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In the formula F=ma, a has a time variable which means F = 0 when time = 0 and Force can not be calculated unless you provide time duration. The parameter a Acceleration is due to the Gravity and Gravity has a set vector / direction, 0 to 180 degree, in other words there is NO Acceleration if there is NO Gravity, and in Gravity direction and Time needed. Force is 0 (zero) unless you give a non zero time. This is what scientists have been hiding and the space time scam is to explain a flawed formula using the gang leader einstein. E=mc2 is also False since you can change the constant 2 to 3 or any other number, it has no effect because E has no Unit. Also all the formulas mentioned as the successor to E=mc2, has the Time variable with the value 0 (zero) which makes all the calculated Forces, Energies and Vectors Zero. Additionally einstein never wrote and published any of these formulas and no other scientist wanted to claim Fallacy.
Would Ri consider a series of videos with Michio Kaku with the Ri giving him a series of topics to discuss without interruption or others on stage just him by himself..
I'm 70 year old retired Physics teacher and was mesmerised by Carroll's wonderful presentation. The best teachers have a way of bringing clarity and simplicity to very difficult concepts. Brilliant, thank-you.
This man made advanced physics accessible to the masses. If there is something similar to the Nobel Prize for science communication then he truly deserves one.
If you ever find yourself saying "made advanced physics accessible to the masses", you're working with an inaccurate definition of either "advanced physics" or "masses".
@@davidhand9721 I'd like to know what's wrong with my comment as English is not my first language. General Relativity (and the whole series called "The Biggest Ideas in the Universe" by Sean Carroll) is not exactly basic physics, that's why I used the word "advanced". By "masses" I mean ordinary people, those who don't have a high degree of education in physics, or any other field of science for that matter.
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@@kurtgodel28 Then you just need to define accessible :-)
@ My bad then, I thought my comment was clear. By "accessible" I mean, as explained in another user's comment, that he made understandable to the average people essential points at the foundations of certain theories. In the series of videos by Sean Carroll that I mentioned earlier, he covers topics that, until now, only a student of a master's degree in Physics would hear about. For instance, he talks about field quantization, renormalization, the work of Kenneth Wilson, as well as symmetry groups, general relativity and so on. But he goes beyond words and provides heuristic, yet correct, mathematical descriptions. The main prerequisite to understand the level of those lectures is basically high school mathematics. In my opinion, this work deserves more media attention because these are very specific topics that rarely find a place in popular science.
I suffered a brain injury a few years ago and it is sometimes difficult to understand simple concepts, nevermind complex concepts. Thank you Sean Carroll for simplifying subject matter for those of us who want to understand the science we love so much. Thank you RI for the same. I may not be able to do the math and I may never be an engineer again but this video makes me feel like im included again.
I had a head injury at the age of 10. So the side effects dropped me from the top of the class, to the bottom, and eventually had me dropping out of school altogether. Teachers basically thought of me as the dumbest person in the class, due to me now having difficulty retaining long term memories. However, despite me having no physics education what so ever, I still managed to independently discover the special relativity phenomena, and how this phenomena is created, along with deriving the special relativity mathematical equations at the same time. Have a look at how I did it, if interested. Anyhow, never let brain injuries hold you back.
This was the best presentation I've seen on this subject. And I'm not at all surprised that it was given by Sean Carrol with his brilliant ways of explaining things, his clear voice, and keeping your attention. The historical context shown behind the equation, and the motivation behind its construction over time was not only fascinating, but so excellently and expertly presented, without having to go off on any tangents or use too many analogies. And without insulting the intelligence of the audience with things like "imagine the swing you played on as a kid" or "imagine the strings on a guitar", just straight build up of the logic behind going from the Newtonian formulation up to the final Einstein equation, and all the players involved along the way. Perfect.
Plot twist: After this lecture was over, the audience tried to leave the hall and found they were in a rocket ship far out in space accelerating at 1g.
As I get older I find the admiration I used to have for my favourite musicians is fading (only a little) and I’m becoming more fascinated by what people like Sean M. Carroll have to teach me. I may be too old for out-and-out hero worship, but I am definitely a big fan of these big thinkers. Hooray for RI, Mindscape and Sean Carroll!
@@JRush374 Totally agree, it’s a great book and you really have to concentrate - well I did! Feynman is a hero of mine and I think I have all his books. I remember the BBC Horizon documentary when it came out and have a VHS copy somewhere. But thanks to UA-cam anyone can see this extraordinary man talk about jiggling atoms and flowers.
I agree totally too. I'm not daft or particularly intelligent.. I can think like this now too, appreciate possibly more than understand incredibly brighter minds more than ours. I wonder how many possible, probable almost genius minds have been missed, shunned or ignored at schools? Young men especially, develop and mature intelligently years after Girls...
The step that follows is teaching the basics of relativity and quantum mechanics to 10 year olds. And start teaching the accompanying maths at about 14yo, when there's a little algebra and geometry knowledge. Maybe :) And maybe that's not for all children, but my youngest nephew of 10yo loves it and has a very quick understanding of complex abstract physics because of his intuitive and creative mind that has no problems with thinking of spacetime as four dimensional curving geometry or how probability would lead to a particle to potentially end up on the other side of a barrier. He just sees the barrier as a wall that holds back part of the probability wave as it would a water wave, but if the wall is thin enough some of it might leak through, especially if you consider that most of the wall is empty space. But the point is that children can understand a lot more than we think they can. I'm guessing that we think that they can't because the maths is difficult and we're usually taught such things when we can understand the accompanying equations and maths, but that's entirely unnecessary for the basics of physics. You can easily show a relation between push and acceleration without making a child calculate it. If you push harder, there's a larger acceleration. A child can see that easily. We don't have to know the exact ratio to understand the principle.
Sean is a great communicator and a sweetheart. I think equations are fun but they often look misleading largely for short hand reasons. Unpacking equations and looking at all the knobs hidden by symbols really is the only way to understand them. Having Sean break them open and show their inner working bits is an enormous help.
Indeed. On the enterprise in engineering they turned knobs =ing the short hand way to communicate to the computer the shorthand of what to do; as the computer could read the equation showing also people who built it knew from us today that Eventually, man did figured how to be as smart as the equation itself :)
I really like the way Sean Carroll presents all the scientific concepts. He always explains how they evolve over time and that really helps me understand how we get where we are in science for a certain topic. Most worthy membership I have ever had.
Thanks so much for joining as a member! We're very glad you liked Sean's latest video, he's definitely one of the best when it comes to explaining scientific concepts.
Agree. I wish my college professors would have spent a bit more time on the history of science as well, rather than endless formulas. It (1) would have helped put things in perspective / allowed me to connect the dots better and (2) I would have realized that certain concepts didn't just pop up one day in someone's super-smart brain, but literally took centuries to be developed / discovered.
There’s a certain similarity between Sean Carroll and James woods. James woods has a 180 iq (or so the internet says) and I would bet Sean Carroll is near that . He’s great at illustrating his point on complex subjects in a simple and understandable way.
I agree. He's great. Fantastic communicator and such a nice guy with a sense of humour. Pity he's wrong about quite a lot! For example, his Many Worlds Interpretation is complete nonsense.
