e'. 'i' and 'j' are there i*j=-k. We don't need k, but it makes it look nicer. [-t, f(t)], where f(t) returns the three imaginary numbers. So, with polar curves, we integrate, then differentiate to get the arc length. -t -> -1. But we gotta square it anyway. Never mind, this isn't my deal. I'll leave it to the freaky autistic people. I'm probably a little autistic, but not autistic enough for this.
Bro is Length contraction Really An effect of superposition or Quantum wave mechanics ?As Dialect proposed in his interpretation of Relativity and Length contraction can You make a video about it
Hi, yes you can get a length contraction from classical mechanics. I am currently making a video about how you can get a special relativity purely from classical series of mechanical pendula
I don't think it's correct to say SR doesn't tell you which frame is accelerating. Because it says "The laws of physics are the same in all inertial reference frames". And the laws of physics tell you which frame is accelerating. If we use Newton's Laws for the Laws of Physics, the first Law tells us which objects are accelerating. It's basically the statement that inertial bodies follow geodesics. We can modify the laws to be relativistic, but that doesn't change the result. Acceleration, even in SR, is defined relative to geodesics. Whether or not that is entirely internally consistent is another matter and subject to much debate(see Mach's principle etc.) The point is that the "laws of physics" should provide a way to determine acceleration. GR gives us a more refined way to calculate geodesics, but that doesn't really change anything about the principle. Invoking the equivalence principle seems circular. You either have to already know that clocks tick faster ahead of an accelerated observer, which is a result purely from SR, or know all results from GR, which uses SR locally. And this has nothing to do with "gravitational time dilation", because there is simply no gravity there. A local measurement simply has nothing to do with gravity exactly by the equivalence principle. We shouldn't expect SR to reproduce gravitational effects. The time dilation between the earth twin and the rocket twin is in no way equivalent to gravitational time dilation because it is not a local effect.
yes if we take the special principle of relativity then the laws of physics determine who is inertial and we can therefore calculate everything. Acceleration is absolute and no paradox. The paradox can be restored if we take the general principle of relativity which states that the laws of physics are the same in all frames of reference. Then we have to use equivalence principle. So yes, STR as it is formulated has no paradox. I don't fully understand this statement though. "And this has nothing to do with "gravitational time dilation", because there is simply no gravity there. A local measurement simply has nothing to do with gravity exactly by the equivalence principle." As far as I understand equivalence principle tells us that we can treat inertial forces as gravitational.
@@lukasrafajpps I think what he means to say is that true gravitational time dilation has a derivative for the gradient instead of the gradient alone. For example, if an observer floating in space has two clocks on his head ticking at the same rate, a person in an upward-accelerating elevator might see the clocks on both ends ticking at different rates, but because he is in free-fall (geodesic), he doesn't see any deviation. It's an apparent effect. In the true gravity case, two satellites in free-fall around the Earth, separated by a large distance, still experience different amounts of time due to curvature, which also causes tidal forces.
@@lukasrafajpps "Gravity", if you're interested in involving General Relativity, means spacetime curvature. A "gravitational force" is an inertial force resulting from being in an accelerated reference frame. These are different things. Gravitational Time Dilation is a spacetime curvature effect. There is no spacetime curvature in the twin paradox. The time dilation the accelerating twin observes has _nothing_ to do with spacetime curvature, but is an effect from from curved _coordinates_ (Rindler) in flat Minkowski Space. The fact that it is a globally uniform effect tells us that there is no curvature. The gravitational force we observe close to the surface of earth is _entirely_ explained by being in an accelerated reference frame. In GR that isn't an "equivalence" but an equality. The surface of earth is factually accelerating outward. But this is a _local_ effect. To see the difference, consider the Pound-Rebka experiment as an example. The redshift is calculated using local earth acceleration g. The surface gravity. But the gravitational time dilation at the surface of earth, compared to a distant observe, is not related to the surface gravity but to the local escape velocity. A different planet, with the same surface gravity but a different escape velocity, due to different size and density, would reproduce the local redshift(assuming we didn't introduce large tidal forces to the experiment), but have a different gravitational time dilation. We don't have to _use_ the equivalence principle to give us predictions. Because it doesn't tell us what the connections are. It doesn't explain anything. We have to _satisfy_ it in our formulation of the laws of physics. GR does this by using a covariant formulation that always includes a spot for inertial forces, the Christoffel Symbols. The Christoffel Symbols in Rindler coordinates will have non-zero components, showing the time dilation in the direction of acceleration, because they are curved (so do simple polar coordinates on a flat plane), that does not indicate spacetime curvature, as the Riemann Tensor is still zero. The Christoffel Symbols can indicate both, curved coordinates, and/or spacetime curvature.
No, the laws of physics don't tell you shit. As in, the parameters of those laws don't change. You're just rambling in discourse space to make it “sound right” rather than anything mathematically trackable.
While relativity comes down to making good predictions for what instruments will verifiably record, and so no evidence has yet contradicted it, it’s outside these cases of verifiability that I take issue. The paradox is not what will happen when we verify what will happen (upon the twins return), but rather, what is happening at a distance. When the twins are traveling apart or towards each other before the return, who is aging less. Under the relativistic model, Depending on who you ask and their frame of reference, all aging possibilities are happening simultaneously. Both twins are aging less, more AND not at all relative to the other, and by varying degrees on a continuum. This to me points to a model error.
When two people walk away from each other, each person will see the other person appear to be smaller as they get further away from each other... but each person stays the same size, yet the other person sees them shrink. How is it possible for things to look smaller when they are further away?
@CausalDiscoveries The point is, that it's the same model that you're objecting to. Alice and Bob travel away from each other at a high velocity. From Alice's clock, Bob's clock will appear to be running slow. And from Bob's clock, Alice's clock will appear to be running slower. This isn't a problem.
@CausalDiscoveries Neither. Every inertial observer will *_always_* be at rest with respect to themselves, and *_always_* measure one hour per hour, one minute per minute, and one second per second on their own "proper time" clock. Always. Space and time are the same thing. Every location in space is also a location in time. No two things are ever "at the same time" unless they are "at the same place". Every point in space is located in the past of every other point in space. Both ways, symmetricly. Your feet are located about six nanoseconds in the past from your head, and your head is located about six nanoseconds in the past from your feet. When you look with your eyes at what is a straight line, radially from the tip of your nose to the _visible_ edge of the universe, you are looking down a 45° line on a Minkowski diagram. (In General Relativity, it's a geodesic path.) What you see "right now" is the past. That's "time", it's the radius of a 3D sphere in Cartesian space. Using complex numbers is a clever math trick for translating between points that are located "in each other's past"... because velocity (space/time) is a rotation angle. (Complex Numbers are rotations.) Oh, I should mention, just like you get a stack of 2D circles by slicing a 3D cone. You get a stack of 3D spheres by slicing a 4D hypercone. Hence the name "Light Cone" for the present moment of "things happening *_right now_* ". If you rotate the slicing plane through the cone, you get ellipses, parabola, and hyperbolas... which is "velocity" - a rotation of the slicing angle - a ratio of a space coordinate to a time coordinate. This is literally the math for Special Relativity. Anyway, the thing about the so-called "Twin Paradox" is that each twin is traveling along a different path _through space_ *AND* a different path *_through time_* If Alice and Bob live in the same house, and Alice walks 5km to the store, while Bob walks 4km to the post office, and then 3km to meet Alice at the store. Then Bob measures 7km of space to have passed, but Alice only measured 5km of space to have happened between when she last interacted with Bob. You don't find that confusing? The twins also traveled a different distance in time. You don't notice planes of simultinaity (3D slices of a 4D light cone) rotating very much at the human scale on Earth, with the senses of the human body. So, most discussions of this use _relative_ velocities a significant fraction of the speed of light to make the effects obvious. Personally, for me, they way that I would explain why one twin is younger than the other after taking two different paths though 4D spacetime between two different points in 4D spacetime (departure and reunion) is that (in the basic setup) the younger twin turned around in the past of the older twin. Because that distant (in space) turn around location is located in the past of the older twin. Remember: "right now", that is "zero time", is defined by the speed of light (the surface of a light cone). There are only two absolute velocities in Special Relativity: zero, for anything with inertia (mass), and the speed of light relative to zero "inertial" velocity. That's it. What you should ask yourself is: "Why does anything travel _slower_ than light?"
Hi…the person that is in the ship accelerating does not feel an uniform acceleration…it’s shown in the Rindler diagram,,everypoint in space has a different hyperbola that describes a different acceleration..
HI, what I was saying it’s that the accelerating twin does feel a different acceleratiion in the front of his ship compared to the back of the ship,,,, in the first part of his journey..
Só acceleration is not relative then? If an observer B is accelerating away from A then this is an absolute universal fact and B will not assume A is in fact accelerating away from him? So not all frames of reference are equally valid?
"proper" acceleration is absolute. If A and B have accelerometers, and one of them is experiencing a "force", it will be a universal fact which one of the accelerometers will measure an acceleration. This still leaves either frame equally valid, but not equal. The principle of special relativity only applies to the one who is not accelerating. The accelerating one will need to use different laws of physics (include inertial forces, etc). In General Relativity things get more interesting. In curved spacetime two observers can accelerate relative to each other without either accelerometer measuring anything. The principle of general relativity applies to _all_ observers and they can all use the laws of physics as formulated by General Relativity. The possibility of inertial forces is included by default in the formulation of these.
_"So not all frames of reference are equally valid?"_ - correct. Frames that accelerate differ from frames that don't; the physics laws are different. In accelerated frames there is a mystical pseudo force that pulls everything to one side.
Out of curiosity, though I completely understand the physical manifestation of the measurements, of two Reference frams. What is occurring in the space of two different frames. Ie. At the quantum level, what is occurring in the interactions, especially in different gradients of a gravitational field. Ie not simply the passage of time but the physical mechanics of the gradient in time dilation. Like... Is there an adjustment (phase change) to renormalization. I'm curious if there is research on the subject that you may provide links too.
@@kylelochlann5053 it does only for gravitatational time dilation, for motional time dilation and synchronization of clocks, it uses galileian equations where speed of light is not a constant. Why?
Equivalence and Acceleration doesn't solve it though... assume the acceleration of your engines goes from 0g to Xg; your computed time dilation would then be a square wave from 1 to whatever dilation that gravitational acceleration gives you, and then back. That's a simple sum doesn't even really require calculus... but whatever that is, you could change the length of the trip such that that does not match the same total dilation that happened. (did you even attempt the math?) The postulates of special relativity should be refined to say 'the speed of light that travels the same distance in two-ways'. Second - the postulate that all physics is the same in all frames is an assumption that cannot be proven... it's also hard to falsify at our current level of technology though. Parker solar probe is only 191km/s - which is 1/2 of our speed through the universe, though I suppose the additive velocity might at times be 1.5x our speed... that's still a small fraction of the speed of light, I suppose they should include a particle accelerator and muon detector on the next parker-space-probe-like craft... and measure a different anomalous G-2 result.... the difference between experiment and measurement is 0.012%... this is exactly the fraction of the speed of light that the solar system is moving in the universe. (Is physics REALLY the same in all frames?)
Which is actually not to say that the laws of physics aren't the same in all frames..... But they would have to include the time dilation of the frame that they're in and/or speed... Then they would end up being the same donatos we currently have them define
The original paradox addressed by Einstein is not about twins aging at different rates after one of them started a journey from Earth at high speed and returned back years later. It's about identical clocks ticking at different rates when moving relative to each other according to special relativity. For clock A clock B is ticking faster. For click B clock A is ticking faster. That is the original paradox which could be called "the identical clock paradox". And it was solved by Einstein by addressing it as a problem of simultaneity of events, not by using gravity or accelerated frames of reference. You mention you cannot write the same spacetime diagram for the travelling observer because it only applies for inertial observers but as far as I can see the travelling observer is also inertial, i.e. not accelerating. That's unclear to me.
Its sad that Don Lincoln tries to defend the validity of his argument, when clearly he is only partially correct and his argument is shoddy science because he tries to use authority to argue science rather than logic. "Im an authority so accept my argument as correct-just cause im me, dont worry about it dont question other aspects and viewpoints just forget about it" That seems to be the tone of his exposition. Then he makes a follow up video saying basically, whatever critiscism they have on me, basically Im still right --if you squint your eyes and dont look directli at my presentation. The point of something like this and other's criticism of his presentation is to spark debate on a subject thats many faceted--as witnessed by the many examples that exist supporting different viewpoints. In some acceleration is important and in others not. Dons too worried about the promotion of his video rather than about science---and that is deeply dangerous!
Shut up and calculate. That was the essence of Sabine's video. I don't know if these people are dumb, or just playing dumb. Space and Time are separate frames of reference. Light travels in its own frame of reference. Independent of its source. The source's frame has been accelerated but not the photon's. You have to be a complete moron (Albert Einstein) to not understand why the moving clock is slower. The clocks cesium-133 atom is being chilled to absolute zero. Are the observers atoms also being frozen? The observer is not even in the same time frame of reference as the clock. Once again. Space and Time are separate frames of reference. Clocks measure motion in space expressed in units of time. They are not measuring time. They are measuring distance traveled in space. And as for Einstein’s relativity. SR is Newton's non-inertial frame where the mass is accelerating itself. Walking down the street, the mass is accelerating itself. GR? Inertial frame, conservation of energy. The mass is being accelerated by an outside force. Gravity is an artifact of that Inertial frame. The resistance of the mass to being accelerated. Standing on the ground, the earth is accelerating you and you are accelerating the mass of air above you. Which is why you get lighter as altitude increases. There is less mass above you, pushing back. The traveling twin? E=mc where c is the maximum acceleration of the mass or the person's lifespan. Since there is no data on E for the observers, we can only go by the clocks energy usage. Since both clocks used the same amount of energy, both twins experience the same amount of time. One just experiences more space - distance traveled. Relativity is a scam. Einstein was a dimwitted plagiarizing patent clerk who didn't understand what he was stealing. Of course his minions are going to defend him and leave out information. Like astronaut's heart rates being in an accelerated state during lift-off (high g-forces). Or that clocks in motion use the same amount if energy as stationary clocks - space and time are separate frames of reference. F=G(m1m2)/R2. The universe is gravitationally bound to Earth's frame of reference. These clowns actually think the universe revolves around the earth. Which is a stationary frame. So what are you going to do about it? The scientific community is either lying to you are complete idiots. As Carl Sagan would say, both possibilities are equally frightening.
