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there is a little problem in the video, information can move faster than light, spooky action at a distance, is mass that can't travel faster, in this case force is transmited via mass movement, so it is limited by c, but pure information is not limited by c, that is why only information can escape a black hole
Alen, if information could move faster than light, then it would be possible to send messages backwards in time. The "information" that is transmitted in spooky action at a distance are random outcomes that we have no control over, and hence we can't use this to encode useful information, like sending the winning lottery numbers backwards in time. I cover this in detail in my video on this topic at ruclips.net/video/v657Ylwh-_k/видео.html
Police are currently looking for Sarah in relation to several train crashes. If you see her please remain calm, do not approach her, and alert the authorities.
+Yan G That also struck me as great detail as Lorentz contraction only appears in the direction of motion. I really like the situations used and how things are visually explained. Eugene K. has earned himself a +1 subscription.
I do not know if you are being sarcastic because Im really bad at telling the difference. But if you are...IT'S CALLED SPEACIAL RELATIVITY!! Just if you are being sarcastic though.
Instead of resorting to nonrigid bodies, i think it is much easier to understand if you keep in mind that for lengths and distances to shrink the speed of the train has to be CONSTANT. The moment the locomotive hits the exit door at the end of the tunnel it decelerates from whatever speed it was going to a complete stop, but nothing can accelerate or decelerate from a constant speed to zero speed in zero time. The very moment the speed starts decreasing towards zero special relativity length-contraction does not apply anymore and you have to use general relativity. Of course the effect of such sudden (but not instantaneous) deceleration is that the tunnel "resizes" quickly to its original size, that is, the size it had when the train is at rest and neither the train nor the tunnel are moving at a CONSTANT speed relative to one another. QED
If you think about the energy from the train versus the energy from the door, the train could pass through it because it has the higher energy (E=mc^2). Idk if I'm correct but that is what I think.
+tommy cane115 Einstines theories are fundamental to our understanding of the universe and therefore our full potential. Unfortunately mankinds potential is mostly being used to destroy itself. He unlocked pandoras box because he was not as cynical as he should have been about mankinds paranoi and corruption. Same for doctors who do stem-cell research to cure sick babies, naive to the fact that they will bring about the breeding out of everything human about humans. The history of technological advances amongst us neanderthals is everything gets weaponised. Nuclear power, Social media, Life itself. It's not the scientists fault it's the warmongers. It's Trump, Putin, May, Bush x2, Blair, Thatcher and all their 'Sponsors'
Special relativity *is* this complicated and weird, you really can't simplify it down further than this. Watch any undergraduate introduction to special relativity and you'll see that.
Peter D Morrison Helped me ubderstand it alot, I was confused about this, you have to understand what someone who has no clue how this paradox plays out knows and what they don't know.
This is a wonderful video. I learnt things about S. Relativity I never knew were there to learn. Just a question - does elasticity behave differently at higher speeds? Surely, in the last scenario Adam sees the train bend like molten puddy while Sarah sees it fall with a plot as one rigid piece. Since there cannot be distortion in the direction perpendicular to the line of motion, what is the resolution of this paradox?
I think there is acceleration in vertical direction so we should apply general relativity ,you can think space in the train has been bended ,so there is no elasticity in the train
I think Adam will feel the distortion.. due to gravity pulling and bending the train through the missing slab of bridge. And the distortion will be restored once moments of falling of train is completed. Restoration will begin from the front portion of the train. I can be wrong.
I have contacted a number of train authorities and it seems that none of them are willing to participate in any of these dangerous experiments. I guess we will never know for sure what really happens to the train. I have observed a number of autos on the freeway travelling at near light speed and I have to tell you it is really bizarre. They didn't appear any shorter or longer, mostly just a blurry streak. When the police travel at light speed I notice the sound of the siren takes about 10 seconds to catch up to the blue lights. Really weird.
j7ndominica0 You are now getting into details out of the scope of this video! It will be very difficult to show what is really going on, SINCE the relative motion of the camera that show us what is going on, will ALSO create relativistic artifacts! It all becomes a trippy visual mess when you ask what is exactly going on! That's why I would love some special relativity 3D simulator program to be created by someone so we can visualise all that in more detail! But sadly there is nothing yet... Someone needs to make one! EDIT: oh wow, I found this ruclips.net/video/qol-zP9W5J4/видео.html I was 100% correct on the trippy visual mess XD Special Relativity really is a hell of a trip!
7:49 Truly a sad moment. Seeing a young man with a great future ahead get trapped in an unbreakable tunnel by a malicious entity (It may be Sarah, it may be God, it may be Eugene K.).
@@MaksKCS "Explains" is also relative. Explain calculus to a newborn. Sometimes you need to up your knowledge base before you can understand. Things can only be dumbed down so much before you need to smarten up.
Aww, you didn't put in the REALLY interesting part. What if in the closing-doors scenario, you had TWO trains going opposite directions? Sarah would see both doors closing at once, while the passengers aboard the trains would see the doors closing one after another. But the passengers on each train would disagree about which door closed first, demonstrating that in special relativity, even the DIRECTION of time is relative!
Why does the second door closes before the first from Adam's perspective? I can't understand this part. Just to make the fact of the train getting trapped into the tunnel possible from both perspectives? I mean, what's the physical meaning of it according to the theory of special relativity? And how is it that both things are just as valid, I mean, how is it that in a frame reference both close at the same time, and in another one closes before the other, and both are equally correct? If the doors are programmed to close exactly at the same time, then isn't that the actual reality? Really they are closing at the same time cause that's how it was programmed to happen by an exact mechanism, so what someone sees from some frame is actually an optical illusion that doesn't match the factual reality that both of the doors are closing at the same exact time?
@@OP-lk4tw There isn't really any way to easily explain it. But in short, the doors are programmed to close at the same time from the tunnel's reference frame, but NOT from the train's. If someone on the train could see the electrons in the circuitry telling the doors to close, the mechanism altered by lorentz contraction would cause a time delay between the doors.
I hope that I can help those who are still confused, because I was until I realized that what is important is the measurements of the two objects that are made when both objects are at rest to one another. When both frames are at rest with respect to each other, the train is the same size as the tunnel (and the hole in the final example). THIS is what dictates what Sarah and Adam must see. In order for both of them to see the predicted effects of the rest-lengths, simultaneity HAS to go out the window, causing these weird resolutions to occur. It is clear, then, that neither Sarah not Adams measurements are "preferred." Rather, it is the measurements made when the entire system is at rest that dictates the outcome. Hope that helps.
+jeremy: I sure hope so...she was sure sporting a nice pair of breasts at the beginning of the vid.... but I can assure you, that had it been me instead of Adam, Sarah's tunnel would have definitely experienced more than just a few fully elastic collisions with an inelastic, solid member...
tommy cane115 yet there are GPS which comes from that relativity. I don't care if he cheated on his cousin or not. but I'm not happy that mileva didn't got the credit on relativity. we use light to send information too. that's how relativity works, next time you check ur maps, think about this.
tommy cane115 oh my god, I start to feel you are more of a social justice thinker rather than a scientist and logic thinker. If you think that those theories is only coincide with gps, so the person who invent the gps, will try to test joke-technology to see if it's work? And if he didn't deserve credit from the gps, so why mileva his wife deserve credit from relativity? the counter theories is just not fully proven yet, honestly I'm trying to prove him wrong too,
@@MrGodofcar pretty sure this does not classify as a reliable source, rather as a conspiracy channel. Example: There was an argument that the right triangles don't remain right triangles when traveling at high speeds, which is, like, predicted by the theory and causes no problems whatsoever.
@@creativenametxt2960 Pretty sure this is not a conspiracy channel, just alternative scientific theories. The Big Bang, gravity only-governed universe theory of mainstream physics cannot explain several anomalies, such as Martian blueberries or the mineral Trydimite on Mars, some "impossible" stars, faster-than-expected outer arms of galaxies without inventing the ad-hoc theory called dark matter, [...]. And I've never seen an object that is a triangle and not a triangle at the same time.
Thank you, thank you so much. I'm from Brazil and recently graduated in physics and this concept I couldn't understand. Your channel is helping me alot.
@@uncolorr you don't need to understand every single topic to graduate. I graduated physics without understanding how waves are formed by different kind of instruments, and special relativity. Sure I knew how to use the formulas, but I didn't understand it.
About the train crashing into the door of the tunnel part, since the train's perspective sees that the entire tunnel is contracted, instead of the train shrinking down to fit inside the tunnel, how about the train doesn't shrink but the tunnel expands back to its original size and the train fits perfectly in it?
but in one case (Adam's case) the train is destroyed when the two tunnel doors close... but in Sarah's case, the train is still in tact. so which is it? when the doors of the tunnels reopen and we look inside, do we see a wrecked train or an in tact one?