@@MI-qj6xrJames Woods definitely does not have an IQ of 180 (at least not in any meaningful sense). This for a multitude of reasons. Mainly because no well established IQ tests have any reliability in that range and a score that high on a typical IQ test (which are unreliable outside 2 standard deviations of the mean, i.e. outside 70-130) is basically meaningless. Part of the same rumors was that he was a member of MENSA, or that MENSA was the source of this oft quoted score, something that MENSA quickly denied (they were also stonewalled by Woods and his publicist when they tried to reach them about the rumors, since some sources implied that Woods himself might be the original source of the claims). He did supposedly score very high on his SAT, but his score was not on par with the 1 in 20 million that an IQ of 180 is (I couldn't verify his SAT score either, but it's a far less extreme claim and the guy did supposedly get into MIT based on his SAT and I couldn't find any repudiation of this from MIT). Basically, nobody seems to know where the 180 figure really comes from (and it's often quoted as 184 or 160 as well). It seems to have started as tabloids, gossip bloggers, and clickbait sites bouncing the rumor back and forth, though the rumor also seems to have had a resurgence in right-wing media in the last couple of years. The guy might at some point in time have taken a test that gave him a score of 180, but so did most everyone who has access to the web in the early 2000s. I remember that I scored over 200 on some of those ridiculous tests floating around the web back then. Another popular claim is that Woods has an IQ higher than Leonardo Da Vinci, and this one might actually be true. However, this is not really a meaningful claim either. If we extrapolate the Flynn effect that far back, a lot of us probably have an IQ higher than Leonardo, maybe most of us. And even if we ignore the Flynn effect, there is basically no reliable way to estimate the IQ of someone living that far back. And since we do know that the Flynn effect is at least true in the last century and thus that IQ scores change significantly over time, someone living that far back can't be meaningfully compared with someone living today. Don't get me wrong, the guy might be super smart. There's just no reason to believe any specific claims that high unless there is very strong evidence from a reputable source.
You are fully blown away by this guy's rhetorical talent and the uninterrupted talk. He never stutters, hangs or uses filler words. By the way: Great to hear a german word he uses (Ansatz). 😀
This is perhaps my favorite RI lecture I've seen yet. I really love getting a better look at these more complex ideas about physics, and I hope to see now like this. Really nice work, Sean and RI!
Always love a Sean Carroll lecture, just think without the Internet we'd have to smart enough to get into his class and I suspect many of us wouldn't make it, what a time to be alive.
The simplest and easiest explanation of Einstein's tensors I have ever seen. Crystal clear exposé by someone who not only masters this stuff but has integrated it into a unified coherent concept. Kudos!
Whenever I feel discouraged about the U.S. and our mess...seeing/hearing/watching Sean Carroll gives a boost to the spirit. Thank you RI for hosting him...again.
This is the best lesson on General Relativity I have attended, ever. Compliments to Prof. Carroll for his unequalled ability in explaining such complex matter with simple words. Regards Anthony
@@kurtgodel28 I don't need to be "better" than Einstein or anyone else, I only need to examine his claims in his hypothesis and weight them up to the accepted standards of rational analysis and Logic. And unfortunately for Einstein his claims do not make the grade in any way. In fact, it would be fair to say that he seems to have based his hypothesis in a purposeful deception, in other words he lied by telling half truths mixed in with truths in order to deceive. It worked well on you is seems, because you have never bothered to read his hypothesis with a scientific mind set, that of being skeptical. If you did read his paper, it would have been form the point of view of a fawning, awe struck worshiper.
Equations are too special I remember in highschool gauging at the Archimedes' principle for quite a lot of time and when you finally understand the mathematical realations between the symbols / quantities, it's amazing
That happened to me almost 10 years ago when I finally figured out what the symbols of differential equations meant. remember solving the same physics problems again and again in that summer at the beach struggling with all the d's and coming up with my own boundary condition problems. Up until then I was performing terrible at math courses. Then, it finally clicked. From that moment I fell in love with math again.
I found it a very challenging presentation to listen to. It felt quite "tensor" for me. It wasn't Sean that I struggled with; he's a good communicator with a nice smile and some humor and wit. My issue lies in my disbelief with Einstein, and I certainly don't believe the "established science". The fact that the "establishment" fully supports Einstein raises a flag with me. Let's face it, the establishment virtually lies about everything to us! The Newton science is provable repeatable and "anyone" can repeat his experiments... you can't do that with Einstein, you have to have computers and software... but that's not out there in the real world. With Newtonian science we can all independently verify his theories! Whereas Einstein's theories only work in supercomputers. Despite how much Sean says he doesn't consider Einstein primarily a mathematician, it's hard to see him as primarily a physicist when he couldn't perform his experiments! Tesla once called Einstein an idiot. In summary, I doubt relativity, or at least the context of what they mean by it. The speed of light isn't constant. It's not the fastest thing out there. Einstein could only work in the realm of theory, and his theories are only "proven" in a theoretical space-mostly in supercomputers with specialised software. And, fittingly, that's where his space-time theories "live" and work. Speaking of Tesla, there's an interesting story where a reporter asked Einstein what it's like being the smartest person alive, and he replied, "I don't know; go ask Tesla!"
I had trouble accepting his moon stuff. I watched it live and was suss about how poor quality it was. Finally watching the astronauts being tracked by the camera at the end, getting in the craft, with no camera operator??
Absolutely first rate explanation . thanks so much. Much better than my professor in 1969. I get it!! I must say I bought Hawkins book about black holes and that made a lot of sense at the time, but this whole subject does require a light touch, otherwise is so easy to get lost in the woods. Your introduction of the various tensors was brilliant. [6 months later - re-watched - got so much more. I cant thank you enough]
I would love to see a similar lecture by Sean explaining the Schrodinger equation in the same level of complexity and detail. Not everyone is a physicist but many people have an interest in the equations used and how they are attained.
That'll be the next book (this lecture is based on his latest book in case you weren't aware, with the second book in the series, "Quanta and Fields", due in May of 2024). And as @maxproph says, the books themselves are based on a set of UA-cam videos he did over the pandemic called "The Biggest Ideas in the Universe" - a bit less polished but still utterly fascinating (and available now on his UA-cam channel). (or if you're comfortable with some not _too_ crazy maths you could also check out either "A Student's Guide to the Schrodinger Equation" by Daniel Fleisch or "The Quantum Cookbook" by Jim Baggott in the meantime)
I so wanted to get a ticket for this lecture. The RI is such a special place and Sean Carroll is always brilliant and engaging and witty. But it’s great to see the video. Science is cool!
Sean Carroll is a joy to read, but he is way funnier and more to the point in a lecture! Perhaps the best explanation of Einstein's field equations I have seen. Thank you!
Bravo! What a delight. At some point I noticed I had a big grin on my face. It stayed there till the end, at which point I also had a tear in my eye. I think I have a nerdcrush!
8:22 to me the fact that gravity acts equally on different mass objects was actually quite intuitive. Not that I’m some genius who intuited the math lol. But the way I saw it, gravity was acting on each bit of mass equally, so regardless if it’s 100K atoms or 100 trillion atoms, each atom is accelerating at the same rate so more mass doesn’t change how fast something falls.