I enjoy your presentations, but I have to disagree vehemently with this one. I believe that you have things exactly backwards when it comes to the Equivalence Principle. The way that you (and very many popular explainers of General Relativity) describe it is this way: To calculate the effect of acceleration on clocks: 1. We invoke the Equivalence Principle, and transform the problem into an equivalent problem involving gravity. 2. The feeling of acceleration is interpreted as a kind of gravitational field that suddenly turns on. 3. We use gravitational time dilation to calculate the effect of this gravitational field on clocks. Okay. What's wrong with this description? Well, ask yourself how gravitational time dilation is computed. The answer is exactly the reverse process. To calculate the effect of gravity on clocks: 1. We invoke the equivalence principle to transform it into an equivalent problem involving acceleration. 2. The gravitational field is then interpreted as the inertial forces that result from acceleration. 3. We use special relativity to calculate the effect of this acceleration on clocks. The latter description is the way that Einstein DERIVED gravitational time dilation. By applying Special Relativity to accelerated clocks. To quote WIkipedia: Gravitational time dilation was first described by Albert Einstein in 1907 as a consequence of special relativity in accelerated frames of reference. This was 8 years BEFORE he developed a theory of gravity. So you've got things exactly backwards. Einstein didn't use the equivalence principle as a way to apply gravitational theory to accelerated observers---he used the theory of accelerated observers (as described using Special Relativity) as a tool for developing his theory of gravity. You don't need the equivalence principle to calculate the effect of acceleration on clocks. You need the equivalence principle to calculate the effect of gravity on clocks. The equivalence principle allowed him to reduce an unsolved problem---how does the Earth's gravitational field affect clocks--to a solved problem--how does acceleration affect clocks. This is a confusion that has persisted in physics ever since Special Relativity. Even Einstein took some time to get it straight. Many people think that Special Relativity is a theory of inertial observers, and General Relativity is a theory of noninertial observers. That is completely wrong. Special Relativity is a theory of FLAT spacetime, while General Relativity is a theory of CURVED spacetime. You can handle accelerated observers in Special Relativity in exactly the same way that Newtonian physics can handle accelerated or rotating observers. It's just a change of coordinate system. Newtonian physics is usually presented using inertial Cartesian coordinates. Newton's laws look the simplest in those coordinates. But if you really want to, you can rewrite them using curvilinear or accelerated coordinate systems. It's just calculus---if you know equations of motion in one coordinate system, then you can use calculus to figure out the equations of motion in another coordinate system. But things are messier in curvilinear or accelerated coordinate systems. In those coordinates, there are apparent "fictitious forces" that have no physical cause, but are just artifacts of your choice of coordinate system. These include (1) the "g-forces" that you feel when you are accelerating, (2) the centrifugal force that is felt when one is traveling in circular motion, (3) the Coriolis force that is felt when you move in a rotating coordinate system. These forces are "fictitious" in that they don't actually result from interactions with matter or fields, but they are extra mathematical terms that appear in the equations of motion. Newtonian physics works perfectly well in non-inertial, curvilinear coordinates, it's just a little more complicated looking. In exactly the same way, Special Relativity works perfectly well in non-inertial, curvilinear coordinates, as well. It's just more complicated looking. If you try to apply Special Relativity to accelerated observers, or to use it with curvilinear coordinates, you get "fictitious" forces in the same way that Newtonian physics does. These fictitious forces in Special Relativity do not only affect the motion of objects (in the way the Centrifugal and Coriolis forces do) but also it affects clocks. This is not a new effect that requires General Relativity for justification--it is an effect that is derivable from Special Relativity by just using calculus to change coordinates. The connection between General Relativity and curvilinear, noninertial coordinates is that in the presence of gravity, there ARE no inertial coordinate systems. So curvilinear and noninertial coordinates are required to do anything. And those coordinates have effects on the motions of objects and on the elapsed time on clocks, just as they do in Special Relativity. So there's three different stages in going from Special Relativity to General Relativity: 1. Special Relativity in flat spacetime using inertial, Cartesian coordinates. 2. Special Relativity in flat spacetime using noninertial, curvilinear coordinates. 3. General Relativity in curved spacetime using noninertial, curvilinear coordinates. 4. A theory of how matter and energy cause spacetime curvature. Going from 1 to 2 doesn't require a theory of gravity, it only requires calculus. Going from 2 to 3 requires a theory of curved spacetime, which is also not fully a theory of gravity. You need 4 to get a full theory of gravity.
You do know that Nicholas Tesla labeled relativity as mathematical nonsense and your posting proves it as such. Relativity stems from a lack of not understanding Newton's Laws of motion. But that's okay. Newton himself didn't understand them which is why he developed his gravitational attraction nonsense. First Law. An inertial frame is one that gets its acceleration from an outside force. You riding the bus is an inertial frame. A non-inertial frame is one that accelerates itself. You walking forward on the moving bus is a non-inertial frame. 2nd law. F=ma. Force TIMES Acceleration. Force comes from Acceleration of the mass. Not the mass itself. There is no gravitational attraction because mass is not the actionable force. 3rd Law. Action and Reaction. Gravity/g-force is a Reactionary force. The resistance of the mass to being accelerated by an external force. Rubbing two sticks together creates resistance. That resistance is 'gravity' according to Newton's laws of motion. The Equivalence principle states that gravity and Acceleration are equivalent. What it fails to say is that acceleration creates gravity. Newton's Reactionary force. That's why Einstein labeled gravity a 'fictitious' force. It's an effect. The Equivalence principle as it relates to Energy. Mass and Energy are interchangeable stems from Energy can be neither created nor destroyed, only transformed. E=mc where mass is a form of energy that is transformed via Acceleration. What Einstein didn't understand concerning his relativity theories is that motion is absolute. Nothing can travel faster than light = motion is absolute. Light travels in its own frame of reference = motion is absolute to the frame of reference. What Einstein didn't understand is that Space and Time are separate frames of reference. The earth rotating on its axis as it orbits the sun is motion in space. The energy being emitted by the sun is what accelerates plants in Time. Southern trees have higher growth growth rates than northern trees because of the differences in sunlight. Tree ring patterns change from year to year because of changes in weather. A tree doesn't grow faster or slower because of some 'fictitious' force. It accumulates mass based on energy. E=mc. So what is going on with atomic clocks. Why one is slower than the other. First. The cesium-133 atom is being chilled to absolute zero. This takes out any Acceleration/oscillation the atom has. It is then accelerated to the proper frequency for its location by an electrical current. Electromagnetic waves travel in there own frame of reference, independent of the source. That's two frames of the reference. The source frame and photon's frame. The clock's frame has been accelerated but not the photon's. Applying Newton's Laws of motion, the inverse square law of motion, the photon's force decreases with distance. Clocks measure motion in space expressed in units of time. Any 'time-dilation' taking place is strictly in the clocks frame of reference which is translated into increased motion in space. Clocks in motion use the same amount of energy as stationary clocks showing that they both experienced the same amount of time. One just experiences more space. The observer is not in the same Time frame of reference as their atoms/cells get their Acceleration/Energy from a different form. Relativity = pseudo-science = mathematical nonsense. Astronaut's have ACCELERATED heart rates in a high g-force environment. The clock is slowing down because the photon has a greater distance to travel while the Astronaut's heart rate is increasing because more force is being applied and resisted. Same as rubbing two sticks together. Gravity = Reactionary Force. Relativity = pseudo-science = mathematical nonsense. Motion is absolute to the frame of reference. An accelerated heart rate does not equal a longer lifespan.
@@stewiesaidthat : Your explanation here does not make much sense to me. First point: You wrote: F=ma. Force TIMES Acceleration. Force comes from Acceleration of the mass. Not the mass itself. There is no gravitational attraction because mass is not the actionable force. I can't make sense of that. The way that Newton understood it was that force was a CAUSE of acceleration. If you pull or push on an object, it will accelerate. The mass determines how much acceleration is caused by a given force. If the mass is small, then the same force produces a larger acceleration. If the mass is large, then the same force produces a smaller acceleration. You can see this by trying to push an automobile. It doesn't accelerate very much. Saying "mass is not the actionable force" doesn't make any sense to me. Mass is not a force. It is a measure of how much stuff--electrons, neutrons, protons, etc.--are in an object. Saying that there is no gravitational attraction is just completely wrong. Take a ball. Let go. It falls to the ground. That's gravitational attraction at work. You wrote: "The Equivalence principle states that gravity and Acceleration are equivalent. What it fails to say is that acceleration creates gravity. Newton's Reactionary force." That's not correct. Acceleration does not produce gravity. If by "gravity" you mean the tendency of massive objects such as a rock to be attracted to another massive object such as the Earth, that is not produced by acceleration. Even if nothing is accelerating, there will be that force.
To go on: You wrote: "The Equivalence principle as it relates to Energy. Mass and Energy are interchangeable" That's completely wrong. The equivalence principle is not about matter and energy being interchangeable. It's specifically about gravity. The equivalence of matter and energy was a consequence of Special Relativity, which doesn't have gravity at all. The word "equivalence" appears in both, but they're not the same principle. One relates gravity with fictitious forces. One relates matter and energy. Two different principles.
First of all - too many words and sideways explanations before explanation. OK, let say that one twin gets older. What happens when they meet again in the same space time? If I turn really fast can I meet my older self?
I do not really agree with the premise of this video, and by now we should not be calling these things paradoxes 100 years later, rather than early confusion for a few years when smart people were making sure the theory was consistent. If you had two twins A & B and B left for a trip, the video argues you need to define one (A in this case) as the base inertial frame and you need that knowledge. But that is not correct. Imagine B did leave for the trip, but they then instantly forgot who left and who stayed. if they forgot who left and A thought they had left, and then A "turned around (for want of a better description)" and went back to B (which is really just a huge acceleration given B will never stop), the result will be the same, but in reverse. It is simply wrong to imply you need to know the starting inertial frame.
The variables in gravity math are NOT causal. Number analogies are not an understanding, and that math can lie to you. "The wheels on the bus go round and round." This song describes everything you see a bus do EXACTLY like math does, but you wouldn't agree that wheels going round are causal - WOULD YOU? Dimensions are a number game that helps math work, but you cannot show me dimensions 1 or 2 in real life, and you have a series of theories that ADJUST these fake dimensions. What if that math is lying to you? It's the only thing taught to anyone. Even if it was obviously wrong, in these conditions, you wouldn't see it, because that's how paradigms work.
Great video. I was with you until you said you have no tools in SR to interpret the force, but that's not true: they will see a change in red/blue shift. You can actually watch the changes in all clocks around you via light. The trick with the accelerometer is that it only works when you fire your engine, or stand on the ground pushing you up in a gravitational field. If the whole accelerometer (springs and all) are accelerated uniformly, it won't tell you anything. But light... ligt will tell you the whole picture.
Light is subject to gravity. A laser accelerometer will show the same results in a local part of the gravitational field. And neither will show any proper acceleration in free fall.
_"you have no tools in SR to interpret the force"_ - he meant, you have no tools to distinguish between acceleration by a rocket engine, and standing on the surface of a planet. _"they will see a change in red/blue shift"_ - they will see the same red/blue shift in the light, so that does not distinguish them either. Light appears to blue-shift when traveling down a gravitational field.
@@renedekker9806 Light "traveling down a gravitational field" is both red-shifted and blue-shifted, depending upon the observer, e.g. Lemaitre and shell observers, respectively.
@@kylelochlann5053 _"Light "traveling down a gravitational field" is both red-shifted and blue-shifted"_ - ok, I should probably have phrased that more precisely. For light received by a stationary observer lower in a gravitational field, which comes from a stationary light source higher in the gravitational field, the received frequency will be blue-shifted wrt. the source frequency. If that gravitational field can be considered to be a uniform field, then that frequency shift will be the same as in a similar accelerated frame. Or the point in short: you cannot use light to distinguish between a uniform gravitational field and an accelerated reference frame.
Yes, the Twin Paradox requires acceleration and here's why: The Triplet example gives the same elapsed times as the Twin Paradox when you sum the elapsed time on B's clock from B departing A to where it is coincident with C, and the elapsed time on C's clock from when C meets B to its arrival at A. However, if for the sake of argument B and C's clocks are synchronized when B leaves A, B and C's clocks will not agree when they meet up; The time on B's clock will be further ahead than C's. This is due to the Relativity of Simultaneity when the clocks were synchronized. Now consider the scenario where B reverses direction, i.e. undergoes an acceleration, so that it too returns to A, alongside C, so they arrive back at A together (i.e. the Triplet example returns to the Twin Paradox, where A and B are the twins),. Remembering that the Triplet and Twin Paradox scenarios give the same result, and that B's clock was ahead of C's, B's clock must slow to match C's clock before they both arrive at A together. If this wan't the case B and C would disagree on A's age when they all meet up. An explanation of how this slowing down of B's clock occurs is gravitational time dilation given by General Relativity. But just to confuse things further, you can also calculate the slowing of B's clock using Special Relativity alone with Rindler coordinates or if B reverses instantaneously when B and C meet, with the simple Lorentz transformations in a flat, Minkowski spacetime.
1) Space and Time are separate frames of reference 2) Clocks are instruments that measure motion in space 3) the clocks cesium-133 atom is being chilled to absolute zero while the observer's are at room temperature. 4) the clock is being energized by an electrical current emiited at a constant frequency. The observer's cells get their energy from the oxygen in the environment. 5) Both clocks use the same amount of energy. The difference in readouts is due to the extra motion in space. Clocks measure motion in space. 5) astronauts experience accelerated heart rates during lift-off while the onboard clock is registering fewer clock cycles. Space and Time are separate frames of reference. Acceleration in time is energy dependent. Since the biometrics are not included, the only logical conclusion is that both twins experienced the same amount of time, and are the same age. One just experienced more space.
I am afraid there is a very important conceptual mistake in the explanation. It is definitely not correct to say that in special relativity (SR) every observer is inertial by definition. SR is not a relationist theory, i.e., motion is not merely relative but Newton's absolute space reigns. The accelerometer absolutely tells you if you are inertial or not. Newton's absolute space is also present in special relativity (even in GR). Inertial frames are those where the principle of inertia holds and that does not happen in arbitrary frames. Another way to define inertial frame is (according to, for instance, Landau & Lifshitz) that time is homogenous and space is homogenous and isotropic. Those properties of spacetime do not hold in non-inertial frames. The author (who I used to follow and admire) should discuss this issue with an expert and see if he can correct his presentation.
The laws of physics are equally applicable in ALL frames of reference. That rules out a Special and General law right there. Need I go further? Gravity/mass attraction is not a fundamental force of nature. F=ma. Force comes from Acceleration of the mass not the mass itself. Comprende. E=mc where c is the speed of light. Acceleration is defined, bounded, limited. Motion is absolute. There is no Relativity when you have absolutes. Speed is distance/time. Two separate frames of reference. Motion in space is independent of that in time. So much for that spacetime nonsense. What is truly inconceivable is that not a single experiment. Not a single equation, shows that mass is an actionable force. There is no evidence to support Einstein’s fantasy universe and yet it's preached as gospel. Why? Galileo proved experimentaly that mass is not an actionable force. Newton provided the math. F=ma, Force comes from Acceleration. Einstein himself said that gravity was a fictitious force and that acceleration was the frame of reference. Then Newton and Einstein tool it back. Reversed course and have force back to mass. Why? F=ma. Force equals Acceleration equals Acceleration equals Acceleration. Get the picture? If Acceleration is the fundamental force of nature, what is Acceleration. Where did it come from. E=mc. Who turned on the lights. E=mc. Acceleration creates mass. What is Acceleration then. Do you think a dimwitted patent clerk like Einstein could answer that question when he didn't even understand that Space and time are separate frames of reference. That clocks measure motion in space. That light travels in its own frame of reference, independent of its source. That the source's frame has been accelerated but not the photon's. Do you honestly expect a plagiarist who didn't understand what he was stealing to be able to answer the ultimate question. Where does Acceleration come from? Right back to the passage in the Bible. And God said, let there be light. And out of the darkness, the universe was created. That's why these idiots back tracked on Acceleration being the fundamental force of nature and not mass. Acceleration requires an outside force to set everything in motion. What is that outside force? Is anything even real if all there exists is Acceleration. F=ma -> E=mc. Out of nothing, absolute zero, complete darkness, you now have something. Explain that Einstein. How do you get something from nothing? E=mc. Only Acceleration is defined. Bounded, limited, Absolute. Mass/space is undefined, boundless, infinite. You can't warp space because Space doesn't exist. It hasn't been defined, bounded. You can only warp Acceleration. Now, do you think a couple of simpletons like Newton and Einstein could understand what Acceleration is? It all leads back to one thing. An outside force acting on this universe. A god of Acceleration so to speak. Can't have that in science. There must be some other explanation. But they themselves invoke a god with the BB theory. Out of nothing something is created. They just theorize that space and time are created in concert while E=mc shows that only Time was created at the moment of the BB. Space is infinite. It's time (information about the infinite universe) that is expanding. And that is what Acceleration is. What light is. Information. You are back to two possibilities. There is a god or nothing is real. Virtual reality. A computer simulation. The Matrix for a movie reference.
@@stewiesaidthat You really did not need to go further after your second sentence. This website might also be interesting insti.physics.sunysb.edu/~siegel/quack.html
@@justopastorlambare2933 I know. That's the problem with modern physics. They don't want to go any further than their flat earth view of the universe. Where does Acceleration as the frame of reference take them? Is anything real? To them, Acceleration is not real. Only mass is real. You can touch it, taste it smell it and even see it. But that is all just information. How do you know that information depicts reality and not a virtual world. Just as your ancestors created a god to separate man from beast, there also needs to be a 'god' to separate real from virtual. Acceleration is beyond physics. Is mankind ready to go there? Why else would they create a god in Einstein? First he says motion is absolute and then it's relative. Next he says gravity is an emergent property of Acceleration and then says mass creates Acceleration. Newton. Same thing. Acceleration takes them out of the matrix and into a new reality. What is that new reality?
