I don't claim i fully grasped all the details, but this is the best description i heard of curved space time and how it genrrates gravity. Much, much better than the massive ball placed on thin fabric animation.
Idiots only explain gravity with a stretched fabric and a ball. There is no fabric in space. The perception of top and bottom is only for us. There is no top or bottom for space. There is no direction for space, so there is no possibility of a fabric in one space plane. Also, this idiot should explain where the curvature first come to be in the first place. It is a circular stupid explanation, curvature comes from gravity and gravity came from curvature. Fact is, all physicists are lying to us about the Space.
It doesn't describe how it generates gravity. In fact, Gravity remains one of the most perplexing phenomena in physics. It explains how space-time, under the _influence_ of a gravitational field causes the attributes of falling objects. It is also defective, as are most such popular expositions, in explaining why _not-falling_ objects-such as the apocryphal apple hanging over Newton's head-seem to be under some mysterious influence. Eg., the mysterious apple(s) seem always to bend their branches _down._ That question always elicits a separate video, such as the ingenious/notorious dialekt's river-model of the matter. Yet others present the baffling accelerating-surface claim about GR: the apple is exerting no force on the branch, the branch is continually accelerating... _upwards_ . Entailed by that interpretation is the understanding that apple trees in southern New Zealand have their branches' acceleration in another direction. If all that is too hard for the average person to grasp, even with the help of some dodgy videos to help you over their spongy arguments, they may eventually resort to the claim that in HS physics the teachers lied to us about the meaning of... _direction._ I think that's easier than redefining the meanings of vectors, momenta, and acceleration.
i thought the same. If the object is standing still and only moves through time it should just follow the time path. So why it starts shifting towards the space part of the diagram i can understand either and the video doesn't explain this
Because of the warping of spacetime. The object was moving in a straight line through spacetime, along the time axis. Now the presence of the massive object has caused the underlying 'grid' of spacetime to warp in such as way that the line of movement through spacetime (ie geodesic) is no longer parallel with the time axis but pointing into the space axis as well. So some of the movement through time is diverted into movement through space in the direction of the massive object. No external forces are acting on the object - the shift of movement into space is caused by the change in spacetime geometry itself. Pretty mind bending.
The shortest distance between two points is a straight line. All celestial bodies warp the "fabric" of space, and create gravity wells. When a smaller object comes close to the rim of a larger object's gravity well, it gets caught in that object's orbit through mass bending space-time. It's similar to how water circles a drain, but it's an all directions. Everything in space is falling.
@@jonathanspruance4502 I am sitting here glued by gravity to my seat (and by my interest in the topic). But since I am absolutely certain that 'time' is a concept only, I'm in need of a different explanation. What is it in actuality that the temporal concept is actually 'about'?
@@jonathanspruance4502 Why does the object have to move in a straight line? Of course if it moves in a straight line it will move towards the space axis and thus the “falling” of the Apple. But why does the path have to be a straight line? Why doesn’t it just move along the curved time path since it’s standing still?
I'd be curious to know how to calculate how long it would take for two masses to get to the speed of light by mutual gravity and how far apart they would have to start. I'd like to know if that's really possible with anything that doesn't include a black hole as one of the objects.
Its never possible to reach the speed of light ...ever. ...unless it involves event horizon of black hole. Here spacetime is falling into (or rather warped) at light speed but only at point of event horizon. And once at that that horizon you are never coming back to report. A neutron star is closest next thing and you could crash into one of these at 99%+ light speed.. but never at 100%. You can have 2 neutron stars at 2 solar masses each crash together. They would crash together at 100% light speed but the boundary of where that happened would be exact the formation of a new event horizon of a new black hole which (as we know from theory and now from gravity wave evidence) always forms from merging of neutron stars.
Damn, you guys are good. I am kinda keeping up (when somebody offers amazingly structured explanation mostly) and i always feel like i would need a little bit more IQ or computing/projecting brainpower to join the top thinkers. Maybe a lot of power lol looking at some of the complex math implications some ppl can do. Hopefuly big part is knowledge and training and im not actually too far apart to justify using the word "im actually stupid conpared" 😅
Excellent explanation. After watching other videos on this topic, your video using the cone and illustrating how objects move around the cone -- really helps clarify the topic. Thank you. New subscriber.
If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
Sometimes (rarely) I'm in a mindset to understand videos like this. This one hit me in the right way at the right time. Very well done. I learned a lot. Thanks.
2 questions that the video made me confused about. 1. The initial flashlight beam of light had to have been significant in width for the difference in distances traveled between top and bottom "light fibers" to be different. Was the initial experiment based on two stars spaced far apart from one another? In that case, how did we determine that the light arrived to us from each star at the same time, since light has always been streaming from them to us, and we don't know precisely when a given photon was emitted? 2. When you roll up the spacetime diagram and say that "light only travels through space," I understand this is correct from the photon's perspective, but you appear to be rolling up the stationary apple's spacetime diagram. Wouldn't that diagram also have light spiraling along a helix, since from the apple's perspective light travels through the apple's time at a 45 degree angle to apple's space? It seems like you are mixing/combining the apple's perspective into the photon's perspective into one unified spacetime manifold, on which I just don't understand how you can be certain about the geometry of circular, helical, and straight line paths coursed out by different material objects. Maybe we can call this some higher dimensional "God's" spacetime manifold who sees the absolute truth in terms of distance and time?
@@HowDoYouKnowThough so we don’t spiral along. We move in a straight path along curved spacetime. This was found out by how light acted. We took measurements of this and found out the limit to motion of mass & energy as the equivalence principle was found. Taking this into account we know have lights constant speed over distance and distance. Hell that means to get time (the rest of the equation) we just plug and play. Let me know if ya have any questions
@@MrMoose1347there's no such thing as a straight path of you want to really get into it. Space is not straight, there are no fixed points anywhere in all of existence and everything is moving at a relative speed and rate of time to everything else.
@@MrMoose1347 the point you were making was a bit pedantic, I went a bit further. Everything is relative, everything interacts with everything, there's literally no such thing as a straight line.
At 06:07, can we say that the “stationary” object in space-time would move in parallel to the original timeline direction? I understand the analogy of cone to visualise space-time distortion. Under this analogy, the “stationary” object “is moved” in straight line in space-time. But what is the actual rule of this behaviour? Another question is... what if the huge object (i.e. the Earth) completely losses its mass after the “stationary” object is accelerated by space-time distortion for a period of time? Will that object stops immediately in space? Your video has the best analogy of gravity from my point of view (I am just an Information Technology guy). It makes me feel that gravity is a cause of distorted space-time by mass, and it acts on other objects with mass. However, can you tell me why mass can distort space-time?
The use of gravity to illustrate "space-time" which in turn causes gravity is not an explanation. Also, Einstein's failed General Theory implies that gravity is not a force also implies that light and massive objects should follow the same path through space and that light is not affected by gravity, because of the claim that light is massless, yet His General Theory implies that gravity can suck light into a hypothetical singularity. The entire General Theory of Einstein is built on impossible conundrums. Light bending in an atmosphere was always considered to be why light bends in the Sun's atmosphere. Others had predicted this refractive index accurately prior to Einstein, such as Soldner. Einstein simply did not understand this concept of refractive index in optical lensing. Gravity is caused by the implied flux density gradient of Gauss's Law for Gravity, which acts as an energy gradient, confirmed by GPS and atomic clocks.
@@JoeDeglman Where is the evidence that General Relativity has failed? Where? Proof by assumption statement like this is typical of someone with a pet belief and no education. General Relativity states gravity is a force. Someone has not read the General Theory of Relativity. Light being affected by gravity is what General Relativity is all about. Where did you get this stuff? Are you familiar with the experiments? "His General Theory implies that gravity can suck light into a hypothetical singularity." - No. Have you ever taken a course in physics?
@@geoffwales8646 the JWST also shows that these galactic halos also have a substantial dust atmosphere that acts as an optical lense to do the bending as a refractive index. Just like the Sun, bending of light only occurs through an atmosphere as a refractive index as an optical lensing function. No bending of light has ever been observed through the vacuum of space around a massive object, in contradiction of the GRT, where there is no atmosphere. The previous images of galaxies from Hubble were in the optical range and the dust atmosphere wasn't observed previously because the atmosphere of galactic halos emits in the infrared not in the visible. .
Depends on which arrow of time you’re referring to. The psychological arrow of time is an illusion. (Kind of) It’s more like our brain’s way of interpreting one piece of the great universal puzzle. It’s like saying colors are an illusion; depending on your definition of illusion…I guess they are, because colors are nothing more than your brain’s way of interpreting different wavelengths of visible light, but light waves are still very real though
Why would you think that? In physics, time is defined as the measure of a change in a physical quantity or a magnitude used to quantify the duration of events. You can find other definitions, especially ones that connect time with entropy, but in any case, it is certain that time is not an illusion.
The thing that throws people off is this name, “curved spacetime.” Sure, when you look at a rolled up piece of paper, or a digital graphic, we see the curve. But in reality there is no curve. Space is devoid of geometry. There is nothing surrounding the earth. Its literally enpty space. Wheres the curve? You have to remember that einsteins theory is just that, a theory. Yes it happens to align with how we perceive things to work, but it doesnt provide all the answers. Its just the best explanation we currently have. We dont understand the nature of space. Thats the issue here. When you consider this example, a rolled up piece of paper, that is one way to describe gravity. But the age old question remains unanswered, WHY does gravity exist? I believe thats something we can never know. Einstein explained the how. The why he had absolutely no idea. No one does, and no one ever will. Thats why after watching all these gravity videos, everyone has the same response, “eh, i guess it makes sense.” It can never make total sense until we understand the fundamental nature of the universe. Unknowable unfortunately. Why are things attracted to each other? Who knows, the just are 😁
1:45 - if space is contracted around a mass, then time doesn't actually need to run slower because the photon is still moving over the same amount of space. If you stretched a 10 x 10 grid and watched a ball cross that grid, it would still cross 10 grid lines.
You’re confusing the speed of time with the device that’s measuring time . Time is not speeding up or slowing down , it’s the device that you’re using to measure time that is measuring it faster or slower . Time is a constant and doesn’t speed up or slow down , however the device measuring it does .
Yes … the device you are using to measure “time” is affected by its place in a gravitational field, and the various accelerations it undergoes… once you account for those variables, any differences in two time measuring devices will be factored out …
“Time isn’t speeding up or slowing down it’s the device you are using” um….its measured motion so both time and the clock are being talked about when dilating.
There are a few mistakes because of over simplification in this video. For example the ball falling from an infinite high tower would not reach ligthspeed. The potential energy in a gravitational field is finite! So an object with mass cannot reach the speed of light.
Agreed, of course. I wrote the followingI comment ... f the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
Why does light moves only through time in the flat spacetime diagram wrapped in a cilinder at 3:25? Light does not travel through space only, it also travel through time, its speed is not infinite.
There is no "time" to move through, unless you mean the along the direction of some observer world-line, but you still have to choose such a world-line. That said, yes, light will move equally through the spatial and temporal coordinates of the observer, Δx=Δt.
7:09 - I am not a physicist, but I think that is the definition of terminal velocity. "The velocity a free-falling object would reach by the time it struck the surface". It's the same velocity as would take to achieve escape (velocity). On the Earth, that is around 11.186 km/s., not C. Now, from the event horizon of a Black Hole, it would be C.
My comment was: If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
@@MrMoose1347 but it would average the two? As you move away from one time is speeding up but as you move closer to the other it’s slowing down, so there has to be a point in the middle that matches the surface time right?
@@nunya3399 ah I see what you are getting at. We do account for travel gravitationally and by acceleration. Gravity is general relativity and acceleration is special relativity. When gps orbit earth it accounts for both. So not were they meet in the middle just where we account for both
I'm not against the use of SI, but I am against the notion of one person or a group of people telling others what convention they can or cannot use. I use both conventions, and I also use proper conversions when necessary. It all depends on the context of the problem that I'm working with. I do not buy fuel by the liter. I buy it by the gallon, and I measure my vehicles economic efficiency based on miles per gallon. When I buy milk, I buy it by the gallon or 1/2 gallon, not by the liter. Again, it all depends on the domain and context of the workspace. Now, if I was working in a lab and doing some chemistry and or physics, perhaps I would use the SI units, but again that still depends on the domain, context and workspace of the current problem. Only someone who is either ignorant or arrogant wouldn't understand this. I have the understanding and intelligence to use multiple formats and conventions, and I'm sure there are many others that do too. There is nothing wrong with someone else using miles as opposed to kilometers. Also, when I step on a scale to measure my weight, I'm measuring weight in lbs., I'm not measuring my mass in kilograms. The comment alone "stop using miles..." is condescending.
7:03 The iron ball would reach the speed of light? Relative to what? How could the height of the tower be infinite? How long would reaching the speed of light take? How would the speed of the ball be measured?
You would need infinite energy to move a massed object at the speed of light! My comment was: If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
speed of lite is the same relative to everyting, if you don't know that what are you doing here, watch some basic videos or you'll just get more confused
Question? since even deep space contains micro-gravity, what is creating the micro-gravity? The Gravity Probe B experiment detected something called "Frame Grabbing", where the Earth is grabbing space/time as it turns on its axis. Wonder if this had been further examined as to impacts to time?
Can you expand just a little more and in the extreme case of going trough an event horizon where the time and space axis switch? How would you represent that in a video graphic? And by the way....excelent video!
For a particular choice of coordinates, the Schwarzschild-Droste coordinates, the temporal and radial components of the metric tensor switch algebraic sign.