I began as a physics major in college and immediately changed majors. I eventually graduated with a degree in mathematics, with a 3.95/4.0 in math classes, and loved every minute of it.
Physics is just mathematical nonsense now. Nobody understands physics. Just a bunch of equations. F=ma? What's you frame of reference. E=mc^2? What does it say? Don't ask me, just shut up and calculate is the response now.
Your videos have ignited a passion for science and the mysteries of the universe within me. Thank you for being such an incredible source of inspiration.
The big bang means that when there was little mass at the beginning, there may have been a lot of anti-mass. the sum of the amounts of matter and anti-matter must be equal to zero. If the amount of metri is variable, so is anti-matter.
Hi Sean! Since listening to a few of your lectures and podcasts, this stuff doesn't seem quite so scary to me anymore. Keep in mind, I am just a lowly meteorologist... but it's still useful to hear your explanations, which help put these concepts into perspective for me. Question... Is any of this going to be on the test? 😊
@@DrDeuteron Yes, it can be. But for some reason I understand weather way better than this material. Which is one reason I enjoy Sean's presentations so much.
@@TheWeatherbuff "for some reason"--- the reason is that you haven't been exposed to it enough. Once you get familiar with all the stuff, it becomes easy.
Sean Carroll is probably the best advanced science communicator in the world because even though he has profound knowledge of the things he's saying, he still manages to retain the perspective of someone who knows nothing about those things. It's remarkable.
Sean Carroll has no intelligence on what he is talking about. The earth is not a stationary frame but is in motion around the sun. That's more than his brain cells can deal with. Newton's gravity? Try the 3rd law of motion. Gravity is a Reactionary force, the resistance of the mass to being accelerated by an outside force. There is no gravitational attraction but mass is not an actionable force. F=ma. Acceleration is the actionable force. E=mc. Energy comes from Acceleration of the mass. Not the mass itself. Mass is not an actionable force as proven by numerous drop tests in a vacuum. The earth is ROTATING on its axis as it ORBITS the sun. Two frames of reference. That's why you have 2 tides a day. One being accelerated clockwise and the other, counterclockwise. That's what flat earthers like Carroll and Greene, and Cox, Neil deGrasse Tyson, Stephen Hawkings, Albert Einstein, even Isaac Newton himself. Gravitational attraction is incompatible with the laws of motion. F=ma. Mass or Acceleration. E=mc. Mass or Acceleration. F=ma = ma=ma = m=m and a=a. Mass is just mass. Matter that takes up space.
I love it any time Sean Carroll lectures, and most especially when he does so at the RI! His wife publishes some of my favorite articles on Ars Technica as well!
Sean Carroll's explanation of Einstein's equation makes reading about cosmology more exciting. I was always curious about how such a simple looking equation can be so foundational. ...feels like a grand epiphany. Thanks Sean😊
That is not a simple looking equation by any means. It just hides the complexity to those who don't know what the symbols mean. He pointed that out in the talk, by the way. Whether it's foundational is not known. It's just one version of an infinite number of similar equations that nature may also follow in the classical approximation. It just happens to be one of the most simple versions of all possibilities. We have, so far, not found any deviations from it, but that's mostly due to the measurement errors that we are limited by. The bigger issue is that it has a distinct thermodynamic form... which may be an indication that gravity is a thermodynamic remnant (rather than a quantum mechanical one). Or that's just coincidence. People have been wondering about that for the better part of a century. The limited success with direct quantization of gravity might be a hint that we are missing a thermodynamic layer there.
I came up with a formula for thermodynamic radiation envelopment for interstellar photon retraction. It is ¥ -6 = 5 x speed of light. It works a treat. Nobel thingy prize for sure next year! Thank you
15:46 I don’t think that “t” is a “universal time coordinate”, as stated in the video. It is just the time axis of the frame of reference we’re working with. The “t” of one frame is, in general, different than the “t” of another frame.
Equations are the blueprint, they speak louder and look like pictures and geometry the more you understand them. Thanks for helping me understand this compact notation.
So I'm slightly confused anytime someone refers to gravity as a "force", because it was my understanding that gravity is merely an emergent property of the geometry of space-time being warped locally by mass.
Yeah, it seems like that we call "gravity" has more to do with how we are given the illusion of acceleration through each 3D "slice" or "moment" we experience, even though the universe described would seem to indicate a static 4D spacetime where everything has already "happened".
It's the same way centrifugal force and coriolis force are not technically forces. We still call them forces sometimes because they act like forces if your reference frame is spinning. Likewise, gravity looks like a force if your reference frame is accelerating. A reference frame fixed to the ground is really accelerating upwards, so it looks like there is gravity accelerating downwards. It's useful to think of it as a force because it's useful to use a reference frame fixed to the ground, it matches how we usually experience the world.
The confusion lies within GR's particular framework, and the way Newton is 'carved out' of the geodesic equation and Poisson's law out of the EFE; however, this is far from an universal necessity: yours truly, for instance, has constructed a theory in which gravity is simply viewed as a force in the traditional sense, and yet one can still draw observational conclusions comparable to GR's. Oh, and before you dismiss that as some ramblings from a rando who doesn't know what they're talking about: currently under peer-review - in a fancy journal and everything 😉
As someone who studied General Relativity from Prof. Carroll's excellent book 'Spacetime and Geometry', it feels like betrayal seeing the (+ - - -) metric signature! And excellent lecture as always!
The mathematical symbology of equations is just a way to avoid long, verbose natural language statements. You can think faster with equations. An added benefit is that new equations can easily follow.
I appreciate the enthusiasm of Professor Carroll. The capacity to set the discussion at a level that isn´t too low or too high, and the logical thread that makes it clear and enjoyable. Not least the vein of irony that put the public at ease. Would be possible to have a link to the Riemann´s paper? Or the title? That one where he makes funny comments because it wasn´t his favorite subject? Thank you.
Most of the weirdness of spacetime comes from the more basic principle that time (the fourth dimension, at 90 degrees to all others) is imaginary. You still use the Pythagorean theorem, but when you square the imaginary time element, it becomes negative, converting the Euclidean function (a^2 + b^2 = c^2) into a hyperbolic one (a^2 - b^2 = c^2). The principle is simple. The implications are profound.
@@themcchuck8400 You confuse the nature of the time variable with the fact that a pseudo-Euclidean metrics can be transformed in an Euclidian one by substituting -t^2 with (it)^2
@@alexleibovici4834 And yet the math works out the same, while my version has explanatory power. I believe the equivalence principle applies to this discussion. If it walks like a duck and quacks like a duck...
It's immensely valuable and satisfying to hear an overview of a subject, if only to get a feel for how the logic works without understanding the detail; and Sean Carroll does it brilliantly, making it seem effortless both in subject and delivery. However mathematics is not science. New data wags the tail of science, not mathematics.
Fifty Five years ago or so We worked with this concept and the nasty calculations with slide Rules and paper. I was predominantly in E&M, but particle was the expanding field. Physics in the 60's was an exciting time. Famous professors talked about basic and advanced physics. So May it Be.