Omg STR is about inertial motion only! That is why STR has always had a twin paradox and was rightly considered as nonsense. Don’t believe me then read Einstein’s paper from 1918. He was force to give a solution to this from all the criticism he got and he used GTR. Basically this means he is abandoning STR. You need to look at the history. Try “Relativity from Lorentz to Einstein: A guide for beginners, perplexed and experimental scientists” Lots of references to relevant literature. Here are some others, “Science at the crossroads” by Herbert Dingle, “A scientific adventure. Reflection on the riddles of relativity” by Ian McCausland and the recent “New Relativity in the Gravitational Universe” by C S Unnikrishnan. Another is Tim Maudlin’s “The Philosophy of Physics. Space and Time” where he also says that acceleration does not solve the twins paradox but gives his solution … which also doesn’t work😂
That's just not correct. Special Relativity works for accelerated frames, as is mentioned in the video. It just doesn't extend the principle of relativity to them. They need to use different laws of physics. What Special Relativity doesn't deal with is gravity. But there is no gravity in the twin paradox.
@@narfwhals7843 I will make it more clear. Well if you want to rewrite the theory so dilation is caused by acceleration and not speed then go ahead. But it isn’t STR.
@@markszlazak I don't want to do that. Time dilation is not caused by acceleration. But special relativity has no problem dealing with acceleration. That has nothing to do with history. These are facts of the theory.
There is no twin paradox because they are always the same age in a flat space without gravity. It's just an observer illusion, and is not real. The time period is the same on both ships.
It is not an illusion. Two clocks that get separated and returned together will not necessarily read the same elapsed time. This is experimentally verified.
a signal travelling a longer distance doesn't mean time is slowing down.. its ridiculous. And speaking of paradox. If you and light are travelling in the same direction and your accelerating and your time slows down it keeps the soeed of light c, but if light is coming towards you and you are moving towards the light accelerating or not , your time slows down meaning its no longer c, its much faster the speed of ç. It only works when you and light are travelling in the same direction, relativity is pure imagination and not true
The speed of light is not constant for accelerated observers. Only for inertial ones. "Time slows down" is basically a meaningless statement. It just means that observers in relative motion have different ideas of what time should mean.
@@dexter8705 It's all just an observer illusion. The time intervals do not change in speed for any object, only the appearance of from a distance. What I just said goes against popular interpretation where everyone whats to believe in SciFi time travel. Light clocks are a flawed concept. The ships (different observers) are not the same thing as the photons traveling between the ships. Observers see/view photons, not another ship/object moving at velocity. Both different objects photons and ships. > P.S. Working from the possibly flawed concepts of relativity.
Have you heard of the channel: @ChrisTheBrain ? He has some really interesting videos about physics, but I can't tell whether or not they're nonsense. I'd be curious to hear the opinion of someone more knowledgeable
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Hello, Lukas. What do you think about counterexample to length contraction in 1-page article: Do Planets, Flattened in Special Relativity, Wobble?
Really appreciated two things about this video: 1) Your clarification that SR treats inertial frames as given - something you’re likely to get pushback on from commenters (as we once did) but about which you’re absolutely correct. 2) Your noting that proper acceleration as a solution doesn’t generalize to GR - something almost everyone who treats on the topic of the twin paradox overlooks.
In our long study of the twin paradox, we learned that, within the context of the current theories of relativity, there is only one “resolution” to who is younger - and that is whichever twin traveled the shorter spacetime path. In flat spacetime, this will always be the accelerating twin, while in curved spacetime considerations of the metric will determine who travels the shorter spacetime path.
But of course, if one asks, what is the physical meaning of spacetime distance - the only answer the theory can give is that it is the amount of proper time which elapses on a co-moving clock. So the “resolution” to the twin paradox is precisely this: the twin who comes back younger is the twin who experiences less elapsed proper time. Quite tautological.
The problem you may or may not be grasping is that Relativity is not a theory of causes, it is a mathematical description of correlations between measuring instruments/coordinate systems. And the paradox of the twins is essentially not asking what breaks the symmetry, but asking what causes time dilation in the first place. And as both we know, Relativity can’t answer that question.
Indeed it seems you still have not grasped the full significance of the one-way-speed-of-light problem. If nothing requires observers to choose epsilon = 1/2, then the twins can choose appropriate epsilon values such that they both agree that it is the traveling twins clocks that are running slower - and so there is no paradox in the first place. Of course, everyone’s understanding progresses at its own pace, and there was a time when we too still believed relativity to be correct, and dismissed all those who told us that only an ether could explain time dilation as essentially crackpots. Sometimes one must taste the medicine they dish.
Relativity is a description of the gravitational field.
The one-way speed of light doesn't exit. Just like the one-way speed of a goat. You have a pair of clock world-lines so there's an arbitrary choice of synchronization.
Shut up
Thanks for offering a rational alternative view. Well done.
Started well, ended like nonsense. Why the hell did you mention Ether? Every attempt to show that it exists has failed, suggesting it doesnt exist in the first place. Relativity is wrong? We believe that it is incomplete, yes, not wrong. As there exists many quantum gravity issues and einstein's relativity doesnt work to solve them, we believe it must be at least incomplete. However, i think you said that because you believe in some Mumbo Jumbo ether theory or any shit related, which is very funny.
SR doesn't say anything about acceleration.
Each observer is given identical clocks and measuring rods. One moves at constant velocity, the other doesn't. In SR it doesn't matter who is A and who is B. They both measure the same values within their respective inertial frames, for example, they measure the same value for the speed of light. Time dilation and length contraction falls from a comparison of A to B or B to A. Without the comparison there is no time dilation nor length contraction. Both will experience time dilation and length contraction depending on the point of view. A says B is moving. But B says A is moving. Swap your perspective and you get the same answers.
The twin paradox arises because we compare the twins (thru observation of clocks) and say one is older than the other (time dilation). We define a point of view and define 'who' is 'moving'. We interpret that time dilation to be persistent once both twins return to the same inertial frame. Is it real? Perhaps neutrino decay is the best evidence for this?
But, isn't there a larger concern here? If it is real, then can't we claim there is a preferred inertial frame. Wouldn't such a preferred inertial frame justify the ether? Wouldn't an ether change physics completely? Suppose that the ether could be explained as a series of coupled mechanical pendula.
Special Relativity Hidden in a Series of Coupled Mechanical Pendula
ua-cam.com/video/e7nA5y497U4/v-deo.html
So when I think about measurements in internal frames and use the verb "see", I never think about light reaching the observer. I think about his infinite lattice of graduate students with synchronized clocks and calibrated rulers, and "see" means what does the grad student who is at the distant event "now", at the time of seeing, measure.
Right before turn around, the space twins grad student (bob) sees a younger earth twin. Then bam, turn around happens. Bob still sees a younger twin on earth, but bob is no longer synchronized with his adviser space twin. Space twin needs a whole new lattice of grad students, and the one he needs on Earth is a much older bob (if bob waits). This new grad student is now standing next to a much older Earth twin, who ages more slowly on space twins return trip.
Great video. Just one minor thing to add. Those who argue that the Twin Paradox can be resolved by simply considering inertial frames and use the Triplet example to show this to be the case, miss the obvious; The ‘Triplet Paradox’ is not the ‘Twin Paradox'! The Twin Paradox requires the twin to return to Earth, and hence accelerate. The Triplet example leads to a different paradox; Namely, when B and C pass each other they both agree they are the same age. A also agrees that B and C are the same age. But B and C disagree on the age of A.
The relative ages of b and c never play a role. When they meet, they synchronize their clocks. C can be infinitely old before that, and it makes no difference.
Sure, that's not the twin paradox, but it leads to the same conclusion. That all that matters for the end result is the spacetime length of the journey, which is well defined.
@@narfwhals7843 'Age' above is simply used to make reference to the elapsed time recorded by the clocks on A, B, and C. No matter how you choose to synchronize the clocks, given the particulars of the thought experiment, B and C will disagree on how much time has elapsed on A. So when C arrives at A, C will conclude that more time has elapsed on A, whilst B on the other hand will conclude that less time has elapsed on A. Or, if A, B and C synchronize their clocks when B and C pass each other, B and C will disagree on the time at which A synchronized its clock due to the Relativity of Simultaneity.
That B and C disagree on the age of A is the resolution of the paradox, so this example makes it very clear that B and C are at the exact same event in spacetime but cannot agree on the definition of "now" everywhere in the universe.
A lot of ppl struggle with relativity because they fail to abstract, I mean just read comments "but earth is moving", "but earth is spinng", "but the sun is moving", "but there's gravity on earth"--they can't just say "F-that, I'm moving the problem to a deep space space station"...oh, and then you ppl invoking quantum and atomic structure in some of the classic paradoxes..., this problem crops up in the normal formulation because B has to accelerate at absurd gees (even infinite), and they just can't get past that in a thought experiment. keyword: thought.
So the triplet version just abstracts that away, we see that A sees B and C age less, and B and C see A age less, so that A + A < B + C for B and C, while A + A > B + C for A...yet because B and C disagree on when now is at distant locations, all the proper time is accounted for.
tl;dr the triplet formation zeroes in on the resolution in an entirely abstract manner.
@@DrDeuteron Thanks for the comment. I'm unclear what you meant in your last paragraph. But, let A, B and C choose to synchronize their clocks at the point where C and B pass each other according to each of their frame's of reference. C then travels onto A. At the point where C passes A, the time on A, B and C's clocks are recorded, once again according to when A, B and C determine C and A to be coincident in their frame of reference. The results are as follows; More time has elapsed on A’s clock than on C’s clock; And, more time has elapsed on B’s clock than on both A’s and C’s clocks. There’s no paradox, but it’s viewed as paradoxical if one solely considers the rate at which ‘clocks tick’ and ‘rulers contract’, and ignore that when and where events occur is relative to the observers frame of reference i.e. the two events in question here being when C is coincident with B and the clocks are synchronized and when C is coincident with A and the time on the clocks are recorded. This is the no agreement on the universal ‘now’ as you said.
They're both the "twin paradox" which is just a comparison of world-line arc lengths connecting a common pair of events.
The gravitational field does not care about the names of triplets.
It's simpler than we all imagine, you don't always see things in slow motion when you move, sometimes you see things in fast motion, things in the direction of motion move in fast motion, if you hover above a gravitational field, the universe above you is in fast motion.
If you were to move very fast in the direction of Proxima Centauri, you would see it in fast motion, because you are moving in relation to it. When you get there, your're younger.
When you reach it, it's older than it would've been if its aging were only determined by the time light takes to reach you, and you catching the light rays faster as you get close to it.
You don't need acceleration, you don't need to go back to "compare clocks" and you don't need to be close to it beforehand.
With "it moves in fast motion", I assume you mean "its apparent clock rate is higher." Otherwise, your text does not make much sense.
Also, you seem to equate apparent clock rate with the Doppler shift of light arriving at the observer. But relativistic Doppler shift consists of two components: the normal Newtonian frequency shift between the light leaving the source and arriving at the observer, and relativist time dilation of the source.
Using the relativistic Doppler shift as if it is the clock rate simply makes everything harder to calculate. There is also a fundamental flaw with it, because light can travel from the source to the observer via multiple paths. Each of these paths will have its own Doppler shift that differ from each other. That makes the measurements inconsistent.
@@renedekker9806 you lost me at multiple paths. These are one spatial dimension thought experiments.
@@DrDeuteron _"you lost me at multiple paths"_ - then I probably misinterpreted your original statements. You might want to clarify what exactly you mean with "move in fast/slow motion", "see it in fast motion"
The term "motion" is usually used for something that has relative speed. You don't seem to use it in that manner, which makes your comments unclear.
@@renedekker9806, Thanks a lot for reading my comment and taking some time to talk to me about reality! I really love talking to smart people, and I loved your way of thinking. I have some stuff to add:
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I am precisely saying that it is not just the Doppler effect. I am saying that it IS in fact time dilation, lenght contraction and simultaneity. Even if the relativistic doppler effect has an aditional relativistic factor.
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What I am saying is: In a scenario in which there is a Traveler, Earth and Proxima Centauri, when you move fast towards Proxima, during the trip, if you look in the direction of Proxima out of the window, it is "moving in fast motion", its clock is "speeding up", things are literally moving faster, and if you look back to Earth, it is "moving in slow motion", it's "time dilated".
From the perspective of people on Earth and Proxima, the Traveler would reach Proxima in 4 years, and the part of the rocket in the direction of motion "happens later" than the part of the rocket in the opposite direction of motion, which "happens first", like this you explain the Relativity of simultaneity from both perspectives.
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TV imagination:
Imagine a television system on which there is a movie being displayed, passing by you horizontally, extremelly fast. The movie would not pass normally in all the parts of the TV, the movie would "pass first" in the part of the TV opposite to the direction of motion, and the movie would "pass later" in the direction of motion.
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Perspective of the traveler:
- Distance between planets is contracted, therefore it gets there in less time. Traveler ages less.
- Simultaneity: the universe in the direction of motion "happens first". The universe in the direction opposite to the motion "happens later", because of this, the forward region "happens in fast motion" and the other direction "happens in slow motion", this is simultaneity.
Perspective of the Planets:
- Distance between planets is not contracted, the traveler takes 4 years to reach it, the traveler is contracted, the region of the rocket in the direction of motion "happens later" and the region of the rocket in the direction opposite to the motion "happens first", simultaneity again.
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How I thought about this:
Imagine two planets A, B and a Traveler, all share the same inertial frame of reference. Their clocks read the same time.
The Traveler moves from A to B. When the Traveler reaches planet B, he has aged less than people on both planets, therefore, during the trip, if the Traveler were to look out the window, he would see planet B in "fast motion", and the planet A in "slow motion".
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At the speed of light example:
If the Traveler moves at the speed of light, he reaches planet B instantaneously.
Then, at the planet B, when he looks back to planet A, it is exactly at the moment when the Traveler left it. Planet A is as old as planet B, but its light still hasn't reached the Traveler. THIS explain the relativity of simultaneity as well.
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Conclusion:
So, as I see it, you do not need general relativity to explain the Twin Paradox.
@@renedekker9806 I’m not OP.
I've really enjoyed this video and the one about whether or not falling charges radiate. My opinion is that in the framework of Special Relativity we are allowed to make a measurement to decide if we are accelerating. It could be an accelerometer, or just letting go of a golf ball in front of our eyes and seeing whether it changes speed. I think we are allowed to interpret the result of such an experiment within the framework of SR and measure our acceleration that way. The falling charge is fascinating, and after looking into it for some time I have to agree with Feynman. It solves all the paradoxes and preserves the equivalence principle if only a charge whose acceleration is changing produces radiation.
That is exactly how you use SR to get that result...
Very clear, as usual. Interesting "fact": in a not so popularly known formulation of the paradox, one twin is on earth, subject to earth's gravitational acceleration (ok, the floor imparted acceleration upwards... of 9,81 m/s^2) while the travelling twin starts from a high tower. Bear with me; the final makes one reflect on the nature of 3D-space.
Well: Since he's starting from a high tower, with lesser gravitational strength, he can "use" the difference (say he's subject to 9,80 m/s^2, not 9,81) of 0,1 m/s^2 to move further up. As he gets away, the gravitational strength diminishes, so, in order to maintain his acceleration equal to the other twin's (=9,81 m/s^2) more and more "moving" acceleration becomes available.
When the earth's gravitation becomes negligible, due to the *inverse square law* , the 9,81 m/s^2 are used practically only to increase his velocity. Then, to invert the motion he takes on a speed higher than orbital velocity around the - now far away - earth, so that he must maintain himself centripetally accelerated at 9,81 m/s2 while turning around, and finally heads back home, where he then decelerates, always maintaining his "perceived weight" at 9,81 m/s^2 against the spaceshift's floor.
And, when he returns, he's younger. But the difference is only one: earth's gravitational field is spatially limited, whereas the "apparent" gravitational field arising from the (absolute) acceleration is not.
So when the "fictitious", spatially infinite gravitational field acts, the one making time go faster on earth (therefore making the earthbound twin age faster) *from the travelling twin's perspective* , it acts at the *distance* between "orbital" (not really) motion and the earth. We call it "Radius", obviously.
Now: different journeys with combinations of parameters: acceleration, journey duration, distance reached, etc... will result in different experiences, and different age offsets between twins.
For example:
A- if you decide to "orbit" (not really: you have to maintain centripetal acceleration of around 9,81 m/s^2 = 1 g) *very far away* , you'll experience 1g centripetally only to sustain circular motion; but here, far from earth, the circle is very wide: much time is needed to complete at least 1 circle to head back home. The circumference is = 2*pi*Radius.
