So good! The animations were well-chosen and super helpful, and the motivation for each successive step feels so natural, despite the fact that you built up to a famously unintuitive idea.
Please, would you do a video that uses your linear algebra animations and explanations to come up with the matrix for the Lorentz transformations? Sorry, I've asked you for this many times already, but it would make so many things click for so many people!
3Blue1Brown I love your videos. Could you do another physics video? The math is great, but if you made a video on relativity and cleared up as much as this video did for me, that'd be amazing for the entire TH-cam science community.
3Blue1Brown I loved your calculus and linear algebra series! since i just recently watched the linear algebra one I'm always looking for possible connections haha, from this video i guess that the change to different reference frames is some sort of linear transformation and the light world lines are like the eigenvectors of that transformation? idk its just a guess
We do Agree with You, 3Blue1Brown, for the Quality of this video but concerning the idea it is about a "unintuitive idea", we can't follow You while it is FULLY INTUITIVE as soon we Realise that Lorentz's Transforms implies The Existence of "AN UNIVERSAL REFERENTIAL" and that THE SPEED OF LIGHT IS CONSTANT BECAUSE// IT CAMES FROM THE INTRINSIC PROPERTIES OF THE ELECTROMAGNETIC FIELDS: THE PERMITTIVITY AND PERMEABILITY OF THE FREE SPACE AS THE FORMER IS THE COMMUNICATION LAG OF THE DIELECTRIC INDUCTION AND THE LATER THE COMMUNICATION LAG OF THE MAGNETIC INDUCTION, THE COMMUNICATION LAG OF INDUCTION BEEN THE INVERT OF THE SPEED OF INDUCTION, THE SCARE ROOT OF THE INVERT OF THEIR PRODUCT BEEN THE AVERAGE EFFECT OF BOTH INDUCTION LAG. This just to say that yes Indeed, light is CONSTANT, but only in a Universal Referential, very in Opposite what is used to be said. Regards, Didier.
Einstein’s Special Theory of Relativity requires systems of clock-synchronized stationary observers and the Lorentz Transformation. Without both, the Theory of Relativity fails. A system of clock-synchronized stationary observers is, however, inconsistent with the Lorentz Transformation because it is Galilean. The Special Theory of Relativity insists that systems of Galilean observers must transform not by the Galilean Transformation, but by the non-Galilean Lorentz Transformation. The Theory of Relativity is, therefore, invalid due to an intrinsic logical contradiction.
Such a great video! Thanks for making it! The visualisations are really helpful to understanding and you are great a breaking down explanations into perfectly sized steps.
@@VirenderKumar-ss9qk THE ULTIMATE, BALANCED, AND CLEAR SCIENTIFIC EXPLANATION OF TIME DILATION: Consider what is E=mc2. c squared CLEARLY and necessarily represents a dimension of SPACE (ON BALANCE) in relation to E AND “m”. Indeed, BALANCED inertia/INERTIAL RESISTANCE is fundamental ON BALANCE. Consider what is a TWO dimensional surface OR SPACE ON BALANCE, AS invisible AND VISIBLE SPACE is CLEARLY fundamental ON BALANCE. E=mc2 is taken directly from F=ma. Consider TIME (AND time dilation) ON BALANCE. The stars AND PLANETS are POINTS in the night sky ON BALANCE, AND consider what is the speed of light (c) ON BALANCE. Great. Therefore, I have explained why THE PLANETS move away very, very, very, very slightly in relation to what is the Sun ON BALANCE. I have explained the cosmological redshift AND the supergiant stars. I have also CLEARLY explained the fourth dimension AND the term c4 from Einstein's field equations. ELECTROMAGNETISM/energy is CLEARLY AND NECESSARILY proven to be gravity (ON/IN BALANCE). This CLEARLY AND NECESSARILY represents, INVOLVES, AND DESCRIBES what is possible/potential AND actual ON/IN BALANCE. By Frank DiMeglio
You explained the idea of Special Theory of Relativity so easily that I wish you were one my profs teaching me in college. I had to read so many books and visualize so much to understand the intuitive ideas of relativity, wish I had got this video in the 2nd year of my college... terrific job dude...
Honestly tho I think the journey of you reading through all that and struggling internally to visualize and understand, while incredibly painful and tedious, is still well worth while, and something a lot of learners avoid at their own peril.
Abdullah Almosalami learning to enjoy and speed up that educational journey is where the real fun in learning comes. When you start messing up in ways that haven’t been done and start asking questions that haven’t been asked. I fully agree.
I went through much of grad school for my PhD in physics. I was always bad at relativity but it didn't matter because it wasn't part of my field. I ended my grad school with a masters and went into the private sector to work, and this is the first explanation of Lorentz transforms that has ever made sense to me. I need to go revisit my old books now.
@@debrachambers1304 I was in a field that could be described as "ultra low force sensing". We developed a lot of experiments around detection of very small forces produced by particles. (e.g. Sympathetic cooling, spin dependent forces, attonewton force detection)
That's the popular, incomplete equation. The complete one is E² = (mC²)² + (pc)² where p is momentum. C is the speed of light (not cats) which we can make equal to 1, so E² = m² + p² With this equation, a photon has energy even though it's mass is zero. Don't get confused by the expression, "relativistic mass". It's an unfortunate term. Mass is "rest mass"; does not change with velocity.
Truman Burbank someone doesn't understand humor. But yes I understand. P is pets per second, C is the constant velocity of cats and M is meows per second.
Second sudden realization: This is similar to the rolling shutter effect, except instead of the rows of the frame affecting the lag, it's the distance.
The moment I saw the transformation where two lines didn't change, I audibly shouted "Holy crap" in a Starbucks when I realized that it's an eigenvector of the transformation. That was so cool!
Einstein’s Special Theory of Relativity requires systems of clock-synchronized stationary observers and the Lorentz Transformation. Without both, the Theory of Relativity fails. A system of clock-synchronized stationary observers is, however, inconsistent with the Lorentz Transformation because it is Galilean. The Special Theory of Relativity insists that systems of Galilean observers must transform not by the Galilean Transformation, but by the non-Galilean Lorentz Transformation. The Theory of Relativity is, therefore, invalid due to an intrinsic logical contradiction.
Only by the current 'understanding' which is incomplete. Science is infamous for throwing out plausible or even very real ideas because it isn't convenient for them.