Watching Sean do his stuff makes me feel like I am back at UW again. The prof would explain the subject using differential equations making it look simple. But aterwards I would spend hours trying to wrap my head around it what initially was shown to be "simple".
Sean's lectures are always entertaining and informative, never makes one fall asleep. Too bad I am not intelligent enough to study particle physics or cosmology else I will be very blessed to have him as my lecturer.
F = ma is the way we remember the equation and indeed use it, I used to explain it my Physics students by rearranging it. In this arrangement, we add up all the forces acting on the body and if the sum is something other than zero, we know the body is accelerating. In some cases, like a book sitting on a desk the forces sum to zero, so there is no acceleration. To understand the equation a little better, rearrange it to a = F/m. F is the force trying to move the body while m, the mass, is the resistance to the force (inertia). Obviously the greater the force, the greater the acceleration, i.e., the harder you push on the car in his picture, the greater the acceleration. The greater the mass (weight) of the car the lower the acceleration, i.e., it is more difficult to push a more massive (greater weight) car than a less massive car. This is why this equation looks like this, and rearranged gives us the famous F = ma. An important point is that the acceleration is the result of the force acting on the mass, NOT that the force is the result of mass times acceleration as implied by F = ma. ma does not generate force, force acting on mass gives rise to acceleration. 9:00 The reason the mass of the body does not matter is very simple to understand. If you have a body B which has twice the mass of body A, it needs twice the force to have the same acceleration as body A since it has twice the resistance (inertia). However, the gravitational force on body B is twice the gravitational force acting on body A (body B weighs twice body A). So, body B needs twice the force, but gravity acts with twice the force so the mass of the body has no effect on its acceleration. 15:44 My favorite wording of this idea is one I read somewhere many decades ago. "As you travel faster and faster, you trade space for time." Time runs slower (time dilation) giving you more time while space shrinks (length contraction). The coolest thing is that the time gained is exactly equal to the space lost. For example, say you travel at a speed where one day on your spaceship is equal to two days back on Earth. You have doubled your time. However, the distance you measure between any two bodies will be half of what is measured by an observer on Earth. You doubled your time and halved your space. This means both sets of observers will always agree on the speed of the spaceship. The Earthbound observer will say you traveled a distance, d in time t, giving speed = d/t. You will say you traveled 1/2d in time 1/2t, giving speed = (1/2d)/(1/2t) = d/t.
> To understand the equation a little better, rearrange it to a = F/m. I found too that this form is more useful in teaching: on the RHS is the cause (acting force), on the LHS is the effect - acceleration.
I am not a physicist, but I am attempting to study and understand the math to create programmed computer simulations. This placed a lot of the math into perspective for me. Thank you :)
The likes ratio on this video should be much higher than it is. Excellent summation of Einstein's equation. I remember having to do this stuff by hand. I am always so impressed with our forefathers because they did not have the benefits of mathematica (et al.) to help them visualise these geometric landscapes.
A minor quibble. It was GALILEO who first discovered the principle of inertia (and that objects fall at the same rate regardless of weight). It was also Galileo who first discovered GALILEAN Relativity (as Einstein always pointed). Lastly, Robert Hooke was the first to discover/conjecture that gravity obeyed an inverse square law, not Newton. Just wanted to correct the historical record.
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In the formula F=ma, a has a time variable which means F = 0 when time = 0 and Force can not be calculated unless you provide time duration. The parameter a Acceleration is due to the Gravity and Gravity has a set vector / direction, 0 to 180 degree, in other words there is NO Acceleration if there is NO Gravity, and in Gravity direction and Time needed. Force is 0 (zero) unless you give a non zero time.
This is what scientists have been hiding and the space time scam is to explain a flawed formula using the gang leader einstein. E=mc2 is also False since you can change the constant 2 to 3 or any other number, it has no effect because E has no Unit. Also all the formulas mentioned as the successor to E=mc2, has the Time variable with the value 0 (zero) which makes all the calculated Forces, Energies and Vectors Zero. Additionally einstein never wrote and published any of these formulas and no other scientist wanted to claim Fallacy.
Òòòòòò ll òo 2:40 😮go gl4r6
Would Ri consider a series of videos with Michio Kaku with the Ri giving him a series of topics to discuss without interruption or others on stage just him by himself..
@ShonMardani maybe this is why Einstein never got the Nobel for his Relativity😢
Einstein was an bad actor who had relations with both of his cousins, hence his equation... Einstein = Married Cousins x2 .
I'm 70 year old retired Physics teacher and was mesmerised by Carroll's wonderful presentation. The best teachers have a way of bringing clarity and simplicity to very difficult concepts. Brilliant, thank-you.
Mesmerized, Wow
Veritasium on youtube is fantastic. Math and physics. Outstanding
God bless him
I had a really good math/physics teacher in high school. Then I studied at the Royal Institute of Technology and he went there too to do his PhD.
yes Stephen .... I too am a semi-retired Physics teacher of the same generation 1954 who appreciated Carols excellent presentation. Thanks
This man made advanced physics accessible to the masses. If there is something similar to the Nobel Prize for science communication then he truly deserves one.
If you ever find yourself saying "made advanced physics accessible to the masses", you're working with an inaccurate definition of either "advanced physics" or "masses".
@@davidhand9721 I'd like to know what's wrong with my comment as English is not my first language. General Relativity (and the whole series called "The Biggest Ideas in the Universe" by Sean Carroll) is not exactly basic physics, that's why I used the word "advanced". By "masses" I mean ordinary people, those who don't have a high degree of education in physics, or any other field of science for that matter.
@@kurtgodel28 Then you just need to define accessible :-)
I understand the comment and maybe could be better expressed by "comprehensible by the average individual"
@ My bad then, I thought my comment was clear. By "accessible" I mean, as explained in another user's comment, that he made understandable to the average people essential points at the foundations of certain theories. In the series of videos by Sean Carroll that I mentioned earlier, he covers topics that, until now, only a student of a master's degree in Physics would hear about. For instance, he talks about field quantization, renormalization, the work of Kenneth Wilson, as well as symmetry groups, general relativity and so on. But he goes beyond words and provides heuristic, yet correct, mathematical descriptions. The main prerequisite to understand the level of those lectures is basically high school mathematics. In my opinion, this work deserves more media attention because these are very specific topics that rarely find a place in popular science.
I suffered a brain injury a few years ago and it is sometimes difficult to understand simple concepts, nevermind complex concepts.
Thank you Sean Carroll for simplifying subject matter for those of us who want to understand the science we love so much.
Thank you RI for the same.
I may not be able to do the math and I may never be an engineer again but this video makes me feel like im included again.
I had a head injury at the age of 10. So the side effects dropped me from the top of the class, to the bottom, and eventually had me dropping out of school altogether. Teachers basically thought of me as the dumbest person in the class, due to me now having difficulty retaining long term memories. However, despite me having no physics education what so ever, I still managed to independently discover the special relativity phenomena, and how this phenomena is created, along with deriving the special relativity mathematical equations at the same time. Have a look at how I did it, if interested. Anyhow, never let brain injuries hold you back.
It's all bs... maybe you are a zombie and don't realize it.
@@kwimms meaning?