B- decide for a lower "orbit"? but then you've got to accelerate less - and for a shorter duration, as you're not so far away and the circumference isn't big - to invert the motion, because there's still a non negligible earth's gravitational field _helping_ you turn without accelerating. Being - "nearby" means that the "fictitious" gravitational field that you feel acts at a lesser distance and makes the earthbound twin age faster (from your perspective) at a much much lesser rate during that phase of accelerated motion, than in the previous (earth far away) example! Also, your proper time offset from pure SR isn't big, because the whole experience takes less time, distance, etc...
Now, maintaining the relation between radius and circumference (2*pi), suppose we ask for the *gravitational strength distance relation* that has to be in place for a traveller that stays in the loop for a certain fixed duration and ends up experiencing a certain *fixed* age offset between stationary and travelling twins.
The result is NEWTON's INVERSE SQUARE law for the gravitational field!!!!!!!!!!
(the initial "tower" is only a kickstarter, a "trick" and can be reduced to zero at the limit)
Newton's law of motion, F=ma, Force equals Acceleration. Acceleration equals Force. Acceleration equals Acceleration.
The twin undergoing the most force on their frame of reference is the one that is 'older'. Zero gravity/equalized Acceleration = less force on the twin's body. The only way to accurately compute "age' differences is by heart rates. The hummingbirds lifespan is shortened by its accelerated heart rates. By the extra energy it uses.
E=mc. C is not just the speed of light but also the speed of time. C is absolute motion in time or one's lifespan. C is acceleration and that acceleration comes from an energy source. The food you eat accelerates you in time. The food you eat also accelerates you in space.
Example. Solar sails. The energy that is not reflected back goes into accelerating the sail in time - radioactive decay. Around .2c, the sail goes into catastrophic meltdown- bursts into flames.
Numerous astronomers and astrophysicists have rebutted Lerner’s claim, accusing it of opportunism, being thin on proof and supported by inconsistent arguments.
Sounds like relativity. Where is the proof that time slows down the faster one travels in space? Does it delay embryo development. Seed germination. Plant growth. Reaching physiological maturity?
Relativity is what is wrong with physics. Relativity is rebranded Flat Earth science.
@@stewiesaidthat yeah this sounds like it has no relation whatsoever with what I wrote. Furthermore, mine is a physicists' try to explain something very deep. you know... nothing for laymen, with all my respect.
One thing you've got right, though: generally, the twin feeling more "force" foe example through the feet touching the floor is the younger one. ONLY: why would the twin on earth, in my example, who is feeling the very same "force" through his feet during the whole experience as the earthbound twin, be any older than the travelling twin? BECAUSE .... well: re-read the comment ! 🙂
And no, "c" isn't the "speed of time" but the speed of CAUSALITY. That's why to me, "c" stands exactly for "causality" instead of like originally thought: "celeritas" = celerity = speed.
The speed of something is the units of that something per second (meter/hour, dollars/month etc...); in the case of time it would be just a dimensionless 1. Its UNITS? [seconds per second], or [s]* [s^-1] = 1#.
@@diemme568 thought so. You are just as confused by acceleration as Newton and Einstein.
(c) is absolute acceleration. Both in space and in time. Mass is what determines how much acceleration (time/distance) one can has already/achieved.
The Cause is instantaneous. The effect is what travels at (c) the carrier wave.
E=mc. The process of converting atomic energy to radiant energy and back via Acceleration.
C is absolute acceleration in time (radioactive decay) as you run out of atomic energy to convert to radiant energy. (c) is the absolute acceleration point in space as you run out of mass to accelerate and energy to accelerate said mass. Acceleration in space equals Acceleration in time. Whether you are using an outside force, the F in F=ma or the inside stored energy (mass) of the spaceship.
The (m) in F=ma is the ships fuel tanks. Once they run out, there is no more acceleration.
The (c) in E=mc is the physiological maturity of plants. Once (c) absolute acceleration is reached, the plant dies.
The (m) in E=mc is the photon's wavelength. Once the photon reaches its wavelength, it propagates a new photon.
Now, what happens to your causality limit when (c) gets redefined. When tachyons are discover and information can be transmitted faster than light.
You are thinking 2 dimensional. You are a blind man that doesn't know anything at all about light. You're universe is bounded/defined at the speed of sound.
I'm not saying that tachyons exist. Just that you are a blind person who has no concept of light.
As far as which twin is 'older', they both experienced the same amount of time as shown by the energy each clock used. One just experienced more space.
Two cars going around the track turning identical laps. One speeds up. The lead car is experiencing more space, more laps, more force going around the corners. How can a person possibly be aging less when they are experiencing more force?
Motion is absolute. Everything is an emergent property of acceleration. Time, temperature, gravity. All measurements of acceleration. (C) is bounded acceleration. Both in space and in time. (C) is your lifespan. How long you live. (M) determines how long you live (photon's wavelength for instance) (e) is what gets you there. The energy from the sun accelerates the plant to (c) its physiological maturity date.
C isn't just how fast one can go in space but also how far one can go in time.
The gas in your tank is stored energy. (c) is how far that tank of gas will get you. Not only in space but also in time. Comprende.
100 gallons of fuel (mass) at an acceleration rate of 10 gallons per hour equals a maximum acceleration time of 10 hours, (c). At a mile per gallon, you get 100 miles in space.
That's the law of motion.
Speed is distance/time. Two separate frames of reference. (C) is the absolute amount of motion you can have either in space or in time.
@@stewiesaidthat yeah whatever 🖐🙄🤨
@@diemme568F=ma. Nothing is real. The universe is unbounded, undefined.
Whatever you want it to be. Like walking into a dark room and imaging it's filled with all kinds of stuff.
E=mc. The contents of the room are now being refined to you at the speed of light.
Only Acceleration is defined. Acceleration defines mass. Water? Solid, liquid, gas. All defined by its acceleration value.
F=ma to E=mc. Only Acceleration is defined.
Motion is absolute.
Have a nice day.
Changing the direction of travel of your spaceship, such as going in circles, is said to be "Acceleration", in the world of physics. That sounds a bit confusing. Meanwhile, if your spaceship travels in a straight spatial line, but constantly accelerates while in the process of doing so, it too in truth is also constantly changing its direction of travel. All this goes on, while the magnitude of the motion of the spaceship, NEVER actually changes. All that can be changed, is its direction of travel. Within the 4D space-time environment, the more your spaceships ongoing motion is directed to being across space, the less of your ongoing motion is now directed across the dimension of time. Taking this 4D perspective into account, throws the paradoxes out the window.
The answer is a firm NO. In SR, you can work in Minkowski space and integrate proper time along a world line and get the answer without contradiction. Thus SR is enough, because it is a self-consistent theory.
The reason you get a paradox is when you leave Minkowski space and work in 3 + 1 frames. The paradox is not the asymmetry, its that each twin sees the other's clock tick less time on each leg, so the sum of elapsed times disagree,
Ofc the paradox is resolved when you remember a line takes the form: y = mx + b, and we're just looking at "m" (time dilation), you need to include "b" (clock bias), and that changes at turn around.
It's not time dilation---you can make b "run" forward or backward--it's just clock bias (see Andromeda paradox).
Now you can invoke GR, and ofc it gives you the correct results, but it is absolutely not necessary.
If you want to describe it in apparent physical terms, it really is paradoxical, in the limit of zero turns around (TA) time: Space twin ages zero TA, Earth Twin sees space twin age zero during TA, Earth twin sees Earth twin age zero during TA, but Space twin just picks a whole new "now" on Earth that is much later. It's not aging, it's just a new now. You know it's not aging, because if he turns around again, boom Earth twin is young again.
This is the Andromeda paradox, where "now" at distant locations depended on which way you drive your car here on Earth, and ofc, the ppl living in Andromeda don't care.
Well said.
I'm not trolling, from what you have said above does one of the twins end up being older than the other? I'll just accept it as your view without further discussion.
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I haven't looked at the Andromeda paradox but it does appear to highlight an issue in "what is time?" in the 3D and 4D geometries. I personal have serious doubts about so called 3D and 4D geometries as they appear to work from an ambiguous concepts of time. This is a fundamental question for me around for relativity and Minkowski diagrams with regard to which version of time is used. We have global (persistent) time, and we have motion where time does not exist. The geometries may look similar, but can be abstracted to many different versions of our human interpretations. Which geometry do you feel is asserted with regard to time?
Again, just your view, as I have no desire left for entering into debates.
Yes if you know who is inertial observer and who changes the frame of reference then all proper times can be straightforwardly calculated.
@@lukasrafajpps Is your reply to the OP?
The difference in age of the twins doesn't come from time dilation, time dilation is symmetrical.
However, length contraction is not symmetrical.
While the stationary twin sees the rocket shorter, the traveling twin sees the entire length of the trip shorter.
So the traveler needs less time to complete the journey.
What exactly happens during the acceleration phases doesn't really matter for the twin paradox.
As Lukas said, it can be made arbitrarily short.
@10:50: "Whereas the observer accelerated in a rocket detects a uniform gravitational field spanning the entire universe."
I think it is easy to proof that relative velocity difference does not necessarily cause relative time dilation.
Instead of twins consider triplets. L travels to left, E remains on earth, R travels to right with exactly same, but exactly opposite acceleration as L.
There will be no time dilation between L and R, despite the HUGE difference velocity, but both will have time dilation against E.
Also, if we only use SRT with straight lines then infinite acceleration within zero time at the starting, ending and turning point must be assumed. This is impossible to calculate. When it is neglected, we get an error.
You have to take simultaneity into account with your scenario. Both, R and L, will see say there is time dilation on the other for the entire trip. But they will disagree when the turnarounds occurred, which will result in their clocks being synchronized in the end.
The elapsed time on their clocks only depends on the length of the trip, which you can calculate with or without acceleration.
Depends what you take as your inertial observer, L maybe decelerating, while E and R are accelerating, with respect to an inertial observer.
Wrong. Why can't you people just learn SR and GR. It is really simple. Stop thinking your are going to save the world. GR does not need your help!!
_"There will be no time dilation between L and R"_ - only when viewed from E. The clock rate of R will appear to be slow when viewed from L, and L's clock rate will appear to be slow when viewed from R. From L's point of view, both E and R are moving away from him, R with almost double the speed as E. So both E's and R's clocks will appear to run slower according to L.
_"[infinite acceleration] is impossible to calculate"_ - it is possible to calculate if, instead of zero turnaround time, you take the limit for the turn around time approaching zero.
@@renedekker9806 When L and R meet again on earth, there is no time difference between them.
It does not matter in which direction they travel. If both travel in the same direction parallel, then the result ist the same.
Therefore the relative velocity between L and R has no influence on time difference between their clocks.
In this special case. This proofs relative velocity alone does not cause actual clocktime difference.
It only influences the time which will be observed by a remote observer.
8:40 There is a paradox, it's just not a contradiction. one definition of a paradox is an apparent contradiction, and that's the one we're talking about.
The twin paradox is rigorously solved in this tutorial, with a realistic acceleration, from both points of view of the traveler and the stay-at-home twin: ua-cam.com/video/QFWF90bch3c/v-deo.html
I am confused by something I thought you said: my clock will tick slower if I am moving at uniform velocity wrt another, external Observer. I thought that wrt to my own inertial frame of reference, there is NO time dilation. So my clock would APPEAR to tick slower to the Observer but not to ME. I hope you agree so far. In your example, my elapsed time would be 5.75 years, from my perspective, before I turned around, although to the Observer it would seem like 2.84 years. When Observer and I meet again, after I turned around, my clock would have recorded MY time, which would be 11.5 years, not the time (5.75 years) that Observer thought I had clocked. The Observer looking at my clock when we are “sitting across a table and wondering who is older”, is no longer the scenario where we were moving relative to each other at near-light speed. My point simply is: my clock recoded my time, not the time perceived by Observer. So the so called “paradox” may be a “red herring”. Am I missing something?
You have that wrong.
The "proper time" is the time elapsed on the clock that takes that path. So if the proper time on your path is 2.84 years, then that is the time _you_ consider to have passed. An observer who sees you move will notice that your clock has recorded that much time, but they will also notice that their own clock has recorded _more_ time in that period, so they will conclude that yours is "ticking more slowly".
In the duration it takes you to reach the turnaround point the observer on earth measures 5.75 years in the time it takes your clock to measure 2.84.
The total time elapsed on your clock when you meet again is twice that, so ~5.75. The total time elapsed on the earth observers clock is 11.5.
There is less time elapsed on your clock, than on earth's.
Each observer's clock records their own proper time. There is no paradox.
@@narfwhals7843 Thanks for your explanation but I still don’t see how it hangs together. You say, “proper time is the time elapsed on the clock that takes that path”. How can that be different from the time experienced in MY inertial reference frame? After all, they are MY clocks, residing on my spaceship. Proper Time cannot be my time observed from an external reference frame, as it would immediately raise the question: which reference, and attack the very foundation of the concept of SR. Note further that clocks are made with springs or crystals, none of which have any awareness of the uniform speed of my reference frame relative to the speed of light and therefore couldn’t be influenced by the ratio of the two. Likewise for my beard, which would grow at the same rate regardless of my speed. Every assertion of SR is about the observations of someone in an EXTERNAL reference frame, not in the SAME reference frame as containing the subject clocks.
@@sdutta8 If you are traveling with the clock then the clock will measure your proper time. *All* observers agree on what that clock reads. They do not agree on how that compares to their own clocks, which measure their own proper times.
I think you are conflating two different things. "Your time" is just the time on your clock. How that relates to some other observers time is what we use the Lorentz Transformations for.
Clocks and beards operate by the laws of physics, regardless of their construction. If the Principle of Relativity is to hold and include the speed of light, then different observers will disagree on how fast clocks tick or beards grow.
Is your disagreement that, even though different observers will disagree on the rate of clocks, this can not have physical consequences?
What does "external" mean? Any inertial reference frame is equally valid.
@@narfwhals7843 I agree with you that if we were traveling in different spaceships at uniform speeds, each of our clocks would tick at 1 second/second for each of us but might appear to be ticking more slowly if we had a radio link between our spaceships, providing visibility of each other’s clock times. You can guess that from logic and intuition - you don’t need SR or Lorentz for that. My issue is with the way the Twin Paradox is posited. The usual story is that the twins reunite and cannot agree who is younger. If they were having this discussion while the were passing each other at quasi-light speeds, then yes, they would have this conundrum. On the other hand, if they both alighted on Earth and checked their clocks, they should both see the same elapsed time on their clocks and biological aging in their bodies. If that was not the case, I wouldn’t understand why.
@@sdutta8 If all we use is Newtonian logic and intuition, we might conclude that the ships will see each other's clocks slow down if they move away from each other, and speed up if they move toward each other, due to doppler effects.
This will not result in a difference in elapsed time when they meet again.
This is present in special relativity, as well, but that is not time dilation. Time dilation is irrespective of direction and a result of demanding that the speed of light must be the same for all observers.
This does result in a physical difference in elapsed time when they meet again.
Time is just a certain idea of distance in spacetime and a clock measures that distance.
That distance is different along different paths.
The paradox is posited that way to appear paradoxical. It only does so until you properly consider the situation and see that it is not symmetric. The situation is clear and and fully resolved when you realize that you can not treat both twins equally because only one of them is inertial the entire time. The one who wasn't is invariably younger.
This has been verified experimentally.
Very clear-cut explanation!
I understand that the ship frame is not an inertial frame and I trust what you said, but I imagine a light clock on Earth. In the ship frame the light ray path is longer, so I think the twin on Earth is younger as it moves in the ship frame. (even though the ship accelerates and decelerates)
Maybe the speed of light changes?
I really enjoyed your video, you are number one! (and I'm proud to follow you since your first videos)
🙂🙃🙂
A few years ago, as an interested layperson, I came up with the following concept to better understand the twin paradox: shells of light. When Alice moves towards Bob, she breaks through Bob's light shells more frequently, causing her to see Bob in fast motion (imagine a periodic signal emitted by both and counted by both). The key idea is that these light shells contain all the information about the relative present. Accordingly, one travels into the relative future or past of the other.
For example, if Alice is 4 light years away at Alpha Centauri and Bob waves to her from Earth, and Alice instantly travels to Bob at the speed of light, no time would have passed for Alice, and she would be the same age upon arrival as she was when Bob last saw her in his telescope - since Alice traveled with her own light shell. Conversely, Alice would have broken through many of Bob's light shells during her journey, causing her to see Bob in extreme fast motion and experience him as 4 years older upon her arrival, according to the number of light shells she passed through. Essentially, both would just need to count their relative light pulses.