I cannot express how much I love this channel! It has always explained physics in a crystal clear detail, and there's nothing from these videos that I don't understand. Literally! One of the best channels I've ever found on TH-cam and I think this channel deserves more! Very grateful to understand these stuff and be able to imagine. Love TH-cam ❤️
Watching and understanding the physics and the fast physical English in these videos is kinda a challenge for me since I'm only 16 and English is not my mother tongue. But I do really enjoy watching your videos, bc they do not only help me to better understand Physics but also to improve my English! And I actually understand what you are teaching us here! Thank you for that!
Yes, visualization first then the equations. I've never been able to create the visual intuition from the Lorentz transformations myself. This video helps a lot. I hope you look closer and slower at these transformations.
Many people complain about how technology has ruined humans and has made them dumber or less interested in reading; they are all true, but we are forgetting that the internet gives people and young people access to genuinely great videos like this one or others. We could benefit more if we would know how to use it, but it’s not technology that’s ruining us. Love this channel.
I feel like technology is more of a neutral thing, and the outcome it will bring to you depends on the use you make of it.... In layman's terms, it could be used to help your brain get more powerful, or it could be used to replace it....and it just so happens that the second is our case....but I don't think that's "technology" 's fault... It looks more like when these new powerful tools came out, people weren't trained on how to make good use of them, and actually people were just being shown in mainstream channels how to make BAD use of it..... Why would a boy/girl use the internet to find and learn useful things, if most of his/her classmates would call him a nerd for that??? I happens to be a person that just likes more being alone so I don't care (not anymore at least 😂) but that's not always the case.... I'm honestly afraid we've already passed some kind of point of no return 😅
Ugh where was this device 20 years ago... this is brilliant. Clearly shows how red/blue shifts occur too. Thanks. Looking forward to the next installment... hopefully it comes soon.
me: pauses the video to read the small remarks youtube: places the navigation bar and play/pause controls over the text, without any way to dismiss them
Try pausing about when the remarks appear and then use comma( , ) and full-stop( . ) keys to move one frame at a time, makes it really easy to see these and less frustrating if the remarks are covered. Edit: Sorry if you are on mobile.
Yeah, i was at max volume coz i just finished watching some people whispering so i expected this vid to be not too loud but then... he knew he fucked up at 0:12
I'm so glad you're going into this in more detail. I remember when you did your "Einstein and The Special Theory of Relativity" video (wow, was that really 6 years ago?), you just kind of was like "Hey, you can do this weird sort of rotating thing" and the entire comments section was like "wut" - actually explaining in more detail this idea makes it make significantly more sense.
Henry, this is a wonderful series. Thank you for your tireless effort in making this subject more tangible and intuitive. The time globe is such a clever teaching device.
When I was in college a decade ago, doing my CS degree, I would have loved to have videos like this that helped me understand why I was learning certain mathematical functions. I was always very good with math until I got to portions of calculus and then linear algebra. The math involved became so abstract, I could not connect the application of the functions, which for me, hindered my understanding and ability to learn. I know many people have different learning styles, of which, none of the methods apply to me (verbal, written, etc. are the same), but without understanding the application, my mind becomes limited. These videos would have been great primers for aiding my understanding. I never used the "high-level" math that I learned when programming, but learning should never cease, so I greatly appreciate videos of this nature.
One of the best demonstrations of special relativity I've ever seen. I would buy a time globe if you make more of them. Absolutely beautiful engineering used to explain something so deeply profound and elegant. Everything in space is so far away but nothing is unreachable. If you dont mind the rest of us waiting 60,000 years you can cross the milky way in a few min. Of course it is beyond our current propulsion abilities but it is not fiction either, the universe provides a way to cover vast distances within your lifetime. Magic!
So, if the scale of the space axis is one meter per tick, then the line representing light would appear practically horizontal, and a lorentz transformation effecting a cat moving at 3 m/s would appear skew the diagram purely to the left and right, thus functionally identical to a shear transformation. And so the shear transformation is the intuitive assumption for relative motion. Right?
At the speed of cat, time stands still, so cats experience no time. Outdoor cats are indoor cats going back in time. The light from a laser pointer moves to wherever a cat will be a moment later.
Since I first heard about relativity a couple of years ago from my brother who learned it at school, I simply couldn't imagine or even accept that time dilates and space contracts when you're going faster. I'm hard-wired to think of time and space as static planes and it feels absurd to be able to change space and time itself. As if an animation on a computer screen can physically grab the screen and stretch and turn it. But by simply watching this explanation and the animation, it immediately all feels intuitive. I can now literally see in front of my own eyes how it actually works. At the end of the video I was literally clapping because you did what my brother failed to do for a long time: make me fundamentally accept how all of this fits together. Thank you for this.
Ok second episode had me a little lost. This one just turned on a whole bunch of light bulbs that had me stumped for a long time, and theres a lot more still to switch on. This is amazing man, thanks for doing this!! I feel like this level of understanding is being lost within university walls, at least for the aging discoveries. We are taught "of them" but not always "about" them. Its great to have this kind of thing available should one want a deeper understanding.
OK, one more comment to say the same thing, but... I'M READY TO BUY THE DEVICE, BUILD A COMMERCIAL PAGE MATE! (Mark Rober, I mean... By the way, great job as usual, minutephysics! :) :) :) )
I just found out about this (I reckon I arrived a little late) and it's the first time the whole thing makes some sort of sense! Thank you so much for making special relativity closer and easier for all of us, I hope one day my kids find these videos as intuititve and entertaining as I do. Keep up the good work!
THANK YOU. In no way did I ever understand a single part of this in the past - no number of books or videos helped. But now, at last, THE LIGHT! (It makes sense now, thank you).
From this video, it is obvious that space is curved and the Lorentz Transformations are describing the relationship between curved space and linear time. If you think of space as an inverted cone (tip of the cone at the bottom of the graph and what would normally be the base - wide circular portion - at the top) and your perspective axis is the center of that cone and the cat or sheep's movement is the edge of the curved cone, then twisting the cone left or right would do the same thing as the Lorentz Transformation. Great video.