I think that the train is not a solid rectangule is a forced explanation, as the Adam is slowing down from light speed, everything in his perspective will become gradually enlarged as in real life, therefore, as the train slows down the length of the tunnel becomes larger, train will fit inside without hitting
Its strange... For the first time in your (wonderful) videos, I didn't feel satisfied with the animated explanation. That last scenario just... doesn't close on me.
Because she failed to mention that the hole is actually larger than the length of the train, it just appears to be smaller from adam's perspective because he is approaching it.
In the last scenario, to let the train fall through the hole (in the speed of light), the gravity / force to pull the train down has to be extremely strong. Therefore, the train falls apart like this
Close to speed of light the train can easily bridge a gap the size of itself or even significantly bigger. It will keep its direction and proceed on the other side of the gap. Both agree that the train has not fallen through the hole
Oh and btw what if Adam saw the train cross the bridge, should not Sarrah saw that too? The gravity pulling train moving at near light speed through such tiny hole must be insane.
Not the least of which is the fact that when they're done, Sarah is now an old woman in a nursing home while Adam is only a day or so older than he was when they started...
I would love to see you guys make a video on how fast traveling objects look like colorwise. Since it changes from violet to red as it passes you according to the theory of relativity. An animation of an object traveling though a 3D grid would look amazing from the perspective of the object.
Can anyone answer me: Why does Adams view of events revert to Sara’s in order to solve to paradox? In the second scenario Adam see the train is longer Sarah sees the train is shorter The train crashes and the paradox resolves to Sarahs point of view where the train shrinks Why doesn’t it resolve itself to adams? In the third scenario. Adam sees the hole is shorter than the train. Sarah sees the train is shorter than the hole. The train falls though the hole why? Why not the hole adjusting its length to allow the train to cross?
Ill answer myself in case anyone else is asking this question. The outcome is based on what who happen if both pieces of the puzzle where at the same reference frame. To each actor the paradox resolves itself in different ways despite what the author stated.
In fact Adams and Sara's views can not be the same. if they would, this would violate logic ( whatever logic means ). The only solution to this, is that either Adam either Sara will continue to live in two different realities or "parallel universes" ( they already do, but those two parallel universes were quite similar until train approached the hole ). From the moment two universes "split", in Sara's universe Adam will fall through the hole and she will celebrate his funeral. In Adam's universe, Sara will die , being hit by the train. And Adam will celebrate her funeral. They will both continue to live in their respective universes.
While the first example was amazing, I think the explanation could have been much much better. For example, it illustrates one of the fundamental assumptions of special relativity: all observers must agree that events occur. They will simply disagree about when and where those events occur. In this case, the opening and closing of the two gates are two events and hence both Adam and Sarah must agree that they happen. However, they need not agree on when those two events happen. This takes us to the difference between spacelike and timelike events. In Sarah's frame of reference, the opening/closing of the two gates happens simultaneously, meaning that the two events couldn't possibly be causally related and are thus spacelike. And for spacelike events, the order of the events doesn't matter. One of the events could occur before the other, or vice versa, or they could happen at the same time. However, if the two events were causally related (and so timelike), then the results would be very different. For example, if one of the doors closed first and then sent a signal to the other door to close as well, then both Adam and Sarah would have to agree about which door closed first. Now I guess you could ask why the train being inside the tunnel doesn't count as an event, forcing both Adam and Sarah to agree that it happened. And honestly, I don't know. What counts and doesn't count as an event?
_"What counts and doesn't count as an event?"_ - everything physical that happens at a defined location and time is called an event. So there are countless of events happening. The video just concentrates on those that are important for explaining the paradox.
@@renedekker9806though as wide object the entrance and outtage of both ends of train must be considered too, they are as important as in classical physics in my opinion to get rid of any doubts. The thing that catches me is the last one, also know as the bar and hole paradox. That and the second seem weird, though I don't know if there is a concrete experiment to find out what actually happens in this scenario.
+Moreg I confirm, and knowing that since the start of the channel every video followed a logical order, I expect videos to come after videos about relativity and thermodynamic, which should be soon :)
From the perspective of the animator, these events would have taken place within a black hole. Otherwise the train would not have fallen in the gap; it would have shot into space! The background music should have been from Soundgarden. 😎
This is so useful as analogy to explain, in terms relativistic, why the Quantum Eraser and even the Delayed Choice Quantum Eraser experiments produce the results that we, as "static" observers see: because for the photons all the process is happens simultaneously, in a perfectly synchronous "now" and perfectly compacted "here" (space-time is absolutely compressed at light speed). Cool.
As the train approaches the hole becomes bigger. Probably something this video missed is that Adam will see the hole expand and engulf the train. Even if on previous inspection it was much smaller.
Not sure if anyone mentioned it but I have to clarify that the last example with the hole in the track is wrong, unfortunately. In your explanation you started in Sarah's reference frame, assumed some physical truth (that the train will fall) and, then, you enforced the same truth in Adam's reference frame. But there is this strange sudden deformation thing happening with the train, right? I mean, what's the physical reason that Adam's train experiences a vertical force in its own reference frame that is strong enough to deform the whole train? Therefore, let's instead do the opposite thing and start our reasoning in Adam's frame. What would we see? First, the train would just pass the hole in the track as the hole would become very short. If we now transformed to Sarah's frame, what would we get? Well, a short train floating over a too large gap without falling into it. So, is there a physical explanation for the deformed train in Adam's reference frame as depicted in the video? No, there isn't as trains should not deform that much under their own weight in their own reference frame. But can we, instead, explain how the short train floats over the gap in Sarah's frame? In fact, this can be explained. The physical reason was already given in the middle of the video: Forces do not act faster than the speed of light. This means that the forces holding the train up floating in the air would result from an instant in time when the train still was in contact with the track. I would like to see this animated in a corrected video. :-)
It is not "wrong." If the gap is several light years long, then it is clear that that the train will fall through the gap from Sarah's perspective. However, if Adam is travelling at close to the speed of light, then even this gap will appear to him to be shorter than his train. And hence we have the paradox that this is covered by the explanation in the video.
I disagree. Sarah will see the train float over the gap. I hope I can make the physics clear: The front of the train will not fall into the gap as long as there is a small chunk of train connected to the track. This is because the forces emerging from the track are transported through the train material until they reach the front of the train. Now, consider the moment, when the train loses contact with the track. You assumed that the train will start falling down at that moment. However, you did not consider that, at relativistic speeds, *all* actions including forces act with a certain delay. This means, even if the train is no longer connected to the track, there are still, let's call it force waves, acting on the front of the train emerging from earlier moments in time when the train was still connected to the track. And the closer the train moves at the speed of light, the longer it takes for the force waves to propagate through the train. This means, Sarah could even see the train floating over a lightyear large gap with the front of the train still feeling forces coming from one year in the past, i.e. when the train was connected. Even if this sounds strange at first sight, the observations described in the video are a lot stranger. The video says that Adam's train will get deformed in order to make it through the hole. But why should that happen at all? For Adam who is sitting in the train the train is just a regular train standing at rest. If there was any deformation coming from relativistic effects, it would mean that Adam can feel that he is moving at very high speeds. But as all reference frames are equivalent in relativistic physics feeling the own speed is never possible. To make it short: The transformation displayed in the video is correct. Therefore, the history seems consistent between the two reference frames. However, the events theirselves are wrong. Start with Adam's train passing over the gap and transform to Sarah's frame. Then you get what's really happening. Please recheck your physics. I really like videos of this kind, especially if they look professional as yours does. But then the physics they describe should be correct in order to prevent disinformation. Cheers!
+Woyten When the train starts falling down light has travelled all across its length. It took the same amount of time for both observers, so the result is the same. You just changed one example with another different. In your example the train is a single piece. In the video the train is not a single piece.
+Luis Calderari. You're right. If you assume that the train is made of jelly or the gravitation is extraordinary strong, the situation would be as shown in the video. However, in educational videos like this, you usually make common-sense assumptions about physical properties. This means, trains are rigid. Not completely but rigid enough to carry their own weight. And gravity is moderate, maybe even equal to earth's gravity. If you want to explain the relativistic behavior of jelly on a neutron star, the picture of a train on an earth-like environment is just inappropriate as it only leads to confusion.