@@thomasdaniel100 he's an asshole, ignore him and always believe that you will make a comeback. Sometimes as they say reality is stranger than fiction
Keep up the good work.
The brain is always working to overcome injuries.
Be vigilant, and your brain will respond
This was the best presentation I've seen on this subject. And I'm not at all surprised that it was given by Sean Carrol with his brilliant ways of explaining things, his clear voice, and keeping your attention. The historical context shown behind the equation, and the motivation behind its construction over time was not only fascinating, but so excellently and expertly presented, without having to go off on any tangents or use too many analogies. And without insulting the intelligence of the audience with things like "imagine the swing you played on as a kid" or "imagine the strings on a guitar", just straight build up of the logic behind going from the Newtonian formulation up to the final Einstein equation, and all the players involved along the way. Perfect.
Plot twist: After this lecture was over, the audience tried to leave the hall and found they were in a rocket ship far out in space accelerating at 1g.
One of the best communicators in science. I’ve never failed to be equally entertained and educated by listening to his talks.
Maybe on your words but 99.99% of us did not understand ANYTHING he said ... Most of us were just amazed any human could dream this up...
One of the best liars in Science.
Sean Carroll has an astounding gift for explaining very complex concepts into much simpler terms.
Prof. Carroll is the only science communicator who can pull off this feat of educating the general public about Maths. So vivid. So approachable.
And so profoundly desperately needed!!!
As I get older I find the admiration I used to have for my favourite musicians is fading (only a little) and I’m becoming more fascinated by what people like Sean M. Carroll have to teach me. I may be too old for out-and-out hero worship, but I am definitely a big fan of these big thinkers. Hooray for RI, Mindscape and Sean Carroll!
Read QED by Richard Feynman and watch his lectures and videos. The video Fun to Imagine is great.
@@JRush374 Totally agree, it’s a great book and you really have to concentrate - well I did! Feynman is a hero of mine and I think I have all his books. I remember the BBC Horizon documentary when it came out and have a VHS copy somewhere. But thanks to UA-cam anyone can see this extraordinary man talk about jiggling atoms and flowers.
I agree totally too. I'm not daft or particularly intelligent..
I can think like this now too, appreciate possibly more than understand incredibly brighter minds more than ours.
I wonder how many possible, probable almost genius minds have been missed, shunned or ignored at schools?
Young men especially, develop and mature intelligently years after Girls...
Actually I totally agree with you being an old person, very old person.
Wow!!!👍
Thank you!!!
When Sean speaks I listen
This is clearly the next step: start explaining the math in a friendly way. Sean Carroll at his best. Thank you so much.
The step that follows is teaching the basics of relativity and quantum mechanics to 10 year olds. And start teaching the accompanying maths at about 14yo, when there's a little algebra and geometry knowledge. Maybe :)
And maybe that's not for all children, but my youngest nephew of 10yo loves it and has a very quick understanding of complex abstract physics because of his intuitive and creative mind that has no problems with thinking of spacetime as four dimensional curving geometry or how probability would lead to a particle to potentially end up on the other side of a barrier. He just sees the barrier as a wall that holds back part of the probability wave as it would a water wave, but if the wall is thin enough some of it might leak through, especially if you consider that most of the wall is empty space.
But the point is that children can understand a lot more than we think they can. I'm guessing that we think that they can't because the maths is difficult and we're usually taught such things when we can understand the accompanying equations and maths, but that's entirely unnecessary for the basics of physics. You can easily show a relation between push and acceleration without making a child calculate it. If you push harder, there's a larger acceleration. A child can see that easily. We don't have to know the exact ratio to understand the principle.
Always fantastic to see a Sean Carroll lecture, especially at the RI. Day one of the membership has started well!
This is great to hear! And a huge thank you to you for joining our UA-cam channel membership and supporting science 😀
Sean is a great communicator and a sweetheart.
I think equations are fun but they often look misleading largely for short hand reasons. Unpacking equations and looking at all the knobs hidden by symbols really is the only way to understand them. Having Sean break them open and show their inner working bits is an enormous help.
Indeed. On the enterprise in engineering they turned knobs =ing the short hand way to communicate to the computer the shorthand of what to do; as the computer could read the equation showing also people who built it knew from us today that Eventually, man did figured how to be as smart as the equation itself :)
I really like the way Sean Carroll presents all the scientific concepts. He always explains how they evolve over time and that really helps me understand how we get where we are in science for a certain topic. Most worthy membership I have ever had.
Thanks so much for joining as a member! We're very glad you liked Sean's latest video, he's definitely one of the best when it comes to explaining scientific concepts.
Agree. I wish my college professors would have spent a bit more time on the history of science as well, rather than endless formulas.
It (1) would have helped put things in perspective / allowed me to connect the dots better and (2) I would have realized that certain concepts didn't just pop up one day in someone's super-smart brain, but literally took centuries to be developed / discovered.
There’s a certain similarity between Sean Carroll and James woods. James woods has a 180 iq (or so the internet says) and I would bet Sean Carroll is near that . He’s great at illustrating his point on complex subjects in a simple and understandable way.
I agree. He's great. Fantastic communicator and such a nice guy with a sense of humour. Pity he's wrong about quite a lot! For example, his Many Worlds Interpretation is complete nonsense.
@@MI-qj6xrJames Woods definitely does not have an IQ of 180 (at least not in any meaningful sense). This for a multitude of reasons. Mainly because no well established IQ tests have any reliability in that range and a score that high on a typical IQ test (which are unreliable outside 2 standard deviations of the mean, i.e. outside 70-130) is basically meaningless.
Part of the same rumors was that he was a member of MENSA, or that MENSA was the source of this oft quoted score, something that MENSA quickly denied (they were also stonewalled by Woods and his publicist when they tried to reach them about the rumors, since some sources implied that Woods himself might be the original source of the claims). He did supposedly score very high on his SAT, but his score was not on par with the 1 in 20 million that an IQ of 180 is (I couldn't verify his SAT score either, but it's a far less extreme claim and the guy did supposedly get into MIT based on his SAT and I couldn't find any repudiation of this from MIT).
Basically, nobody seems to know where the 180 figure really comes from (and it's often quoted as 184 or 160 as well). It seems to have started as tabloids, gossip bloggers, and clickbait sites bouncing the rumor back and forth, though the rumor also seems to have had a resurgence in right-wing media in the last couple of years. The guy might at some point in time have taken a test that gave him a score of 180, but so did most everyone who has access to the web in the early 2000s. I remember that I scored over 200 on some of those ridiculous tests floating around the web back then.
Another popular claim is that Woods has an IQ higher than Leonardo Da Vinci, and this one might actually be true. However, this is not really a meaningful claim either. If we extrapolate the Flynn effect that far back, a lot of us probably have an IQ higher than Leonardo, maybe most of us. And even if we ignore the Flynn effect, there is basically no reliable way to estimate the IQ of someone living that far back. And since we do know that the Flynn effect is at least true in the last century and thus that IQ scores change significantly over time, someone living that far back can't be meaningfully compared with someone living today.
Don't get me wrong, the guy might be super smart. There's just no reason to believe any specific claims that high unless there is very strong evidence from a reputable source.