I have many questions... if we do a lorentz transformation from the light's perspective (just for theoretical purposes), then what would happen? Will the whole thing shift according to the light's perspective? But that obviously can't happen because that ruins everything. So, what will happen? Or am I getting some fundamental wrong? Also, is the only proof of light speed being constant an experimental proof? I always thought that the theory itself proved that light speed is constant, and we double checked that with experiments. Lastly, and this is a confirmation, we chose the rotation which involved placing the x=4 point at t=3 just because that was the only one that confirmed experimentally with the fact that light's speed in vacuum was constant, right? What I understood was that they tried both options, i.e. placing the x=4 point at t=5 and placing it at t=3, and what do you know, the t=3 option just worked. If someone knows answers to any of these questions then please reply me. I 'd be grateful. Thanks in advance btw how many of you have used brilliant?? is it worth a subscription?
"if we do a lorentz transformation from the light's perspective (just for theoretical purposes), then what would happen?" You can't, everything falls apart. You're asking for light to be both not moving with respect to the observer, while still moving at the speed of light with respect to the observer (because it always does). That's two different answers to the same question, which is impossible. Einstein's math collapses into infinities and zeroes, and MinutePhysics's "time globe" would actually break if you tried it. "Also, is the only proof of light speed being constant an experimental proof? I always thought that the theory itself proved that light speed is constant, and we double checked that with experiments." The theory *supposes* the speed of light is constant, and shows that a wide variety of phenomena, from the behavior of subatomic particles to the light from distant galaxies to ordinary magnets, can be explained, leaving no doubt that the assumption is in fact true.
Jason Goodman if light is not moving at all (theoretically) that's the only case when observer is moving at the speed of light (makes light appears to be not moving at all to observer) but is impossible practically as nothing can match the speed of light as we know.
Let's answer pointwise : 1. We cannot ever do anything from the light's perspective. Why? Because, suppose you are in a frame which is moving at the speed of light. But according to the postulates of our theory, light still moves at the speed of light and so it's not at rest. But if you are already moving at the speed of light, you cannot increase your velocity any further and thus the inevitable conclusion is that "light has no frame in which it is at rest" or "light has no perspective". Done. 2. Actually, there is something subtle here. If you just assume that all inertial frames (frames with a constant velocity wrt to another frame at rest ) are equivalent i.e. no inertial frame is special ( and also take into account that the universe is homogenous and isotropic ), then you actually find a frame invariant speed, although the value has to be checked by experiment or from other theories (like electromagnetism). Cool? 3. Just like I said in the previous point, there is a general transformation that comes out even if you don't assume the constant speed postulate. And, as any mathematician would say to you, this transformation is exactly equivalent to the squeeze transformation that he showed us. (I have no idea what transformation the rotation one covers). Hope this clears some doubts of yours!😊 Oh, and for the Brilliant part : 4. If you want to learn some quick concepts and apply them to stuff, then yeah, a subscription is the best thing to do. But... If you want to go deep inside things and then apply them, then I would personally suggest listening to lectures, audio books and even buying some good old topic-specific books to learn. And then, going to Brilliant to solve their beautiful sums. 😊😊
I can't say much about the other questions, but for 'boosting' into light's perspective, I might be able to help. Consider the two fundamental properties of lorentz transforms: The speed of light stays constant, and we transform a constant-velocity path into a constant 0 velocity path on the origin. Now, what does it mean for the speed of light to stay constant during a transformation? It means that any light-speed event (point in time-space that lies on the causality cone) must also be a lightspeed event for any other observer. To transform a constant-velocity path through the origin into a 0-velocity path through the origin, we need to take all events along the starting path and make them strictly temporal (they're only separated from the origin by time). If we try to boost to the speed of light, we must simultaneously have all lightspeed events on the causality cone and on the 0-motion time axis. The only way for this to happen is for all the events to be at the origin. What does that mean? Light doesn't experience time or space. Emission and absorption of a photon, from the photon's perspective, happen simultaneously and in the same position. It is in this sense we can say that light doesn't travel, because from its own perspective, it doesn't make sense to talk about time and space, thus travel is also nonsense. I personally try to think about light in this way, and it gives a new perspective on interpreting quantum theory. The Copenhagen interpretation, where quantum things don't exist until the wave function collapses is actually quite reasonable, since the photon itself doesn't travel, but from its perspective any and all lightspeed paths we observe between the emission and absorption events collapse down into the same moment. This is more obvious when we think about light in a 2-d plane and an actual causality cone instead of a degenerate pair of lines.
Robin Sinha that’s an awesome question, and you can sort of see the answer in the video. Take a look at the segment starting at 7:14. In that segment, he’s transforming the space time diagram so that the blue sheep line is along the t axis. But look at what has happened to the light-cat snapshots on the right. You’d think they’d get closer to the t axis as well, but all they’ve done is gotten squished closer together. Let’s pretend that the cat, instead of going on forever, hits something on the right. We’ve been trying to get the cats snapshots to all be on the t axis, and now we can do so, by squishing the limited number of cats all the way down to the (0, 0) point. One way to interpret this is that to the cat (or photon), the journey from the start to when it hit something took no time at all. This is a really important point, and I’m sure we’ll get a whole video on this at some point. You can try to think about what such a transformation would do to the rest of the graph as well; it turns out that light has a really weird perspective where space is all squished in on itself.
I had no idea that the TH-cam community is so connected, that 3blue1brown knows minutephysics knows Mark Rober knows Mr Beast and etc. It's really cool to think about!
I really enjoy watching this series, and I notice once again how similar these videos are to my first introduction to special relativity - probably the main reason I love physics this much
Suppose we have objects A, B and C. Does that mean that: If from the perspective of A, B is moving at 3 km/h and C is moving at 5 km/h, 1)then from the perspective of B, C will *NOT* be moving at 2 km/h? Meaning that the angle between B and C will *NOT* always be the same? 2)But from the perspective of B, will A be moving at -3 km/h? (as stated in the video at 10:10 for the example of the person moving at -1/3 the speed of light from the perspective of the cat)
7.15 that's when my mind blown. " Length contraction", now i got the idea. And I'm just so grateful for you , you just made it look simple. If you have a teacher with correct intuition you can achieve great heights
I graduated from university, I studied physics .... but only now I know what the hell Lorentz transformations were good for :D (besides driving students insane)
just a 2 cents about the change of different spacing of the cat after the transformation. The speed stays the same but the wave length of light changes similar to doppler's effect.
Thank you so much for this video, i finally understand a lot more how relativity works while having light as a constant, and red-blue shifts in light make more sense, because the speed doesn't change, but if you imagine each point as a wavelength, then they get more spread out as they move away from you, or closer together, as they get closer.