You should've stuck around for the 1st movement of the Moonlight Sonata! I guess they figured that the backup music for Einstein (German by birth) should be two other Germans. Fred
I appreciate everyone trying to explain these complex concepts. Maybe a bit faster animation and speech will make it more attractive (in addition to Sarah’s mini-skirt)
"Adam does not see the gates closing at the same time." Excuse me, but by what arbitrary and convenient (for Adam) bit of timing does Adam see particularly the _further_ gate close before the other, the nearer? I presume the engineer put the timing mechanism in the middle and timed both gates to close simultaneously, certainly at least for Sarah's POV. Sarah can help us out here. Let's assume c=1 m/s. She calculates photons bouncing off _both_ rising gates (which she can _see_ rising simultaneously) will reach Adam's retina some 10 seconds sooner from the _near_ gate than the far gate. She can objectively state, relativistics aside, that Adam will see the _near_ gate start to rise first. She will therefore have every apprehension for Adam's mental state that according to Adam's and her shared knowledge of Lorentz contraction that poor Adam is going to both see and experience a slow-motion train wreck. She of course, will not flee the site of the danger because she knows the contracted train is in no danger from a certain destiny with fast-moving gates. But she empathically appreciates that Adam will (mistakenly) foresee his certain death, and in fact is taking out his (contracted) phone and is trying to reach his mother and father to tell them he loves them, and his gf can have his car and the dog. (But of course his phone frequency is doppler shifted and the cell tower cannot even communicate...)
Now, don't quote me on this, but i believe its because Adam is traveling at the speed of light and since photons bouncing off the wall nearest to him (since he's moving away from it) would not be able to catch up to him as quickly as the photons bouncing off the wall he is moving towards (furthest from him). That's why physicist say we could never travel at or over the speed of light because causality would be thrown out of the window.
You have it mixed up. It's not Adam's distance from the gates that matters, it's the motion of the gates relative to the signal sent from the center of the tunnel. Remember, in Adam's reference frame he is sitting still, and the GATE is moving toward him. Thus, the far gate is racing toward the signal sent from the center of the tunnel and the near gate is racing away from it, requiring more time for the signal to reach the near gate.
At rest is the train longer then the tunnel? if it is then you can not close each end of the tunnel no matter what right? The train does not physically change length, the light coming from the train just makes it appear different lengths. atleast that's what I thought Einstein meant.
The train at rest is longer than the tunnel, yet you can still close the doors when the train is moving inside it. The train does not just "appear" to be shorter when moving. Einstein's theory is more profound than that.
So at V=light speed this makes sense, but as per the analogy the train goes to v=0mph. There must he something I'm not understanding about or unless the situation is a snapshot in time.
Couple of points: In second demo that has to do with the reference frame consistently set to of the man on the train before collision, right? Sarah would see a train hit the wall and telescope outward from front to back to its proper length. Adam would see the tunnel expand forward as he came to a stop to its proper length. (edit) - my bad. that first point is clarified in the video following second example. Sorry The last one doesn't make sense to me. Doesn't Adam see a length-contracted hole as well? Let's make the case that the train is of negligible height and the tracks are of negligible thickness so ANY downward displacement from the track can be defined as "falling through the hole." Or make gravity as big as needed so your trajectory is like dropping a lead balloon. This avoids any charlatan whipping out momentum conservation to muddy the waters. Ok. So the faster you go the smaller the hole is. But the skinnier she sees the train. So the tendency is to make it MORE of a problem in her frame that the train falls (bigger hole relative to train) and LESS likely for him (smaller hole relative to train). In the case of the tunnel, the increasing lack of simultaneity of the closing doors compensates for this Lorentz contraction so everything is consistent. I can't understand what compensates for the length-contracted hole - humongous time delay on front and back of the train? If I replace the hole with a big spotlight that encompasses the entire length-contracted size of the train and shines on it for a finite but sufficient time as it passes in Sara's frame, it completely engulfs the train in light during that time. But it is smushed as train passes in Adam's, so while the spotlight will shine on the ENTIRE train at once in Sarah's frame, the shining while being slowed down for a long time in Adam's, such that the front sees it long before the back, but the back WILL eventually see it as the train passes. this should be the logical equivalent of the hole case. But the train, regarding the falling, is composed of infinitesimal slices of "velocity frames" as it falls, but however nonrigid that may be, that isn't like an elongated cylinder of fluid pouring down a hole as it passes over. Something isn't really right. Can someone shed light on this?
@Dr Deuteron thank you. I have 'grown up' a little since last year, in that special relativity in (linearly) accelerated frames opens a new can of worms and that the modifications show that the devil is in the details. Interpreting things using the understanding of special relativity when the frames are inertial (which I was doing) leads to contradictions. the first example is the only one that allows for that.
there's a flaw. Sarah cannot see the train fall through the hole because the train is moving at near the speed of light, which is so fast that it will go from one end of the hole to the other end almost instantly and continuing on it's path. Same goes for Adam's perspective.
+Angel Angelov Consider the gravity is so intense it can pull the near-lightspeed train into a hole that small. It's a thought experiment, anything goes.
+Physics Videos by Eugene Khutoryansky Doesn't this actually depend on the speed of the train? If the train travels at near the speed of light, it will be able to "jump" over a huge hole due to inertia. This video seems forced/unreal to me. The train is indeed not perfectly rigid, but it's still quite rigid. It will never bend over a tight curve so that it will fall through the hole. Why would it behave like that? What force makes it to be bend like it would be a flexible piece of paper? As far as I understand, the properties of steel (the material from which the train is made) will remain the same, even near the speed of light.
I am still a bit puzzled by the train on the bridge. If Sarah and Adam's points of view are both valid AND they have to correspond with each other, what decides if the train is long enough to cross the bridge? Sarah's "God" or Adam's "God"?
what decides? math. Lenght=Length at rest x square root (1-(velocity^2 /speed of light ^2)) each reference frame will observe a spacial contraction in the other. The faster the object you observe, the more it shrinks in its direction of motion. Both reference frames are equally valid and true. As for Einstein's special theories on relativity, objects share the same reference frame when neither is moving with respect to the other. when there is relative motion between them, each will have their own reference frame.
Ronald de Rooij Sorry but it does not, because time dilatation, T = Tr / sqr(1-v^2/c^2), also changes Adam's perception of the acceleration due to gravity. Hence why Adams train does't make it across the gap.
Great work ! But I didn't get why we considered the train as pieces of rectangles rather than a solid mass. If it were so, would it violate relativity. In the 3rd scenario, for the train moving at the speed of light gravity would too weak to pull it down.
What about the tunnel door's perspective? They must be moving near the speed of light to open and close as fast as the train going through it. So what does the train look like from the door's perspective? Or the rest of the tunnel for that matter?
Your videos are nice but there is one thing. In the last scenario where a part of the bridge is missing, suppose we first take Adam's point of view in account. Now Since Adam sees the missing bridge or the gap is very small, it won't fall. Now Sara must also see the train not falling. So in short the train will not fall if we take Adam's point of view and it will if we first take Sara's point of view, so isn't it wrong or confusing ?
What if the train is long enough for Adam to pass over the missing section without falling through, but from Sarah's perspective the length contraction has shortened the train enough that it falls through the missing section, how can they agree?
To me, when something travels approximatly the speed of light. What we sees might shrink or stretch, but that does not translate the actual physical object shrinked or stretched. We sees the object shrink is because the light cannot travel faster than Light speed constant, physically the object does not shrink unless there is seriously heavy gravity working on it like the black hole. CORRECT ME IF I AM WRONG... TQ...
As always, great videos. Thanks for going into the different scenarios. ..?.. If it is worthy of a video, may I ask for examples explaining where and how Einstein's equations break down in quantum mechanics and on up to large scales such as neutron stars and black holes? I'm sure you are plenty busy, so Its no biggie if you don't. its just that thru all I have studied in the last few years none of any sources have ever shown any work. Not that there are answers but examples of where unifying gravity and quantum mechanics doesn't work...is there a "Line in the sand" if you will?
+Andrew Karpinen The reason why no one shows the work is because the break between QM and GR is rooted pretty much completely in mathematics. And really difficult mathematics at that. I don't think there's much to visualize about it.
Wished I was your friend in real life Eugene, I would probably be a pesky friend but a grateful one if you unconditionally answered all my questions. Anyway... thank you for sharing thru the inter-web :)
To get the correct visual appearance you have to do special relativistic ray tracing, i.e. use light paths, not a calculation of a supposed length on a non observable spacelike interval . The language you used of what Sara "sees" is incorrect. No one sees the calculated "Lorentz contraction."