For the full picture, you must take into account the change in direction and acceleration, but the basic concept should hold.
Edit: Also, the situations in the twin paradox are not symmetrical from the start. If Alice travels to Alpha Centauri, 4 light years away, at the speed of light, she experiences it as follows: She leaves Bob, arrives immediately, and sees him as he appeared to her "just now," because she has traveled with his light. Conversely, Bob sees Alice disappear. He sees her arrive at Alpha Centauri after 8 years, appearing as she did 8 years ago when she left him, since no further light from her reached him in the meantime. If Alice returns to him shortly after her arrival, she sees him again in the next moment, but suddenly 8 years older - in that one moment, she has received 8 years of his light. From his perspective, she returns and is immediately back with him, not having aged, because he received no further light from her in the intervening time.
Yeah, this explanation gets bundled up as "Relatavistic Doppler Shift". The peaks of an electromagnetic wave can be thought of as the ticks of an oscillating electric charge.
If you go through "shells of light "more frequently" under whose time--see one guy going through more shells than another is objective. As soon as you tank about more frequently you introduce time and thats relative--reminds me of people who say "everythigs vibrations-time is a vibration---but to talk about vibrations one uses time so this is circular logic.
@@whatitis4872 When we talk about one person moving through more shells of light than another, this is indeed an objective observation. The number of light shells intersected by each observer can be quantified without reference to a specific frame of time.
The notion of "more frequently" does indeed introduce the concept of time, which is relative according to the theory of relativity. However, this relativity is exactly what the concept aims to illustrate. When Alice moves towards Bob, she intersects Bob's light shells at a rate that appears faster to her due to her relative motion. This is a direct consequence of time dilation.
The idea of "everything being vibrations" or "time as a vibration" can indeed lead to circular reasoning if not carefully defined. In the context of the light shells, the "ticks" or intersections are not described as vibrations but as discrete events marked by the passage of light fronts. These intersections are used to illustrate the relative experience of time between moving observers.
The light shells provide a visual and conceptual tool to understand how information travels and how the perception of events changes with relative motion. They help to show that what one observer perceives as a short duration can be experienced differently by another observer due to their relative velocities.
The concept of light shells helps me better understand the interplay between space and time. I imagine Bob surrounded by onion-like, nested light shells. Each of these shells shows an image of him at a specific point in time. No matter how Alice moves through space, the light shell of Bob that she is on is uniquely defined by her distance from Bob.
When Alice moves towards Bob, she breaks through these light shells in quicker succession, causing her to see Bob in fast motion. Conversely, when she moves away from Bob, she sees him in slow motion. These light shells contain all the information about the relative present and illustrate that Alice travels into Bob's relative future or past, depending on her relative motion.
@sorokan761 As a concrete example, you can imagine a flashing light bulb/LED on a clock. If the LED blinks on an off once every second (or whatever duty cycle you want to use) and moving observers will see the period of the blinking cycle be at a higher or lower frequency depending on direction and speed.
It *is* exactly described by the Relatavistic Doppler Effect. Red-shifting and blue-shifting is exactly the same thing for exactly the same reason.
I should note that this is a *_DIFFERENT_* effect from _kinematic_ time dilation. (Moving clocks running slower, twin paradox and all that stuff.) and different from _gravitational_ time dilation.
With the Doppler shift alone, observers moving apart will see the each other slowed down "red-shifted", and when moving towards each other, they will see each other sped up "blue-shifted". But when they are both going the same speed and direction, there's no shift.
Kinematic time dilation will slow moving clocks in *all* directions of travel. Two observers traveling towards each other will both be blue-shifted by the Doppler effect *_AND_* red-shifted by kinematic time dilation!
It's the kinematic time dilation in the so-called "Twin Paradox" that results in the twins being different ages when reunited together. Just Doppler Shift alone doesn't change proper time (age).
@@juliavixen176 Thank you for this enlightening and detailed explanation. I was not aware of this difference between the Doppler effect and kinematic time dilation. However, if I understand correctly, the following must hold true:
1. The difference in the number of mutually crossed light shells corresponds to the aging difference.
2. The image that an observer sees of another corresponds to the light shell they are currently traversing, and this is defined solely by the spatial distance.
Didn't you mention in a previous video that you can rotate your accelerometer by 90° and know that if there's no change then you are in an inertial reference frame? (Proper acceleration will make your accelerometer different in each orientation.)
@@juliavixen176 He was right then but wrong now. I do not undrestand why.
The Twin Paradox emerged from Relativity. So yes :)
Yes, just amazing and what I expected. Special relativity can handle acceleration and even the time gradient of the gravitational field by hyperbolic geometry, or two frames, or worldlines arc length, but it is itself against its first postulate, that everyone can claim to be stationary.
In a spacetime diagram, if the moving twin (the zigzag line) was chosen to be stationary (straight line), it would mean that the structure of the diagram must change in such a way that it keeps his worldline shorter, kind of like changing from Cartesian to polar coordinates doesn't affect the path, or making the earth flat on a map doesn't affect the path.
But for this mathematical assumption to be known, we must have the information about who is inertial in the first place. If we don't provide this information, the twin doesn't even know what his spacetime geometry is. So, General Relativity fixed that by allowing him to claim himself to be stationary no matter how much he accelerated and how many times he experienced a gravitational field, which allowed both of them to claim to be stationary.
The first postulate says nothing about being stationary. It says all inertial observers can use the same laws of physics.
The geometry of spacetime in this scenario is Minkowski Space. There is no curvature and this is not observer dependent. Since there is no curvature, we only need Special Relativity.
All observers can consider themselves "stationary", because that is a meaningless statement. One is always stationary with respect to ones own coordinates.
This, too, has nothing to do with General Relativity.
What we need to do is identify which twin is accelerating, which we can do by giving them accelerometers. During the acceleration period, we must concede that the person experiencing acceleration can not use the same laws of physics as one who is not, which is perfectly in line with special relativity, and have to include what we may call fictitious forces.
What General Relativity does for this is to _always_ include the possibility of fictitious forces in the formulation of the laws of physics, allowing _everyone_ to always use the same ones.
This is useful but not necessary to get the right result.
@@narfwhals7843 Thanks for your reasoning!
I see it in a way that pushing the twin paradox too far can lead to a philosophical argument instead of a physical one. The idea is that worldlines are invariant and honest whether they are closed, hyperbolic, zig-zag, or whatever. If we make one of these worldlines straight through time, it would mean the diagram has a different line element formula to conserve their length. This is because the Lorentz transformation can only handle one section of the zigzag, or you can cut it out by adding many time coordinates as given moments, like the Rindler coordinate if you know the law of physics you are experiencing as a twin.
But our twins cannot see spacetime and, therefore, cannot know if their worldline is shorter or longer. They cannot come up with the Rindler coordinate. However, if there is any asymmetry, it would indicate the difference in a relative way.
Suppose you give everyone an accelerometer, and these twins have learned special relativity and understand the worldline concept but haven't learned general relativity. One of them has experienced acceleration, and one of them is free-falling near a black hole. After they come back, all they know about computing worldlines is based on special relativity, and they will be confused because they don't know the true geometry of spacetime near a black hole.
All their assumptions about their worldlines based on the forces they experienced are wrong because one is falling around a black hole, but that person is thinking of themselves in Minkowski space. How does he know that he was wrong? Because all we did is formulate spacetime, and what they experience is very subjective, they cannot see their own worldlines.
If the twins don't understand anything about physics, and you tell them that A's worldline is shorter and B's worldline is longer, that is enough. But they will be confused.
@@narfwhals7843 I think the word "relativity" is what caused this suffering for people. We first came up with the idea that every inertial frame shares the same laws of physics, and the speed of light is the same for all inertial observers. Then we proposed that a moving clock ticks slower, relative just like kinetic energy. But now, the twin paradox requires the understanding of worldlines and metrics, which are far beyond the simple photon clock that people think is the basis of relativity.
We showed that worldlines are invariant. However, worldlines aren't a single moment or small duration; they are entire journeys when we already know the beginning and the end. This creates an invariant that everyone agrees on. We then conclude that worldlines are absolute, and coordinate systems are relative, serving as a standard measurement to observe worldlines.
We ignored the fact that time dilation is caused by relative motion and developed the idea of proper time and worldline intervals to explain the entire twin paradox. We must accept that the initial idea showing that a moving clock moves slower is just part of the entire journey. It has now become an invariant concept that is far more complex than relative motion. Ultimately, we learn that relativity is based on things that are not relative. It's kind of like we came up with the idea of relative kinetic energy and found ourselves with an absolute kinetic energy. I don't know how to describe this feeling.
@@eigenvector123 I like to think of it like this.
We had the principle of relativity, telling us that the laws of physics should be the same in all inertial reference frames.
This leads to some problems with electromagnetism.
Lorentz and others tried to solve this, while preserving an aether model, by introducing a length contraction relative to the aether frame.
This gives the illusion of a constant speed of light and makes the aether undetectable.
Einstein said "well, lets make the speed of light a law of physics" (or a constant of nature).
That isn't actually a new postulate, as much as an observation.
Length contraction and time dilation are a consequence of this, because it demands that space and time by themselves are just coordinate definitions.
I don't quite understand what you mean by "ignore the fact that time dilation is caused by relative motion".
That's the premise of the paradox. Time dilation is a discrepancy between clock readings and coordinate time.
The resolution is to realize that clocks measure proper time, not coordinate time.
If you place one twin near a black hole, that is a completely different scenario. They can _locally_ think they are in Minkowski space, but then they can't be aware of the black hole, so they also shouldn't be allowed to look at the distant twin. They can draw conclusions about the geometry from the end result of the experiment. One of the conclusions must be that special relativity is not enough to describe the whole situation. But that is a very different situation from the traditional twin paradox, with different results.
They are right to be confused. They have a whole new theory of gravity to figure out.
@@narfwhals7843 Thanks for the last part. When I read, "They are right to be confused. They have a whole new theory of gravity to figure out," I was laughing. It was nice to talk with you; you are really smart.
The first part, where time dilation is caused by relative motion, is still a thing. The first postulate really makes sense because Einstein was so magically genius that he chose the speed of light to be the truth. It was a perfect choice by accident, even after general relativity came out.
After all, we figured out the speed of light is not constant in curvilinear coordinates and curved spacetime manifolds, but we still give "c" as the truth and define the concept of local speed of light, proper speed, proper distance, and proper time in a sense independent of the coordinate system we choose.
The first logic of special relativity, which Lorentz and Einstein did, is viewing a photon clock ticking in a zigzag pattern. Using Pythagoras' theorem, we have the most basic formula, which is t = t'/sqrt(1-v^2/c^2), with no Minkowski metric and worldlines at all. We say that time dilation is relative, as long as there is no coming back, no hyperbolas, or zigzag worldlines, just straight to infinity.
But after we figure out that if time dilation means comparing clocks when they share the same event, in the right space and time, we will find that only one person is older. They found out some invariants. This means we say time dilation is absolute, in the sense that we are giving up the first idea, which comes purely from coordinates, and now we rely on worldlines and proper time instead. A simple photon clock is not able to explain it anymore.
In Rindler coordinates or curved spacetime, we must assume that the global speed of light can vary, and the photon clock can tick faster as those photons tick faster. But not everyone wants to learn complex geometric things. They want an explanation like a photon clock, realistic and simple, which was also the first idea of time dilation. They stay attached to those ideas, which is why many crackpots cannot get relativity easily.
Einstein's 1905 paper establishes a unification of Galileo's Principle of Relativity with Electromagnetism - it is not a theory of spacetime. Relativity is just general relativity and the machinery of the special theory can be used in the special case of the ground state gravitational field (the gravitational field such that the Riemann curvature is zero on all components).
He wrote 4 papers that year. Read "Does the Inertia of a Body Depend Upon Its Energy Content?"
That papers proves the one you are taking about also works in accelerating frames of reference, but it affect the kinetic energy of a Body and ergo a mass is equal to Energy divided by c squared
@@ExistenceUniversity No, the papers have nothing to do with acceleration.
In the E=m paper the kinetic energy is zero, K=(γ-1)m=0, and hence why it's called the rest energy. The total energy γm is the p^0 component of the 4-momentum.
Anyway the point is that in 1905 we don't have notion of "spacetime" which wouldn't even be introduced as a concept until years later.
@kylelochlann5053 "Does the Inertia of a Body Depend Upon Its Energy Content?"
Is 100% about acceleration. It's where Einstein writes gravity is equivalent to acceleration in that paper. I have it right in front of my for my history Of General Relativity video I will be publishing in a week
Where do you think GR comes from?
@@ExistenceUniversity Then you haven't read the 1905 paper and your video will be filled with incorrect information.
GR is predicated upon precise measurements of WEP, LLI, and LPI and subsequent measurements of the structure on top of the metric field. You cannot arrive at GR from SR.
@kylelochlann5053 Go it is dummy
Leo Moser posed the problem of the largest sofa you can move down a hallway and around a 90 degree turn. I just wonder if you could use length contraction to move a very long object down this hallway and around the turn as along as it maintains its high speed in the straight portions of the hallway and accelerates around the turn maintaining its speed? I don't understand how to do the math and if it could actually make the turn in the hallway. I know the car that is too long for the garage can fit from the stationary observers frame but how would this apply to an object too long to make a turn in a hallway ?
Could you look at this problem , it might make an interesting video. I already asked this question on the stack exchange and pretty well got brushed off. They told me length contraction was not real and was just apparent. Also got a bunch of other non answers that it was off topic.
If you think about time keeping (like a light clock) as an electric oscillation on the smallest possible scale in any object you will find that any movement will result in a slowing of this time keeping. Explanation: If you look at a particle as a circle and the time keeping as an electric signal going from one side to the other and then back again (oscillating) it will take longer to make a cycle if the whole thing is moving. Einstein's famous light clock in a train works as well if it is laying down as when it is perpendicular.
Seeing at time dilation this way points to that there is an absolute "Zero speed" in the universe. Acceleration has nothing to do with it other than you must accelerate (or decelerate) to get a different speed.
That people stay younger when traveling fast is really no different to that frozen meat stays good longer than fresh meat.
This is my opinion as it all makes sense to me. Also why shouldn't there be a "Zero speed"? We have a zero temperature and we have a maximum speed. It is just very difficult to find "absolute speeds" as we can't measure Electro Magnetic Emission (like light) in one direction only. Not yet at least.
Time itself is in my opinion a momentary thing. We have a past that we can't change and a future that we don't know. That is why I say "Time keeping" (or time counting it should be).
Also how can a future be deterministic if radioactivity is random? Radio activity can influence every thing.
Energy can be neither created nor destroyed only transformed. What transforms it?
E=mc. Acceleration is what transforms mass from a solid to a liquid to a gas to radiant energy. (c) is absolute acceleration of the mass. Once the mass has been accelerated to c, it's transformed into the next phase of matter.
Now, you have two quandaries. What is energy at Absolute Zero and what is Energy at +c.
Since scientists still think the earth is a stationary plan (mass as an actionable force) a century's worth of progress has been lost on account of flat earther Einstein and 400 years lost because Galileo's peers were flat earthers.
Even today, the entire scientific community is made up of science deniers.
E=mc. Everything is an emergent property of acceleration, including mass. Why are scientists stuck on stupid still using mass as the actionable force.
@@stewiesaidthat Actually I would say it a little different about energy and mass. I would say that light or any other Electro Magnetic Emission is the purest form of energy and mass is energy decelerated to near stand still. For that to be possible it must be some thing like a standing wave if you know what that is - in my current opinion at least. I change my mind if I learn some thing new and it makes sense.
Basically EME, like light, is at speed c and mass is energy some how caught at near stand still as we observe it.
I believe the problem for scientists today is that for firstly getting their degrees they must stick to the norm and for getting a job and later funding for research they must stick to it too. It is daring to through away your future if you are game enough to say any thing different. I am not a physicist. I am only a design engineer and I no longer need a job. The government pays me a pension and as long as I don't do anything criminal they don't care much what I do or say especially if it isn't too political.
@@leonhardtkristensen4093 I have no idea what the problem with academia is. Surely they don't subscribe to this relativity nonsense. I always thought that relativity was one of those fringe flat earth type groups that didn't understand nature. You didn't see or hear it mentioned much until UA-cam came around and everyone started making videos trying to explain, as Nicholas Tesla put it, mathematical nonsense.
It was then I realized how deep down the rabbit hole academia had gone.