This seems to be the most time consuming video of this channel, from the creators perspective (pun intended). So many details, so many movements, it does seems like a lot of work. And as a physicist, it gave me a clearer view of relativity. Thank you.
Small remark at 4:07 (so you don't have to pause and try to read through TH-cam controls): *And also so that the inverse of the transformation corresponds to a transformation with velocity -v And that one in 10:41 *or software that does Lorentz transformations for you... but that's much less hands-on
This blew my mind. I took a course on special relativity in college and found the concepts super interesting but the complicated math felt really cryptic to me. I love the idea of a mechanical representation that people can play around with and use to develop intuitive understandings.
@@manueljesusarredondoruiz2444 you know like the "👍" under videos. I come back to videos that I watched years or months earlier, and "like" isn't marked by me anymore.
6:00 This is not the point that confuses me the most, think about water ripples or sound rather. The speed at which it spreads out through the medium(relitive to the emmiting object) depends on the speed of the wave-emitting object relitive to the parts that make up the medium. Because light is a wave right? What does confuse me though is the fact that the speed measured doesnt change as my speed changes. It would make more sense if I could use my measurements to culculate a sort of absolute speed relative to the medium(Space). But I guess I shoult just take for granted that it does stay constant alltough this is totally in conflict with the understanding I have built up about quantum fields and waves. It probably is inexplainable. Thanks for the great series!
As others have already mentioned that in spacetime diagrams ct is on the vertical axis, x is on the horizontal axis. We, however, write it as (ct,x). This is just for 2D spacetime. For full 4D version, we write it as (ct,x,y,z).
Seriously man, you're so hyped about your grid machine and you should be, it's hella cool! It's one of the most useful tools in visualising the transformations I've seen!
So good! The animations were well-chosen and super helpful, and the motivation for each successive step feels so natural, despite the fact that you built up to a famously unintuitive idea.
Please, would you do a video that uses your linear algebra animations and explanations to come up with the matrix for the Lorentz transformations? Sorry, I've asked you for this many times already, but it would make so many things click for so many people!
3Blue1Brown I love your videos. Could you do another physics video? The math is great, but if you made a video on relativity and cleared up as much as this video did for me, that'd be amazing for the entire TH-cam science community.
3Blue1Brown I love your videos! They’re so visually intuitive and beautiful, thanks for doing what you do!
3Blue1Brown I loved your calculus and linear algebra series! since i just recently watched the linear algebra one I'm always looking for possible connections haha, from this video i guess that the change to different reference frames is some sort of linear transformation and the light world lines are like the eigenvectors of that transformation? idk its just a guess
We do Agree with You, 3Blue1Brown, for the Quality of this video but concerning the idea it is about a "unintuitive idea", we can't follow You while it is FULLY INTUITIVE as soon we Realise that Lorentz's Transforms implies The Existence of "AN UNIVERSAL REFERENTIAL" and that THE SPEED OF LIGHT IS CONSTANT BECAUSE// IT CAMES FROM THE INTRINSIC PROPERTIES OF THE ELECTROMAGNETIC FIELDS: THE PERMITTIVITY AND PERMEABILITY OF THE FREE SPACE AS THE FORMER IS THE COMMUNICATION LAG OF THE DIELECTRIC INDUCTION AND THE LATER THE COMMUNICATION LAG OF THE MAGNETIC INDUCTION, THE COMMUNICATION LAG OF INDUCTION BEEN THE INVERT OF THE SPEED OF INDUCTION, THE SCARE ROOT OF THE INVERT OF THEIR PRODUCT BEEN THE AVERAGE EFFECT OF BOTH INDUCTION LAG. This just to say that yes Indeed, light is CONSTANT, but only in a Universal Referential, very in Opposite what is used to be said. Regards, Didier.
"Assume the cat moves at a third of the speed of light" that is one speedy little kitten
But it's a perfect sphere, so that's OK.
Einstein’s Special Theory of Relativity requires systems of clock-synchronized stationary observers and the Lorentz Transformation. Without both, the Theory of Relativity fails. A system of clock-synchronized stationary observers is, however, inconsistent with the Lorentz Transformation because it is Galilean. The Special Theory of Relativity insists that systems of Galilean observers must transform not by the Galilean Transformation, but by the non-Galilean Lorentz Transformation. The Theory of Relativity is, therefore, invalid due to an intrinsic logical contradiction.
Yeah I noticed that too
@@RenneDanjoule dude, the original comment was a joke about cats
@@RenneDanjoule But it's backed by experimental evidence, so it's close enough for the time being, right?
Such a great video! Thanks for making it! The visualisations are really helpful to understanding and you are great a breaking down explanations into perfectly sized steps.
How does your comment only have one like. Here, a second one.
How does your comment only have 71 likes. Here, have another one.
How does your comment only have 138 likes. Here, have another one.
@@VirenderKumar-ss9qk THE ULTIMATE, BALANCED, AND CLEAR SCIENTIFIC EXPLANATION OF TIME DILATION:
Consider what is E=mc2. c squared CLEARLY and necessarily represents a dimension of SPACE (ON BALANCE) in relation to E AND “m”. Indeed, BALANCED inertia/INERTIAL RESISTANCE is fundamental ON BALANCE. Consider what is a TWO dimensional surface OR SPACE ON BALANCE, AS invisible AND VISIBLE SPACE is CLEARLY fundamental ON BALANCE. E=mc2 is taken directly from F=ma. Consider TIME (AND time dilation) ON BALANCE. The stars AND PLANETS are POINTS in the night sky ON BALANCE, AND consider what is the speed of light (c) ON BALANCE. Great. Therefore, I have explained why THE PLANETS move away very, very, very, very slightly in relation to what is the Sun ON BALANCE. I have explained the cosmological redshift AND the supergiant stars. I have also CLEARLY explained the fourth dimension AND the term c4 from Einstein's field equations. ELECTROMAGNETISM/energy is CLEARLY AND NECESSARILY proven to be gravity (ON/IN BALANCE). This CLEARLY AND NECESSARILY represents, INVOLVES, AND DESCRIBES what is possible/potential AND actual ON/IN BALANCE.
By Frank DiMeglio
Thanks for the dom burgress shoutout his channel is a hidden gem
You explained the idea of Special Theory of Relativity so easily that I wish you were one my profs teaching me in college. I had to read so many books and visualize so much to understand the intuitive ideas of relativity, wish I had got this video in the 2nd year of my college... terrific job dude...