The problem is that Special Relativity has accepted Minkowski's space-time. I, on the other hand, continue to believe the Lorentz Transformations to be true. I consider the two Lorentz transformations: a) x_1 = gamma * (x - v * t) b) x = gamma * (x_1 + v * t_1) With gamma I obviously indicated the Lorentz factor, and I do not consider the other two Lorentz transformations because they depend on a) and b). If two distances are in relative motion to each other at speed v, the distances overlap. In my opinion, if we denote with t the time spent in the frame of the tunnel and if we denote with t_1 the time spent in the frame of the train, it is t = t_1. (and the distances overlap, no problem) If x_1 = - x, then t = t_1 (and the two distances overlap because x_1 = - x, do not consider x = v * t and do not consider x_1 = - v * t_1) The Pole and Barn Paradox is not a paradox! (The tunnel Paradox is not a paradox!) Now consider a spaceship moving with uniform rectilinear motion at speed v in the frame of the Earth, in this case we know that x = v * t. If x = v * t, then t_1 < t. (the spaceship's clock slows down relative to the Earth's clock) If x = v * t, then x_1 = 0. If x_1 = 0, then v * t = gamma * v * t_1, t_1 = t / gamma, t_1 < t. The twin paradox is not a paradox! Special Relativity is a paradox! x = v * t, x_1 = - v * t_1 and x_1 = - x are mutually exclusive.
Brian Greene, Neil DeGrass-Tyson, Jim Al-Khalili, Max Tegmark - great hosts of science documentaries and science conferences (all on RUclips) ! Walter Lewin - his lectures (all on RUclips) can make everybody love science ! Chris Bishop and Andrew Szydlo - their experiments in front of audience can make all children on this planet want to become scientists (again, see RUclips) ! Eugene Khutoryansky - I have watched lots of visual representations of natural laws and occurencies, but I have never seen a better way to present and explain (!) them than the way Eugene does it in his clips. All thumbs up and fingers crossed that he will keep up the good work ! And the voice of Kira Vincent is really the best choice for the clips - she speaks in a slow and very understandable manner, so that non-native speakers can hear clearly.
+Milen Cenov I second that. As a non-native speaker, I would highlight the quality of both the animations and the voice narration. Keep up the good work guys ! Ps: Mind to share the song list ?
+Florent_ATo, thanks for the compliment on the video. All the music is from the free RUclips Audio Library, and the names of the songs are the following: Ride_of_the_Valkyries_by_Wagner, Renaissance_Castle, Moonlight_Sonata_by_Beethoven
8:50 _If we start the following reasoning not from Sarah, but from Adam, then logic will lead us to the opposite result:_ *From Adam’s point of view, the train is much longer than the section of the missing bridge, and will, therefore, cross the hole successfully. From Sarah’s point of view, the hole is much longer than the train. However, since Adam saw the train cross the hole, Sarah must also see the train cross the hole. This is possible if we keep in mind that the train can consist not only of many rectangles that are connected through flexible connections but can be a rigid object as well. Therefore, Sarah will see the whole train cross the hole as shown* _(a different movie)._ *In this way, Adam and Sarah will both agree that the train has crossed the hole without violating Einstein’s Theory of Relativity.*
Does this mean that these two scenarios where adam or sarah is right are equally likely? if we repeat the experiment several times with the same initial conditions (same speed and hole). Will the train pass the hole in 50% of experiments and fall into the hole in the other 50% of experiments. if no reference frame is preferred.
@@josip_giuseppe As I see, nobody can answer your question because of the ‘if.’ “What will happen IF…?” we can know only in case of having such an experience. So, let’s experiment as many times as you’d like, and then we may get an answer - that’s the only thing I can offer you trying to honestly answer your question.
8:22 Sarah: "A train! Let's stand in it's way and see what happens." SPOILER ALERT: the train fell off the bridge from every perspective. R. I. P. Adam. I didn't like how it's always Adam who dies. It's just unfair.
I regret that I can't donate becoz I m only 16 years old. But pls make more video for visualisation of Relativity and quantum mechanics , your efforts are really appreciatiable.🙏🙏🙏🙏
Thanks. I understand that many of my viewers are students and don't have any money to donate. That is OK. I am simply glad that my videos are useful. You can always help by encouraging your classmates to subscribe to my channel, and sharing links to my videos. Thanks.
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Just added portuguese-brazilian subtitles. Portugal's portuguese may differ a little bit, but yet, still understandable to the european side of the atlantic.
Where Einstein erred was his thought that nothing else can go faster than light. He was wrong and that limited his possibilities. The fact is that we cannot calculate or apply theories based on something we cant measure, That is a huge flaw in theoretical science.
5:50 etc The slice analogy of the (contracted!) train body works only for pushing forces. It breaks down for pulling forces which would instead 'elongate' the train. Slicing up is not the way to illustrate length contraction. What's needed is detailing the force transmission information 'protocol' through the train body. A protocol with EM signals being sent to and fro, in other words, with the help of arrays of adjoined light clocks. And light clocks do length contract, in fact they are used to explain length contraction! So the body matter regulated by light clock signals will length contract with them.
Your Waifu Sucks Not that it became liquid. The train has always been considered as a not perfectly rigid object. So that when the train is falling down, the acceleration that caused the trajectory you observed must be huge in both frames of reference since it was moving at very high speed. Therefore, the train gets deformed, even though from Sarah's point of view is hard to notice such thing.
Luis Calderari but when adam sees the train, will the train look like those blocks with gaps in the middle. I mean adam will still see it as a rigid material right?
+Rocksmith Pdl No, they both agree that the train is not a rigid object. But in Sarah's frame of reference the train looks very short, so it's harder to notice the train is not rigid.
Excellent video illustrating the "pole in a barn" "paradox". Thank you for making it. Two points of interest: 1. The video clearly implies, but does not state directly, the Principle of Relativity: The laws of physics are the same for all observers. All observers will agree on the physical outcome of an event, even if they disagree on measured quantities like space and time (and velocity). 2. Did you notice what happened when the tunnel doors closed, as shown from Adam's point of view? They stretched in a strange way. This correctly reflects the fact that length contraction occurs only along the axis of motion and not along a perpendicular axis. Thus the "door/track" was shorter when it lay flat, parallel to the track than when it was folded up. Kudos to Dr. Khutoryansky for getting this subtlety right.
Thanks. The reason I didn't directly state the principle of Relativity is because I had already covered it in my main video on Relativity at ruclips.net/video/ev9zrt__lec/видео.html
Yeah let's tell these these theoretical physicists to stand in front of the train, let's see how those flexible tiles really work in the real world. xD
@@BillAnt That's not the point. Of course the train is "solid" in our common definition, but nothing is actually 100% solid, meaning impossible to deform. Look at buildings like skyscrapers, for example: we can all agree that they are pretty solid, but when they are built one of the factors that has to be accounted is how much wind is going to bend the top. The deformation of the train due to its speed is just too small to be measured, unless it's traveling at near lightspeed. And of course every person standing in front of it would just be obliterated in a fraction of a second regardless of deformation...
@@BillAnt Thanks to you for not just insulting me as most of the people on the internet would have done at this point! That was really nice, for a change.
@stefano olivotto < No problem man... respect towards other goes a long way, whether you agree or not with their point of view. By the way anytime someone personally insults me, I never waste my time on them, simply press the report button next to the message, and let RUclips handle it. ;D
Questions for the bridge thought experiment 1. Why is the consequence of Sarah is any more prefferable than Adam? 2. If Sarah isnt there to observe, will Adam train pass the small hole on the bridge? 3. Why the slides model and its effect (each slide falling) only appear when the speed approaching C? Why our everyday experience dont see this ?
1. The consequences for one observer are not preferrable to any other observer. 2. If Sarah is not present to observe, the results will still be the same. 3. Relativistic effects are always present. It is just that they are so small that we don't notice them until the relative speeds are close to the speed of light.
@@EugeneKhutoryansky Does this mean that these two scenarios where adam or sarah is right are equally likely? if we repeat the experiment several times with the same initial conditions (same speed and hole). Will the train pass the hole in 50% of experiments and fall into the hole in the other 50% of experiments. if no reference frame is preferred.
@@josip_giuseppe The Theory of Relativity is not probabilistic. If we repeat the same experiment, then in Relativity we will always get the same result. (This is different in Quantum Mechanics.) Also, Adam and Sarah must always agree on whether or not the train falls through the hole.
1. Does this mean that if the train indeed not moving and the earth indeed moving against the train at the speed close to C, the train will still fall into a hole that is much smaller than its size? Also if take into consideration that the hole moving at close to C would make it even smaller? Appreciate all your answers. Ive been watching for your vids since 10 years ago and still occasionally going to be make sense of knowledge more and more.
@@vuhoangbiz A scenario where the train passes contracted(small) hole is impossible. Because Adam feels inertial forces while accelerating the train, but Sara does not. Therefore, both will agree that Adam is accelerating relative to Sarah. I watched a video about the twin paradox. If one twin in a rocket feels inertial forces as it turning back, but other twin from earth does not. They will agree that the one in the rocket is moving.