You are fully blown away by this guy's rhetorical talent and the uninterrupted talk. He never stutters, hangs or uses filler words.
By the way: Great to hear a german word he uses (Ansatz). 😀
In applied mathematics, Ansatz is the second most popular German word, only slightly less popular than Scheisse! :)))
@@u.v.s.5583 😶😜
Yes! A new Sean Carroll lecture! This man is such a good presenter and spokesperson for science.
He is, hands down, one of my favorite presenters. He can make a droll topic interesting.
This is perhaps my favorite RI lecture I've seen yet. I really love getting a better look at these more complex ideas about physics, and I hope to see now like this. Really nice work, Sean and RI!
You're wright. A well deserved 'excellent too' second is the one on quantum fields. Try it.
Always love a Sean Carroll lecture, just think without the Internet we'd have to smart enough to get into his class and I suspect many of us wouldn't make it, what a time to be alive.
One of the best lecturers on UA-cam. Makes me want to study physics again. On a note, his books are great 👍. Thank you.
What a great lecture. Thanks to Sean and the Royal Institute for making it accessible.
Absolutely stunning. To be a master both of the subject AND of how to convey it is remarkable.
One of the best lectures I have ever heard. A fantastic mixture of math, science history and humor.
Fantastic talk as usual from Sean Carroll and his books are worth reading. Great content thanks RI
The simplest and easiest explanation of Einstein's tensors I have ever seen. Crystal clear exposé by someone who not only masters this stuff but has integrated it into a unified coherent concept. Kudos!
Wish we had more professors like this guy.
Whenever I feel discouraged about the U.S. and our mess...seeing/hearing/watching Sean Carroll gives a boost to the spirit. Thank you RI for hosting him...again.
This is the best lesson on General Relativity I have attended, ever.
Compliments to Prof. Carroll for his unequalled ability in explaining such complex matter with simple words.
Regards
Anthony
A bit too simple.. He forgot to explain why the theory, like all Einsteins theories are nonsensical. He forgot to mention that little gem.
@@everythingisalllies2141 A "little gem" that only science deniers could say, which he's not.
@@kurtgodel28 I'm not "denying science", that is real science, I'm calling out liars who spread nonsense dressed up as science.
@@everythingisalllies2141 Yeah, because of course you know better than Einstein.
@@kurtgodel28 I don't need to be "better" than Einstein or anyone else, I only need to examine his claims in his hypothesis and weight them up to the accepted standards of rational analysis and Logic. And unfortunately for Einstein his claims do not make the grade in any way. In fact, it would be fair to say that he seems to have based his hypothesis in a purposeful deception, in other words he lied by telling half truths mixed in with truths in order to deceive. It worked well on you is seems, because you have never bothered to read his hypothesis with a scientific mind set, that of being skeptical. If you did read his paper, it would have been form the point of view of a fawning, awe struck worshiper.
Sean's enthusiasm and deep knowledge is what makes his talks informative and entertaining. Never disappoints.
Equations are too special
I remember in highschool gauging at the Archimedes' principle for quite a lot of time and when you finally understand the mathematical realations between the symbols / quantities, it's amazing
That happened to me almost 10 years ago when I finally figured out what the symbols of differential equations meant. remember solving the same physics problems again and again in that summer at the beach struggling with all the d's and coming up with my own boundary condition problems. Up until then I was performing terrible at math courses. Then, it finally clicked. From that moment I fell in love with math again.
I found it a very challenging presentation to listen to. It felt quite "tensor" for me. It wasn't Sean that I struggled with; he's a good communicator with a nice smile and some humor and wit.
My issue lies in my disbelief with Einstein, and I certainly don't believe the "established science". The fact that the "establishment" fully supports Einstein raises a flag with me. Let's face it, the establishment virtually lies about everything to us! The Newton science is provable repeatable and "anyone" can repeat his experiments... you can't do that with Einstein, you have to have computers and software... but that's not out there in the real world. With Newtonian science we can all independently verify his theories!
Whereas Einstein's theories only work in supercomputers. Despite how much Sean says he doesn't consider Einstein primarily a mathematician, it's hard to see him as primarily a physicist when he couldn't perform his experiments! Tesla once called Einstein an idiot.
In summary, I doubt relativity, or at least the context of what they mean by it. The speed of light isn't constant. It's not the fastest thing out there. Einstein could only work in the realm of theory, and his theories are only "proven" in a theoretical space-mostly in supercomputers with specialised software. And, fittingly, that's where his space-time theories "live" and work.
Speaking of Tesla, there's an interesting story where a reporter asked Einstein what it's like being the smartest person alive, and he replied, "I don't know; go ask Tesla!"
I had trouble accepting his moon stuff. I watched it live and was suss about how poor quality it was. Finally watching the astronauts being tracked by the camera at the end, getting in the craft, with no camera operator??
Absolutely first rate explanation . thanks so much. Much better than my professor in 1969. I get it!! I must say I bought Hawkins book about black holes and that made a lot of sense at the time, but this whole subject does require a light touch, otherwise is so easy to get lost in the woods. Your introduction of the various tensors was brilliant. [6 months later - re-watched - got so much more. I cant thank you enough]
This is the best presentation I have ever seen that explains General Relativity in very straight forward manner. Excellent!
What an accessible lecture! Brilliant exposition - simple, no simpler.
This lecture is exceptionally well-crafted and provides a comprehensive understanding of the subject matter. Brilliant !
I would love to see a similar lecture by Sean explaining the Schrodinger equation in the same level of complexity and detail. Not everyone is a physicist but many people have an interest in the equations used and how they are attained.
Definitely check out his biggest ideas in the universe podcast series, it's excellent
That'll be the next book (this lecture is based on his latest book in case you weren't aware, with the second book in the series, "Quanta and Fields", due in May of 2024). And as @maxproph says, the books themselves are based on a set of UA-cam videos he did over the pandemic called "The Biggest Ideas in the Universe" - a bit less polished but still utterly fascinating (and available now on his UA-cam channel).
(or if you're comfortable with some not _too_ crazy maths you could also check out either "A Student's Guide to the Schrodinger Equation" by Daniel Fleisch or "The Quantum Cookbook" by Jim Baggott in the meantime)
I so wanted to get a ticket for this lecture. The RI is such a special place and Sean Carroll is always brilliant and engaging and witty. But it’s great to see the video. Science is cool!
We've got some incredible lectures coming up, that can be watched online from anywhere in the world - www.rigb.org/whats-on?type=6
@@TheRoyalInstitution Thank you so much for your reply and the link. I really appreciate that. Yours truly, a 70-year-old science geek!
Sean Carroll is a joy to read, but he is way funnier and more to the point in a lecture! Perhaps the best explanation of Einstein's field equations I have seen. Thank you!
This is really one of the best RI lectures available on UA-cam! Great stuff.
More of this, please. It would be great to have a quantum mechanics version of this, maybe to understand the Schrodinger equation.
Meow
He's done on on this channel before exploring and explaining that
Bravo!
What a delight. At some point I noticed I had a big grin on my face. It stayed there till the end, at which point I also had a tear in my eye. I think I have a nerdcrush!
He is a phenomenal orator.