@Divyajyoti
I couldn't handle this guy's voice for more then two minutes, let alone everyday in a classroom.
Honestly tho I think the journey of you reading through all that and struggling internally to visualize and understand, while incredibly painful and tedious, is still well worth while, and something a lot of learners avoid at their own peril.
Abdullah Almosalami learning to enjoy and speed up that educational journey is where the real fun in learning comes. When you start messing up in ways that haven’t been done and start asking questions that haven’t been asked. I fully agree.
@@AA-gl1dr me too.
If you're looking for a great introduction to the General Theory of Relativity you should have a look here: th-cam.com/video/z1o32hKx5hI/w-d-xo.html
I went through much of grad school for my PhD in physics. I was always bad at relativity but it didn't matter because it wasn't part of my field. I ended my grad school with a masters and went into the private sector to work, and this is the first explanation of Lorentz transforms that has ever made sense to me. I need to go revisit my old books now.
What type of physics did you specialize in?
@@debrachambers1304 I was in a field that could be described as "ultra low force sensing". We developed a lot of experiments around detection of very small forces produced by particles. (e.g. Sympathetic cooling, spin dependent forces, attonewton force detection)
This has been one of the best explanations of Lorentz transformations I have ever seen. I want you to know that.
srsly
E=mC^2 where the C represents the constant velocity of cats in a vacuum?
semi awesomatic now i got it why they choose the symbol for speed as "c" for cats
"m" stands for the meow the cat does by the way.
Cat speeds aren't invariant though, the speed of a cat on a vacuum depends on how fast the Roomba is going. :)
That's the popular, incomplete equation. The complete one is
E² = (mC²)² + (pc)²
where p is momentum. C is the speed of light (not cats) which we can make equal to 1, so
E² = m² + p²
With this equation, a photon has energy even though it's mass is zero.
Don't get confused by the expression, "relativistic mass". It's an unfortunate term. Mass is "rest mass"; does not change with velocity.
Truman Burbank someone doesn't understand humor. But yes I understand. P is pets per second, C is the constant velocity of cats and M is meows per second.
Major sudden realization: The speed of light is the eigenvector of the Lorentz transformation!
Second sudden realization: This is similar to the rolling shutter effect, except instead of the rows of the frame affecting the lag, it's the distance.
The moment I saw the transformation where two lines didn't change, I audibly shouted "Holy crap" in a Starbucks when I realized that it's an eigenvector of the transformation. That was so cool!
? Can you write your statement as an equation?
Nature just loves eigenvectors.
Iago Silva, Watch Three Blue One Brown's video on Eigenvectors/Eigenvalues. You'll get it. :) th-cam.com/video/PFDu9oVAE-g/w-d-xo.html
So Henry is not just abusing cats like Schrödinger did, he's mistreating sheeps as well.
Good one!
Einstein’s Special Theory of Relativity requires systems of clock-synchronized stationary observers and the Lorentz Transformation. Without both, the Theory of Relativity fails. A system of clock-synchronized stationary observers is, however, inconsistent with the Lorentz Transformation because it is Galilean. The Special Theory of Relativity insists that systems of Galilean observers must transform not by the Galilean Transformation, but by the non-Galilean Lorentz Transformation. The Theory of Relativity is, therefore, invalid due to an intrinsic logical contradiction.
Only by the current 'understanding' which is incomplete. Science is infamous for throwing out plausible or even very real ideas because it isn't convenient for them.
Actually, he drew them on paper, and anything can happen on paper, according to my imagination.
I cannot express how much I love this channel! It has always explained physics in a crystal clear detail, and there's nothing from these videos that I don't understand. Literally! One of the best channels I've ever found on TH-cam and I think this channel deserves more!
Very grateful to understand these stuff and be able to imagine. Love TH-cam ❤️
I'm a physics and math instructor. Any way I could get my hands on one of these Time Globes?
I'd like one too!
Even just having one to play with seems fun!
Make one
I want one too! If they started selling them they'd fly off the shelves for sure.
What do you mean globe? It's flat!!
Watching and understanding the physics and the fast physical English in these videos is kinda a challenge for me since I'm only 16 and English is not my mother tongue. But I do really enjoy watching your videos, bc they do not only help me to better understand Physics but also to improve my English! And I actually understand what you are teaching us here! Thank you for that!
Yes, visualization first then the equations. I've never been able to create the visual intuition from the Lorentz transformations myself. This video helps a lot. I hope you look closer and slower at these transformations.
That was beautiful, really showing how the speed of light is an eigenvector in these diagrams
Many people complain about how technology has ruined humans and has made them dumber or less interested in reading; they are all true, but we are forgetting that the internet gives people and young people access to genuinely great videos like this one or others. We could benefit more if we would know how to use it, but it’s not technology that’s ruining us. Love this channel.
I feel like technology is more of a neutral thing, and the outcome it will bring to you depends on the use you make of it....
In layman's terms, it could be used to help your brain get more powerful, or it could be used to replace it....and it just so happens that the second is our case....but I don't think that's "technology" 's fault...
It looks more like when these new powerful tools came out, people weren't trained on how to make good use of them, and actually people were just being shown in mainstream channels how to make BAD use of it.....
Why would a boy/girl use the internet to find and learn useful things, if most of his/her classmates would call him a nerd for that???
I happens to be a person that just likes more being alone so I don't care (not anymore at least 😂) but that's not always the case....
I'm honestly afraid we've already passed some kind of point of no return 😅
It's like how ancient people complained that reading made people dumber by not having to rote-memorize anything
gotta love a good squeeze rotaiony thingies
Ugh where was this device 20 years ago... this is brilliant. Clearly shows how red/blue shifts occur too. Thanks. Looking forward to the next installment... hopefully it comes soon.
me: pauses the video to read the small remarks
youtube: places the navigation bar and play/pause controls over the text, without any way to dismiss them
that annoys me so much
Rodrigo Ângelo YT admins really dig JFK
Try pausing about when the remarks appear and then use comma( , ) and full-stop( . ) keys to move one frame at a time, makes it really easy to see these and less frustrating if the remarks are covered.
Edit: Sorry if you are on mobile.
Seriously!!? Where has this been all my life, trying to pause it at the right moment is so frustrating.