The lens of my glasses bend light also, yet, no one will say they have a gravitational influence. So does gravity actually bend light or is it the atmospheres of the bodies that refracts it.
Einstein was to cool for that, he had other people do his Experiments for him. And the Experiments support his conclusions, so what's the problem.... Oh right... The problem is people not taking the time to learn advanced physics concepts and instead insist that their junior high school understanding of physics is where physics Stops and that people that put the time and energy into science that Beethoven would put into music is just silly.
@@CeriusDeluge so, I see that you have no understanding of these concepts. Great. Of course no one would say that, that makes no sense. And you're still thinking of gravity as a force, instead of it being the shape of the space time continuum. It's not that gravity pulls on light. It's that things with mass change the shape of the spacetime continuum. The shape of spacetime is like the track of a roller coaster for light. It simply has nowhere else to go, because it's the shape of the surface it's traveling on.
If in case of train crossing a section of bridge missing..if the missing section is so small that ,train passes even it is moving faster from sara's point of view...but in adam's point of view train is considered as small pieces and these pieces will fell down ,because even it is a small hole it is a hole to provide a gap for segments of train to fall down.here both situations are not same..how can we explain this..
the last example would need to assume that they are under extreme acceleration due to gravity, something only possible near a singularity as far as I know. This is because the train is going forward near the speed of light, which means for every unit distance forward only an extremely tiny moment of time has occured. For the train to then be pulled through the hole and under the track in that same small moment of time it took for the train to move forward that small distance relative to the train's motion, extreme acceleration would be necessary. This would also cause spaghettification on the train, in the same way that being near a black hole's event horizon would, since it is not a rigid body.
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... but German Language! ?
If someone wants to help add a language that I don't already have, they can send me an email.
there is a little problem in the video, information can move faster than light, spooky action at a distance, is mass that can't travel faster, in this case force is transmited via mass movement, so it is limited by c, but pure information is not limited by c, that is why only information can escape a black hole
Alen, if information could move faster than light, then it would be possible to send messages backwards in time. The "information" that is transmitted in spooky action at a distance are random outcomes that we have no control over, and hence we can't use this to encode useful information, like sending the winning lottery numbers backwards in time. I cover this in detail in my video on this topic at ruclips.net/video/v657Ylwh-_k/видео.html
Do you think about to make a video on the Ehrenfest paradox ?
Police are currently looking for Sarah in relation to several train crashes. If you see her please remain calm, do not approach her, and alert the authorities.
hahahaha
Beware that she may be responsible for certain trolley incidents as well.
funny
haha finally a decent comment on RUclips
Yes!
Sarah is impressive, she can follow the train with her head while it moves near light-speed
All relativistic phenomena are not perceived by Sarah because her head is moving at the same speed of Adam's trains haha
Whiplash!
she's light-headed from these experiments.
@@redcamaro9401lmfao
I can tell about few other reasons for her to be impressive.
the shrunk tunnel little door 4:35 getting bigger as it goes from the horizontal axis to the vertical is a fine detail, well done.
+Yan G, thanks.
+Yan G That also struck me as great detail as Lorentz contraction only appears in the direction of motion.
I really like the situations used and how things are visually explained. Eugene K. has earned himself a +1 subscription.
its a her i think, but idk. the voice is a computer im pretty sure
DrPepper776 Eugene is a man’s name
I do not know if you are being sarcastic because Im really bad at telling the difference. But if you are...IT'S CALLED SPEACIAL RELATIVITY!! Just if you are being sarcastic though.
Instead of resorting to nonrigid bodies, i think it is much easier to understand if you keep in mind that for lengths and distances to shrink the speed of the train has to be CONSTANT. The moment the locomotive hits the exit door at the end of the tunnel it decelerates from whatever speed it was going to a complete stop, but nothing can accelerate or decelerate from a constant speed to zero speed in zero time. The very moment the speed starts decreasing towards zero special relativity length-contraction does not apply anymore and you have to use general relativity. Of course the effect of such sudden (but not instantaneous) deceleration is that the tunnel "resizes" quickly to its original size, that is, the size it had when the train is at rest and neither the train nor the tunnel are moving at a CONSTANT speed relative to one another. QED
10:40 In this way, there's no adam left who can agree with that :(
So we solve this physic issue the Italian way?
If it's an Amtrak train, it will arrive at the tunnel 5 hours late, from any viewpoint.
This made me laugh! Don't forget VIA too!
If it was bulgarian train, it will never arrive. Because it's always broken.
If it was Indian, there would be a station inside the tunnel
If it was Pakistani, the passengers would fall off when they hit the tunnel.
If it was Molvanîan, the train would derail at the same time the tunnel collapsed when the train was five miles away from the tunnel.
Moving near the speed of light with that mass.....I don't think the train will give a shit about the door being shut
what do you think would happen to the door? would it vaporize into elementary particles? or would the train pass through it without damaging it?
If you think about the energy from the train versus the energy from the door, the train could pass through it because it has the higher energy (E=mc^2). Idk if I'm correct but that is what I think.
Alex Martinson f=ma
Vaeza yes finally someone gets it
With that energy some particle can very easily quantum tunnel to the other side, no?
Speed of light in this video is so slow that I fall asleep several times.
you are making me laugh now
san2goog GDF
+tommy cane115 You have a better theory. Do tell.
tommy cane115
Musim will now claim that einstien converted to islam for his marriage to cousin!!!
+tommy cane115 Einstines theories are fundamental to our understanding of the universe and therefore our full potential. Unfortunately mankinds potential is mostly being used to destroy itself.
He unlocked pandoras box because he was not as cynical as he should have been about mankinds paranoi and corruption. Same for doctors who do stem-cell research to cure sick babies, naive to the fact that they will bring about the breeding out of everything human about humans.
The history of technological advances amongst us neanderthals is everything gets weaponised. Nuclear power, Social media, Life itself.
It's not the scientists fault it's the warmongers. It's Trump, Putin, May, Bush x2, Blair, Thatcher and all their 'Sponsors'
09:34 RIP Sarah
We’ll miss you xx
We can conclude that Sara is cute and Adam is dead in this experiment.
Milorad Menjic 😀🤣😄😁
Sara needs her own Hentai channel
Sara may be cute, but she's a real bitch. You have NO idea!
Hence proved
I do not think Adam will agree, I think he will be disintegrated into subatomic particles at that sudden stop in the tunnel.
Ahhh! NOW I understand what Einstein was saying: Don't get on a train with Adam.
Never has a thought experiment made relativity seem so complicated.
Special relativity *is* this complicated and weird, you really can't simplify it down further than this. Watch any undergraduate introduction to special relativity and you'll see that.
Peter D Morrison Helped me ubderstand it alot, I was confused about this, you have to understand what someone who has no clue how this paradox plays out knows and what they don't know.
Peter D Morrison That's because it is complicated. This video just doesn't oversimplify it.
Actually Special Relativity is only mathematics. It has nothing to do with reality. vixra.org/abs/1703.0169
Eric Su - moron.
This is a wonderful video. I learnt things about S. Relativity I never knew were there to learn.
Just a question - does elasticity behave differently at higher speeds? Surely, in the last scenario Adam sees the train bend like molten puddy while Sarah sees it fall with a plot as one rigid piece. Since there cannot be distortion in the direction perpendicular to the line of motion, what is the resolution of this paradox?
I think there is acceleration in vertical direction so we should apply general relativity ,you can think space in the train has been bended ,so there is no elasticity in the train
I think Adam will feel the distortion.. due to gravity pulling and bending the train through the missing slab of bridge.
And the distortion will be restored once moments of falling of train is completed. Restoration will begin from the front portion of the train.
I can be wrong.
I have contacted a number of train authorities and it seems that none of them are willing to participate in any of these dangerous experiments. I guess we will never know for sure what really happens to the train. I have observed a number of autos on the freeway travelling at near light speed and I have to tell you it is really bizarre. They didn't appear any shorter or longer, mostly just a blurry streak. When the police travel at light speed I notice the sound of the siren takes about 10 seconds to catch up to the blue lights. Really weird.
These doors are awesome piece of engineering if they can accelerate from rest to close to the speed of light to react to the train in time.
+j7ndominica0 So is the train.
j7ndominica0 maybe the train and tunnel are long enough?
j7ndominica0 I'd like to experience time in Sarahs hole, while going at the neg. speed of light. I can only imagine!
@Munky Bidness well obviously Maxwell's Demon is operating the massless doors in a vacuum! :)
j7ndominica0 You are now getting into details out of the scope of this video!
It will be very difficult to show what is really going on, SINCE the relative motion of the camera that show us what is going on, will ALSO create relativistic artifacts!