Understanding the "switch" is easier than many think. It sounds brain-bending that time and space switch places, but it's really just the fact that the singularity is the ONLY future of your light cone. Because anywhere you would like to maneuver when "falling" into a black hole, you will ALWAYS (100% of cases) meet the singularity (it's just in your light cone across all possibilities). The Penrose diagram has this brain twist in it, but from a simpler point of view, it's just that. Like when it's Friday night and you are out with friends, the beer is your 100% future :D (if you drink). I like to hypothesize that all singularities are the same (like in the SAME spot), because when you have a spherical universe (like an expanding balloon and space-time is its surface), when you do this 90-degree warp (like black holes do) from the surface, eventually this warp ends in the middle of the sphere. So all black holes point to the same "space/spot/something/singularity" :) . Just food for thought.
The time and space axes never switch. That is nonsense. Time is time and space is space. Minkowski was wrong with his quote ("Henceforth, space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality")!
Not only do objects moving at light speed experience time as zero, the space between their origin and where they land is compressed down to zero distance as well.
OMG, This is the first time I ever had a glimpse of understanding of gravity and space time change nearing a massive object, I THANK YOU so much for making this grasp able. I love eye opening Videos of this nature. Keep the good work :)
If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
at 4:27 what if you turned the funnel around so it was smaller the closer to earth and you swapped the time and space axis? would that work? or does that not make sense?
@@atticuswalker Not equivalent , with the earth scenario its a single mass and photons are taking a similar path , with a supernova the light take wildly different paths
Can anyone help confirm this for me? I've always found the twin paradox a bit confusing because, as I see it, the twins can never meet in a way that would cause one to be older than the other. Here's why: as the twins travel towards each other, their clocks would start to synchronize. By the time they are close enough to "meet," their clocks would essentially align, placing them on the same "time" line and making them the same age again. From my understanding, the only way the paradox could play out is if one twin traveled near the speed of light towards the other and could observe the other's clock. However, the idea that their clocks tick at different rates is something that seems to only hold from the perspective of an external observer outside both reference frames. So, what I'm asserting is that it's not accurate to say the twins could meet and be different ages because they could never technically meet under these conditions. The differences in their clocks are only apparent to an outside observer. Is my reasoning correct?
The gravitational field is not necessarily stronger at the bottom of the ocean trench, as it is highest at the Earth's surface and then gets weaker as one approaches the center of the Earth (where there is no gravitational field at all). So while clocks do go faster higher in the atmosphere, they will also go faster at the center of the Earth.
A clock at the surface of the Earth runs faster than a clock at the center. Not by much, the time dilation is 1.0000000003 between the core and surface.
In 7:24 minute you show curved space and the apple that falls. Please can you show all unit measures of curved space time when the apple falls with 9,81m/s^2 acceleration?
Eddington’s „observation“ was technically a joke. He had not even the needed instruments, or the needed accuracy to perform such observation. He just wanted „to confirm“ Einsteins prediction…no matter what.
@@PADARM Oh yes, Einstein’s prediction had to be proved at any rate. Eddington was cheating and all others later ones too. They sold to you simple refraction for bending of space time and you did buy it.
So that means in a wormhole where the space could be infinite the time slows down almost to a stop and the speed grows as much as it almost gets to the speed of light ?
The speed of light is not a constant as once thought, and this has now been proved by Electrodynamic theory and by Experiments done by many independent researchers. The results clearly show that light propagates instantaneously when it is created by a source, and reduces to approximately the speed of light in the farfield, about one wavelength from the source, and never becomes equal to exactly c. This corresponds the phase speed, group speed, and information speed. Any theory assuming the speed of light is a constant, such as Special Relativity and General Relativity are wrong, and it has implications to Quantum theories as well. So this fact about the speed of light affects all of Modern Physics. Often it is stated that Relativity has been verified by so many experiments, how can it be wrong. Well no experiment can prove a theory, and can only provide evidence that a theory is correct. But one experiment can absolutely disprove a theory, and the new speed of light experiments proving the speed of light is not a constant is such a proof. So what does it mean? Well a derivation of Relativity using instantaneous nearfield light yields Galilean Relativity. This can easily seen by inserting c=infinity into the Lorentz Transform, yielding the GalileanTransform, where time is the same in all inertial frames. So a moving object observed with instantaneous nearfield light will yield no Relativistic effects, whereas by changing the frequency of the light such that farfield light is used will observe Relativistic effects. But since time and space are real and independent of the frequency of light used to measure its effects, then one must conclude the effects of Relativity are just an optical illusion. Since General Relativity is based on Special Relativity, then it has the same problem. A better theory of Gravity is Gravitoelectromagnetism which assumes gravity can be mathematically described by 4 Maxwell equations, similar to to those of electromagnetic theory. It is well known that General Relativity reduces to Gravitoelectromagnetism for weak fields, which is all that we observe. Using this theory, analysis of an oscillating mass yields a wave equation set equal to a source term. Analysis of this equation shows that the phase speed, group speed, and information speed are instantaneous in the nearfield and reduce to the speed of light in the farfield. This theory then accounts for all the observed gravitational effects including instantaneous nearfield and the speed of light farfield. The main difference is that this theory is a field theory, and not a geometrical theory like General Relativity. Because it is a field theory, Gravity can be then be quantized as the Graviton. Lastly it should be mentioned that this research shows that the Pilot Wave interpretation of Quantum Mechanics can no longer be criticized for requiring instantaneous interaction of the pilot wave, thereby violating Relativity. It should also be noted that nearfield electromagnetic fields can be explained by quantum mechanics using the Pilot Wave interpretation of quantum mechanics and the Heisenberg uncertainty principle (HUP), where Δx and Δp are interpreted as averages, and not the uncertainty in the values as in other interpretations of quantum mechanics. So in HUP: Δx Δp = h, where Δp=mΔv, and m is an effective mass due to momentum, thus HUP becomes: Δx Δv = h/m. In the nearfield where the field is created, Δx=0, therefore Δv=infinity. In the farfield, HUP: Δx Δp = h, where p = h/λ. HUP then becomes: Δx h/λ = h, or Δx=λ. Also in the farfield HUP becomes: λmΔv=h, thus Δv=h/(mλ). Since p=h/λ, then Δv=p/m. Also since p=mc, then Δv=c. So in summary, in the nearfield Δv=infinity, and in the farfield Δv=c, where Δv is the average velocity of the photon according to Pilot Wave theory. Consequently the Pilot wave interpretation should become the preferred interpretation of Quantum Mechanics. It should also be noted that this argument can be applied to all fields, including the graviton. Hence all fields should exhibit instantaneous nearfield and speed c farfield behavior, and this can explain the non-local effects observed in quantum entangled particles. *UA-cam presentation of above arguments: ua-cam.com/video/sePdJ7vSQvQ/v-deo.html *More extensive paper for the above arguments: William D. Walker and Dag Stranneby, A New Interpretation of Relativity, 2023: vixra.org/abs/2309.0145 *Electromagnetic pulse experiment paper: www.techrxiv.org/doi/full/10.36227/techrxiv.170862178.82175798/v1 Dr. William Walker - PhD in physics from ETH Zurich, 1997
If the speed of light is not a constant then Relativity can not be correct, any theory based on it is also wrong. General Relativity is not compatible with Quantum mechanics. So either one or both of the theories is wrong. The evidence I present says Relativity is the problem. Science will not advance , if the foundations of physics is not challenged.
@@MrMoose1347If the speed of light is not a constant then Relativity can not be correct, any theory based on it is also wrong. General Relativity is not compatible with Quantum mechanics. So either one or both of the theories is wrong. The evidence I present says Relativity is the problem. Science will not advance , if the foundations of physics is not challenged.
@@rodolfosantana9015 well if you imagine a flat earth (no, not like that) and fire a laser beam horizontally, after 186,232 miles it will fall for one second with acceleration "g", so like 16 feet, and that is following curved space time, and (switching to metric) 300 Mm long parabola curved by 5m has a radius of curvature of c^2/g = 10 Pm. (peta meters)..so about 60,000 AU...space is pretty flat around Earth, yet you can't fall 20 feet without getting hurt.
Gosh I hate it when people put trash on UA-cam. Space and time are both metrics and don't create anything. That is the same as saying the measurement of one meter can create life. I hate ignorant people that can not learn basic stuff.
if light propagates in all directions then why and how do we see/locate the object emitting light? wouldn’t we see the light from the object everywhere?
I think you are mixing up gravitational time dilation (GTD) with spacetime curvature. GTD arises when you think you are stationary and yet you are actually in an accelerated frame of reference, as indeed we are standing on the surface of the Earth. GTD is observer dependent, meaning it is possible to find observers that do not see it (a free falling observer won’t experience GTD for example). Where there is GTD, there is apparent (or fake) gravity. Once we accept the Earth is accelerating upwards, it is actually unsurprising that objects appear to fall and that all objects regardless of their mass ‘fall’ at the same rate, because the Earth is actually accelerating upwards at the same rate. Most of what we see as gravity on Earth is because of its acceleration upwards. What is holding the Earth in, keeping it the same size? Spacetime curvature. Spacetime curvature is caused by mass and energy. It is observer independent; all observers will agree on the curvature. Spacetime curvature is what gives rise to real gravity, and what attracts objects together in space. It emerges in the form of what we call tidal forces. The rolled up diagram you used is flat spacetime but rolled into a cone to illustrate the time dilation. That time dilation is GTD. GTD arises from an accelerating reference frame. When it is flattened out the time axis is curved, while the free falling world line (of a falling object) is not. This is a specific version of a spacetime diagram describing flat spacetime (not curved) and actually drawn from the perspective of a free falling body. The time dilation on the curved diagram is a result of a mapping between the object’s inertial frame of reference and our (standing on Earth) accelerating reference frame and is not the same thing as spacetime curvature. The free falling body has no acceleration itself and sees us and all the Earth accelerating towards it.
If you take the derivative of the space time curve at any point along the curve, will you obtain the acceleration due to gravity at that point as determined by the inverse square law?
That's the backing paper from book covering film... wow, it's all so simple.. but where did the book covering go?where did it come from and if we join the two sides together will it create a worm hole between Rymans and Smith's?
i think the video explaining that object will drop accelerately as it reach toward the earth. But I didn't catch why the object move towards earth as well as why the moon doesn't drop to the earth. Or I miss some concept in the video?
How skillful are scientists in explaining problems they cannot understand with fabricated solutions? They create a paradox with nonsense questions, and then they think they have solved that paradox with another nonsense. The speed of light is constant only if they are in the same plane. When the plane is different, the speed is different. For example, the near beam should reach the large mass earlier because it travels less distance than the far beam logic. It's not like that, though. The ray that stays away from the larger mass appears to arrive at the same time because it moves faster than the one that is closer. When you incorrectly construct the universe, light and movement, such absurd questions and solutions are called science. This is not science. He's deceiving people
Another thing that seems quirky and weird to me is how can light speed up and slow down, or slow down and speed back up depending on the medium that it's going through... And they call this a 'constant"⁉️😂
@@drakeeblis1788 No. It's specifically the speed of light in a vacuum. And it's not primarily about light. Light is a massless particle hence travels at C in a vacuum. But can be slowed by shining through non-vacuum.
@@drakeeblis1788 Let me explain please. First of all, it is necessary to know what light is and how its movement occurs. As you know, the space that is thought to be empty is actually full. It only has a much sparser texture compared to mass. I think that at this point, weak force or weaker forces are involved. (weaker force has not yet been fully defined) weaker force is the subatomic particles that I call formation points, which are too weak to be mass. They move just like a Newton pendulum. But they are connected to each other in every direction. The reason for quantum fluctuations is their movement. The most important task of these structures is the communication network with the ebb. In other words, light seems to move through these structures. Just like the balls from a Newton pendulum do not go anywhere but transmit the movement. Think of it in the same way but in 3 dimensions. The distance between the balls increases or decreases the speed of light. If the distance is greater, therefore it means it is farther from the mass, then light moves faster. Because there is no time between two formation points. It is the collisions of two or more formation points that express time. I hope this was a sufficient explanation for you to understand. In fact, the topic is so broad that it is harder to write. Thank you for bearing with me.
Cann you tell me when you folded then what will be in background of that in which folding occur because space you folded then what will left in background
Nope... you got it wong. Acceleration along space axis . . what we call gravity. . . is direct result of warping of space-time... more specifically differential time. Not the other way round.
@@pretzelogic2689 Space-time (4 dimensions) is what warps - not just space. It is a fundamental fabric of the universe. It does so in the presence of any energy-momentum. Since mass (matter) has an equivalent energy (E=mc2) then it also warps in the presence of mass (any mass size but more noticeable for us with planet size masses like Earth) . That warp gives rise to differences - a gradient - in the flow of time which gives rise to space (which rememeber is connected to time as 4D fabric) flowing in towards the direction of the warp (towards the mass) - which we experience as an acceleration and historically have labelled it as a force of gravity. So it is warped space-time gives rise to what we call gravity. Not the other way round. To go into greater depth involves EInsteinian tensor mathematics. A bit too much for youtube comments section.
@@jayceasar2661 Prove what exactly? that time flows at different rates depending on how close to the energy-momentum (mass) centre you are? Without accepting that the algorthim in your GPS makes allowance for this - then it would not work and you couldn't use google maps to go anywhere. 'Proof' enough for you?
@@bbbf09 You said it yourself: "...it also warps in the presence of mass..." Your "also" refers to energy. Energy mass, fungible. Thanks for repeating what I said.
Imagine traveling a road that takes 5 minutes to reach your destination. If a sinkhole or crash blocks the path (representing mass in space), you can't continue straight. The obstruction diverts traffic, and you must take a longer route. This detour increases your travel time to 8 minutes. This time dilation reflects changes in spacetime; with increased distance, time dilates. Acceleration also affects spacetime but in a different way. Changing your speed alters the perceived contraction of space and consequently affects the duration of time. Relativity encompasses more than just relationships between measurements. It involves how units of measure change relatively due to different conditions experienced while traveling through spacetime.