What makes anyone think that space and time are one and the same? That's what I don't understand. Have they not heard of refrigeration? Do they not know that microwaves accelerate the cooking process? Do they not understand what makes grass grow? It's like all they know is how to manipulate mathematical equations to get the desired outcome. A universe that is defined by mass.
When I started looking into the infamous twin paradox, I thought it was just a simple misunderstanding of not knowing what it is that clocks measure.
The more I looked, the worse it got. The Earth's tides. Galileo already showed that mass does not attract mass and theorized that it's the Earth's motion I'm space thst causes the tides. And yet. The UA-cam community still thinks the moon is creating the tides. Why? Newton's and Kepler's law's of motion clearly explain the tides and yet they are still trying to shoehorn in gravitational attraction.
Newton's gravitational attraction is clearly at odds with his laws of motion. Didn't he understand that. And what about the rest of the scientific community? Surely they have to understand that gravitational attraction is a flat earth tool to explain why objects fall to the ground on a stationary plane.
And Einstein, he contradicts himself left and write. I guess that comes from being a plagiarist and not understanding what he is stealing. Not a single experiment has validated his relativity nonsense. Not a single one. In fact, Hafele-Keating proves its just mathematical BS once you add in the missing data. Clocks in motion using the same amount of energy. The atomic clock's cesium-133 atom being chilled to absolute zero while the observer's atoms are at room temperature. The fact that actual objects accelerated into space are clearly showing to be accelerated in time. Accelerated heart rates, the solar sail's molecules increasing in temperature.
So why the fixation with mass being the actionable force? Because the alternative is Acceleration. And there is already a god of Acceleration in the Bible.
F=ma. Force comes from Acceleration of the mass. Not the mass itself.
E=mc. Energy comes from Acceleration of the mass. Not the mass itself. Everything is an emergent property of acceleration. Acceleration is the actionable force. Now, explain acceleration. You can't without invoking a god of Acceleration.
F=ma. The universe is either an inertial frame (outside force acting on it) or a non-inertial frame (accelerating itself).
One requires a god, they other means the universe is an infinite loop.
E=mc depicts an infinite universe bounded by light. No beginning of space. Only a beginning and end to the structures contained within. The Information about universe is bounded by c. The distance EM waves can travel before they propagate themselves into the CMB - shorter wavelengths.
With tools like the JWST, academia is running out of plausible excuses. It's just that they have so much invested in their flat earth tools and their master craftsman, that they have to keep building using those tools.
Imagine having to tell the entire world that Einstein is a fraud. That Newton was a flat earther and didn't take into account Galileo's findings that mass does not attract mass. That it's the Earth's motion that curves space, not it's mass.
Relativity is the biggest scandal in the scientific community. And experiments like Hafele-Keating proves it.
Nicholas Tesla stood up to these charlatans. Called them out for what they are. Problem is, he never understood why Relativity is mathematical nonsense in order to shut them up. Just like Einstein never understood what clocks are measuring and why clocks in motion run slow. Even though it was he himself that said light travels in its own frame of reference independent of the source. The source's frame has been accelerated but not the photon's. Motion changes the force of light acting on your frame. No need for Special Relativity as all motion can be measured using light as the absolute reference marker.
General relativity? As shown by Galileo, mass is not the actionable force. Acceleration is. Mars gravity is the same as Earth's because it has the same acceleration factor. 1480 minutes in a day vs 1440. Every frame is screaming acceleration but they insist upon using mass. The only reason is because it's impossible to explain what acceleration is. What infinity is. What absolute zero is.
That's the only reason I can think of why the scientific community is still modeling the universe using mass as the actionable force.
For everyone who keeps saying that "we don't know the one-way speed of light" as someone kind of "gotcha!" (as if it actually matters in this case at all) (and, as if the Compton Edge Experiment hasn't measured the speed of light to be isotropic to within one part in 10⁻¹⁴) (and, you know, Maxwell's Equations, etc.)
Here's a really good argument that the speed of light would violate the conservation of energy if it did not propagate at the same velocity in all directions:
ua-cam.com/video/tVm2Cvy6UEY/v-deo.html
Very nice explanation!
How is using GR in this case better than using SR? SR: Rindler coordinates--> solution. GR: metric-->geodesic equation-->Rindler coordinates--> solution. Identical results, SR faster. How does using GR help? Can someone please explain this to me?
What solution are you coming up with. That both twins are the same age having experienced the same amount of time. One just experiences more space.
Space and Time are separate frames of reference.
Light travels in it it's own frame. Independent of the source. The source's frame has been accelerated but not the photon's
Example: two cars on a track turning identical laps. One car speeds up. One car is experiencing more space (additional laps) in the same amount of time.
Newton's law of motion, F=ma, properly explains the twin paradox.
Motion increases the distance the photon has to travel resulting in less force. Less force equals fewer clock cycles. Clocks are instruments that measure motion in space expressed in units of time. Just like rulers measure length expressed in units of inches.
Relativity is flat earth science. As Tesla put it, mathematical nonsense.
Google really needs to start flagging these content creators for peddling debunked science.
You don't use GR in the traditional TP setup as the Riemann curvature is zero on all components and reduces to the ground state gravitational field of SR.
@@kylelochlann5053 the problem with relativity is that motion is absolute
Einstein said as much and then he took it back. Why?
Newton's F=ma. Motion is relative because acceleration is not defined. It's unbounded and infinite.
E=mc. Motion is absolute. Acceleration is defined, bounded, limited to the speed of light.
What is wrong with Newton and Einstein. Newton says the actionable force is acceleration and then back peddled and said mass is the actionable force.
Einstein? Said motion is absolute and the backtracked and said it's relative. Same with gravity. First it's an emergent property of acceleration and then says it caused by mass.
No wonder you kids are confused and think the earth is a stationary plane. Gravity is the excuse given for why objects fall instead of rise like smoke.
So tell us, where is your evidence for mass attraction? I'll go first. Galileo dropped balls of disproportionate mass proving that mass does not attract mass. Nasa followed up with a hammer&feather on the moon. When two objects objects of dissimilar mass fall at the same rate, where is the mass in the equation? It appears when they contact the ground. F=ma becomes ma=F. There is no such thing as gravitational attraction. It's flat earth science. Comprende.
SR? Where to even begin. How about
1) light travels in its own frame of reference, independent of its source
2) the speed of light is constant
3) it's the same for all observers
4) is the fastest anything can travel. In space and in time.
The laws of physics are equally applicable in ALL frames of reference. That includes the photon's frame. Force decreases with distance. You accelerated the source's frame but not the photon's frame. Why? Why don't you understand what happens when one object speeds up while the other maintains speed?
What else do relativists not understand?
The clock's cesium-133 atom is being chilled to absolute zero to prevent an acceleration in time event from occurring when a force is applied. Unless the observer is also in cryostasis, they aren't even in the same time frame of reference.
There is no time-dilation because clocks are instruments that measure motion I'm space. Not motion in time. Space and Time are separate frames of reference.
Relatively is so full of errors, it's impossible to find st least one that invalidates all of relativity. So what's the deal? Why the concerted effort to promote Einstein’s relativity nonsense even though it's been mathematically and experimently disproven exhaustively.
It does not make much sense to use GR. You can use GR if you wish but then you should use a solution to Einstein's eq. without matter that leads to zero curvature of empty space that reduces to SR anyway. Misner-Thorne-Wheeler clearly explain in their book that we construct GR by using SR through the equivalence principle (EP), so it really does not make sense to use GR to solve a special relativistic problem.
Of course, if you get sophisticated, you can say the EP is wrong, but I am talking about the heuristic construction of the theory which is very important to understand the "physics" and not merely the math and the strict logical structure.
@@justopastorlambare2933 I don't understand you logic. It's just circular and goes no where. Which is why Nicholas Tesla labeled relativity mathematical nonsense.
Galileo proved that the mass is not an actionable force. You flat earthers dismissed it as a thought experiment. Gravity/mass attraction is required to keep objects from floating off into space on a stationary plane.
Fast forward to the moon landings and the hammer&feather drop tests. Same thing. Gravity/mass attraction is required to explain why objects don't float off into space on a stationary plane. Only this time you created the lame excuse that is EP. The equivalence principle. Really flat earther. Do you not understand Newton's simple equation, F=ma. Mass TIMES Acceleration? Acceleration is the actionable force. Not mass. How about I show you how even more ignorant you flat earthers are. F=ma. Mass AND Acceleration. Two SEPARATE frames of reference. Space AND TIME. So why do you think it's spacetime? Because your god Einstein told you so?
Shall I continue? F=ma. Neither mass nor acceleration are defined. They are unbounded, infinite. Motion is therefore relative.
E=mc. Acceleration is now defined, limited, bounded by the speed of light. Motion is Absolute.
Didn't Einstein himself say the motion is absolute. That nothing could travel faster than light. That it travels in its own frame of reference, independent of its source. And is the same for all observers. Sounds like light is an absolute reference marker in which to measure all other motion against.
So why the relativity nonsense Einstein.
Newton says Force comes from Acceleration not mass. Why are you still stuck on stupid with your flat earth science?
Light travels through space IN ITS OWN FRAME OF REFERENCE. What is the equation for motion, F=ma? So why aren't you using Newton's law of motion to explain the Twin Paradox flat earther?
I'll help you along. Two cars on the track turning identical laps. One speeds up. The observation, the lead car is experiencing more space (laps) in the same amount of time.
There. Resolved once and for all. Both twins are the same age. One just experienced more space is all.
Have a nice day.
Should the short answer not be simply "gravity is not involved, so of course not"?
The twin paradox is rigorously solved in this tutorial, with a realistic acceleration, from both points of view of the traveler and the stay-at-home twin: ua-cam.com/video/QFWF90bch3c/v-deo.html
I don't get why people don't get this. If two people are going different velocities, then the one that will be younger is the one that decides to change to the other's velocity. The actual definition of how much time passes is based on reference frame.
The _actual_ "paradox" (it's not really a paradox) is determining _who turns around_ i.e. what breaks the symmetry if each twin can consider themselves to be (inertial) standing still... and the solution is that is that two straight lines will only intersect once in flat manifold, so at least one twin can not be in the same inertial reference frame forever, or the twins will never be reunited.
Gravity throws a curve in this, because you can have straight lines intersect at more than one point, but that's another story.
The Twin Paradox with realistic acceleration is rigorously solved in this tutorial: ua-cam.com/video/QFWF90bch3c/v-deo.html
General Relativity is not required, as Special Relativity is perfectly capable of dealing with accelerated frames of reference, as proven in the tutorial.
I'm thinking time has to be a dimension in whatever distance function you are using. sqrt(t^2+i(t)^2+j(t)^2+k(t)^2), or dt, whatever.
In special relativity time is simply added to the distance function with a negative sign. s²=-ct²+x²+y²+z². This calculates the "spacetime interval", which has to be the same for all observers. In _general_ relativity all these germs are multiplied by the "metric", which can be a function of time and space.
@@narfwhals7843 so, I'm guessing you have some kind of quaternion cubic polynomial, the function uses the roots of that and can be expressed with 'e'. 'i' and 'j' are there i*j=-k. We don't need k, but it makes it look nicer. [-t, f(t)], where f(t) returns the three imaginary numbers. So, with polar curves, we integrate, then differentiate to get the arc length. -t -> -1. But we gotta square it anyway. Never mind, this isn't my deal. I'll leave it to the freaky autistic people. I'm probably a little autistic, but not autistic enough for this.
Bro is Length contraction Really An effect of superposition or Quantum wave mechanics ?As Dialect proposed in his interpretation of Relativity and Length contraction can You make a video about it
Hi, yes you can get a length contraction from classical mechanics. I am currently making a video about how you can get a special relativity purely from classical series of mechanical pendula
I don't think it's correct to say SR doesn't tell you which frame is accelerating.
Because it says "The laws of physics are the same in all inertial reference frames". And the laws of physics tell you which frame is accelerating.
If we use Newton's Laws for the Laws of Physics, the first Law tells us which objects are accelerating.
It's basically the statement that inertial bodies follow geodesics.
We can modify the laws to be relativistic, but that doesn't change the result.
Acceleration, even in SR, is defined relative to geodesics.
Whether or not that is entirely internally consistent is another matter and subject to much debate(see Mach's principle etc.)
The point is that the "laws of physics" should provide a way to determine acceleration.
GR gives us a more refined way to calculate geodesics, but that doesn't really change anything about the principle.
Invoking the equivalence principle seems circular.
You either have to already know that clocks tick faster ahead of an accelerated observer, which is a result purely from SR, or know all results from GR, which uses SR locally.
And this has nothing to do with "gravitational time dilation", because there is simply no gravity there. A local measurement simply has nothing to do with gravity exactly by the equivalence principle.
We shouldn't expect SR to reproduce gravitational effects. The time dilation between the earth twin and the rocket twin is in no way equivalent to gravitational time dilation because it is not a local effect.
yes if we take the special principle of relativity then the laws of physics determine who is inertial and we can therefore calculate everything. Acceleration is absolute and no paradox. The paradox can be restored if we take the general principle of relativity which states that the laws of physics are the same in all frames of reference. Then we have to use equivalence principle.
So yes, STR as it is formulated has no paradox.
I don't fully understand this statement though.
"And this has nothing to do with "gravitational time dilation", because there is simply no gravity there. A local measurement simply has nothing to do with gravity exactly by the equivalence principle."
As far as I understand equivalence principle tells us that we can treat inertial forces as gravitational.
@@lukasrafajpps I think what he means to say is that true gravitational time dilation has a derivative for the gradient instead of the gradient alone. For example, if an observer floating in space has two clocks on his head ticking at the same rate, a person in an upward-accelerating elevator might see the clocks on both ends ticking at different rates, but because he is in free-fall (geodesic), he doesn't see any deviation. It's an apparent effect. In the true gravity case, two satellites in free-fall around the Earth, separated by a large distance, still experience different amounts of time due to curvature, which also causes tidal forces.
@@lukasrafajpps "Gravity", if you're interested in involving General Relativity, means spacetime curvature.
A "gravitational force" is an inertial force resulting from being in an accelerated reference frame.
These are different things.
Gravitational Time Dilation is a spacetime curvature effect.
There is no spacetime curvature in the twin paradox.
The time dilation the accelerating twin observes has _nothing_ to do with spacetime curvature, but is an effect from from curved _coordinates_ (Rindler) in flat Minkowski Space.
The fact that it is a globally uniform effect tells us that there is no curvature.
The gravitational force we observe close to the surface of earth is _entirely_ explained by being in an accelerated reference frame. In GR that isn't an "equivalence" but an equality. The surface of earth is factually accelerating outward.
But this is a _local_ effect.
To see the difference, consider the Pound-Rebka experiment as an example.
The redshift is calculated using local earth acceleration g. The surface gravity.
But the gravitational time dilation at the surface of earth, compared to a distant observe, is not related to the surface gravity but to the local escape velocity.
A different planet, with the same surface gravity but a different escape velocity, due to different size and density, would reproduce the local redshift(assuming we didn't introduce large tidal forces to the experiment), but have a different gravitational time dilation.
We don't have to _use_ the equivalence principle to give us predictions. Because it doesn't tell us what the connections are. It doesn't explain anything.
We have to _satisfy_ it in our formulation of the laws of physics.
GR does this by using a covariant formulation that always includes a spot for inertial forces, the Christoffel Symbols.
The Christoffel Symbols in Rindler coordinates will have non-zero components, showing the time dilation in the direction of acceleration, because they are curved (so do simple polar coordinates on a flat plane), that does not indicate spacetime curvature, as the Riemann Tensor is still zero.
The Christoffel Symbols can indicate both, curved coordinates, and/or spacetime curvature.
No, the laws of physics don't tell you shit. As in, the parameters of those laws don't change. You're just rambling in discourse space to make it “sound right” rather than anything mathematically trackable.
update link of nord its not working mr
Hi, it's weird because for me it works. Sadly I don't have any other link.
While relativity comes down to making good predictions for what instruments will verifiably record, and so no evidence has yet contradicted it, it’s outside these cases of verifiability that I take issue. The paradox is not what will happen when we verify what will happen (upon the twins return), but rather, what is happening at a distance. When the twins are traveling apart or towards each other before the return, who is aging less. Under the relativistic model, Depending on who you ask and their frame of reference, all aging possibilities are happening simultaneously. Both twins are aging less, more AND not at all relative to the other, and by varying degrees on a continuum. This to me points to a model error.