It all becomes a trippy visual mess when you ask what is exactly going on!
That's why I would love some special relativity 3D simulator program to be created by someone so we can visualise all that in more detail! But sadly there is nothing yet... Someone needs to make one!
EDIT: oh wow, I found this ruclips.net/video/qol-zP9W5J4/видео.html
I was 100% correct on the trippy visual mess XD Special Relativity really is a hell of a trip!
So instead of saying “I like trains“, I can say “I like man seperate rectangles that are tied together through flexible connections“.
you like men? Dunno, seems pretty gay to me
@@robertr7923 From your perspective and thats how you see him.
7:49 Truly a sad moment. Seeing a young man with a great future ahead get trapped in an unbreakable tunnel by a malicious entity (It may be Sarah, it may be God, it may be Eugene K.).
Poor Adam, at the end he was only trying to commute as fast as possible.
what bothers me is how on earth can Sarah see a train moving at the speed of light?
It’s “close to the speed of light”
Your mistake was thinking she was human
@@DanMoldovan which perfectly explains it?
@@MaksKCS "Explains" is also relative. Explain calculus to a newborn. Sometimes you need to up your knowledge base before you can understand. Things can only be dumbed down so much before you need to smarten up.
@@Chance57 🤓
Aww, you didn't put in the REALLY interesting part. What if in the closing-doors scenario, you had TWO trains going opposite directions? Sarah would see both doors closing at once, while the passengers aboard the trains would see the doors closing one after another. But the passengers on each train would disagree about which door closed first, demonstrating that in special relativity, even the DIRECTION of time is relative!
Ya, swot! Here's a paper plane in your earhole!
awesome! I would love to see that visualised somewhere!
Time has no direction. Point me to the direction of time! This theory is an unproven bullshit hypothesis.
Why does the second door closes before the first from Adam's perspective? I can't understand this part. Just to make the fact of the train getting trapped into the tunnel possible from both perspectives? I mean, what's the physical meaning of it according to the theory of special relativity? And how is it that both things are just as valid, I mean, how is it that in a frame reference both close at the same time, and in another one closes before the other, and both are equally correct? If the doors are programmed to close exactly at the same time, then isn't that the actual reality? Really they are closing at the same time cause that's how it was programmed to happen by an exact mechanism, so what someone sees from some frame is actually an optical illusion that doesn't match the factual reality that both of the doors are closing at the same exact time?
@@OP-lk4tw There isn't really any way to easily explain it. But in short, the doors are programmed to close at the same time from the tunnel's reference frame, but NOT from the train's. If someone on the train could see the electrons in the circuitry telling the doors to close, the mechanism altered by lorentz contraction would cause a time delay between the doors.
I hope that I can help those who are still confused, because I was until I realized that what is important is the measurements of the two objects that are made when both objects are at rest to one another.
When both frames are at rest with respect to each other, the train is the same size as the tunnel (and the hole in the final example). THIS is what dictates what Sarah and Adam must see. In order for both of them to see the predicted effects of the rest-lengths, simultaneity HAS to go out the window, causing these weird resolutions to occur.
It is clear, then, that neither Sarah not Adams measurements are "preferred." Rather, it is the measurements made when the entire system is at rest that dictates the outcome.
Hope that helps.
Did adam get to see sarahs tunnel? 😜
And naturaly someone fell into the gutter. I really should put some bars on it at some point...
+jeremy: I sure hope so...she was sure sporting a nice pair of breasts at the beginning of the vid....
but I can assure you, that had it been me instead of Adam, Sarah's tunnel would have definitely experienced more than just a few fully elastic collisions with an inelastic, solid member...
The Joy of Sex- Scientists edition........
tommy cane115 yet there are GPS which comes from that relativity.
I don't care if he cheated on his cousin or not. but I'm not happy that mileva didn't got the credit on relativity. we use light to send information too. that's how relativity works, next time you check ur maps, think about this.
tommy cane115 oh my god, I start to feel you are more of a social justice thinker rather than a scientist and logic thinker. If you think that those theories is only coincide with gps, so the person who invent the gps, will try to test joke-technology to see if it's work?
And if he didn't deserve credit from the gps, so why mileva his wife deserve credit from relativity?
the counter theories is just not fully proven yet, honestly I'm trying to prove him wrong too,
Kira Vincent does a wonderful job narrating these videos. She has such a pleasant, clear voice. Thank you Kira.
It depends on your perspective..... It's all relative, from my perspective I will never understand.......
Because this is bullshit.
@@MrGodofcar unless you have evidence to support it, I suggest you drop this claim.
@@creativenametxt2960 ruclips.net/video/6zWy6_Mog70/видео.html
@@MrGodofcar pretty sure this does not classify as a reliable source, rather as a conspiracy channel.
Example: There was an argument that the right triangles don't remain right triangles when traveling at high speeds, which is, like, predicted by the theory and causes no problems whatsoever.
@@creativenametxt2960 Pretty sure this is not a conspiracy channel, just alternative scientific theories. The Big Bang, gravity only-governed universe theory of mainstream physics cannot explain several anomalies, such as Martian blueberries or the mineral Trydimite on Mars, some "impossible" stars, faster-than-expected outer arms of galaxies without inventing the ad-hoc theory called dark matter, [...]. And I've never seen an object that is a triangle and not a triangle at the same time.
I think I have fallen in love with Sarah.
I must say she's got some nice racks. ;D
I love you too, ben. Would you like to see more of my tunnel? Sarah
@@raposaraposa553 my incoming train will be too big for her tunnel. At least, in my frame of reference.
Step one: boots. 🤩
Step two: mini. 😍
Step three: go wreck a train. 🤪
This was the most fascinating short video I have ever watched. Thank you.
Glad you liked my video.
Thank you, thank you so much. I'm from Brazil and recently graduated in physics and this concept I couldn't understand. Your channel is helping me alot.
I am glad my videos are helpful. Thanks.
And yet, you graduated....please do not be an engineer!
how'd you graduate then
@@uncolorr you don't need to understand every single topic to graduate. I graduated physics without understanding how waves are formed by different kind of instruments, and special relativity. Sure I knew how to use the formulas, but I didn't understand it.
Kinda informative, I feel like I have more questions than previously now tho
The more you know. The more you know you dont know
You forgot to warn Adam that the track was under construction.
About the train crashing into the door of the tunnel part, since the train's perspective sees that the entire tunnel is contracted, instead of the train shrinking down to fit inside the tunnel, how about the train doesn't shrink but the tunnel expands back to its original size and the train fits perfectly in it?
It's rest size is bigger than the tunnle I belive.
From Sarah's point of view, the train expands. From Adam's point of view, the tunnel expands.
but in one case (Adam's case) the train is destroyed when the two tunnel doors close... but in Sarah's case, the train is still in tact.
so which is it?
when the doors of the tunnels reopen and we look inside, do we see a wrecked train or an in tact one?
I think that the train is not a solid rectangule is a forced explanation, as the Adam is slowing down from light speed, everything in his perspective will become gradually enlarged as in real life, therefore, as the train slows down the length of the tunnel becomes larger, train will fit inside without hitting
Its strange... For the first time in your (wonderful) videos, I didn't feel satisfied with the animated explanation. That last scenario just... doesn't close on me.
Because she failed to mention that the hole is actually larger than the length of the train, it just appears to be smaller from adam's perspective because he is approaching it.
That is because the last scenario is 110% bs.
In the last scenario, to let the train fall through the hole (in the speed of light), the gravity / force to pull the train down has to be extremely strong. Therefore, the train falls apart like this
Close to speed of light the train can easily bridge a gap the size of itself or even significantly bigger. It will keep its direction and proceed on the other side of the gap. Both agree that the train has not fallen through the hole
Yui
Oh and btw what if Adam saw the train cross the bridge, should not Sarrah saw that too? The gravity pulling train moving at near light speed through such tiny hole must be insane.
Adam and Sarah are experiencing more than the usual difficulties in maintaining a long distance relationship.
Not the least of which is the fact that when they're done, Sarah is now an old woman in a nursing home while Adam is only a day or so older than he was when they started...
Why is it that for Sarah, the two doors retain their size upon closing, but for Adam, they had to increase in height upon closing?
I would love to see you guys make a video on how fast traveling objects look like colorwise. Since it changes from violet to red as it passes you according to the theory of relativity. An animation of an object traveling though a 3D grid would look amazing from the perspective of the object.
Can anyone answer me:
Why does Adams view of events revert to Sara’s in order to solve to paradox?
In the second scenario
Adam see the train is longer
Sarah sees the train is shorter
The train crashes and the paradox resolves to Sarahs point of view where the train shrinks
Why doesn’t it resolve itself to adams?
In the third scenario.