Matter tells space-time how to curve, and space-time tells matter how to move. This is because space and time are not flat, but can be warped, stretched, and pulled by matter. Time is relative and not constant. The rate at which time passes depends on your frame of reference. You just need to look at the constant adjustments that have to be made for time dilation to GPS satellites due to Special Relativity (velocity - clocks run slower) and General Relativity (weaker gravitational field - clocks run faster). Overall effect for both GPS satellites and travelling in an aircraft ... clocks tick faster. However, moving at sea level -> clocks run slower, so you age slightly less.
I knew it, I knew that it would come the day when Millennials would start thinking they can think like geniuses too and would start spurting out all kinds of nonsensical krap calling them scientific theories. Time, or time dilation, creates gravity as much as chronometers create speed, duh...
@@somerandomboi8239 You are right, Einstein said many things but the things on which he was right he was able to prove them mathematically, with equations. There is np mathematical proof for this assumption, it is pure speculation.
@@rubenoteiza9261 I may have been wrong to react this way, as I am not yet at this chapter but am just watching stuff in order to gain some basic intuition for when I do get into it seriously. I just do find these playing-arounds with ideas and imagery useful for visualizing concepts, and couldn't comprehend what you meant by dunking on it, esp. with your end sentence about time and gravity. What does cause it then? Because we all agree that it is not a classical force. Then of course, maybe you see something profoundly wrong in the video that I couldn't catch?
Does light really bend? When looking at a fish in water, why is the fish ahead when looking through water? Could the same happen in space near a planet or star?
@@NondescriptMammal ?? How in the world is it not clear? How could anyone possibly think it's a literal representation of spacetime? If you think that, then you shouldn't be bothering to ponder this stuff, you should be watching Bob the Builder or something...
@@xtraspecialj I assume that the maker of this video means for the cylinder to be taken seriously. It isn't just presented as a momentary visual aid to help understand... Everything that follows in this video to reach its conclusions, is derived from the geometry of that cylinder. All the example cases and intermediary conclusions presented afterward, rely directly on the construction of that cylinder. The cylinder is indispensable to this video's attempt to validate the assertion that "the curvature of spacetime causes gravity".
Question. In this model of spacetime it flares wider as it approaches the center of mass of the earth. But, in another model, spacetime funnels into a point towards the center of mass of something like a black hole.
No. In this model the larger diameter denotes longer time taken to cover the same unit of space. The closer to massive object the slower the time gets. Your second sentence is about spacetime, and is correct.
It's just an inverted visualization, since space and time are represented by perpendicular axes. When discussing the differences of motion through space and/or time, it is helpful to invert the cones in order to show the consistency of the distances travelled.
I would also put some explanation to cover the difference between those two persons curved path (since they are forced by the contact with the ground) vs straight path of falling object (since there is no contact with the ground during the path).
I watched 2 videos and i still can't understand it ig. Correct me if i am wrong. So if if throw and object from an height, Its always in rest during mid air. and when i collides with ground it comes in motion, coz ground is in motion too
The cone can work well if a gravity is the only force. I wonder how should air resistance force be put on the cone? Maybe as a force opposite to gravity increasing speed in time direction or maybe air resistance modifies somehow the cone?
Is that true that you eventually reach speed of light if falling down infinitely? If you're jumping off a plane, your falling speed increases but only to a certain speed and then, unless you're not already on the ground (ouch), your falling speed will remain constant (the exact number would be devided from your weight) and yet far from speed of light. that is if the gravity is constant.
Wow. It looks like you could work out the geometry that gravity bends spacetime into by using the acceleration of gravity and that last diagram (6:00).
saying 'the flow of time' is a contradiction as it implies distance traveled of an arbitrary quantity 'q' moving from point 'a' to point 'b'. So how can anyone invoke a term witch itself is defined in terms of time to describe time?
I am not a physicist but have a question on this. Light travels in different velocities in different optical mediums. Are we sure there is nothing in the space? Maybe something near the earth has different density that cause light travel slower.
No,they are not sure. And not only that, they don’t even know if Space is isotropic. Or even worse, they can’t even test it. They only talk and, if you believe it, they don’t need more than that.
@@O-Kyklop Yes, on large scales, space is considered isotropic, meaning it looks the same in all directions. This assumption is a key part of the cosmological principle, which suggests that the universe is homogeneous and isotropic when viewed on a sufficiently large scale. This is supported by observations, such as the uniformity of the cosmic microwave background radiation . However, on smaller scales, the distribution of matter (like galaxies and stars) is not perfectly uniform.
@@MrMoose1347 Ok. It means you can’t make a prediction for a certain location you can’t check up directly.,……which is most of the Universe. Not a very solid theoretical background, isn’t it?
I would like to see an explanation of how "space time" curvature causes the tides. I assume that space time is curved between the moon and the earth ( or between the sun and the earth) and that curvature of space time causes the tides, but I'm having difficulty visualizing how that works.
...little confused here. I heard dropping a steel ball from a height & a feather, they'll fall at the same speed ( in a vaccum - no air resisrance ) , and they'll reach a certain speed but won't keep accellerating infinatly towards light speed. I know I must have missed something in your example though.
If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
Why do goose down and a metal ball fall at the same speed in a vacuum? How does gravity determine how much force to apply to objects of different masses so that they fall at the same speed?
Wait.. at 7:04 you're saying that an iron ball falling infinitely from the Eiffel Tower into a gravitational field would eventually accelerate to the speed of light? Well, problem is, only massless things like photons can travel at light speed, and any object with mass would require energy equivalent to the mass of the entire universe to accelerate to the speed of light, which would also include the mass of the infinitely long Eiffel Tower that the iron ball would be falling next to. So the iron ball would never reach light speed, because if it did it wouldn't be an iron ball anymore, but a stream of photons that used to be the iron ball, the Eiffel Tower, and the rest of the mass of the universe.
Correct. My comment was: If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
@@DABmongerthere's more wrong with the example than that but you're missing the point. Dropping any mass onto a black hole would be a better example. By the way if the tower is infinitely tall the ball wouldn't fall at all because it would be too far from the source. Assuming the tower itself doesn't have mass. On another note if there was no ground and the ball was somehow affected by gravity, any air around it would also be in freefall. Terminal velocity only exists if there is a ground for the air to push against, otherwise there isn't any friction of falling.
@Richinnameonly Me thinks you're overanalysing, and a lot. The creator will giving a simple example, and there is a terminal velocity constraint on Earth, plus nothing with mass can travel at light speed You're adding elements to a simple example, none of which was the creator's intention.
No. If anything you could expect a shorter span as it would be harder to sustain a longer second Though a ‘’low’’ orbit term may be misleading as it depends on whether the observer is in a higher orbit or the surface of the earth
@@skalderman let me be clear because your answer is weird. Do humans born on earths surface experience longer attention spans when they leave earths primary atmosphere and exist in a place of considerably less gravity? The reason why i am wondering is because when i practice becoming aware of my attention span and experience "the moment i can feel it come and go into memory. But does it change in space? Does the moment feel longer?
@@ninjxxitty Interesting question. The term low confused me. In theory as you go higher in the orbit time intervals should shorten and thus you might be able to maintain a longer attention span per second. However frankly I dont think thats practically sensible because there are whole a lot of factors like your energy levels, information entropy, wear and tear of radiation etc. I would say our consciousness would not care about the relative length of a time interval save the energy issue
@@skalderman you gave me an idea. Imagine a spacetime grid. Then pinch it where matter would be. You understand how the lines skew as they intersect? What if you thought of each skewed square as a moment of time. The closer to the center the faster the intervals of time feel. The farther out the slower time feels. Sort of like the shore of an ocean. Big waves take longer and arrive less frequently meanwhile the tiny waves are frequent and everywhere. Thoughts? Its just an idea. What i care most about is how consciousness feels in the moment versus transitioning to memory.
I'm confused now. I thought that if light or any other object travels along the curvature, they would not "feel" any acceleration, i.e. gravitational force and their clocks would tick at the same rate, just as in an inertial frame. Only from the perspective of people on earth, the view of time ticking faster the higher you go becomes plausible. Can someone explain?
You are right. There is no force of gravity and all clocks tick away at the same rate, everywhere, and under all circumstance of motion and orientation.
There is a real effect called gravitational time dilation. Clocks in a sky scraper tick faster than those on the ground. However, you falling feel no force and your wristwatch is normal to you.
Just to follow up with my previous comment: The differences in elapsed clock time in the presence of gravity is owed to the distances along the clock world-lines (the elapsed proper time) to be different lengths owed to the background curvature.
Your explanation is excellent, although you need to be mindful of where the observer is at all times and all events need to be described in relation to a perspective from a certain point within the diagram itself at every stage, one cannot observe the effects as if we can safely refer to any absolute time, every time reference must be relative to another somewhere else, so time doesn't slow down for something falling into a gravity well unless you assume we are observing from outside the well, it's a small, but important distinction that permeates every sentence. On a side note, I believe I have worked out why gravity, not just that gravity is the effect of the curvature, I worked out why the curvature is the shape it is based upon the conservation of angular momentum within Einstein's field equation, if you're interested, I can relate it to you, it provides a reason for the shape of the tensor based up on the careful application of conservation laws and some base postulates from both Newton and Einstein together, I consider it to be the cherry on top of Einstein's field equation, because it explains why an effect like gravity must exist just given the postulates alone, and gravity the same shape does exist according to Einstein and observations.
What force, (force = mass x acceleration) causes the acceleration. The 'rubber sheet' model assumes the object is already moving with respect to the major mass's centre of mass. A static model requires a force to begin acceleration. And more - where does the energy come from to accelerate the object. If an object falls inside a total vacuum calorimeter, it would register heat when the object hits the end of its travel. Where did the energy come from?
From it's initial creation. Everything in space is falling. An object will stay in motion until acted upon by an opposing force. If an object finds itself roaming space alone, then it will speed up because it's falling.
The following doesn't make sense to me: How can two people in different timeframes interact? Surely, everything that currently exists, does so in the present moment. If the implication is that the present moment, the now, doesn't exist and everybody is on their own timeline then, wouldn't that render the past and future meaningless? I'm confused.
The same way you can talk to someone of the phone who is at the opposite side of the Earth - there is a delay, because the speed of light (or the maximum speed at which the information can travel) is not infinite, but each one of you remains in your own timeframe. And YES, you are correct - time is relative! That's the whole point of relativity! You're not confused - you've just graduated yourself to a new understanding. CONGRATULATIONS! 😄 🎆
And someone could talk to another person who is higher or lower than them, or is moving faster or slower (perhaps in circles, say). These two people would have different reference frames, but could stay in contact even without a telephone.
4:19 a cylinder is flat. but also a cone is flat. this is not spacetime curvature, this is the local equivalence principle: gravity due to acceleration in flat minkowski spacetime. notice that you do not need curvature to experience gravity it's a nice visual, but it's very inaccurate because gravity is not caused by curvature, it's cause by being in accelerated reference frame. Geometry, curved or otherwise, dictates what counts as a force free path.
If the Eiffel-Tower were of infinite hight there would be no gravity at all. This is a classical solution which is duplicated by GR in the Newtonian limit of „weak gravity (earth) and slow speeds (v
If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
Wouldn’t Bob be younger since he was moving faster? I could be wrong, but I think you got it backwards. The faster you travel, the slower time goes, right?
They are "moving" at the same space unit per unit of time - the only difference is the influence of gravity. The closer to a massive object the slower the clock.
Time dilation and length contraction are concepts in special relativity that describe how objects moving at high speeds and/or appear different to a stationary observer. And in general relativity there's gravitational length contraction and gravitational time dilation.
The Earth isn't really "pulling" us towards the center of the planet. The spacetime stress tensor (an abstract mathematical object) at every point in space is "pushing" us towards the center of the planet.
@@ericzeigler8669 Earth's gravity is caused by both the mass of the planet and the curvature of space: Mass The mass of a planet determines its gravitational pull, which is the combined gravitational pull of all its mass on all the mass in your body. This is what gives you weight, and if you were on a planet with less mass than Earth, you would weigh less. Curvature According to Albert Einstein's general theory of relativity, gravity is linked to the curvature of spacetime itself. Massive bodies, like Earth, bend and curve the fabric of the universe, which determines the path that objects travel. This curvature is dynamical, moving as those objects move.
@@TerryUniGeezerPeterson You almost have the correct view. You're mixing Newton into your explanation with this whole "pulling" idea. Einstein's description of gravity has replaced Newton's description in all physic's communities.
@@ericzeigler8669 A planet's *mass* determines its gravitational pull, or how strong its gravity is. Gravity is a non-contact force that attracts objects to each other, and *the more mass an object has, the more gravity it has*. For example, Earth's gravity pulls on all the mass in your body, which is what gives you weight. If you were on a planet with less mass than Earth, you would weigh less.
“Object mass" refers to the inherent amount of matter in an object, which is a constant value and does not change with its speed, while "speed mass" is not a standard term, but could be interpreted as the apparent increase in mass an object experiences when moving at very high speeds near the speed of light, according to the theory of relativity; essentially, the faster an object moves, the slightly greater its "relativistic mass" appears to be, although this effect is only noticeable at extreme speeds.