When two people walk away from each other, each person will see the other person appear to be smaller as they get further away from each other... but each person stays the same size, yet the other person sees them shrink.
How is it possible for things to look smaller when they are further away?
@@juliavixen176 why you even asked this question is very confusing to me. It might be best you make your point.
@CausalDiscoveries The point is, that it's the same model that you're objecting to. Alice and Bob travel away from each other at a high velocity. From Alice's clock, Bob's clock will appear to be running slow. And from Bob's clock, Alice's clock will appear to be running slower.
This isn't a problem.
@@juliavixen176 is SR strictly about appearances? Which one’s time is truly running slower than the other?
@CausalDiscoveries Neither.
Every inertial observer will *_always_* be at rest with respect to themselves, and *_always_* measure one hour per hour, one minute per minute, and one second per second on their own "proper time" clock. Always.
Space and time are the same thing. Every location in space is also a location in time. No two things are ever "at the same time" unless they are "at the same place".
Every point in space is located in the past of every other point in space. Both ways, symmetricly. Your feet are located about six nanoseconds in the past from your head, and your head is located about six nanoseconds in the past from your feet.
When you look with your eyes at what is a straight line, radially from the tip of your nose to the _visible_ edge of the universe, you are looking down a 45° line on a Minkowski diagram. (In General Relativity, it's a geodesic path.) What you see "right now" is the past. That's "time", it's the radius of a 3D sphere in Cartesian space. Using complex numbers is a clever math trick for translating between points that are located "in each other's past"... because velocity (space/time) is a rotation angle. (Complex Numbers are rotations.)
Oh, I should mention, just like you get a stack of 2D circles by slicing a 3D cone. You get a stack of 3D spheres by slicing a 4D hypercone. Hence the name "Light Cone" for the present moment of "things happening *_right now_* ". If you rotate the slicing plane through the cone, you get ellipses, parabola, and hyperbolas... which is "velocity" - a rotation of the slicing angle - a ratio of a space coordinate to a time coordinate. This is literally the math for Special Relativity.
Anyway, the thing about the so-called "Twin Paradox" is that each twin is traveling along a different path _through space_ *AND* a different path *_through time_*
If Alice and Bob live in the same house, and Alice walks 5km to the store, while Bob walks 4km to the post office, and then 3km to meet Alice at the store. Then Bob measures 7km of space to have passed, but Alice only measured 5km of space to have happened between when she last interacted with Bob.
You don't find that confusing?
The twins also traveled a different distance in time.
You don't notice planes of simultinaity (3D slices of a 4D light cone) rotating very much at the human scale on Earth, with the senses of the human body. So, most discussions of this use _relative_ velocities a significant fraction of the speed of light to make the effects obvious.
Personally, for me, they way that I would explain why one twin is younger than the other after taking two different paths though 4D spacetime between two different points in 4D spacetime (departure and reunion) is that (in the basic setup) the younger twin turned around in the past of the older twin. Because that distant (in space) turn around location is located in the past of the older twin. Remember: "right now", that is "zero time", is defined by the speed of light (the surface of a light cone).
There are only two absolute velocities in Special Relativity: zero, for anything with inertia (mass), and the speed of light relative to zero "inertial" velocity. That's it.
What you should ask yourself is: "Why does anything travel _slower_ than light?"
Hi…the person that is in the ship accelerating does not feel an uniform acceleration…it’s shown in the Rindler diagram,,everypoint in space has a different hyperbola that describes a different acceleration..
The acceleration is uniform. The traveling twin starts out with v(0)=v_0 and has a constant acceleration of -g until returning with v_f=-v_0.
HI, what I was saying it’s that the accelerating twin does feel a different acceleratiion in the front of his ship compared to the back of the ship,,,, in the first part of his journey..
@@albertomontecarlo6231 Sure, but this contributes next to nothing to the length along the traveler world-line.
Só acceleration is not relative then? If an observer B is accelerating away from A then this is an absolute universal fact and B will not assume A is in fact accelerating away from him?
So not all frames of reference are equally valid?
"proper" acceleration is absolute. If A and B have accelerometers, and one of them is experiencing a "force", it will be a universal fact which one of the accelerometers will measure an acceleration.
This still leaves either frame equally valid, but not equal. The principle of special relativity only applies to the one who is not accelerating. The accelerating one will need to use different laws of physics (include inertial forces, etc).
In General Relativity things get more interesting. In curved spacetime two observers can accelerate relative to each other without either accelerometer measuring anything.
The principle of general relativity applies to _all_ observers and they can all use the laws of physics as formulated by General Relativity.
The possibility of inertial forces is included by default in the formulation of these.
Acceleration is absolute. Everyone can observe who is accelerating and with how much force.
_"So not all frames of reference are equally valid?"_ - correct. Frames that accelerate differ from frames that don't; the physics laws are different. In accelerated frames there is a mystical pseudo force that pulls everything to one side.
I wonder what acceleration is relative to…
@@asherweinerman400 Woah... that's heavy...
Out of curiosity, though I completely understand the physical manifestation of the measurements, of two Reference frams.
What is occurring in the space of two different frames. Ie. At the quantum level, what is occurring in the interactions, especially in different gradients of a gravitational field.
Ie not simply the passage of time but the physical mechanics of the gradient in time dilation. Like... Is there an adjustment (phase change) to renormalization. I'm curious if there is research on the subject that you may provide links too.
It is not the acceleration, it is the total spacial path. Longer spacial path means less time.
Explain why GPS doesnt use einstein equations? Contrary to what many believe...
It does.
@@kylelochlann5053 it does only for gravitatational time dilation, for motional time dilation and synchronization of clocks, it uses galileian equations where speed of light is not a constant. Why?
@@lobohez7222 No, it uses both GR and SR to pre-program the clocks. There are in-flight adjustments.
Equivalence and Acceleration doesn't solve it though... assume the acceleration of your engines goes from 0g to Xg; your computed time dilation would then be a square wave from 1 to whatever dilation that gravitational acceleration gives you, and then back. That's a simple sum doesn't even really require calculus... but whatever that is, you could change the length of the trip such that that does not match the same total dilation that happened. (did you even attempt the math?)
The postulates of special relativity should be refined to say 'the speed of light that travels the same distance in two-ways'. Second - the postulate that all physics is the same in all frames is an assumption that cannot be proven... it's also hard to falsify at our current level of technology though. Parker solar probe is only 191km/s - which is 1/2 of our speed through the universe, though I suppose the additive velocity might at times be 1.5x our speed... that's still a small fraction of the speed of light, I suppose they should include a particle accelerator and muon detector on the next parker-space-probe-like craft... and measure a different anomalous G-2 result.... the difference between experiment and measurement is 0.012%... this is exactly the fraction of the speed of light that the solar system is moving in the universe. (Is physics REALLY the same in all frames?)
Which is actually not to say that the laws of physics aren't the same in all frames..... But they would have to include the time dilation of the frame that they're in and/or speed... Then they would end up being the same donatos we currently have them define
The 2nd postulate is indifferent to the direction of the light.
The speed of our solar system through space is zero.
@@kylelochlann5053 not relative to the CMB or even angular change in the galaxy
@@kylelochlann5053 any direction of the two way path of light yes.
The original paradox addressed by Einstein is not about twins aging at different rates after one of them started a journey from Earth at high speed and returned back years later. It's about identical clocks ticking at different rates when moving relative to each other according to special relativity. For clock A clock B is ticking faster. For click B clock A is ticking faster. That is the original paradox which could be called "the identical clock paradox". And it was solved by Einstein by addressing it as a problem of simultaneity of events, not by using gravity or accelerated frames of reference. You mention you cannot write the same spacetime diagram for the travelling observer because it only applies for inertial observers but as far as I can see the travelling observer is also inertial, i.e. not accelerating. That's unclear to me.
Error: 3:02 A non-zero 3-acceleration does NOT imply a non-zero 4-acceleration, and neither does a zero 4-acceleration imply a zero 3-acceleration.
Its sad that Don Lincoln tries to defend the validity of his argument, when clearly he is only partially correct and his argument is shoddy science because he tries to use authority to argue science rather than logic. "Im an authority so accept my argument as correct-just cause im me, dont worry about it dont question other aspects and viewpoints just forget about it" That seems to be the tone of his exposition. Then he makes a follow up video saying basically, whatever critiscism they have on me, basically Im still right --if you squint your eyes and dont look directli at my presentation. The point of something like this and other's criticism of his presentation is to spark debate on a subject thats many faceted--as witnessed by the many examples that exist supporting different viewpoints. In some acceleration is important and in others not. Dons too worried about the promotion of his video rather than about science---and that is deeply dangerous!
Shut up and calculate.
That was the essence of Sabine's video.
I don't know if these people are dumb, or just playing dumb.
Space and Time are separate frames of reference.
Light travels in its own frame of reference. Independent of its source. The source's frame has been accelerated but not the photon's. You have to be a complete moron (Albert Einstein) to not understand why the moving clock is slower.
The clocks cesium-133 atom is being chilled to absolute zero. Are the observers atoms also being frozen? The observer is not even in the same time frame of reference as the clock.
Once again. Space and Time are separate frames of reference. Clocks measure motion in space expressed in units of time. They are not measuring time. They are measuring distance traveled in space.
And as for Einstein’s relativity. SR is Newton's non-inertial frame where the mass is accelerating itself. Walking down the street, the mass is accelerating itself.
GR? Inertial frame, conservation of energy. The mass is being accelerated by an outside force. Gravity is an artifact of that Inertial frame. The resistance of the mass to being accelerated. Standing on the ground, the earth is accelerating you and you are accelerating the mass of air above you. Which is why you get lighter as altitude increases. There is less mass above you, pushing back.
The traveling twin? E=mc where c is the maximum acceleration of the mass or the person's lifespan. Since there is no data on E for the observers, we can only go by the clocks energy usage. Since both clocks used the same amount of energy, both twins experience the same amount of time. One just experiences more space - distance traveled.
Relativity is a scam. Einstein was a dimwitted plagiarizing patent clerk who didn't understand what he was stealing. Of course his minions are going to defend him and leave out information. Like astronaut's heart rates being in an accelerated state during lift-off (high g-forces). Or that clocks in motion use the same amount if energy as stationary clocks - space and time are separate frames of reference.
F=G(m1m2)/R2. The universe is gravitationally bound to Earth's frame of reference. These clowns actually think the universe revolves around the earth. Which is a stationary frame.
So what are you going to do about it? The scientific community is either lying to you are complete idiots. As Carl Sagan would say, both possibilities are equally frightening.
I enjoy your presentations, but I have to disagree vehemently with this one. I believe that you have things exactly backwards when it comes to the Equivalence Principle.
The way that you (and very many popular explainers of General Relativity) describe it is this way:
To calculate the effect of acceleration on clocks:
1. We invoke the Equivalence Principle, and transform the problem into an equivalent problem involving gravity.
2. The feeling of acceleration is interpreted as a kind of gravitational field that suddenly turns on.
3. We use gravitational time dilation to calculate the effect of this gravitational field on clocks.
Okay. What's wrong with this description? Well, ask yourself how gravitational time dilation is computed. The answer is exactly the reverse process.
To calculate the effect of gravity on clocks:
1. We invoke the equivalence principle to transform it into an equivalent problem involving acceleration.
2. The gravitational field is then interpreted as the inertial forces that result from acceleration.
3. We use special relativity to calculate the effect of this acceleration on clocks.
The latter description is the way that Einstein DERIVED gravitational time dilation. By applying Special Relativity to accelerated clocks.
To quote WIkipedia:
Gravitational time dilation was first described by Albert Einstein in 1907 as a consequence of special relativity in accelerated frames of reference.
This was 8 years BEFORE he developed a theory of gravity. So you've got things exactly backwards. Einstein didn't use the equivalence principle as a way to apply gravitational theory to accelerated observers---he used the theory of accelerated observers (as described using Special Relativity) as a tool for developing his theory of gravity.
You don't need the equivalence principle to calculate the effect of acceleration on clocks. You need the equivalence principle to calculate the effect of gravity on clocks. The equivalence principle allowed him to reduce an unsolved problem---how does the Earth's gravitational field affect clocks--to a solved problem--how does acceleration affect clocks.
This is a confusion that has persisted in physics ever since Special Relativity. Even Einstein took some time to get it straight.
Many people think that Special Relativity is a theory of inertial observers, and General Relativity is a theory of noninertial observers. That is completely wrong. Special Relativity is a theory of FLAT spacetime, while General Relativity is a theory of CURVED spacetime.
You can handle accelerated observers in Special Relativity in exactly the same way that Newtonian physics can handle accelerated or rotating observers. It's just a change of coordinate system. Newtonian physics is usually presented using inertial Cartesian coordinates. Newton's laws look the simplest in those coordinates. But if you really want to, you can rewrite them using curvilinear or accelerated coordinate systems. It's just calculus---if you know equations of motion in one coordinate system, then you can use calculus to figure out the equations of motion in another coordinate system.
But things are messier in curvilinear or accelerated coordinate systems. In those coordinates, there are apparent "fictitious forces" that have no physical cause, but are just artifacts of your choice of coordinate system. These include (1) the "g-forces" that you feel when you are accelerating, (2) the centrifugal force that is felt when one is traveling in circular motion, (3) the Coriolis force that is felt when you move in a rotating coordinate system. These forces are "fictitious" in that they don't actually result from interactions with matter or fields, but they are extra mathematical terms that appear in the equations of motion.
Newtonian physics works perfectly well in non-inertial, curvilinear coordinates, it's just a little more complicated looking.
In exactly the same way, Special Relativity works perfectly well in non-inertial, curvilinear coordinates, as well. It's just more complicated looking. If you try to apply Special Relativity to accelerated observers, or to use it with curvilinear coordinates, you get "fictitious" forces in the same way that Newtonian physics does. These fictitious forces in Special Relativity do not only affect the motion of objects (in the way the Centrifugal and Coriolis forces do) but also it affects clocks. This is not a new effect that requires General Relativity for justification--it is an effect that is derivable from Special Relativity by just using calculus to change coordinates.
The connection between General Relativity and curvilinear, noninertial coordinates is that in the presence of gravity, there ARE no inertial coordinate systems. So curvilinear and noninertial coordinates are required to do anything. And those coordinates have effects on the motions of objects and on the elapsed time on clocks, just as they do in Special Relativity.
So there's three different stages in going from Special Relativity to General Relativity:
1. Special Relativity in flat spacetime using inertial, Cartesian coordinates.
2. Special Relativity in flat spacetime using noninertial, curvilinear coordinates.
3. General Relativity in curved spacetime using noninertial, curvilinear coordinates.
4. A theory of how matter and energy cause spacetime curvature.
Going from 1 to 2 doesn't require a theory of gravity, it only requires calculus. Going from 2 to 3 requires a theory of curved spacetime, which is also not fully a theory of gravity. You need 4 to get a full theory of gravity.
You do know that Nicholas Tesla labeled relativity as mathematical nonsense and your posting proves it as such.
Relativity stems from a lack of not understanding Newton's Laws of motion. But that's okay. Newton himself didn't understand them which is why he developed his gravitational attraction nonsense.
First Law.
An inertial frame is one that gets its acceleration from an outside force. You riding the bus is an inertial frame.
A non-inertial frame is one that accelerates itself. You walking forward on the moving bus is a non-inertial frame.
2nd law.
F=ma. Force TIMES Acceleration. Force comes from Acceleration of the mass. Not the mass itself. There is no gravitational attraction because mass is not the actionable force.
3rd Law. Action and Reaction. Gravity/g-force is a Reactionary force. The resistance of the mass to being accelerated by an external force. Rubbing two sticks together creates resistance. That resistance is 'gravity' according to Newton's laws of motion.
The Equivalence principle states that gravity and Acceleration are equivalent. What it fails to say is that acceleration creates gravity. Newton's Reactionary force.
That's why Einstein labeled gravity a 'fictitious' force. It's an effect.
The Equivalence principle as it relates to Energy. Mass and Energy are interchangeable stems from
Energy can be neither created nor destroyed, only transformed. E=mc where mass is a form of energy that is transformed via Acceleration.
What Einstein didn't understand concerning his relativity theories is that motion is absolute.
Nothing can travel faster than light = motion is absolute.
Light travels in its own frame of reference = motion is absolute to the frame of reference.