This is beautiful, the way Sean arrives at the Schwarzschild radius got me. Wonder how many got inspired here to have a look at the math deeper.
Sean Carroll truly is one of the greatest treasures of science communication.
Gravity is NOT a Force at All Einstein Said Sean is totally lost Very disappointing He says Gravity is a Universal force🤣🤣🤣
8:22 to me the fact that gravity acts equally on different mass objects was actually quite intuitive. Not that I’m some genius who intuited the math lol. But the way I saw it, gravity was acting on each bit of mass equally, so regardless if it’s 100K atoms or 100 trillion atoms, each atom is accelerating at the same rate so more mass doesn’t change how fast something falls.
Not all atoms have the same mass, since part of their mass isn’t even physical mass.
Absolutely brilliant, inspirational lecture. Thank you RI and Sean Carrol.
One of the most exciting lectures I have seen on youtube! Thank you Prof. Carroll!
A new appearance from Sean Carroll is always welcome! Love this guy
I began as a physics major in college and immediately changed majors. I eventually graduated with a degree in mathematics, with a 3.95/4.0 in math classes, and loved every minute of it.
Physics is just mathematical nonsense now. Nobody understands physics. Just a bunch of equations.
F=ma? What's you frame of reference.
E=mc^2? What does it say?
Don't ask me, just shut up and calculate is the response now.
Thoroughly enjoyable.
This is by far the most beautiful lecture featuring tensors that I’ve ever seen.
He is great at explaining.
Was fun to watch his home series during covid lock down.
I remember that
Your videos have ignited a passion for science and the mysteries of the universe within me. Thank you for being such an incredible source of inspiration.
Sean Carroll is like John Mulaney for science.
The big bang means that when there was little mass at the beginning, there may have been a lot of anti-mass.
the sum of the amounts of matter and anti-matter must be equal to zero. If the amount of metri is variable, so is anti-matter.
Hi Sean! Since listening to a few of your lectures and podcasts, this stuff doesn't seem quite so scary to me anymore. Keep in mind, I am just a lowly meteorologist... but it's still useful to hear your explanations, which help put these concepts into perspective for me. Question... Is any of this going to be on the test? 😊
Weather is pretty hard.
@@DrDeuteron Yes, it can be. But for some reason I understand weather way better than this material. Which is one reason I enjoy Sean's presentations so much.
@@TheWeatherbuff "for some reason"--- the reason is that you haven't been exposed to it enough. Once you get familiar with all the stuff, it becomes easy.
Very good presenter for general public on a profound subject. That's a real art.
Heck yeah!!! Always love listening to Sean Carroll.
Sean Carroll is probably the best advanced science communicator in the world because even though he has profound knowledge of the things he's saying, he still manages to retain the perspective of someone who knows nothing about those things. It's remarkable.
Sean Carroll has no intelligence on what he is talking about.
The earth is not a stationary frame but is in motion around the sun. That's more than his brain cells can deal with.
Newton's gravity? Try the 3rd law of motion. Gravity is a Reactionary force, the resistance of the mass to being accelerated by an outside force.
There is no gravitational attraction but mass is not an actionable force.
F=ma. Acceleration is the actionable force.
E=mc. Energy comes from Acceleration of the mass. Not the mass itself.
Mass is not an actionable force as proven by numerous drop tests in a vacuum. The earth is ROTATING on its axis as it ORBITS the sun.
Two frames of reference. That's why you have 2 tides a day. One being accelerated clockwise and the other, counterclockwise.
That's what flat earthers like Carroll and Greene, and Cox, Neil deGrasse Tyson, Stephen Hawkings, Albert Einstein, even Isaac Newton himself.
Gravitational attraction is incompatible with the laws of motion.
F=ma. Mass or Acceleration.
E=mc. Mass or Acceleration.
F=ma = ma=ma = m=m and a=a.
Mass is just mass. Matter that takes up space.
I love it any time Sean Carroll lectures, and most especially when he does so at the RI! His wife publishes some of my favorite articles on Ars Technica as well!
One of the best educators out there always a joy to listen in.
What a great lecture and what a great teller he is 👍🏻👌🏻
Great work.
Sean Carroll's explanation of Einstein's equation makes reading about cosmology more exciting. I was always curious about how such a simple looking equation can be so foundational. ...feels like a grand epiphany. Thanks Sean😊
That is not a simple looking equation by any means. It just hides the complexity to those who don't know what the symbols mean. He pointed that out in the talk, by the way. Whether it's foundational is not known. It's just one version of an infinite number of similar equations that nature may also follow in the classical approximation. It just happens to be one of the most simple versions of all possibilities. We have, so far, not found any deviations from it, but that's mostly due to the measurement errors that we are limited by. The bigger issue is that it has a distinct thermodynamic form... which may be an indication that gravity is a thermodynamic remnant (rather than a quantum mechanical one). Or that's just coincidence. People have been wondering about that for the better part of a century. The limited success with direct quantization of gravity might be a hint that we are missing a thermodynamic layer there.
Sean is the best. I was so happy to see you guys with a new video! Time for me to watch it and I am sure ir’a gonna be epic.
Thanks for sharing :)
I came up with a formula for thermodynamic radiation envelopment for interstellar photon retraction. It is ¥ -6 = 5 x speed of light. It works a treat. Nobel thingy prize for sure next year! Thank you
Sean Carrol is a genius. I can listen him for hours and hours. Wish I had him as a teacher ❤. PS. Thank you Royal Institute
He's a clown that believes there are more than two sexes in humans.
One of the best lectures I've ever seen on these topics. Sean Carroll is a great teacher. Thank you very much.
Good to see Sean Carroll again. He used to be everywhere. Then he went quiet. Now he's back.
He runs his own podcast: Sean Carrolls Mindscape, where he comes to speak every week.
15:46 I don’t think that “t” is a “universal time coordinate”, as stated in the video. It is just the time axis of the frame of reference we’re working with. The “t” of one frame is, in general, different than the “t” of another frame.
Brilliant as usual
Equations are the blueprint, they speak louder and look like pictures and geometry the more you understand them. Thanks for helping me understand this compact notation.
Was there a Q&A for this talk? Could you share it please if that's the case? Thank you! And great talk!
So glad you enjoyed the talk! The Q&A for this event is available as a UA-cam channel member exclusive here - ua-cam.com/video/sO5adbV_mu8/v-deo.html
@@TheRoyalInstitution Got it. Thank you.
Brilliantly explained. Thanks Professor . Kudos to UA-cam which enables access to high quality education for free across the globe.
So I'm slightly confused anytime someone refers to gravity as a "force", because it was my understanding that gravity is merely an emergent property of the geometry of space-time being warped locally by mass.
Yeah, it seems like that we call "gravity" has more to do with how we are given the illusion of acceleration through each 3D "slice" or "moment" we experience, even though the universe described would seem to indicate a static 4D spacetime where everything has already "happened".
It's the same way centrifugal force and coriolis force are not technically forces. We still call them forces sometimes because they act like forces if your reference frame is spinning. Likewise, gravity looks like a force if your reference frame is accelerating. A reference frame fixed to the ground is really accelerating upwards, so it looks like there is gravity accelerating downwards. It's useful to think of it as a force because it's useful to use a reference frame fixed to the ground, it matches how we usually experience the world.