@@KaiVieira-jj7di I agree with this, but from a slightly different perspective. I do have a background in Math, Physics and Chemistry, yet, I've always had my own intuitions about things. So regardless of what we were taught to believe as being the "de-facto" truth, I always tend to challenge everything, put it to the test. When it comes to gravity, I do not see gravity as a force. I never have. Even the term we have come to use as why objects fall to the Earth's surface as being gravity. Now, acceleration itself is a force. The downward acceleration towards earth is what we like to call gravity. This goes back to the notion as to what "physics" is or how it is defined. And traditionally, widely accepted is that physics is the study of motion. Within that, the concepts of forces emerged, and they have always been based on "cause" and "effect". I have never considered gravity to be the cause of anything. I have always seen gravity as being the "effect". The downward acceleration itself has a force carrier. Yet the motion that we observe of something falling down that we like to associate it with gravity is more towards the result of it, the effect of it. I tend to see gravity as being the result or the effect that we are able to observe after a force has been applied causing its acceleration, velocity, displacement to change. I have never considered gravity itself to be an acting force, and always perceived it as a resulting effect. So, if gravity isn't the force or the cause what is the cause then? That's quite simple, it's the mass of the object as well as other acting forces such as temperature, pressure, buoyancy, friction, energy (potential to kinetic), etc. I threw a ball up, it's mass and density are greater than that of the air and after some amount of time, displacement, the air pressure through friction and other forces decreases the ball's upward velocity and momentum to the point where the mass of the ball and its density being greater than the air, begins to reverse its direction or trajectory. At this point, its velocity, momentum and acceleration being to increase in the opposite direction until it reaches terminal velocity or impacts another object. The visual effect of observing the change in its direction, velocity and acceleration is what we tend to call gravity. This is where I've always differed and challenged others to think about it. I've even challenged college professors on this, and I could see it in their eyes. They wanted to agree with me, but they were reluctant to do so and didn't. They didn't want to risk their career or job by going against the established status-quo. Gravity is not a force. It is the resulting observation it's not the cause of anything, it is the effect we witness or observe of things being in motion. Some might argue well what about the planets in orbit? That's quite simple, it's the same thing, the gravity we are observing is the effect of applied forces and not a force itself. The orbits, that's angular momentum, centripetal forces, tension, spiral or cyclical motion. At the foundation of it all, the study of Motion in which that is what Physics is goes back to trying to understand cause and effect. And for me, people need to stop conflating the two. This is a crude analogy, yet I will use it only to illustrate a point. There are two people, Person A, and Person B. Person A punches Person B in the face. Person B ends up with a black eye. Here' Person A's actions the cause is the force of the problem. Person's B's black eye is the resulting effect. Yet, others are now going around and say that the Black Eye is a Force, a Cause, when in fact it never was to begin it. The Black Eye has always been the resulting observable effect. Person A's actions, choices were the cause all along, they are the Cause, the Force of the problem. This is exactly how I see gravity. Gravity is no different than that black eye. It doesn't cause anything because it is not a force. Gravity like that black eye, is the result or effect due to forces being applied. I wouldn't care if I was speaking to others such as Einstein, Newton, etc. I would still argue or debate this case. Would I consider or look at their arguments, suppositions, suggestions? Sure, there is no problem there. I would look at them and consider them. Yet this is my argument. This is what I perceive. And I've had college courses in Physics, Chemistry and Math. I was at the time majoring in Electronic Engineering.
@@skilz8098 What we do in physics is measure. We measure that gravity is not a physical force. We make measurements testing Local Lorentz Invariance, Local Position Invariance, and Weak Equivalence and those measurements tell us that the gravitational field is necessarily a metric field (and so necessarily described by a curved spacetime). If you want to come up with a viable alternative to relativity you need to develop a model that gives different predictions than relativity for a set of measurements.
@@skilz8098 oh god it’s you again. That’s why you wrote an essay. You can’t keep it simple because you don’t understand it. Gravity is a force cause my mass existing in space causing it to stretch around other. Aka curvature.
@@KaiVieira-jj7di There's a slight issue with your last statement: "we need to develop a model that gives different predictions than relativity for a set of measurements." Many within the "scientific community" are under the impression that everything can be or is measurable. In many cases this is true to some extent. We can measure things because we can model finite examples of them. However, not everything that exists is finite, and with that we can never truly completely measure them. Therefore, if every aspect or premises of our foundation of understanding or observation to acquire some kind of evidence or proof is based solely on the framework that everything has to be measurable. It's kind of a moot point. All forms or acts of measurement regardless of the measuring system that is used, regardless of the convention or notation that is used at the end of the day is still purely 100% abstract simply due to the fact that a measurement of something in general is arbitrary. Numbers themselves are abstractions. They are abstract concepts that convey an idea. They don't actually exist in nature itself, yet the properties of nature are in some way still governed by them. One cannot study, perform or execute physics, chemistry, biology, etc. without the use of mathematics and numbers. The truth of the matter is every bit of it regardless of if we're able to perceive it to be discrete and measurable, finite, or if we are able to perceive it to be continuous, analog or infinite at the end of the day it is still all just a mind game. Yet within the field of physics itself where I'm referring to practical applied physics as opposed to theoretical physics, gravity itself irrelevant of what we were taught by some textbook is the effect that we observe do to some cause or action. Gravity itself is not the cause, it's not a force. When we drop an object, and it begins to fall to the ground, it's not falling because of "gravity". The displacement we are seeing over discrete intervals of time in a continuous fashion is the increase and change of direction of that object's velocity and acceleration. These force vectors are related to the change in momentum Mass * Velocity which also has a direct change in its acceleration and position. There are other force vectors involved such as friction, lift and drag (fluid dynamics - properties of gases), changes in temperature, density and pressure, etc. Gravity itself isn't the actual cause of the event. Gravity is the effect of the action that caused the event. Compare these two expressions: Gravity emerges as a side effect or property due to objects moving through time or motion in general. Motion or objects moving is a result of an undetectable force such as gravity. We have observed many times over that "gravity" is relative and that it is directly and proportionally related to mass, but it's not just the mass itself or directly. It is also the mass in conjunction with its velocity, or its momentum as well as other properties or forces such as angular momentum, angular velocity. When I drop a bowling ball it falls due to the fact that its mass: density, temperature, etc. is much greater than that of the air around it. When I drop or let go of a hydrogen or helium balloon, it lifts upwards. It's able generate lift that is greater than its drag and with that there's a buoyancy that is generated around the surface of the balloon due to surface area tension. When I take a volleyball and drop it in the air, it falls to the ground. When I drop it over a body of water, it falls until it hits the surface of the water. Now depending on the ball's velocity (did it reach terminal velocity) and its overall momentum will determine how much of an impact or force it generates with the surface of the water and how deep it will drive into the water before the force (pressure) of the water pushes back and drives the volleyball back up. Eventually the volleyball (provided it didn't pop and fill with water or become crushed due to the pressure of the water) it will float to the surface and generate buoyancy. If I do the same thing with the bowling ball, it will just sink to the bottom of the body of water. Once again, (not you directly just people in general) completely overlook or do not listen to what my argument is, what my perspective is about and pertains to.
...and a few years before that, somebody noticed fruit falling... one gets the feeling that our host believes gravity has an independent metaphysical existence, and it is just "out there."
You just need to look at the constant adjustments that have to be made for time dilation to GPS satellites due to SR (velocity - clocks run slower) and GR (weaker gravitational field - clocks run faster). Overall effect for both GPS satellites and travelling in an aircraft ... clocks tick faster. However, moving at sea level -> clocks run slower, so you age slightly less.
Maybe centripetal force and gravity are the same thing. Since space-time is bent, a centripetal force occurs in the opposite direction. In centrifugal force, centripetal force occurs because we bend the movement of the object in flat space. Where the two are balanced, a stable orbit is formed. As a result, spacecraft in Earth's orbit balance gravity with centrifugal force, that is, centripetal acceleration. In this way, he avoids falling.
Light passes from C to D ( a smaller distance ) with the same amount of time that Light passes from A to B ( a bigger distance ) ??? This is only possible if the time for the Light ( C to D ) passes slower Time curvature, And at 6:00 the draw are not on scale ‘cause 90 degrees = Light speed into the space, The apple goes at the speed of light in time when he is at rest ( in space ) So if we do the drawing at scale… the curve of the border is almost impossible to see ( 9.8 m/s < 300 000 km/s ) and the fact that ( at rest in space ) the apple going forward in time on the Drawing goes towards the border ( where the ticks are separated by larger time ) means that the apple goes naturally where the time passes slowly and slowly, so … right to the center of mass, but we can’t because we have the surface of the planet that stop us to go further towards the center of mass. And if we want to do a accurate drawing for example for a black hole, the more you get into the black hole the more the angles become wide because for each meter ( at a certain point ) times passes a lot slower, so the draw at the borders become like a trumpet until we hit the distance from the center of mass when it forms a perfect quart of a circle and that in consequence the time axis of the space-time is perpendicular compared to the path of the apple in time ( so when he is at rest on space ). And that means that the apple goes at the speed of light into the center of the black hole and time don’t passes anymore
Simply removing mass from directly interacting with other masses, by projecting its effect onto "the fabric of spacetime", does not explain the deflection of a massless photon in a curved spacetime. It just leaves that interaction undefined.
So if an object "fell" into an object of infinite mass it would achieve near light speed while time would be slowed to next to non existent. Would the masses actually meet, or be caught in a paradox?
It's not really a paradox. Space and time are orthogonal dimensions. Whenever mass or speed reach "infinity" they have actually moved in the orthogonal direction. It could be imagined as a rotation through dimensions preserving angular velocity.
The expanding cone coordinates are more intuitive than other curved spacetime videos by far 🙏
that's not saying much. and changes the meaning of intuitive. to sort of understand.
the concensus can't be explained intuitively.
This video is more intuitive
ua-cam.com/video/6H5vYP6ssUY/v-deo.htmlsi=mkPaqWe0o2mSLpeQ
I don't claim i fully grasped all the details, but this is the best description i heard of curved space time and how it genrrates gravity. Much, much better than the massive ball placed on thin fabric animation.
That ball on stretchy fabric analogy, along with the order analogy for entropy, need to go the way of the dodo.
Agree with you. The massive ball placed on a fabric is a nonsense!
It is funny that to demonstrate gravity using stretched material, you need gravity.
Idiots only explain gravity with a stretched fabric and a ball. There is no fabric in space. The perception of top and bottom is only for us. There is no top or bottom for space. There is no direction for space, so there is no possibility of a fabric in one space plane. Also, this idiot should explain where the curvature first come to be in the first place. It is a circular stupid explanation, curvature comes from gravity and gravity came from curvature. Fact is, all physicists are lying to us about the Space.
It doesn't describe how it generates gravity. In fact, Gravity remains one of the most perplexing phenomena in physics. It explains how space-time, under the _influence_ of a gravitational field causes the attributes of falling objects.
It is also defective, as are most such popular expositions, in explaining why _not-falling_ objects-such as the apocryphal apple hanging over Newton's head-seem to be under some mysterious influence. Eg., the mysterious apple(s) seem always to bend their branches _down._
That question always elicits a separate video, such as the ingenious/notorious dialekt's river-model of the matter. Yet others present the baffling accelerating-surface claim about GR: the apple is exerting no force on the branch, the branch is continually accelerating... _upwards_ . Entailed by that interpretation is the understanding that apple trees in southern New Zealand have their branches' acceleration in another direction.
If all that is too hard for the average person to grasp, even with the help of some dodgy videos to help you over their spongy arguments, they may eventually resort to the claim that in HS physics the teachers lied to us about the meaning of... _direction._ I think that's easier than redefining the meanings of vectors, momenta, and acceleration.
6:00 why though? Why is the object moving towards a space where time passes slower?
i thought the same. If the object is standing still and only moves through time it should just follow the time path. So why it starts shifting towards the space part of the diagram i can understand either and the video doesn't explain this
Because of the warping of spacetime. The object was moving in a straight line through spacetime, along the time axis. Now the presence of the massive object has caused the underlying 'grid' of spacetime to warp in such as way that the line of movement through spacetime (ie geodesic) is no longer parallel with the time axis but pointing into the space axis as well. So some of the movement through time is diverted into movement through space in the direction of the massive object. No external forces are acting on the object - the shift of movement into space is caused by the change in spacetime geometry itself. Pretty mind bending.
The shortest distance between two points is a straight line. All celestial bodies warp the "fabric" of space, and create gravity wells. When a smaller object comes close to the rim of a larger object's gravity well, it gets caught in that object's orbit through mass bending space-time. It's similar to how water circles a drain, but it's an all directions. Everything in space is falling.
@@jonathanspruance4502 I am sitting here glued by gravity to my seat
(and by my interest in the topic).
But since I am absolutely certain that 'time' is a concept only,
I'm in need of a different explanation.
What is it in actuality that the temporal concept is actually 'about'?
@@jonathanspruance4502 Why does the object have to move in a straight line? Of course if it moves in a straight line it will move towards the space axis and thus the “falling” of the Apple. But why does the path have to be a straight line? Why doesn’t it just move along the curved time path since it’s standing still?
I'd be curious to know how to calculate how long it would take for two masses to get to the speed of light by mutual gravity and how far apart they would have to start. I'd like to know if that's really possible with anything that doesn't include a black hole as one of the objects.
Its never possible to reach the speed of light ...ever. ...unless it involves event horizon of black hole. Here spacetime is falling into (or rather warped) at light speed but only at point of event horizon. And once at that that horizon you are never coming back to report.
A neutron star is closest next thing and you could crash into one of these at 99%+ light speed.. but never at 100%. You can have 2 neutron stars at 2 solar masses each crash together. They would crash together at 100% light speed but the boundary of where that happened would be exact the formation of a new event horizon of a new black hole which (as we know from theory and now from gravity wave evidence) always forms from merging of neutron stars.
Damn, you guys are good. I am kinda keeping up (when somebody offers amazingly structured explanation mostly) and i always feel like i would need a little bit more IQ or computing/projecting brainpower to join the top thinkers. Maybe a lot of power lol looking at some of the complex math implications some ppl can do. Hopefuly big part is knowledge and training and im not actually too far apart to justify using the word "im actually stupid conpared" 😅
Excellent explanation. After watching other videos on this topic, your video using the cone and illustrating how objects move around the cone -- really helps clarify the topic. Thank you. New subscriber.
The correct question is: why does mass curve spacetime?
The correct question is, why and how does the Higgs field give objects mass?