What Einstein didn't understand is that Space and Time are separate frames of reference. The earth rotating on its axis as it orbits the sun is motion in space. The energy being emitted by the sun is what accelerates plants in Time. Southern trees have higher growth growth rates than northern trees because of the differences in sunlight. Tree ring patterns change from year to year because of changes in weather. A tree doesn't grow faster or slower because of some 'fictitious' force. It accumulates mass based on energy. E=mc.
So what is going on with atomic clocks. Why one is slower than the other. First. The cesium-133 atom is being chilled to absolute zero. This takes out any Acceleration/oscillation the atom has. It is then accelerated to the proper frequency for its location by an electrical current. Electromagnetic waves travel in there own frame of reference, independent of the source. That's two frames of the reference. The source frame and photon's frame. The clock's frame has been accelerated but not the photon's. Applying Newton's Laws of motion, the inverse square law of motion, the photon's force decreases with distance. Clocks measure motion in space expressed in units of time. Any 'time-dilation' taking place is strictly in the clocks frame of reference which is translated into increased motion in space.
Clocks in motion use the same amount of energy as stationary clocks showing that they both experienced the same amount of time. One just experiences more space.
The observer is not in the same Time frame of reference as their atoms/cells get their Acceleration/Energy from a different form.
Relativity = pseudo-science = mathematical nonsense.
Astronaut's have ACCELERATED heart rates in a high g-force environment. The clock is slowing down because the photon has a greater distance to travel while the Astronaut's heart rate is increasing because more force is being applied and resisted. Same as rubbing two sticks together.
Gravity = Reactionary Force.
Relativity = pseudo-science = mathematical nonsense. Motion is absolute to the frame of reference.
An accelerated heart rate does not equal a longer lifespan.
@@stewiesaidthat : Tesla was wrong.
@@stewiesaidthat : Your explanation here does not make much sense to me.
First point:
You wrote: F=ma. Force TIMES Acceleration. Force comes from Acceleration of the mass. Not the mass itself. There is no gravitational attraction because mass is not the actionable force.
I can't make sense of that. The way that Newton understood it was that force was a CAUSE of acceleration. If you pull or push on an object, it will accelerate. The mass determines how much acceleration is caused by a given force. If the mass is small, then the same force produces a larger acceleration. If the mass is large, then the same force produces a smaller acceleration. You can see this by trying to push an automobile. It doesn't accelerate very much.
Saying "mass is not the actionable force" doesn't make any sense to me. Mass is not a force. It is a measure of how much stuff--electrons, neutrons, protons, etc.--are in an object.
Saying that there is no gravitational attraction is just completely wrong. Take a ball. Let go. It falls to the ground. That's gravitational attraction at work.
You wrote: "The Equivalence principle states that gravity and Acceleration are equivalent. What it fails to say is that acceleration creates gravity. Newton's Reactionary force."
That's not correct. Acceleration does not produce gravity. If by "gravity" you mean the tendency of massive objects such as a rock to be attracted to another massive object such as the Earth, that is not produced by acceleration. Even if nothing is accelerating, there will be that force.
To go on: You wrote: "The Equivalence principle as it relates to Energy. Mass and Energy are interchangeable"
That's completely wrong. The equivalence principle is not about matter and energy being interchangeable. It's specifically about gravity. The equivalence of matter and energy was a consequence of Special Relativity, which doesn't have gravity at all. The word "equivalence" appears in both, but they're not the same principle. One relates gravity with fictitious forces. One relates matter and energy. Two different principles.
First of all - too many words and sideways explanations before explanation.
OK, let say that one twin gets older. What happens when they meet again in the same space time? If I turn really fast can I meet my older self?
I do not really agree with the premise of this video, and by now we should not be calling these things paradoxes 100 years later, rather than early confusion for a few years when smart people were making sure the theory was consistent.
If you had two twins A & B and B left for a trip, the video argues you need to define one (A in this case) as the base inertial frame and you need that knowledge.
But that is not correct.
Imagine B did leave for the trip, but they then instantly forgot who left and who stayed. if they forgot who left and A thought they had left, and then A "turned around (for want of a better description)" and went back to B (which is really just a huge acceleration given B will never stop), the result will be the same, but in reverse.
It is simply wrong to imply you need to know the starting inertial frame.
For a second i thought matt parker got hair implants
The variables in gravity math are NOT causal. Number analogies are not an understanding, and that math can lie to you. "The wheels on the bus go round and round." This song describes everything you see a bus do EXACTLY like math does, but you wouldn't agree that wheels going round are causal - WOULD YOU? Dimensions are a number game that helps math work, but you cannot show me dimensions 1 or 2 in real life, and you have a series of theories that ADJUST these fake dimensions. What if that math is lying to you? It's the only thing taught to anyone. Even if it was obviously wrong, in these conditions, you wouldn't see it, because that's how paradigms work.
Dont you have to go to the future to go back to the past?
Great video. I was with you until you said you have no tools in SR to interpret the force, but that's not true: they will see a change in red/blue shift. You can actually watch the changes in all clocks around you via light. The trick with the accelerometer is that it only works when you fire your engine, or stand on the ground pushing you up in a gravitational field. If the whole accelerometer (springs and all) are accelerated uniformly, it won't tell you anything. But light... ligt will tell you the whole picture.
Wrong
Light is subject to gravity. A laser accelerometer will show the same results in a local part of the gravitational field. And neither will show any proper acceleration in free fall.
_"you have no tools in SR to interpret the force"_ - he meant, you have no tools to distinguish between acceleration by a rocket engine, and standing on the surface of a planet.
_"they will see a change in red/blue shift"_ - they will see the same red/blue shift in the light, so that does not distinguish them either. Light appears to blue-shift when traveling down a gravitational field.
@@renedekker9806 Light "traveling down a gravitational field" is both red-shifted and blue-shifted, depending upon the observer, e.g. Lemaitre and shell observers, respectively.
@@kylelochlann5053 _"Light "traveling down a gravitational field" is both red-shifted and blue-shifted"_ - ok, I should probably have phrased that more precisely. For light received by a stationary observer lower in a gravitational field, which comes from a stationary light source higher in the gravitational field, the received frequency will be blue-shifted wrt. the source frequency.
If that gravitational field can be considered to be a uniform field, then that frequency shift will be the same as in a similar accelerated frame.
Or the point in short: you cannot use light to distinguish between a uniform gravitational field and an accelerated reference frame.
Sweet Jesus, could you please answer this yes or no: THE TWINS-PARADOX IS SOLVED BY CONSIDERING THE ACCELERATION.
Yes
It can be solved by considering acceleration. But acceleration is not necessary to get the correct result.
NO. The TP is solved by integrating over the world-lines of the twins. The acceleration is basically irrelevant.
Yes
Yes, the Twin Paradox requires acceleration and here's why: The Triplet example gives the same elapsed times as the Twin Paradox when you sum the elapsed time on B's clock from B departing A to where it is coincident with C, and the elapsed time on C's clock from when C meets B to its arrival at A. However, if for the sake of argument B and C's clocks are synchronized when B leaves A, B and C's clocks will not agree when they meet up; The time on B's clock will be further ahead than C's. This is due to the Relativity of Simultaneity when the clocks were synchronized. Now consider the scenario where B reverses direction, i.e. undergoes an acceleration, so that it too returns to A, alongside C, so they arrive back at A together (i.e. the Triplet example returns to the Twin Paradox, where A and B are the twins),. Remembering that the Triplet and Twin Paradox scenarios give the same result, and that B's clock was ahead of C's, B's clock must slow to match C's clock before they both arrive at A together. If this wan't the case B and C would disagree on A's age when they all meet up. An explanation of how this slowing down of B's clock occurs is gravitational time dilation given by General Relativity. But just to confuse things further, you can also calculate the slowing of B's clock using Special Relativity alone with Rindler coordinates or if B reverses instantaneously when B and C meet, with the simple Lorentz transformations in a flat, Minkowski spacetime.
Maybe time doesn't exist (man made phenomena) and should be seen as a sequence of events.
You just made that up.
You would like Carlo Rovelli
1) Space and Time are separate frames of reference
2) Clocks are instruments that measure motion in space
3) the clocks cesium-133 atom is being chilled to absolute zero while the observer's are at room temperature.
4) the clock is being energized by an electrical current emiited at a constant frequency. The observer's cells get their energy from the oxygen in the environment.
5) Both clocks use the same amount of energy. The difference in readouts is due to the extra motion in space. Clocks measure motion in space.
5) astronauts experience accelerated heart rates during lift-off while the onboard clock is registering fewer clock cycles. Space and Time are separate frames of reference.
Acceleration in time is energy dependent. Since the biometrics are not included, the only logical conclusion is that both twins experienced the same amount of time, and are the same age. One just experienced more space.
I am afraid there is a very important conceptual mistake in the explanation. It is definitely not correct to say that in special relativity (SR) every observer is inertial by definition. SR is not a relationist theory, i.e., motion is not merely relative but Newton's absolute space reigns.
The accelerometer absolutely tells you if you are inertial or not. Newton's absolute space is also present in special relativity (even in GR). Inertial frames are those where the principle of inertia holds and that does not happen in arbitrary frames. Another way to define inertial frame is (according to, for instance, Landau & Lifshitz) that time is homogenous and space is homogenous and isotropic. Those properties of spacetime do not hold in non-inertial frames.
The author (who I used to follow and admire) should discuss this issue with an expert and see if he can correct his presentation.
The laws of physics are equally applicable in ALL frames of reference. That rules out a Special and General law right there. Need I go further?
Gravity/mass attraction is not a fundamental force of nature.
F=ma. Force comes from Acceleration of the mass not the mass itself. Comprende.
E=mc where c is the speed of light. Acceleration is defined, bounded, limited. Motion is absolute. There is no Relativity when you have absolutes.
Speed is distance/time. Two separate frames of reference. Motion in space is independent of that in time. So much for that spacetime nonsense.
What is truly inconceivable is that not a single experiment. Not a single equation, shows that mass is an actionable force. There is no evidence to support Einstein’s fantasy universe and yet it's preached as gospel. Why?
Galileo proved experimentaly that mass is not an actionable force.
Newton provided the math. F=ma, Force comes from Acceleration. Einstein himself said that gravity was a fictitious force and that acceleration was the frame of reference. Then Newton and Einstein tool it back. Reversed course and have force back to mass. Why?
F=ma. Force equals Acceleration equals Acceleration equals Acceleration. Get the picture? If Acceleration is the fundamental force of nature, what is Acceleration. Where did it come from. E=mc. Who turned on the lights. E=mc. Acceleration creates mass. What is Acceleration then.
Do you think a dimwitted patent clerk like Einstein could answer that question when he didn't even understand that Space and time are separate frames of reference. That clocks measure motion in space. That light travels in its own frame of reference, independent of its source. That the source's frame has been accelerated but not the photon's.
Do you honestly expect a plagiarist who didn't understand what he was stealing to be able to answer the ultimate question. Where does Acceleration come from?
Right back to the passage in the Bible. And God said, let there be light. And out of the darkness, the universe was created.
That's why these idiots back tracked on Acceleration being the fundamental force of nature and not mass. Acceleration requires an outside force to set everything in motion. What is that outside force? Is anything even real if all there exists is Acceleration. F=ma -> E=mc. Out of nothing, absolute zero, complete darkness, you now have something. Explain that Einstein. How do you get something from nothing?
E=mc. Only Acceleration is defined. Bounded, limited, Absolute. Mass/space is undefined, boundless, infinite. You can't warp space because Space doesn't exist. It hasn't been defined, bounded. You can only warp Acceleration.
Now, do you think a couple of simpletons like Newton and Einstein could understand what Acceleration is? It all leads back to one thing. An outside force acting on this universe. A god of Acceleration so to speak. Can't have that in science. There must be some other explanation. But they themselves invoke a god with the BB theory. Out of nothing something is created. They just theorize that space and time are created in concert while E=mc shows that only Time was created at the moment of the BB. Space is infinite. It's time (information about the infinite universe) that is expanding. And that is what Acceleration is. What light is. Information. You are back to two possibilities. There is a god or nothing is real. Virtual reality. A computer simulation. The Matrix for a movie reference.
@@stewiesaidthat You really did not need to go further after your second sentence. This website might also be interesting insti.physics.sunysb.edu/~siegel/quack.html
@@stewiesaidthat You really did not need to go further after your second sentence.
@@justopastorlambare2933 I know. That's the problem with modern physics. They don't want to go any further than their flat earth view of the universe.
Where does Acceleration as the frame of reference take them? Is anything real? To them, Acceleration is not real. Only mass is real. You can touch it, taste it smell it and even see it. But that is all just information. How do you know that information depicts reality and not a virtual world.
Just as your ancestors created a god to separate man from beast, there also needs to be a 'god' to separate real from virtual.
Acceleration is beyond physics. Is mankind ready to go there? Why else would they create a god in Einstein?
First he says motion is absolute and then it's relative. Next he says gravity is an emergent property of Acceleration and then says mass creates Acceleration.
Newton. Same thing. Acceleration takes them out of the matrix and into a new reality. What is that new reality?
No
Dialect
You know Dialect has already been writing comments on this video.
@@juliavixen176no I didn’t- thanks
Omg STR is about inertial motion only! That is why STR has always had a twin paradox and was rightly considered as nonsense. Don’t believe me then read Einstein’s paper from 1918. He was force to give a solution to this from all the criticism he got and he used GTR. Basically this means he is abandoning STR. You need to look at the history. Try “Relativity from Lorentz to Einstein: A guide for beginners, perplexed and experimental scientists” Lots of references to relevant literature. Here are some others, “Science at the crossroads” by Herbert Dingle, “A scientific adventure. Reflection on the riddles of relativity” by Ian McCausland and the recent “New Relativity in the Gravitational Universe” by C S Unnikrishnan. Another is Tim Maudlin’s “The Philosophy of Physics. Space and Time” where he also says that acceleration does not solve the twins paradox but gives his solution … which also doesn’t work😂
That's just not correct. Special Relativity works for accelerated frames, as is mentioned in the video. It just doesn't extend the principle of relativity to them. They need to use different laws of physics.
What Special Relativity doesn't deal with is gravity. But there is no gravity in the twin paradox.
@@narfwhals7843 I will make it more clear. Well if you want to rewrite the theory so dilation is caused by acceleration and not speed then go ahead. But it isn’t STR.
@@markszlazak I don't want to do that. Time dilation is not caused by acceleration.
But special relativity has no problem dealing with acceleration.
That has nothing to do with history. These are facts of the theory.
@@narfwhals7843 We are talking about the twins paradox and if you really want to understand it then you do need to spend time going into it.
There is no twin paradox because they are always the same age in a flat space without gravity. It's just an observer illusion, and is not real. The time period is the same on both ships.
Why are you saying that they are in a flat space?
@@cristiandalessandro599 It's SR, not GR.
@@axle.student Acceleration in SR is where gravity comes from
It is not an illusion. Two clocks that get separated and returned together will not necessarily read the same elapsed time. This is experimentally verified.
@@narfwhals7843 Where is this verified. And please don't quote the flawed plane experiments in earths gravitational field.
a signal travelling a longer distance doesn't mean time is slowing down.. its ridiculous.
And speaking of paradox.
If you and light are travelling in the same direction and your accelerating and your time slows down it keeps the soeed of light c, but if light is coming towards you and you are moving towards the light accelerating or not , your time slows down meaning its no longer c, its much faster the speed of ç. It only works when you and light are travelling in the same direction, relativity is pure imagination and not true
You failed to grasp c at all
Yes I grasp it, it's wrong! You'd realise why if you read my comment and understood it..
The speed of light is not constant for accelerated observers. Only for inertial ones.
"Time slows down" is basically a meaningless statement. It just means that observers in relative motion have different ideas of what time should mean.
@@dexter8705 It's all just an observer illusion. The time intervals do not change in speed for any object, only the appearance of from a distance. What I just said goes against popular interpretation where everyone whats to believe in SciFi time travel.
Light clocks are a flawed concept. The ships (different observers) are not the same thing as the photons traveling between the ships. Observers see/view photons, not another ship/object moving at velocity. Both different objects photons and ships.
>
P.S. Working from the possibly flawed concepts of relativity.
How do you know what time it is when light needs more time from one side then the other and yet both clocks from your pov say the same time?
Have you heard of the channel: @ChrisTheBrain ? He has some really interesting videos about physics, but I can't tell whether or not they're nonsense. I'd be curious to hear the opinion of someone more knowledgeable