The confusion lies within GR's particular framework, and the way Newton is 'carved out' of the geodesic equation and Poisson's law out of the EFE; however, this is far from an universal necessity: yours truly, for instance, has constructed a theory in which gravity is simply viewed as a force in the traditional sense, and yet one can still draw observational conclusions comparable to GR's. Oh, and before you dismiss that as some ramblings from a rando who doesn't know what they're talking about: currently under peer-review - in a fancy journal and everything 😉
@@GammaPunkthe coriolis and centrifugal forces are just gravity in GR.
@@thstroyur Ooooh neat! What's the journal, I wanna read it when it comes out!
Thanks!
As someone who studied General Relativity from Prof. Carroll's excellent book 'Spacetime and Geometry', it feels like betrayal seeing the (+ - - -) metric signature!
And excellent lecture as always!
The mathematical symbology of equations is just a way to avoid long, verbose natural language statements. You can think faster with equations. An added benefit is that new equations can easily follow.
This guy is good
I appreciate the enthusiasm of Professor Carroll. The capacity to set the discussion at a level that isn´t too low or too high, and the logical thread that makes it clear and enjoyable. Not least the vein of irony that put the public at ease. Would be possible to have a link to the Riemann´s paper? Or the title? That one where he makes funny comments because it wasn´t his favorite subject? Thank you.
Most of the weirdness of spacetime comes from the more basic principle that time (the fourth dimension, at 90 degrees to all others) is imaginary. You still use the Pythagorean theorem, but when you square the imaginary time element, it becomes negative, converting the Euclidean function (a^2 + b^2 = c^2) into a hyperbolic one (a^2 - b^2 = c^2). The principle is simple. The implications are profound.
> basic principle that time ... is imaginary
It is not, in fact.
@@alexleibovici4834 It is, in fact. That many don't know or understand it does not negate its truth.
@@themcchuck8400
You confuse the nature of the time variable with the fact that a pseudo-Euclidean metrics can be transformed in an Euclidian one by substituting -t^2 with (it)^2
@@alexleibovici4834 And yet the math works out the same, while my version has explanatory power. I believe the equivalence principle applies to this discussion. If it walks like a duck and quacks like a duck...
@@themcchuck8400
> And yet the math works out the same
Oh, I see: you don't know what is a pseudo-Euclidean metrics !
Sean Carroll, Brian Greene and Neil Turok are great explainers. Love' em.
The rest of the world are really wondering why not Trump is in jail yet. So, for the best for US and the rest of the world, make that happen!
It's immensely valuable and satisfying to hear an overview of a subject, if only to get a feel for how the logic works without understanding the detail; and Sean Carroll does it brilliantly, making it seem effortless both in subject and delivery. However mathematics is not science. New data wags the tail of science, not mathematics.
Fifty Five years ago or so We worked with this concept and the nasty calculations with slide Rules and paper. I was predominantly in E&M, but particle was the expanding field. Physics in the 60's was an exciting time. Famous professors talked about basic and advanced physics. So May it Be.
Mr. Carroll is on fire in this one. Excellent lecture
Watching Sean do his stuff makes me feel like I am back at UW again. The prof would explain the subject using differential equations making it look simple. But aterwards I would spend hours trying to wrap my head around it what initially was shown to be "simple".
Thanks Sean. I appreciate the clarity of thought you provided in summarizing the historical development and meaning of Einstein's equation.
i could sit in Sean's class and listen to him all day and feel like i understood it all when i know i dont.
Sean's lectures are always entertaining and informative, never makes one fall asleep. Too bad I am not intelligent enough to study particle physics or cosmology else I will be very blessed to have him as my lecturer.
I will look out for Sean Carroll's books now... A long time since I studied physics but this talk made me interested again. Thank you
F = ma is the way we remember the equation and indeed use it, I used to explain it my Physics students by rearranging it. In this arrangement, we add up all the forces acting on the body and if the sum is something other than zero, we know the body is accelerating. In some cases, like a book sitting on a desk the forces sum to zero, so there is no acceleration.
To understand the equation a little better, rearrange it to a = F/m.
F is the force trying to move the body while m, the mass, is the resistance to the force (inertia). Obviously the greater the force, the greater the acceleration, i.e., the harder you push on the car in his picture, the greater the acceleration. The greater the mass (weight) of the car the lower the acceleration, i.e., it is more difficult to push a more massive (greater weight) car than a less massive car. This is why this equation looks like this, and rearranged gives us the famous F = ma. An important point is that the acceleration is the result of the force acting on the mass, NOT that the force is the result of mass times acceleration as implied by F = ma. ma does not generate force, force acting on mass gives rise to acceleration.
9:00 The reason the mass of the body does not matter is very simple to understand. If you have a body B which has twice the mass of body A, it needs twice the force to have the same acceleration as body A since it has twice the resistance (inertia). However, the gravitational force on body B is twice the gravitational force acting on body A (body B weighs twice body A). So, body B needs twice the force, but gravity acts with twice the force so the mass of the body has no effect on its acceleration.
15:44 My favorite wording of this idea is one I read somewhere many decades ago. "As you travel faster and faster, you trade space for time." Time runs slower (time dilation) giving you more time while space shrinks (length contraction). The coolest thing is that the time gained is exactly equal to the space lost. For example, say you travel at a speed where one day on your spaceship is equal to two days back on Earth. You have doubled your time. However, the distance you measure between any two bodies will be half of what is measured by an observer on Earth. You doubled your time and halved your space.
This means both sets of observers will always agree on the speed of the spaceship. The Earthbound observer will say you traveled a distance, d in time t, giving speed = d/t. You will say you traveled 1/2d in time 1/2t, giving speed = (1/2d)/(1/2t) = d/t.
> To understand the equation a little better, rearrange it to a = F/m.
I found too that this form is more useful in teaching: on the RHS is the cause (acting force), on the LHS is the effect - acceleration.
I’ve watched This three times now. It’s amazing to have this come into focus. Can’t wait to buy his book!
Wonderful talk, breaking things down piece by piece and eloquently explaining them.
Thank you Prof Sean Carroll.
I am not a physicist, but I am attempting to study and understand the math to create programmed computer simulations. This placed a lot of the math into perspective for me. Thank you :)
My gosh I love listening to this guy.
Extremely informative without being scary
I love Einstein so much! ❤
The secrets of his equations are forever mine, and mine alone.
The likes ratio on this video should be much higher than it is.
Excellent summation of Einstein's equation.
I remember having to do this stuff by hand. I am always so impressed with our forefathers because they did not have the benefits of mathematica (et al.) to help them visualise these geometric landscapes.
A minor quibble. It was GALILEO who first discovered the principle of inertia (and that objects fall at the same rate regardless of weight). It was also Galileo who first discovered GALILEAN Relativity (as Einstein always pointed).
Lastly, Robert Hooke was the first to discover/conjecture that gravity obeyed an inverse square law, not Newton.
Just wanted to correct the historical record.
Sean Carroll is an excellent teacher and presenter. Many thanks!
If you can present stuff like this you are also a hero of that science!