If someone knew that, they’d already have multiple Nobel prizes.
Spacetime is just math. It does nothing.
Because mass is a degree of freedom that deflects momentum.
@@geoffwales8646Higgs field contributes 1-2 % of mass to protons and neutrons. The rest of the mass comes from the binding energy of the strong force
By far the best explanation I’ve seen! Thank you
I don't get how the iron ball would reach the speed of light? That's not possible as it has mass.
It would have to travel an infinite distance
That's why iron will be burnt down at some point due to heat and pressure in my point of view. The faster it goes the more mass it gains.
@canadians4trump2024Or lack of knowledge and understanding.
If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance.
The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain.
And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
Infinity is your friend.
Sometimes (rarely) I'm in a mindset to understand videos like this. This one hit me in the right way at the right time. Very well done. I learned a lot. Thanks.
if you believe it. and ignore the contradictions.
@@atticuswalkercontradictions?
@@kwisclubta7175 so, in other words you are mesmerized by the bullshit...
@@drakeeblis1788 That's not very nice.
You explain my first semester of Calculus perfectly. 😀
2 questions that the video made me confused about.
1. The initial flashlight beam of light had to have been significant in width for the difference in distances traveled between top and bottom "light fibers" to be different. Was the initial experiment based on two stars spaced far apart from one another? In that case, how did we determine that the light arrived to us from each star at the same time, since light has always been streaming from them to us, and we don't know precisely when a given photon was emitted?
2. When you roll up the spacetime diagram and say that "light only travels through space," I understand this is correct from the photon's perspective, but you appear to be rolling up the stationary apple's spacetime diagram. Wouldn't that diagram also have light spiraling along a helix, since from the apple's perspective light travels through the apple's time at a 45 degree angle to apple's space? It seems like you are mixing/combining the apple's perspective into the photon's perspective into one unified spacetime manifold, on which I just don't understand how you can be certain about the geometry of circular, helical, and straight line paths coursed out by different material objects. Maybe we can call this some higher dimensional "God's" spacetime manifold who sees the absolute truth in terms of distance and time?
Two very excellent questions.
@@HowDoYouKnowThough so we don’t spiral along. We move in a straight path along curved spacetime. This was found out by how light acted. We took measurements of this and found out the limit to motion of mass & energy as the equivalence principle was found. Taking this into account we know have lights constant speed over distance and distance. Hell that means to get time (the rest of the equation) we just plug and play. Let me know if ya have any questions
@@MrMoose1347there's no such thing as a straight path of you want to really get into it. Space is not straight, there are no fixed points anywhere in all of existence and everything is moving at a relative speed and rate of time to everything else.
@@glenwaldrop8166 bro just read that again. I didn’t say otherwise
@@MrMoose1347 the point you were making was a bit pedantic, I went a bit further.
Everything is relative, everything interacts with everything, there's literally no such thing as a straight line.
At 06:07, can we say that the “stationary” object in space-time would move in parallel to the original timeline direction? I understand the analogy of cone to visualise space-time distortion. Under this analogy, the “stationary” object “is moved” in straight line in space-time. But what is the actual rule of this behaviour?
Another question is... what if the huge object (i.e. the Earth) completely losses its mass after the “stationary” object is accelerated by space-time distortion for a period of time? Will that object stops immediately in space?
Your video has the best analogy of gravity from my point of view (I am just an Information Technology guy). It makes me feel that gravity is a cause of distorted space-time by mass, and it acts on other objects with mass. However, can you tell me why mass can distort space-time?
This explanation of gravity as an effect of curved-space-time is mind blowing.
It’s old. However it’s rarely explained properly
The use of gravity to illustrate "space-time" which in turn causes gravity is not an explanation.
Also, Einstein's failed General Theory implies that gravity is not a force also implies that light and massive objects should follow the same path through space and that light is not affected by gravity, because of the claim that light is massless, yet His General Theory implies that gravity can suck light into a hypothetical singularity.
The entire General Theory of Einstein is built on impossible conundrums.
Light bending in an atmosphere was always considered to be why light bends in the Sun's atmosphere. Others had predicted this refractive index accurately prior to Einstein, such as Soldner. Einstein simply did not understand this concept of refractive index in optical lensing.
Gravity is caused by the implied flux density gradient of Gauss's Law for Gravity, which acts as an energy gradient, confirmed by GPS and atomic clocks.
@@JoeDeglman Where is the evidence that General Relativity has failed? Where?
Proof by assumption statement like this is typical of someone with a pet belief and no education.
General Relativity states gravity is a force. Someone has not read the General Theory of Relativity.
Light being affected by gravity is what General Relativity is all about. Where did you get this stuff?
Are you familiar with the experiments?
"His General Theory implies that gravity can suck light into a hypothetical singularity." - No.
Have you ever taken a course in physics?
@@JoeDeglman Light bends around large masses as can be seen in galactic halos.
@@geoffwales8646 the JWST also shows that these galactic halos also have a substantial dust atmosphere that acts as an optical lense to do the bending as a refractive index. Just like the Sun, bending of light only occurs through an atmosphere as a refractive index as an optical lensing function.
No bending of light has ever been observed through the vacuum of space around a massive object, in contradiction of the GRT, where there is no atmosphere.
The previous images of galaxies from Hubble were in the optical range and the dust atmosphere wasn't observed previously because the atmosphere of galactic halos emits in the infrared not in the visible.
.
I thought time is an illusion
Why?
Depends on which arrow of time you’re referring to. The psychological arrow of time is an illusion. (Kind of) It’s more like our brain’s way of interpreting one piece of the great universal puzzle. It’s like saying colors are an illusion; depending on your definition of illusion…I guess they are, because colors are nothing more than your brain’s way of interpreting different wavelengths of visible light, but light waves are still very real though
Why would you think that? In physics, time is defined as the measure of a change in a physical quantity or a magnitude used to quantify the duration of events. You can find other definitions, especially ones that connect time with entropy, but in any case, it is certain that time is not an illusion.
In part you are right. Time is a perception of reality. In fact one can consider it as a "vector" which belongs to a manifold called "reality"
@@El_Dr_Tacco That doesn't mean it is less real.
man been trying to wrap my head around this, but after watching this, i get it a little...
Me, too. Emphasis on LITTLE.
The thing that throws people off is this name, “curved spacetime.” Sure, when you look at a rolled up piece of paper, or a digital graphic, we see the curve. But in reality there is no curve. Space is devoid of geometry. There is nothing surrounding the earth. Its literally enpty space. Wheres the curve?
You have to remember that einsteins theory is just that, a theory. Yes it happens to align with how we perceive things to work, but it doesnt provide all the answers. Its just the best explanation we currently have. We dont understand the nature of space. Thats the issue here. When you consider this example, a rolled up piece of paper, that is one way to describe gravity. But the age old question remains unanswered, WHY does gravity exist? I believe thats something we can never know.
Einstein explained the how. The why he had absolutely no idea. No one does, and no one ever will. Thats why after watching all these gravity videos, everyone has the same response, “eh, i guess it makes sense.” It can never make total sense until we understand the fundamental nature of the universe. Unknowable unfortunately. Why are things attracted to each other? Who knows, the just are 😁
@@trenken
I read your post... Earth is surrounded by space. Einstein said there is no space or time... it's space time. You changed it to JUST space.
@@francus7227it's just space because you don't know nothing about time...
@@trenkenmaybe that’s the life cycle of matter? Create black holes basically.
1:45 - if space is contracted around a mass, then time doesn't actually need to run slower because the photon is still moving over the same amount of space. If you stretched a 10 x 10 grid and watched a ball cross that grid, it would still cross 10 grid lines.
Space in contracted in the direction of travel.
You’re confusing the speed of time with the device that’s measuring time . Time is not speeding up or slowing down , it’s the device that you’re using to measure time that is measuring it faster or slower . Time is a constant and doesn’t speed up or slow down , however the device measuring it does .
Yes. Time is a constant. The device measuring time changes
Yes … the device you are using to measure “time” is affected by its place in a gravitational field, and the various accelerations it undergoes… once you account for those variables, any differences in two time measuring devices will be factored out …
Does it apply for digital clocks too?
@@kpbalaji
Yes
“Time isn’t speeding up or slowing down it’s the device you are using” um….its measured motion so both time and the clock are being talked about when dilating.
1- How does mass curves spacetime ?
2- How by equilibrium principle earth pushes objects in a curved spacetime ?
There are a few mistakes because of over simplification in this video. For example the ball falling from an infinite high tower would not reach ligthspeed. The potential energy in a gravitational field is finite! So an object with mass cannot reach the speed of light.
Agreed, of course. I wrote the followingI comment ...
f the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance.
The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain.
And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
It sure would; given the infinite amount of time.
@@Know_Him2 Nope, even in infinite time the ball still deals with a finite amount of energy.
Why does light moves only through time in the flat spacetime diagram wrapped in a cilinder at 3:25? Light does not travel through space only, it also travel through time, its speed is not infinite.
There is no "time" to move through, unless you mean the along the direction of some observer world-line, but you still have to choose such a world-line. That said, yes, light will move equally through the spatial and temporal coordinates of the observer, Δx=Δt.
if curved space-time causes gravity, then what are gravitational waves, and how to gravitational waves relate to curved space-time ?
Good questions .
7:09 - I am not a physicist, but I think that is the definition of terminal velocity. "The velocity a free-falling object would reach by the time it struck the surface". It's the same velocity as would take to achieve escape (velocity). On the Earth, that is around 11.186 km/s., not C. Now, from the event horizon of a Black Hole, it would be C.
My comment was:
If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance.
The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain.
And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
If you’re directly between two massive objects of the same mass, does time pass as if you were on the surface of either one?
No. Outside objects and surface of object will yield 2 different times
@@MrMoose1347 but it would average the two? As you move away from one time is speeding up but as you move closer to the other it’s slowing down, so there has to be a point in the middle that matches the surface time right?
@@nunya3399 ah I see what you are getting at. We do account for travel gravitationally and by acceleration. Gravity is general relativity and acceleration is special relativity. When gps orbit earth it accounts for both. So not were they meet in the middle just where we account for both
Stop using miles....
Yep, science is international, maybe use the SI?
If you're so informed, why are you here?
I'm not against the use of SI, but I am against the notion of one person or a group of people telling others what convention they can or cannot use. I use both conventions, and I also use proper conversions when necessary. It all depends on the context of the problem that I'm working with. I do not buy fuel by the liter. I buy it by the gallon, and I measure my vehicles economic efficiency based on miles per gallon. When I buy milk, I buy it by the gallon or 1/2 gallon, not by the liter. Again, it all depends on the domain and context of the workspace. Now, if I was working in a lab and doing some chemistry and or physics, perhaps I would use the SI units, but again that still depends on the domain, context and workspace of the current problem. Only someone who is either ignorant or arrogant wouldn't understand this. I have the understanding and intelligence to use multiple formats and conventions, and I'm sure there are many others that do too. There is nothing wrong with someone else using miles as opposed to kilometers. Also, when I step on a scale to measure my weight, I'm measuring weight in lbs., I'm not measuring my mass in kilograms. The comment alone "stop using miles..." is condescending.
No
@skilz8098 Yeah whatever, the entire world uses kilometers.
7:03 The iron ball would reach the speed of light?
Relative to what?
How could the height of the tower be infinite?
How long would reaching the speed of light take?
How would the speed of the ball be measured?
You would need infinite energy to move a massed object at the speed of light!
My comment was:
If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance.
The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain.
And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
speed of lite is the same relative to everyting, if you don't know that what are you doing here, watch some basic videos or you'll just get more confused
Best explanation yet
Question? since even deep space contains micro-gravity, what is creating the micro-gravity?
The Gravity Probe B experiment detected something called "Frame Grabbing", where the Earth is grabbing space/time as it turns on its axis. Wonder if this had been further examined as to impacts to time?
Can you expand just a little more and in the extreme case of going trough an event horizon where the time and space axis switch? How would you represent that in a video graphic? And by the way....excelent video!
For a particular choice of coordinates, the Schwarzschild-Droste coordinates, the temporal and radial components of the metric tensor switch algebraic sign.
Understanding the "switch" is easier than many think. It sounds brain-bending that time and space switch places, but it's really just the fact that the singularity is the ONLY future of your light cone. Because anywhere you would like to maneuver when "falling" into a black hole, you will ALWAYS (100% of cases) meet the singularity (it's just in your light cone across all possibilities). The Penrose diagram has this brain twist in it, but from a simpler point of view, it's just that. Like when it's Friday night and you are out with friends, the beer is your 100% future :D (if you drink). I like to hypothesize that all singularities are the same (like in the SAME spot), because when you have a spherical universe (like an expanding balloon and space-time is its surface), when you do this 90-degree warp (like black holes do) from the surface, eventually this warp ends in the middle of the sphere. So all black holes point to the same "space/spot/something/singularity" :) . Just food for thought.
@@fjbayt much like going over a waterfall
The time and space axes never switch. That is nonsense. Time is time and space is space. Minkowski was wrong with his quote ("Henceforth, space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality")!
@@romanjanek5283 FYI: singularities don't exist and time and space don't switch.
Why is light beam travelling horizontal in the unrolled up diagram ? It should be 45 degrees, right ?
"Light beams which only move through space..." I cannot get my head around this. So light doesn't move through time?
@@grahamthomas7821 technically they do but it’s the shortest time. All massless objects not just light
Not only do objects moving at light speed experience time as zero, the space between their origin and where they land is compressed down to zero distance as well.
@@reidflemingworldstoughestm1394 that’s perspective.
@@MrMoose1347 That's physics. Perspective is drawing.
@@reidflemingworldstoughestm1394 perspective can be drawn but isn’t strictly drawing.