Adam sees the hole is shorter than the train.
Sarah sees the train is shorter than the hole.
The train falls though the hole why? Why not the hole adjusting its length to allow the train to cross?
Both Sara's and Adam's accounts of events are completely self-consistent. Things never "revert" to one or another POV.
Sarah is the female, and they are always right.
Ill answer myself in case anyone else is asking this question. The outcome is based on what who happen if both pieces of the puzzle where at the same reference frame. To each actor the paradox resolves itself in different ways despite what the author stated.
In fact Adams and Sara's views can not be the same. if they would, this would violate logic ( whatever logic means ). The only solution to this, is that either Adam either Sara will continue to live in two different realities or "parallel universes" ( they already do, but those two parallel universes were quite similar until train approached the hole ). From the moment two universes "split", in Sara's universe Adam will fall through the hole and she will celebrate his funeral. In Adam's universe, Sara will die , being hit by the train. And Adam will celebrate her funeral. They will both continue to live in their respective universes.
@igor: What???
While the first example was amazing, I think the explanation could have been much much better. For example, it illustrates one of the fundamental assumptions of special relativity: all observers must agree that events occur. They will simply disagree about when and where those events occur. In this case, the opening and closing of the two gates are two events and hence both Adam and Sarah must agree that they happen. However, they need not agree on when those two events happen. This takes us to the difference between spacelike and timelike events. In Sarah's frame of reference, the opening/closing of the two gates happens simultaneously, meaning that the two events couldn't possibly be causally related and are thus spacelike. And for spacelike events, the order of the events doesn't matter. One of the events could occur before the other, or vice versa, or they could happen at the same time. However, if the two events were causally related (and so timelike), then the results would be very different. For example, if one of the doors closed first and then sent a signal to the other door to close as well, then both Adam and Sarah would have to agree about which door closed first. Now I guess you could ask why the train being inside the tunnel doesn't count as an event, forcing both Adam and Sarah to agree that it happened. And honestly, I don't know. What counts and doesn't count as an event?
_"What counts and doesn't count as an event?"_ - everything physical that happens at a defined location and time is called an event. So there are countless of events happening. The video just concentrates on those that are important for explaining the paradox.
@@renedekker9806though as wide object the entrance and outtage of both ends of train must be considered too, they are as important as in classical physics in my opinion to get rid of any doubts. The thing that catches me is the last one, also know as the bar and hole paradox. That and the second seem weird, though I don't know if there is a concrete experiment to find out what actually happens in this scenario.
It is not about what an observer sees with the eye but exclusively about events = (place, time) in different and calibrated reference frames.
7:10 This is a way how to say in a polite way that the train as well as Adam would be crushed.
Lol @ the paper airplane transition. wtf?
I also like the "temporary services" office
don't forget the armory
I'd be really great if you did a video about string theory.
+Moreg I confirm, and knowing that since the start of the channel every video followed a logical order, I expect videos to come after videos about relativity and thermodynamic, which should be soon :)
uhm the train at near light speed would fall a few atoms in the time it took to cross that gap and cross right over the gap.
It looks like from Adams point of view time is sped up. Therefore, Gravity would accelerate objects much faster in Adams POV then Sarah's.
From the perspective of the animator, these events would have taken place within a black hole. Otherwise the train would not have fallen in the gap; it would have shot into space!
The background music should have been from Soundgarden. 😎
Alexander Rookey no no no no
A train travelling at the speed of light would not be effected by gravity in the way indicated in this example....
This is so useful as analogy to explain, in terms relativistic, why the Quantum Eraser and even the Delayed Choice Quantum Eraser experiments produce the results that we, as "static" observers see: because for the photons all the process is happens simultaneously, in a perfectly synchronous "now" and perfectly compacted "here" (space-time is absolutely compressed at light speed). Cool.
Good video amazing
and the background music of moonlight sonata and ride of the Valkyries was awesome
moral of the story - if you think you can cross the hole in the bridge, you can't. the hole is much bigger.
As the train approaches the hole becomes bigger. Probably something this video missed is that Adam will see the hole expand and engulf the train. Even if on previous inspection it was much smaller.
@@emjay1606 i thought it'd contract?
@@emjay1606 no it won't. This theory is not a theory -- it's a hypothesis for it has never been proven.
@@MrGodofcar wtf the theory of special relativity has been scientifically proven u wouldnt have gps if it werent fr the theory
@@abhyudaychauhan2738 Space cannot bend or distort because it's not an object...
Not sure if anyone mentioned it but I have to clarify that the last example with the hole in the track is wrong, unfortunately.
In your explanation you started in Sarah's reference frame, assumed some physical truth (that the train will fall) and, then, you enforced the same truth in Adam's reference frame. But there is this strange sudden deformation thing happening with the train, right? I mean, what's the physical reason that Adam's train experiences a vertical force in its own reference frame that is strong enough to deform the whole train?
Therefore, let's instead do the opposite thing and start our reasoning in Adam's frame. What would we see? First, the train would just pass the hole in the track as the hole would become very short. If we now transformed to Sarah's frame, what would we get? Well, a short train floating over a too large gap without falling into it.
So, is there a physical explanation for the deformed train in Adam's reference frame as depicted in the video? No, there isn't as trains should not deform that much under their own weight in their own reference frame. But can we, instead, explain how the short train floats over the gap in Sarah's frame? In fact, this can be explained. The physical reason was already given in the middle of the video: Forces do not act faster than the speed of light. This means that the forces holding the train up floating in the air would result from an instant in time when the train still was in contact with the track.
I would like to see this animated in a corrected video. :-)
It is not "wrong." If the gap is several light years long, then it is clear that that the train will fall through the gap from Sarah's perspective. However, if Adam is travelling at close to the speed of light, then even this gap will appear to him to be shorter than his train. And hence we have the paradox that this is covered by the explanation in the video.
I disagree. Sarah will see the train float over the gap. I hope I can make the physics clear:
The front of the train will not fall into the gap as long as there is a small chunk of train connected to the track. This is because the forces emerging from the track are transported through the train material until they reach the front of the train. Now, consider the moment, when the train loses contact with the track. You assumed that the train will start falling down at that moment. However, you did not consider that, at relativistic speeds, *all* actions including forces act with a certain delay. This means, even if the train is no longer connected to the track, there are still, let's call it force waves, acting on the front of the train emerging from earlier moments in time when the train was still connected to the track. And the closer the train moves at the speed of light, the longer it takes for the force waves to propagate through the train. This means, Sarah could even see the train floating over a lightyear large gap with the front of the train still feeling forces coming from one year in the past, i.e. when the train was connected.
Even if this sounds strange at first sight, the observations described in the video are a lot stranger. The video says that Adam's train will get deformed in order to make it through the hole. But why should that happen at all? For Adam who is sitting in the train the train is just a regular train standing at rest. If there was any deformation coming from relativistic effects, it would mean that Adam can feel that he is moving at very high speeds. But as all reference frames are equivalent in relativistic physics feeling the own speed is never possible.
To make it short: The transformation displayed in the video is correct. Therefore, the history seems consistent between the two reference frames. However, the events theirselves are wrong. Start with Adam's train passing over the gap and transform to Sarah's frame. Then you get what's really happening.
Please recheck your physics. I really like videos of this kind, especially if they look professional as yours does. But then the physics they describe should be correct in order to prevent disinformation.
Cheers!
i must say, your explanation is how I thought it would work while watching
+Woyten When the train starts falling down light has travelled all across its length. It took the same amount of time for both observers, so the result is the same. You just changed one example with another different. In your example the train is a single piece. In the video the train is not a single piece.
+Luis Calderari. You're right. If you assume that the train is made of jelly or the gravitation is extraordinary strong, the situation would be as shown in the video. However, in educational videos like this, you usually make common-sense assumptions about physical properties. This means, trains are rigid. Not completely but rigid enough to carry their own weight. And gravity is moderate, maybe even equal to earth's gravity. If you want to explain the relativistic behavior of jelly on a neutron star, the picture of a train on an earth-like environment is just inappropriate as it only leads to confusion.
All I got from this video was the Ride of the Valkyries
You should've stuck around for the 1st movement of the Moonlight Sonata!
I guess they figured that the backup music for Einstein (German by birth) should be two other Germans.
Fred
I appreciate everyone trying to explain these complex concepts. Maybe a bit faster animation and speech will make it more attractive (in addition to Sarah’s mini-skirt)
"Adam does not see the gates closing at the same time."
Excuse me, but by what arbitrary and convenient (for Adam) bit of timing does Adam see particularly the _further_ gate close before the other, the nearer?
I presume the engineer put the timing mechanism in the middle and timed both gates to close simultaneously, certainly at least for Sarah's POV.