Go out of full screen.
Or go out of widescreen mode.
this video series is absolutely amazing. Very well done. I've learned more in the past 20 mins than the last 3 weeks in class
Oh! So the 'c' stands for cat!
yes!
I think it stands for causality.
My bad, just googled it.
it's for "celeritas" from latin :)
@@Assywalker no it stands for cat
I thought my sound wasn't working at the start - and then I had my ears blown off 5 seconds in after trying to turn up the volume 🙈🙉
Lmao rip ears
Yeah, i was at max volume coz i just finished watching some people whispering so i expected this vid to be not too loud but then... he knew he fucked up at 0:12
Same
Exactly same thing happened to me
Same here lmao
I'm so glad you're going into this in more detail. I remember when you did your "Einstein and The Special Theory of Relativity" video (wow, was that really 6 years ago?), you just kind of was like "Hey, you can do this weird sort of rotating thing" and the entire comments section was like "wut" - actually explaining in more detail this idea makes it make significantly more sense.
Henry, this is a wonderful series. Thank you for your tireless effort in making this subject more tangible and intuitive. The time globe is such a clever teaching device.
When I was in college a decade ago, doing my CS degree, I would have loved to have videos like this that helped me understand why I was learning certain mathematical functions. I was always very good with math until I got to portions of calculus and then linear algebra. The math involved became so abstract, I could not connect the application of the functions, which for me, hindered my understanding and ability to learn. I know many people have different learning styles, of which, none of the methods apply to me (verbal, written, etc. are the same), but without understanding the application, my mind becomes limited. These videos would have been great primers for aiding my understanding. I never used the "high-level" math that I learned when programming, but learning should never cease, so I greatly appreciate videos of this nature.
One of the best demonstrations of special relativity I've ever seen. I would buy a time globe if you make more of them. Absolutely beautiful engineering used to explain something so deeply profound and elegant. Everything in space is so far away but nothing is unreachable. If you dont mind the rest of us waiting 60,000 years you can cross the milky way in a few min. Of course it is beyond our current propulsion abilities but it is not fiction either, the universe provides a way to cover vast distances within your lifetime. Magic!
hey Henry can you put the time-globe for sale?
Yeah I'll fight someone for one
My computer version: drive.google.com/file/d/1lUImLYng-nfb0oKn2K2Vy8ETGpfCEeJY/view?usp=sharing
You just explained a very complex thing in 12 minutes. I’m so lucky that youtube exists
Incredible explanation. Presentation is on point.
Oh of course, Rober helped make that. He's a genius.
Probably the only comprehensive and lucid explanation of this topic I have had the fortune of coming across! Keep them coming mate.
This is by far the best video you have made, never have i seen special relativity clearer. Hope you continue in this direction!
So, if the scale of the space axis is one meter per tick, then the line representing light would appear practically horizontal, and a lorentz transformation effecting a cat moving at 3 m/s would appear skew the diagram purely to the left and right, thus functionally identical to a shear transformation. And so the shear transformation is the intuitive assumption for relative motion. Right?
wow!! watched so many videos on relativity, but this is one of the best ones!! What a great intuition!! Thank you so much for making this.
Which other videos on relativity you recommend?
I clicked on this with the speed of cat
The speed of cat is secretly faster than the speed of light, scientists just haven't been able to prove it yet.
OrangeC7 because cats are so darn lazy
Faster than a sheep cat, or Time Globe cat?
Of course; c = speed of cat.
At the speed of cat, time stands still, so cats experience no time. Outdoor cats are indoor cats going back in time. The light from a laser pointer moves to wherever a cat will be a moment later.
Since I first heard about relativity a couple of years ago from my brother who learned it at school, I simply couldn't imagine or even accept that time dilates and space contracts when you're going faster. I'm hard-wired to think of time and space as static planes and it feels absurd to be able to change space and time itself. As if an animation on a computer screen can physically grab the screen and stretch and turn it.
But by simply watching this explanation and the animation, it immediately all feels intuitive. I can now literally see in front of my own eyes how it actually works. At the end of the video I was literally clapping because you did what my brother failed to do for a long time: make me fundamentally accept how all of this fits together. Thank you for this.
Ok second episode had me a little lost. This one just turned on a whole bunch of light bulbs that had me stumped for a long time, and theres a lot more still to switch on. This is amazing man, thanks for doing this!! I feel like this level of understanding is being lost within university walls, at least for the aging discoveries. We are taught "of them" but not always "about" them. Its great to have this kind of thing available should one want a deeper understanding.
OK, one more comment to say the same thing, but... I'M READY TO BUY THE DEVICE, BUILD A COMMERCIAL PAGE MATE! (Mark Rober, I mean... By the way, great job as usual, minutephysics! :) :) :) )
I'm ready to buy it too.
3d printer model?
Best NOTIFICATION of the month! :) 😃😄
Thanks a lot HENRY! 😊😊
Perfect intro video for my highschool physics special relativity section. Preparing my young padawan's for college.
I like that using youtube to teach it makes things so much more simple and easy to understand
I just found out about this (I reckon I arrived a little late) and it's the first time the whole thing makes some sort of sense! Thank you so much for making special relativity closer and easier for all of us, I hope one day my kids find these videos as intuititve and entertaining as I do. Keep up the good work!
"Time globe" sounds like something from Doctor Who. I approve.
Probably gunna have to watch this video a few times before I get it. But looks awesome!
World History With Dan check out PBS space time series of videos on this, it'll help
same
See, if this were a 3b1b video, you wouldn't have to watch it multiple times. He explains things better. Minutephysics talks too fast
Always set these videos to 0.75x, makes them bearable.
This shit is too easy. I wouldn't bother going deeper if you didn't understand the first time.
This was awesome, thank you for making it understandable 💛
Relativity is one of the things that encourage me to become a physicist.
THANK YOU. In no way did I ever understand a single part of this in the past - no number of books or videos helped. But now, at last, THE LIGHT! (It makes sense now, thank you).
From this video, it is obvious that space is curved and the Lorentz Transformations are describing the relationship between curved space and linear time. If you think of space as an inverted cone (tip of the cone at the bottom of the graph and what would normally be the base - wide circular portion - at the top) and your perspective axis is the center of that cone and the cat or sheep's movement is the edge of the curved cone, then twisting the cone left or right would do the same thing as the Lorentz Transformation.
Great video.