OMG, This is the first time I ever had a glimpse of understanding of gravity and space time change nearing a massive object, I THANK YOU so much for making this grasp able. I love eye opening Videos of this nature. Keep the good work :)
really..."the iron ball would reach the speed of light". as far as physics goes, objects with mass can't ever get to the speed of light.
Inside a blackhole? Speed of communication.
If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance.
The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain.
And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
at 4:27 what if you turned the funnel around so it was smaller the closer to earth and you swapped the time and space axis? would that work? or does that not make sense?
The assumption that all photons from A/B should reach C/D at same time needs a proof. It may not.
they don't. we saw the same light from a supernova . arrive 3 different times.
@@atticuswalker Not equivalent , with the earth scenario its a single mass and photons are taking a similar path , with a supernova the light take wildly different paths
@@stoppernz229 Because spacetime curved. Floathead says the same thing as this guy.
@@atticuswalker did you?
@@wiktorchm what. see the light myself. nope. but I haven't seen the cmb either. don't doubt it's real.
Can anyone help confirm this for me? I've always found the twin paradox a bit confusing because, as I see it, the twins can never meet in a way that would cause one to be older than the other. Here's why: as the twins travel towards each other, their clocks would start to synchronize. By the time they are close enough to "meet," their clocks would essentially align, placing them on the same "time" line and making them the same age again.
From my understanding, the only way the paradox could play out is if one twin traveled near the speed of light towards the other and could observe the other's clock. However, the idea that their clocks tick at different rates is something that seems to only hold from the perspective of an external observer outside both reference frames.
So, what I'm asserting is that it's not accurate to say the twins could meet and be different ages because they could never technically meet under these conditions. The differences in their clocks are only apparent to an outside observer. Is my reasoning correct?
That’s why it’s a paradox. Neither can be older than the other
The gravitational field is not necessarily stronger at the bottom of the ocean trench, as it is highest at the Earth's surface and then gets weaker as one approaches the center of the Earth (where there is no gravitational field at all). So while clocks do go faster higher in the atmosphere, they will also go faster at the center of the Earth.
Excellent point
A clock at the surface of the Earth runs faster than a clock at the center. Not by much, the time dilation is 1.0000000003 between the core and surface.
@@fjbayt NO - the time dilation runs proportional to the Newtonian potential, which is lowest at the center of the Earth.
@@KaiVieira-jj7di You are right, my mistake, i got confused, i ll erase the comment
Interesting. I've just been taking a look at 'How Does Gravity Work Underground? (An In-Depth Explanation)'
3:34 into the video . Time is not in a straight line . It should be . Distance is curved .
Hence more time to cover the distance .
Great video
In 7:24 minute you show curved space and the apple that falls. Please can you show all unit measures of curved space time when the apple falls with 9,81m/s^2 acceleration?
Eddington’s „observation“ was technically a joke. He had not even the needed instruments, or the needed accuracy to perform such observation. He just wanted „to confirm“ Einsteins prediction…no matter what.
It's incredible how the press just picked up on Einstein after that.
@@greggstrasser5791
At first sight, yes.
@@O-Kyklop It was later demonstrated countless times with modern technology.
@@PADARM
Oh yes, Einstein’s prediction had to be proved at any rate.
Eddington was cheating and all others later ones too. They sold to you simple refraction for bending of space time and you did buy it.
So that means in a wormhole where the space could be infinite the time slows down almost to a stop and the speed grows as much as it almost gets to the speed of light ?
The speed of light is not a constant as once thought, and this has now been proved by Electrodynamic theory and by Experiments done by many independent researchers. The results clearly show that light propagates instantaneously when it is created by a source, and reduces to approximately the speed of light in the farfield, about one wavelength from the source, and never becomes equal to exactly c. This corresponds the phase speed, group speed, and information speed. Any theory assuming the speed of light is a constant, such as Special Relativity and General Relativity are wrong, and it has implications to Quantum theories as well. So this fact about the speed of light affects all of Modern Physics. Often it is stated that Relativity has been verified by so many experiments, how can it be wrong. Well no experiment can prove a theory, and can only provide evidence that a theory is correct. But one experiment can absolutely disprove a theory, and the new speed of light experiments proving the speed of light is not a constant is such a proof. So what does it mean? Well a derivation of Relativity using instantaneous nearfield light yields Galilean Relativity. This can easily seen by inserting c=infinity into the Lorentz Transform, yielding the GalileanTransform, where time is the same in all inertial frames. So a moving object observed with instantaneous nearfield light will yield no Relativistic effects, whereas by changing the frequency of the light such that farfield light is used will observe Relativistic effects. But since time and space are real and independent of the frequency of light used to measure its effects, then one must conclude the effects of Relativity are just an optical illusion.
Since General Relativity is based on Special Relativity, then it has the same problem. A better theory of Gravity is Gravitoelectromagnetism which assumes gravity can be mathematically described by 4 Maxwell equations, similar to to those of electromagnetic theory. It is well known that General Relativity reduces to Gravitoelectromagnetism for weak fields, which is all that we observe. Using this theory, analysis of an oscillating mass yields a wave equation set equal to a source term. Analysis of this equation shows that the phase speed, group speed, and information speed are instantaneous in the nearfield and reduce to the speed of light in the farfield. This theory then accounts for all the observed gravitational effects including instantaneous nearfield and the speed of light farfield. The main difference is that this theory is a field theory, and not a geometrical theory like General Relativity. Because it is a field theory, Gravity can be then be quantized as the Graviton.
Lastly it should be mentioned that this research shows that the Pilot Wave interpretation of Quantum Mechanics can no longer be criticized for requiring instantaneous interaction of the pilot wave, thereby violating Relativity. It should also be noted that nearfield electromagnetic fields can be explained by quantum mechanics using the Pilot Wave interpretation of quantum mechanics and the Heisenberg uncertainty principle (HUP), where Δx and Δp are interpreted as averages, and not the uncertainty in the values as in other interpretations of quantum mechanics. So in HUP: Δx Δp = h, where Δp=mΔv, and m is an effective mass due to momentum, thus HUP becomes: Δx Δv = h/m. In the nearfield where the field is created, Δx=0, therefore Δv=infinity. In the farfield, HUP: Δx Δp = h, where p = h/λ. HUP then becomes: Δx h/λ = h, or Δx=λ. Also in the farfield HUP becomes: λmΔv=h, thus Δv=h/(mλ). Since p=h/λ, then Δv=p/m. Also since p=mc, then Δv=c. So in summary, in the nearfield Δv=infinity, and in the farfield Δv=c, where Δv is the average velocity of the photon according to Pilot Wave theory. Consequently the Pilot wave interpretation should become the preferred interpretation of Quantum Mechanics. It should also be noted that this argument can be applied to all fields, including the graviton. Hence all fields should exhibit instantaneous nearfield and speed c farfield behavior, and this can explain the non-local effects observed in quantum entangled particles.
*UA-cam presentation of above arguments: ua-cam.com/video/sePdJ7vSQvQ/v-deo.html
*More extensive paper for the above arguments: William D. Walker and Dag Stranneby, A New Interpretation of Relativity, 2023: vixra.org/abs/2309.0145
*Electromagnetic pulse experiment paper: www.techrxiv.org/doi/full/10.36227/techrxiv.170862178.82175798/v1
Dr. William Walker - PhD in physics from ETH Zurich, 1997
Interesting, but it is a book rather than a comment.
@@walidkhier5640See my short UA-cam presentation.
Well it’s been proven and you can say otherwise but your comment and sources don’t disprove relativity. It all works very well.
If the speed of light is not a constant then Relativity can not be correct, any theory based on it is also wrong. General Relativity is not compatible with Quantum mechanics. So either one or both of the theories is wrong. The evidence I present says Relativity is the problem. Science will not advance , if the foundations of physics is not challenged.
@@MrMoose1347If the speed of light is not a constant then Relativity can not be correct, any theory based on it is also wrong. General Relativity is not compatible with Quantum mechanics. So either one or both of the theories is wrong. The evidence I present says Relativity is the problem. Science will not advance , if the foundations of physics is not challenged.
How much gravitational field/gravitational constant to make light bend?
The radius of curvature is c^2/g
You lost me at ^@@DrDeuteron
@@rodolfosantana9015 well if you imagine a flat earth (no, not like that) and fire a laser beam horizontally, after 186,232 miles it will fall for one second with acceleration "g", so like 16 feet, and that is following curved space time, and (switching to metric) 300 Mm long parabola curved by 5m has a radius of curvature of c^2/g = 10 Pm. (peta meters)..so about 60,000 AU...space is pretty flat around Earth, yet you can't fall 20 feet without getting hurt.
@@DrDeuteron
Why do Laser beams, in fact, bend upwards when fired parallel to the ground?
Indeed fleeing Earth mass.
@@O-Kyklop omg. please learn to abstract. We're doing a flat earth model.
beautiful explanation and illustration.
It is described as curvature but is something else. In Einstein’s theory, it is more of a functional analogy
Gosh I hate it when people put trash on UA-cam. Space and time are both metrics and don't create anything. That is the same as saying the measurement of one meter can create life. I hate ignorant people that can not learn basic stuff.
if light propagates in all directions then why and how do we see/locate the object emitting light? wouldn’t we see the light from the object everywhere?
I think you are mixing up gravitational time dilation (GTD) with spacetime curvature. GTD arises when you think you are stationary and yet you are actually in an accelerated frame of reference, as indeed we are standing on the surface of the Earth. GTD is observer dependent, meaning it is possible to find observers that do not see it (a free falling observer won’t experience GTD for example). Where there is GTD, there is apparent (or fake) gravity. Once we accept the Earth is accelerating upwards, it is actually unsurprising that objects appear to fall and that all objects regardless of their mass ‘fall’ at the same rate, because the Earth is actually accelerating upwards at the same rate. Most of what we see as gravity on Earth is because of its acceleration upwards. What is holding the Earth in, keeping it the same size? Spacetime curvature.
Spacetime curvature is caused by mass and energy. It is observer independent; all observers will agree on the curvature. Spacetime curvature is what gives rise to real gravity, and what attracts objects together in space. It emerges in the form of what we call tidal forces.
The rolled up diagram you used is flat spacetime but rolled into a cone to illustrate the time dilation. That time dilation is GTD. GTD arises from an accelerating reference frame. When it is flattened out the time axis is curved, while the free falling world line (of a falling object) is not. This is a specific version of a spacetime diagram describing flat spacetime (not curved) and actually drawn from the perspective of a free falling body. The time dilation on the curved diagram is a result of a mapping between the object’s inertial frame of reference and our (standing on Earth) accelerating reference frame and is not the same thing as spacetime curvature. The free falling body has no acceleration itself and sees us and all the Earth accelerating towards it.
If you take the derivative of the space time curve at any point along the curve, will you obtain the acceleration due to gravity at that point as determined by the inverse square law?
I see it backwards. Gravity (mass) creates time and space.
Gravity doesn’t create time. Motion is time. That’s why gravity (distances) warp time. And speed affects velocity. Mass warps spacetime.
No, a photon is the most extreme form of motion, yet time = zero.
No, at the time of inflation, there was time AND space, but no mass at all.
@ that energy still has motion
@@JockularK yes because it’s a force carrier. Showing the limit to information travel.
That's the backing paper from book covering film... wow, it's all so simple.. but where did the book covering go?where did it come from and if we join the two sides together will it create a worm hole between Rymans and Smith's?
Why are you using miles / second to express the speed of light. Ughh.
i think the video explaining that object will drop accelerately as it reach toward the earth. But I didn't catch why the object move towards earth as well as why the moon doesn't drop to the earth. Or I miss some concept in the video?
if you want more explanation : ua-cam.com/video/6H5vYP6ssUY/v-deo.htmlsi=tpzlCClld2pBPfU5
How skillful are scientists in explaining problems they cannot understand with fabricated solutions? They create a paradox with nonsense questions, and then they think they have solved that paradox with another nonsense. The speed of light is constant only if they are in the same plane. When the plane is different, the speed is different. For example, the near beam should reach the large mass earlier because it travels less distance than the far beam logic. It's not like that, though. The ray that stays away from the larger mass appears to arrive at the same time because it moves faster than the one that is closer. When you incorrectly construct the universe, light and movement, such absurd questions and solutions are called science. This is not science. He's deceiving people
Your comment may be deceitful even to yourself,
there is a big difference between hypothesis and fact.
Seems wild to claim scientists are just full of nonsense and 'construct the universe' incorrectly, hinting you have all the answers.
Another thing that seems quirky and weird to me is how can light speed up and slow down, or slow down and speed back up depending on the medium that it's going through... And they call this a 'constant"⁉️😂
@@drakeeblis1788 No. It's specifically the speed of light in a vacuum.
And it's not primarily about light. Light is a massless particle hence travels at C in a vacuum. But can be slowed by shining through non-vacuum.
@@drakeeblis1788 Let me explain please. First of all, it is necessary to know what light is and how its movement occurs. As you know, the space that is thought to be empty is actually full. It only has a much sparser texture compared to mass. I think that at this point, weak force or weaker forces are involved. (weaker force has not yet been fully defined) weaker force is the subatomic particles that I call formation points, which are too weak to be mass. They move just like a Newton pendulum. But they are connected to each other in every direction. The reason for quantum fluctuations is their movement. The most important task of these structures is the communication network with the ebb. In other words, light seems to move through these structures. Just like the balls from a Newton pendulum do not go anywhere but transmit the movement. Think of it in the same way but in 3 dimensions. The distance between the balls increases or decreases the speed of light. If the distance is greater, therefore it means it is farther from the mass, then light moves faster. Because there is no time between two formation points. It is the collisions of two or more formation points that express time. I hope this was a sufficient explanation for you to understand. In fact, the topic is so broad that it is harder to write. Thank you for bearing with me.
Cann you tell me when you folded then what will be in background of that in which folding occur because space you folded then what will left in background
You got it wrong. The curvature of space time is a symptom of gravity.