Still hurts my head. Probably should rewatch several times when I am at a better mental state.
Wow, good job Mark Rober! Hats off to you, Mr. MinutePhysics guy.
I have many questions...
if we do a lorentz transformation from the light's perspective (just for theoretical purposes), then what would happen? Will the whole thing shift according to the light's perspective? But that obviously can't happen because that ruins everything. So, what will happen? Or am I getting some fundamental wrong?
Also, is the only proof of light speed being constant an experimental proof? I always thought that the theory itself proved that light speed is constant, and we double checked that with experiments.
Lastly, and this is a confirmation, we chose the rotation which involved placing the x=4 point at t=3 just because that was the only one that confirmed experimentally with the fact that light's speed in vacuum was constant, right? What I understood was that they tried both options, i.e. placing the x=4 point at t=5 and placing it at t=3, and what do you know, the t=3 option just worked.
If someone knows answers to any of these questions then please reply me. I 'd be grateful. Thanks in advance
btw how many of you have used brilliant??
is it worth a subscription?
"if we do a lorentz transformation from the light's perspective (just for theoretical purposes), then what would happen?"
You can't, everything falls apart. You're asking for light to be both not moving with respect to the observer, while still moving at the speed of light with respect to the observer (because it always does). That's two different answers to the same question, which is impossible. Einstein's math collapses into infinities and zeroes, and MinutePhysics's "time globe" would actually break if you tried it.
"Also, is the only proof of light speed being constant an experimental proof? I always thought that the theory itself proved that light speed is constant, and we double checked that with experiments."
The theory *supposes* the speed of light is constant, and shows that a wide variety of phenomena, from the behavior of subatomic particles to the light from distant galaxies to ordinary magnets, can be explained, leaving no doubt that the assumption is in fact true.
Jason Goodman if light is not moving at all (theoretically) that's the only case when observer is moving at the speed of light (makes light appears to be not moving at all to observer) but is impossible practically as nothing can match the speed of light as we know.
Let's answer pointwise :
1. We cannot ever do anything from the light's perspective. Why? Because, suppose you are in a frame which is moving at the speed of light. But according to the postulates of our theory, light still moves at the speed of light and so it's not at rest. But if you are already moving at the speed of light, you cannot increase your velocity any further and thus the inevitable conclusion is that "light has no frame in which it is at rest" or "light has no perspective". Done.
2. Actually, there is something subtle here. If you just assume that all inertial frames (frames with a constant velocity wrt to another frame at rest ) are equivalent i.e. no inertial frame is special ( and also take into account that the universe is homogenous and isotropic ), then you actually find a frame invariant speed, although the value has to be checked by experiment or from other theories (like electromagnetism). Cool?
3. Just like I said in the previous point, there is a general transformation that comes out even if you don't assume the constant speed postulate. And, as any mathematician would say to you, this transformation is exactly equivalent to the squeeze transformation that he showed us. (I have no idea what transformation the rotation one covers).
Hope this clears some doubts of yours!😊
Oh, and for the Brilliant part :
4. If you want to learn some quick concepts and apply them to stuff, then yeah, a subscription is the best thing to do. But... If you want to go deep inside things and then apply them, then I would personally suggest listening to lectures, audio books and even buying some good old topic-specific books to learn. And then, going to Brilliant to solve their beautiful sums. 😊😊
I can't say much about the other questions, but for 'boosting' into light's perspective, I might be able to help.
Consider the two fundamental properties of lorentz transforms: The speed of light stays constant, and we transform a constant-velocity path into a constant 0 velocity path on the origin. Now, what does it mean for the speed of light to stay constant during a transformation? It means that any light-speed event (point in time-space that lies on the causality cone) must also be a lightspeed event for any other observer. To transform a constant-velocity path through the origin into a 0-velocity path through the origin, we need to take all events along the starting path and make them strictly temporal (they're only separated from the origin by time).
If we try to boost to the speed of light, we must simultaneously have all lightspeed events on the causality cone and on the 0-motion time axis. The only way for this to happen is for all the events to be at the origin.
What does that mean? Light doesn't experience time or space. Emission and absorption of a photon, from the photon's perspective, happen simultaneously and in the same position. It is in this sense we can say that light doesn't travel, because from its own perspective, it doesn't make sense to talk about time and space, thus travel is also nonsense.
I personally try to think about light in this way, and it gives a new perspective on interpreting quantum theory. The Copenhagen interpretation, where quantum things don't exist until the wave function collapses is actually quite reasonable, since the photon itself doesn't travel, but from its perspective any and all lightspeed paths we observe between the emission and absorption events collapse down into the same moment. This is more obvious when we think about light in a 2-d plane and an actual causality cone instead of a degenerate pair of lines.
Robin Sinha that’s an awesome question, and you can sort of see the answer in the video. Take a look at the segment starting at 7:14. In that segment, he’s transforming the space time diagram so that the blue sheep line is along the t axis. But look at what has happened to the light-cat snapshots on the right. You’d think they’d get closer to the t axis as well, but all they’ve done is gotten squished closer together. Let’s pretend that the cat, instead of going on forever, hits something on the right. We’ve been trying to get the cats snapshots to all be on the t axis, and now we can do so, by squishing the limited number of cats all the way down to the (0, 0) point. One way to interpret this is that to the cat (or photon), the journey from the start to when it hit something took no time at all. This is a really important point, and I’m sure we’ll get a whole video on this at some point. You can try to think about what such a transformation would do to the rest of the graph as well; it turns out that light has a really weird perspective where space is all squished in on itself.
That moment when a thing you kinda sorta understand on an abstract level suddenly makes intuitive sense.
Phenomenal work!
I had no idea that the TH-cam community is so connected, that 3blue1brown knows minutephysics knows Mark Rober knows Mr Beast and etc. It's really cool to think about!
just had a final exam over this and more. and this pops in my recommended?
coincidence? i think not!
They are listening!
8:08 .. the sheep is moving 50 percent of the speed of light in that example 🤯
C actually stands for cat
@@NegativeAccelerateunless you're in Nicaragua, then it translates to cantaloupe.
I'm 12 and I understand- thank you so much. English isn't even my 1st language
I really enjoy watching this series, and I notice once again how similar these videos are to my first introduction to special relativity - probably the main reason I love physics this much
Suppose we have objects A, B and C.
Does that mean that:
If from the perspective of A, B is moving at 3 km/h and C is moving at 5 km/h,
1)then from the perspective of B, C will *NOT* be moving at 2 km/h?
Meaning that the angle between B and C will *NOT* always be the same?
2)But from the perspective of B, will A be moving at -3 km/h?
(as stated in the video at 10:10 for the example of the person moving at -1/3 the speed of light from the perspective of the cat)
Very good explanation and I love the time globe. Thank you.
On graphs points are placed as (x,y) or (y,x) ; because here where i live it is (x,y) and when i saw you put it (4,2) i was like whoaaa
Well illustrated and explained.
7.15 that's when my mind blown. " Length contraction", now i got the idea.
And I'm just so grateful for you , you just made it look simple.
If you have a teacher with correct intuition you can achieve great heights
This is the first time (after many attempts) that I was actually able to understand the concepts of special relativity! Thank you!!!
I graduated from university, I studied physics .... but only now I know what the hell Lorentz transformations were good for :D (besides driving students insane)
just a 2 cents about the change of different spacing of the cat after the transformation. The speed stays the same but the wave length of light changes similar to doppler's effect.
Thank you so much for this video, i finally understand a lot more how relativity works while having light as a constant, and red-blue shifts in light make more sense, because the speed doesn't change, but if you imagine each point as a wavelength, then they get more spread out as they move away from you, or closer together, as they get closer.
I like this much much better than having everything compressed into a minute. Well done.
This is the first time someone has described special relativity for me using the vectors, and the first time it has made any sense.
thanks
I thought coordinates were (x,y) but at 3:13 you're doing (y,x)
The convention is (t,x) for SR
A TH-cam channel for you was a smart move, because you wouldn't be making the money you make as a physics teacher. :-)
and reach that amount of people and help them to understand physics.
That is not entirely true, and you tube ads barely make money.
@@davel7037 Sponsorships
i want a time globe!! seriously, can i buy one?
Googled it and found a fake version. Some graphic artist made an ad for one for practice. Unfortunately it was fake.
This seems to be the most time consuming video of this channel, from the creators perspective (pun intended). So many details, so many movements, it does seems like a lot of work. And as a physicist, it gave me a clearer view of relativity. Thank you.
This was the first timee I've heard an intuitve description of Lorentz Transformation. Well Done!
7:50 cat lines = horizon lines on a penrose diagram?
Nope, they are null (3-)cones; "horizon lines" in a Penrose diagram of Minkowski ST would be the borders, which represent infinity ;)
I honestly just memorized this so I can make my friend’s brain hurt
0:11 That music's hype.
Small remark at 4:07 (so you don't have to pause and try to read through TH-cam controls):
*And also so that the inverse of the transformation corresponds to a transformation with velocity -v
And that one in 10:41
*or software that does Lorentz transformations for you... but that's much less hands-on
This is suprisingly the most simplified explanation on relativity i've ever seen
Truly, cats can make understanding Special Relativity easy.
At the 8 Minute Mark: couldnt that be also explained via linear algebra in terms of eigenvalues and vectors?
Dude! You teach soo damn well ♥. lovin the lessons..........
like to show support 😅
Great job at explaining technical things while keeping it popular
This blew my mind.
I took a course on special relativity in college and found the concepts super interesting but the complicated math felt really cryptic to me.
I love the idea of a mechanical representation that people can play around with and use to develop intuitive understandings.
My likes keep disappearing...
That’s weird, your comment is suddenly on top with 6 likes.
@@thatonedynamitecuber Update: they still keep disappearing.
Explain, please?
@@manueljesusarredondoruiz2444 you know like the "👍" under videos. I come back to videos that I watched years or months earlier, and "like" isn't marked by me anymore.
@@gustavgnoettgen yes, but how could they disappear? Any idea?
Dogs can’t operate MRI scanners but catscan.
Thank you. Wishing you a beautiful day x) 🦋
Yes! I always struggled to understand Lorenz transformations, now after this video things become so much easier to grasp! Thanx!
this is literally one of the best videos on relativity that I have watched!
12:17 minutes physics 🖒
outright better than my college education
Oh, I see.
There are hyperbolic rails keeping the product of the eigenvalues constant.
c².
😵
You might be right, but socks with sandals is still wrong. Lose the sandals.
6:00 This is not the point that confuses me the most, think about water ripples or sound rather.
The speed at which it spreads out through the medium(relitive to the emmiting object) depends on the speed of the wave-emitting object relitive to the parts that make up the medium.
Because light is a wave right?
What does confuse me though is the fact that the speed measured doesnt change as my speed changes.
It would make more sense if I could use my measurements to culculate a sort of absolute speed relative to the medium(Space).
But I guess I shoult just take for granted that it does stay constant alltough this is totally in conflict with the understanding I have built up about quantum fields and waves.
It probably is inexplainable.
Thanks for the great series!
The best approach to relativity and LT ive ever seen!!!
10:30 actually i find the equations less confusing
"Suck it, Sheldon! An engineer did this." - Howard Wolowitz, circa 2018
...I think...
A cat in motion stays in motion.
semi awesomatic unless acted upon by an unbalanced force
semi awesomatic *
Sorry, but my cat seems to be at rest about 18 hours a day.
oscargordon looks like your cat has an enormous inertia
oscargordon From your perspective, yes. From the cat's perspective, it's moving at the speed of cat, c.
Thank You mr minutePhysics. I don't know if I would understand these things without people like you. Thank you very much.
when I was introduced to minkowski diagrams in the 1980 they seemed very dry, you have made them come alive
He writes the coordinates in reverse😶😶
Udip Adhikari That's the standard for space-time diagrams 😊 . ct for vertical, x for horizontal.
Udip Adhikari Actually, in minkowski spacetime diagrams the horizontal axis is used for distance(x), and the vertical axis is used for time(ct)
I was thinking the same thing😂😂
As others have already mentioned that in spacetime diagrams ct is on the vertical axis, x is on the horizontal axis. We, however, write it as (ct,x). This is just for 2D spacetime. For full 4D version, we write it as (ct,x,y,z).
That's just because he's left-handed.
😂 I don't get it at all but i like the video
Light!
It's not a ball
the series is one of the best simple explanation to special relativity .....thanks for making me understand minutephysics
Seriously man, you're so hyped about your grid machine and you should be, it's hella cool! It's one of the most useful tools in visualising the transformations I've seen!