Nope... you got it wong. Acceleration along space axis . . what we call gravity. . . is direct result of warping of space-time... more specifically differential time. Not the other way round.
@@bbbf09
Why does space warp?
@@pretzelogic2689 Space-time (4 dimensions) is what warps - not just space. It is a fundamental fabric of the universe.
It does so in the presence of any energy-momentum. Since mass (matter) has an equivalent energy (E=mc2) then it also warps in the presence of mass (any mass size but more noticeable for us with planet size masses like Earth) . That warp gives rise to differences - a gradient - in the flow of time which gives rise to space (which rememeber is connected to time as 4D fabric) flowing in towards the direction of the warp (towards the mass) - which we experience as an acceleration and historically have labelled it as a force of gravity. So it is warped space-time gives rise to what we call gravity. Not the other way round. To go into greater depth involves EInsteinian tensor mathematics. A bit too much for youtube comments section.
@@jayceasar2661 Prove what exactly? that time flows at different rates depending on how close to the energy-momentum (mass) centre you are? Without accepting that the algorthim in your GPS makes allowance for this - then it would not work and you couldn't use google maps to go anywhere. 'Proof' enough for you?
@@bbbf09
You said it yourself: "...it also warps in the presence of mass..." Your "also" refers to energy. Energy mass, fungible. Thanks for repeating what I said.
So you're saying the difference in the flow of time between 2 locations is the gradient that drives the apparent force of gravity?
Imagine traveling a road that takes 5 minutes to reach your destination. If a sinkhole or crash blocks the path (representing mass in space), you can't continue straight. The obstruction diverts traffic, and you must take a longer route. This detour increases your travel time to 8 minutes. This time dilation reflects changes in spacetime; with increased distance, time dilates.
Acceleration also affects spacetime but in a different way. Changing your speed alters the perceived contraction of space and consequently affects the duration of time.
Relativity encompasses more than just relationships between measurements. It involves how units of measure change relatively due to different conditions experienced while traveling through spacetime.
Matter tells space-time how to curve, and space-time tells matter how to move. This is because space and time are not flat, but can be warped, stretched, and pulled by matter.
Time is relative and not constant. The rate at which time passes depends on your frame of reference.
You just need to look at the constant adjustments that have to be made for time dilation to GPS satellites due to Special Relativity (velocity - clocks run slower) and General Relativity (weaker gravitational field - clocks run faster).
Overall effect for both GPS satellites and travelling in an aircraft ... clocks tick faster.
However, moving at sea level -> clocks run slower, so you age slightly less.
I knew it, I knew that it would come the day when Millennials would start thinking they can think like geniuses too and would start spurting out all kinds of nonsensical krap calling them scientific theories. Time, or time dilation, creates gravity as much as chronometers create speed, duh...
Can't wait until you get the Nobel for refuting Einstein.
@@somerandomboi8239 Einstein never came up with that krap. He new better.
@@rubenoteiza9261 ok
@@somerandomboi8239 You are right, Einstein said many things but the things on which he was right he was able to prove them mathematically, with equations. There is np mathematical proof for this assumption, it is pure speculation.
@@rubenoteiza9261 I may have been wrong to react this way, as I am not yet at this chapter but am just watching stuff in order to gain some basic intuition for when I do get into it seriously. I just do find these playing-arounds with ideas and imagery useful for visualizing concepts, and couldn't comprehend what you meant by dunking on it, esp. with your end sentence about time and gravity. What does cause it then? Because we all agree that it is not a classical force.
Then of course, maybe you see something profoundly wrong in the video that I couldn't catch?
Does light really bend? When looking at a fish in water, why is the fish ahead when looking through water? Could the same happen in space near a planet or star?
But why do you wrap space-time in a cylindrical shape? What physical phenomenon explains this? Some kind of periodicity?
I believe it's just a way to visualize it to help understand. It's not a literal interpretation.
@@xtraspecialj Then that should be made clear when presented that way, or it just helps misunderstand
@@NondescriptMammal ?? How in the world is it not clear? How could anyone possibly think it's a literal representation of spacetime? If you think that, then you shouldn't be bothering to ponder this stuff, you should be watching Bob the Builder or something...
@@xtraspecialj I assume that the maker of this video means for the cylinder to be taken seriously. It isn't just presented as a momentary visual aid to help understand... Everything that follows in this video to reach its conclusions, is derived from the geometry of that cylinder. All the example cases and intermediary conclusions presented afterward, rely directly on the construction of that cylinder. The cylinder is indispensable to this video's attempt to validate the assertion that "the curvature of spacetime causes gravity".
@NondescriptMammal ... Yes, but it doesn't mean to be taken literally. It's simply an aid to help in understanding...
This is easily one of the better explanations of gravity. Kudos to you.
Question. In this model of spacetime it flares wider as it approaches the center of mass of the earth. But, in another model, spacetime funnels into a point towards the center of mass of something like a black hole.
No. In this model the larger diameter denotes longer time taken to cover the same unit of space. The closer to massive object the slower the time gets. Your second sentence is about spacetime, and is correct.
It's just an inverted visualization, since space and time are represented by perpendicular axes. When discussing the differences of motion through space and/or time, it is helpful to invert the cones in order to show the consistency of the distances travelled.
Why does the universe choose to have mass and light move on geodesic paths? Does it have anything to do with the law of least action?
I would also put some explanation to cover the difference between those two persons curved path (since they are forced by the contact with the ground) vs straight path of falling object (since there is no contact with the ground during the path).
I watched 2 videos and i still can't understand it ig. Correct me if i am wrong.
So if if throw and object from an height, Its always in rest during mid air. and when i collides with ground it comes in motion, coz ground is in motion too
Things are only at rest in their frame
The cone can work well if a gravity is the only force. I wonder how should air resistance force be put on the cone? Maybe as a force opposite to gravity increasing speed in time direction or maybe air resistance modifies somehow the cone?
Is that true that you eventually reach speed of light if falling down infinitely? If you're jumping off a plane, your falling speed increases but only to a certain speed and then, unless you're not already on the ground (ouch), your falling speed will remain constant (the exact number would be devided from your weight) and yet far from speed of light. that is if the gravity is constant.
Wow. It looks like you could work out the geometry that gravity bends spacetime into by using the acceleration of gravity and that last diagram (6:00).
saying 'the flow of time' is a contradiction as it implies distance traveled of an arbitrary quantity 'q' moving from point 'a' to point 'b'. So how can anyone invoke a term witch itself is defined in terms of time to describe time?
I tell you, Millennials have already gone to college, graduated, and think they can also revolucionize Physics.
Energy is always in motion. Motion is time. So yes by the existence of energy distance has be traveled
I am not a physicist but have a question on this. Light travels in different velocities in different optical mediums. Are we sure there is nothing in the space? Maybe something near the earth has different density that cause light travel slower.
@@phillee8666 yes we are sure
No,they are not sure. And not only that, they don’t even know if Space is isotropic. Or even worse, they can’t even test it. They only talk and, if you believe it, they don’t need more than that.
@@O-Kyklop Yes, on large scales, space is considered isotropic, meaning it looks the same in all directions. This assumption is a key part of the cosmological principle, which suggests that the universe is homogeneous and isotropic when viewed on a sufficiently large scale. This is supported by observations, such as the uniformity of the cosmic microwave background radiation . However, on smaller scales, the distribution of matter (like galaxies and stars) is not perfectly uniform.
@@MrMoose1347 Ok. It means you can’t make a prediction for a certain location you can’t check up directly.,……which is most of the Universe.
Not a very solid theoretical background, isn’t it?
@@O-Kyklop but we can though
I would like to see an explanation of how "space time" curvature causes the tides. I assume that space time is curved between the moon and the earth ( or between the sun and the earth) and that curvature of space time causes the tides, but I'm having difficulty visualizing how that works.
...little confused here. I heard dropping a steel ball from a height & a feather, they'll fall at the same speed ( in a vaccum - no air resisrance ) , and they'll reach a certain speed but won't keep accellerating infinatly towards light speed. I know I must have missed something in your example though.
@@paulfogarty7724 they will drop at the same rate and will never reach the speed of light if given the opportunity.
@@paulfogarty7724 this is because gravity is constant here but factors act against it like air resistance.
If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance.
The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain.
And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
Why do goose down and a metal ball fall at the same speed in a vacuum? How does gravity determine how much force to apply to objects of different masses so that they fall at the same speed?
Gravity is a constant and without air resistance they don’t flutter or slow either
Wait.. at 7:04 you're saying that an iron ball falling infinitely from the Eiffel Tower into a gravitational field would eventually accelerate to the speed of light? Well, problem is, only massless things like photons can travel at light speed, and any object with mass would require energy equivalent to the mass of the entire universe to accelerate to the speed of light, which would also include the mass of the infinitely long Eiffel Tower that the iron ball would be falling next to. So the iron ball would never reach light speed, because if it did it wouldn't be an iron ball anymore, but a stream of photons that used to be the iron ball, the Eiffel Tower, and the rest of the mass of the universe.
Correct.
My comment was:
If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance.
The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain.
And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
@@DABmongerthere's more wrong with the example than that but you're missing the point. Dropping any mass onto a black hole would be a better example. By the way if the tower is infinitely tall the ball wouldn't fall at all because it would be too far from the source. Assuming the tower itself doesn't have mass. On another note if there was no ground and the ball was somehow affected by gravity, any air around it would also be in freefall. Terminal velocity only exists if there is a ground for the air to push against, otherwise there isn't any friction of falling.
@Richinnameonly Me thinks you're overanalysing, and a lot. The creator will giving a simple example, and there is a terminal velocity constraint on Earth, plus nothing with mass can travel at light speed
You're adding elements to a simple example, none of which was the creator's intention.
One of the best explanations I have seen. Thanks
Do people in low earth orbit have longer attention spans?
No. If anything you could expect a shorter span as it would be harder to sustain a longer second
Though a ‘’low’’ orbit term may be misleading as it depends on whether the observer is in a higher orbit or the surface of the earth
@@skalderman let me be clear because your answer is weird.
Do humans born on earths surface experience longer attention spans when they leave earths primary atmosphere and exist in a place of considerably less gravity?
The reason why i am wondering is because when i practice becoming aware of my attention span and experience "the moment i can feel it come and go into memory. But does it change in space? Does the moment feel longer?
@@ninjxxitty Interesting question. The term low confused me. In theory as you go higher in the orbit time intervals should shorten and thus you might be able to maintain a longer attention span per second. However frankly I dont think thats practically sensible because there are whole a lot of factors like your energy levels, information entropy, wear and tear of radiation etc. I would say our consciousness would not care about the relative length of a time interval save the energy issue
@@skalderman you gave me an idea.
Imagine a spacetime grid. Then pinch it where matter would be. You understand how the lines skew as they intersect? What if you thought of each skewed square as a moment of time. The closer to the center the faster the intervals of time feel. The farther out the slower time feels.
Sort of like the shore of an ocean. Big waves take longer and arrive less frequently meanwhile the tiny waves are frequent and everywhere.
Thoughts? Its just an idea. What i care most about is how consciousness feels in the moment versus transitioning to memory.
What is miles? Something like m/s ?
I'm confused now. I thought that if light or any other object travels along the curvature, they would not "feel" any acceleration, i.e. gravitational force and their clocks would tick at the same rate, just as in an inertial frame. Only from the perspective of people on earth, the view of time ticking faster the higher you go becomes plausible. Can someone explain?
You are right. There is no force of gravity and all clocks tick away at the same rate, everywhere, and under all circumstance of motion and orientation.
There is a real effect called gravitational time dilation. Clocks in a sky scraper tick faster than those on the ground. However, you falling feel no force and your wristwatch is normal to you.
Just to follow up with my previous comment: The differences in elapsed clock time in the presence of gravity is owed to the distances along the clock world-lines (the elapsed proper time) to be different lengths owed to the background curvature.
Your explanation is excellent, although you need to be mindful of where the observer is at all times and all events need to be described in relation to a perspective from a certain point within the diagram itself at every stage, one cannot observe the effects as if we can safely refer to any absolute time, every time reference must be relative to another somewhere else, so time doesn't slow down for something falling into a gravity well unless you assume we are observing from outside the well, it's a small, but important distinction that permeates every sentence.
On a side note, I believe I have worked out why gravity, not just that gravity is the effect of the curvature, I worked out why the curvature is the shape it is based upon the conservation of angular momentum within Einstein's field equation, if you're interested, I can relate it to you, it provides a reason for the shape of the tensor based up on the careful application of conservation laws and some base postulates from both Newton and Einstein together, I consider it to be the cherry on top of Einstein's field equation, because it explains why an effect like gravity must exist just given the postulates alone, and gravity the same shape does exist according to Einstein and observations.
What force, (force = mass x acceleration) causes the acceleration. The 'rubber sheet' model assumes the object is already moving with respect to the major mass's centre of mass. A static model requires a force to begin acceleration. And more - where does the energy come from to accelerate the object. If an object falls inside a total vacuum calorimeter, it would register heat when the object hits the end of its travel. Where did the energy come from?
From it's initial creation. Everything in space is falling. An object will stay in motion until acted upon by an opposing force. If an object finds itself roaming space alone, then it will speed up because it's falling.
The following doesn't make sense to me: How can two people in different timeframes interact? Surely, everything that currently exists, does so in the present moment. If the implication is that the present moment, the now, doesn't exist and everybody is on their own timeline then, wouldn't that render the past and future meaningless? I'm confused.
The same way you can talk to someone of the phone who is at the opposite side of the Earth - there is a delay, because the speed of light (or the maximum speed at which the information can travel) is not infinite, but each one of you remains in your own timeframe.
And YES, you are correct - time is relative! That's the whole point of relativity! You're not confused - you've just graduated yourself to a new understanding. CONGRATULATIONS! 😄 🎆
And someone could talk to another person who is higher or lower than them, or is moving faster or slower (perhaps in circles, say).
These two people would have different reference frames, but could stay in contact even without a telephone.
4:19 a cylinder is flat. but also a cone is flat.
this is not spacetime curvature, this is the local equivalence principle: gravity due to acceleration in flat minkowski spacetime. notice that you do not need curvature to experience gravity
it's a nice visual, but it's very inaccurate because gravity is not caused by curvature, it's cause by being in accelerated reference frame. Geometry, curved or otherwise, dictates what counts as a force free path.
If the Eiffel-Tower were of infinite hight there would be no gravity at all. This is a classical solution which is duplicated by GR in the Newtonian limit of „weak gravity (earth) and slow speeds (v
7:05 terminal velocity?
If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance.
The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain.
And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.
Wouldn’t Bob be younger since he was moving faster? I could be wrong, but I think you got it backwards. The faster you travel, the slower time goes, right?
They are "moving" at the same space unit per unit of time - the only difference is the influence of gravity. The closer to a massive object the slower the clock.
0:13 which light? 🤔
Listen again
Isn’t there any length contraction due to the existence of massive objects? Doesn’t this factor contribute to gravity?
Time dilation and length contraction are concepts in special relativity that describe how objects moving at high speeds and/or appear different to a stationary observer. And in general relativity there's gravitational length contraction and gravitational time dilation.
So does curved space cause the gravity we experience on Earth, or is it due to the Earth's mass that keeps us from flying off into space?
The Earth isn't really "pulling" us towards the center of the planet. The spacetime stress tensor (an abstract mathematical object) at every point in space is "pushing" us towards the center of the planet.
@@ericzeigler8669 Earth's gravity is caused by both the mass of the planet and the curvature of space:
Mass
The mass of a planet determines its gravitational pull, which is the combined gravitational pull of all its mass on all the mass in your body. This is what gives you weight, and if you were on a planet with less mass than Earth, you would weigh less.
Curvature
According to Albert Einstein's general theory of relativity, gravity is linked to the curvature of spacetime itself. Massive bodies, like Earth, bend and curve the fabric of the universe, which determines the path that objects travel. This curvature is dynamical, moving as those objects move.
@@TerryUniGeezerPeterson You almost have the correct view. You're mixing Newton into your explanation with this whole "pulling" idea. Einstein's description of gravity has replaced Newton's description in all physic's communities.
@@ericzeigler8669 A planet's *mass* determines its gravitational pull, or how strong its gravity is. Gravity is a non-contact force that attracts objects to each other, and *the more mass an object has, the more gravity it has*. For example, Earth's gravity pulls on all the mass in your body, which is what gives you weight. If you were on a planet with less mass than Earth, you would weigh less.
@@ericzeigler8669 If Einstein got it right about Gravity, why are we still driving around with gasoline?
“Object mass" refers to the inherent amount of matter in an object, which is a constant value and does not change with its speed, while "speed mass" is not a standard term, but could be interpreted as the apparent increase in mass an object experiences when moving at very high speeds near the speed of light, according to the theory of relativity; essentially, the faster an object moves, the slightly greater its "relativistic mass" appears to be, although this effect is only noticeable at extreme speeds.
Could you describe gravity equally well by considering it as a force acting on the momentum vector of an object?
No, the force is always zero. And in the case where a pseudo-force is used as in Newtonian gravity, it doesn't reproduce observational data.
@@KaiVieira-jj7di I agree with this, but from a slightly different perspective. I do have a background in Math, Physics and Chemistry, yet, I've always had my own intuitions about things. So regardless of what we were taught to believe as being the "de-facto" truth, I always tend to challenge everything, put it to the test.
When it comes to gravity, I do not see gravity as a force. I never have. Even the term we have come to use as why objects fall to the Earth's surface as being gravity.
Now, acceleration itself is a force. The downward acceleration towards earth is what we like to call gravity. This goes back to the notion as to what "physics" is or how it is defined. And traditionally, widely accepted is that physics is the study of motion. Within that, the concepts of forces emerged, and they have always been based on "cause" and "effect".
I have never considered gravity to be the cause of anything. I have always seen gravity as being the "effect". The downward acceleration itself has a force carrier. Yet the motion that we observe of something falling down that we like to associate it with gravity is more towards the result of it, the effect of it.
I tend to see gravity as being the result or the effect that we are able to observe after a force has been applied causing its acceleration, velocity, displacement to change. I have never considered gravity itself to be an acting force, and always perceived it as a resulting effect.
So, if gravity isn't the force or the cause what is the cause then? That's quite simple, it's the mass of the object as well as other acting forces such as temperature, pressure, buoyancy, friction, energy (potential to kinetic), etc.
I threw a ball up, it's mass and density are greater than that of the air and after some amount of time, displacement, the air pressure through friction and other forces decreases the ball's upward velocity and momentum to the point where the mass of the ball and its density being greater than the air, begins to reverse its direction or trajectory. At this point, its velocity, momentum and acceleration being to increase in the opposite direction until it reaches terminal velocity or impacts another object. The visual effect of observing the change in its direction, velocity and acceleration is what we tend to call gravity.
This is where I've always differed and challenged others to think about it. I've even challenged college professors on this, and I could see it in their eyes. They wanted to agree with me, but they were reluctant to do so and didn't. They didn't want to risk their career or job by going against the established status-quo.
Gravity is not a force. It is the resulting observation it's not the cause of anything, it is the effect we witness or observe of things being in motion.
Some might argue well what about the planets in orbit? That's quite simple, it's the same thing, the gravity we are observing is the effect of applied forces and not a force itself. The orbits, that's angular momentum, centripetal forces, tension, spiral or cyclical motion.
At the foundation of it all, the study of Motion in which that is what Physics is goes back to trying to understand cause and effect. And for me, people need to stop conflating the two.
This is a crude analogy, yet I will use it only to illustrate a point.
There are two people, Person A, and Person B. Person A punches Person B in the face. Person B ends up with a black eye. Here' Person A's actions the cause is the force of the problem. Person's B's black eye is the resulting effect. Yet, others are now going around and say that the Black Eye is a Force, a Cause, when in fact it never was to begin it. The Black Eye has always been the resulting observable effect. Person A's actions, choices were the cause all along, they are the Cause, the Force of the problem. This is exactly how I see gravity. Gravity is no different than that black eye. It doesn't cause anything because it is not a force. Gravity like that black eye, is the result or effect due to forces being applied.
I wouldn't care if I was speaking to others such as Einstein, Newton, etc. I would still argue or debate this case. Would I consider or look at their arguments, suppositions, suggestions? Sure, there is no problem there. I would look at them and consider them. Yet this is my argument. This is what I perceive. And I've had college courses in Physics, Chemistry and Math. I was at the time majoring in Electronic Engineering.
@@skilz8098 What we do in physics is measure. We measure that gravity is not a physical force. We make measurements testing Local Lorentz Invariance, Local Position Invariance, and Weak Equivalence and those measurements tell us that the gravitational field is necessarily a metric field (and so necessarily described by a curved spacetime).
If you want to come up with a viable alternative to relativity you need to develop a model that gives different predictions than relativity for a set of measurements.
@@skilz8098 oh god it’s you again. That’s why you wrote an essay. You can’t keep it simple because you don’t understand it. Gravity is a force cause my mass existing in space causing it to stretch around other. Aka curvature.
@@KaiVieira-jj7di There's a slight issue with your last statement: "we need to develop a model that gives different predictions than relativity for a set of measurements."
Many within the "scientific community" are under the impression that everything can be or is measurable.
In many cases this is true to some extent. We can measure things because we can model finite examples of them.
However, not everything that exists is finite, and with that we can never truly completely measure them.
Therefore, if every aspect or premises of our foundation of understanding or observation to acquire some kind of evidence or proof is based solely on the framework that everything has to be measurable. It's kind of a moot point.
All forms or acts of measurement regardless of the measuring system that is used, regardless of the convention or notation that is used at the end of the day is still purely 100% abstract simply due to the fact that a measurement of something in general is arbitrary.
Numbers themselves are abstractions. They are abstract concepts that convey an idea. They don't actually exist in nature itself, yet the properties of nature are in some way still governed by them.
One cannot study, perform or execute physics, chemistry, biology, etc. without the use of mathematics and numbers.
The truth of the matter is every bit of it regardless of if we're able to perceive it to be discrete and measurable, finite, or if we are able to perceive it to be continuous, analog or infinite at the end of the day it is still all just a mind game.
Yet within the field of physics itself where I'm referring to practical applied physics as opposed to theoretical physics, gravity itself irrelevant of what we were taught by some textbook is the effect that we observe do to some cause or action. Gravity itself is not the cause, it's not a force.
When we drop an object, and it begins to fall to the ground, it's not falling because of "gravity". The displacement we are seeing over discrete intervals of time in a continuous fashion is the increase and change of direction of that object's velocity and acceleration. These force vectors are related to the change in momentum Mass * Velocity which also has a direct change in its acceleration and position. There are other force vectors involved such as friction, lift and drag (fluid dynamics - properties of gases), changes in temperature, density and pressure, etc.
Gravity itself isn't the actual cause of the event. Gravity is the effect of the action that caused the event.
Compare these two expressions:
Gravity emerges as a side effect or property due to objects moving through time or motion in general.
Motion or objects moving is a result of an undetectable force such as gravity.
We have observed many times over that "gravity" is relative and that it is directly and proportionally related to mass, but it's not just the mass itself or directly. It is also the mass in conjunction with its velocity, or its momentum as well as other properties or forces such as angular momentum, angular velocity.
When I drop a bowling ball it falls due to the fact that its mass: density, temperature, etc. is much greater than that of the air around it.
When I drop or let go of a hydrogen or helium balloon, it lifts upwards. It's able generate lift that is greater than its drag and with that there's a buoyancy that is generated around the surface of the balloon due to surface area tension.
When I take a volleyball and drop it in the air, it falls to the ground. When I drop it over a body of water, it falls until it hits the surface of the water. Now depending on the ball's velocity (did it reach terminal velocity) and its overall momentum will determine how much of an impact or force it generates with the surface of the water and how deep it will drive into the water before the force (pressure) of the water pushes back and drives the volleyball back up. Eventually the volleyball (provided it didn't pop and fill with water or become crushed due to the pressure of the water) it will float to the surface and generate buoyancy.
If I do the same thing with the bowling ball, it will just sink to the bottom of the body of water.
Once again, (not you directly just people in general) completely overlook or do not listen to what my argument is, what my perspective is about and pertains to.
May I have another? please?
...and a few years before that, somebody noticed fruit falling... one gets the feeling that our host believes gravity has an independent metaphysical existence, and it is just "out there."
Why should we make it cilynder?
It’s just an analogy,just like flat map of Earth, we can’t really see spacetime.
I like this except for the tendency to over-populate the video with excessive numbers of models and experiments.
then why do the atomic clocks on satellites travel slower than the ones on the ground? His cone diagram is turned the wrong way
You just need to look at the constant adjustments that have to be made for time dilation to GPS satellites due to SR (velocity - clocks run slower) and GR (weaker gravitational field - clocks run faster).
Overall effect for both GPS satellites and travelling in an aircraft ... clocks tick faster.
However, moving at sea level -> clocks run slower, so you age slightly less.
Maybe centripetal force and gravity are the same thing. Since space-time is bent, a centripetal force occurs in the opposite direction. In centrifugal force, centripetal force occurs because we bend the movement of the object in flat space. Where the two are balanced, a stable orbit is formed. As a result, spacecraft in Earth's orbit balance gravity with centrifugal force, that is, centripetal acceleration. In this way, he avoids falling.
If gravity is caused by bending space-time, how about centrifugal force?
Mass existing causes space to curve around it.
Acceleration is just like gravity.
@@party4keeps28 not quite “just like it” more like related.
@@MrMoose1347
*"Mass existing causes space to curve around it.“*
It means Space must have a mass too.
According to Newtons law of universal gravation any two masses atract each other. So light must have mass?
Light passes from C to D ( a smaller distance ) with the same amount of time that Light passes from A to B ( a bigger distance ) ???
This is only possible if the time for the Light ( C to D ) passes slower
Time curvature,
And at 6:00 the draw are not on scale ‘cause 90 degrees = Light speed into the space,
The apple goes at the speed of light in time when he is at rest ( in space )
So if we do the drawing at scale… the curve of the border is almost impossible to see ( 9.8 m/s < 300 000 km/s )
and the fact that ( at rest in space ) the apple going forward in time on the Drawing goes towards the border ( where the ticks are separated by larger time ) means that the apple goes naturally where the time passes slowly and slowly, so … right to the center of mass, but we can’t because we have the surface of the planet that stop us to go further towards the center of mass.
And if we want to do a accurate drawing for example for a black hole, the more you get into the black hole the more the angles become wide because for each meter ( at a certain point ) times passes a lot slower, so the draw at the borders become like a trumpet until we hit the distance from the center of mass when it forms a perfect quart of a circle and that in consequence the time axis of the space-time is perpendicular compared to the path of the apple in time ( so when he is at rest on space ).
And that means that the apple goes at the speed of light into the center of the black hole and time don’t passes anymore
Nice way to illustrate! :)
Simply removing mass from directly interacting with other masses, by projecting its effect onto "the fabric of spacetime", does not explain the deflection of a massless photon in a curved spacetime.
It just leaves that interaction undefined.
So if an object "fell" into an object of infinite mass it would achieve near light speed while time would be slowed to next to non existent. Would the masses actually meet, or be caught in a paradox?
It's not really a paradox. Space and time are orthogonal dimensions. Whenever mass or speed reach "infinity" they have actually moved in the orthogonal direction. It could be imagined as a rotation through dimensions preserving angular velocity.