Sarah can help us out here. Let's assume c=1 m/s. She calculates photons bouncing off _both_ rising gates (which she can _see_ rising simultaneously) will reach Adam's retina some 10 seconds sooner from the _near_ gate than the far gate. She can objectively state, relativistics aside, that Adam will see the _near_ gate start to rise first.
She will therefore have every apprehension for Adam's mental state that according to Adam's and her shared knowledge of Lorentz contraction that poor Adam is going to both see and experience a slow-motion train wreck. She of course, will not flee the site of the danger because she knows the contracted train is in no danger from a certain destiny with fast-moving gates. But she empathically appreciates that Adam will (mistakenly) foresee his certain death, and in fact is taking out his (contracted) phone and is trying to reach his mother and father to tell them he loves them, and his gf can have his car and the dog. (But of course his phone frequency is doppler shifted and the cell tower cannot even communicate...)
Now, don't quote me on this, but i believe its because Adam is traveling at the speed of light and since photons bouncing off the wall nearest to him (since he's moving away from it) would not be able to catch up to him as quickly as the photons bouncing off the wall he is moving towards (furthest from him). That's why physicist say we could never travel at or over the speed of light because causality would be thrown out of the window.
"Now, don't quote me on this"
~Ryan Karl, October 2016
You have it mixed up. It's not Adam's distance from the gates that matters, it's the motion of the gates relative to the signal sent from the center of the tunnel. Remember, in Adam's reference frame he is sitting still, and the GATE is moving toward him. Thus, the far gate is racing toward the signal sent from the center of the tunnel and the near gate is racing away from it, requiring more time for the signal to reach the near gate.
Scabbage He ordered you not to, rebel!
tubeist- dan what about the light bouncing from the ending gate travelling towards and the light from the starting gate travelling with adam?
At rest is the train longer then the tunnel? if it is then you can not close each end of the tunnel no matter what right? The train does not physically change length, the light coming from the train just makes it appear different lengths. atleast that's what I thought Einstein meant.
The train at rest is longer than the tunnel, yet you can still close the doors when the train is moving inside it. The train does not just "appear" to be shorter when moving. Einstein's theory is more profound than that.
Physics Videos by Eugene Khutoryansky I am confused. If the train is at rest, then it is not moving at the speed of light. How is this reconciled?
It does really change length from the other one point of view
At rest, the train will come back to its original length.
So at V=light speed this makes sense, but as per the analogy the train goes to v=0mph. There must he something I'm not understanding about or unless the situation is a snapshot in time.
How about you speed up the explaining. The video could be 3 minutes long, not 11...
+MaDrung Yeah, I watched it at double speed and it was still sluggish.
+MaDrung its all relative my man. is your brain working too fast or is the presentation too slow ?
Freddy Krueger my brain works fast relative to yours
Interestingly, I stopped watching at 4 minutes in, because it was repeating itself.
It's a relativistic effect
I sent this to my friends Adam and Sarah.
Couple of points: In second demo that has to do with the reference frame consistently set to of the man on the train before collision, right? Sarah would see a train hit the wall and telescope outward from front to back to its proper length. Adam would see the tunnel expand forward as he came to a stop to its proper length.
(edit) - my bad. that first point is clarified in the video following second example. Sorry
The last one doesn't make sense to me. Doesn't Adam see a length-contracted hole as well?
Let's make the case that the train is of negligible height and the tracks are of negligible thickness so ANY downward displacement from the track can be defined as "falling through the hole." Or make gravity as big as needed so your trajectory is like dropping a lead balloon. This avoids any charlatan whipping out momentum conservation to muddy the waters.
Ok. So the faster you go the smaller the hole is. But the skinnier she sees the train. So the tendency is to make it MORE of a problem in her frame that the train falls (bigger hole relative to train) and LESS likely for him (smaller hole relative to train). In the case of the tunnel, the increasing lack of simultaneity of the closing doors compensates for this Lorentz contraction so everything is consistent. I can't understand what compensates for the length-contracted hole - humongous time delay on front and back of the train?
If I replace the hole with a big spotlight that encompasses the entire length-contracted size of the train and shines on it for a finite but sufficient time as it passes in Sara's frame, it completely engulfs the train in light during that time. But it is smushed as train passes in Adam's, so while the spotlight will shine on the ENTIRE train at once in Sarah's frame, the shining while being slowed down for a long time in Adam's, such that the front sees it long before the back, but the back WILL eventually see it as the train passes. this should be the logical equivalent of the hole case.
But the train, regarding the falling, is composed of infinitesimal slices of "velocity frames" as it falls, but however nonrigid that may be, that isn't like an elongated cylinder of fluid pouring down a hole as it passes over. Something isn't really right. Can someone shed light on this?
@Dr Deuteron thank you. I have 'grown up' a little since last year, in that special relativity in (linearly) accelerated frames opens a new can of worms and that the modifications show that the devil is in the details.
Interpreting things using the understanding of special relativity when the frames are inertial (which I was doing) leads to contradictions. the first example is the only one that allows for that.
there's a flaw. Sarah cannot see the train fall through the hole because the train is moving at near the speed of light, which is so fast that it will go from one end of the hole to the other end almost instantly and continuing on it's path. Same goes for Adam's perspective.
+Angel Angelov Also, I should get high af and THEN watch these videos! Hurray
+Angel Angelov, Not if the hole is big enough.
+Angel Angelov Consider the gravity is so intense it can pull the near-lightspeed train into a hole that small. It's a thought experiment, anything goes.
+Physics Videos by Eugene Khutoryansky Doesn't this actually depend on the speed of the train? If the train travels at near the speed of light, it will be able to "jump" over a huge hole due to inertia.
This video seems forced/unreal to me. The train is indeed not perfectly rigid, but it's still quite rigid. It will never bend over a tight curve so that it will fall through the hole. Why would it behave like that? What force makes it to be bend like it would be a flexible piece of paper? As far as I understand, the properties of steel (the material from which the train is made) will remain the same, even near the speed of light.
Razvan MIHAIU They won't in the way you think they do.
I really like how the animation makes it so easy to understand, anyone with me ? :D
+julius groenjes, I am glad to hear that my animation made it easy to understand. Thanks.
I am still a bit puzzled by the train on the bridge. If Sarah and Adam's points of view are both valid AND they have to correspond with each other, what decides if the train is long enough to cross the bridge? Sarah's "God" or Adam's "God"?
+Ronald de Rooij In this situation the hole is big enough for the train to fall through, if it were smaller then adam would be right
what decides? math. Lenght=Length at rest x square root (1-(velocity^2 /speed of light ^2)) each reference frame will observe a spacial contraction in the other. The faster the object you observe, the more it shrinks in its direction of motion. Both reference frames are equally valid and true. As for Einstein's special theories on relativity, objects share the same reference frame when neither is moving with respect to the other. when there is relative motion between them, each will have their own reference frame.
+Keith Reynolds But that would mean that Sarah sees the train fall and Adam makes it to the other side.
Ronald de Rooij Sorry but it does not, because time dilatation, T = Tr / sqr(1-v^2/c^2), also changes Adam's perception of the acceleration due to gravity. Hence why Adams train does't make it across the gap.
+Keith Reynolds Of course I believe you. I cannot doubt Einstein! So, I will have to try to understand the video again...
Great work ! But I didn't get why we considered the train as pieces of rectangles rather than a solid mass. If it were so, would it violate relativity.
In the 3rd scenario, for the train moving at the speed of light gravity would too weak to pull it down.
The hole isn't too scale.
I liked that, very interesting, my understanding of relativity improved, thanks Eugene Khutoryansky.
My physics professor just tried to show us this during class and I busted out laughing
What about the tunnel door's perspective? They must be moving near the speed of light to open and close as fast as the train going through it.
So what does the train look like from the door's perspective? Or the rest of the tunnel for that matter?
The hell I'm fookin tired with relativity, skipped the class
The observer on the train sees everything as normal.
Your videos are nice but there is one thing. In the last scenario where a part of the bridge is missing, suppose we first take Adam's point of view in account. Now Since Adam sees the missing bridge or the gap is very small, it won't fall. Now Sara must also see the train not falling. So in short the train will not fall if we take Adam's point of view and it will if we first take Sara's point of view, so isn't it wrong or confusing ?
@silverrahul Can you explain how ?
@silverrahul ok got it
What if the train is long enough for Adam to pass over the missing section without falling through, but from Sarah's perspective the length contraction has shortened the train enough that it falls through the missing section, how can they agree?
if the train passed the missing section then sarah won't be seeing the train falling because it didn't fall
To me, when something travels approximatly the speed of light. What we sees might shrink or stretch, but that does not translate the actual physical object shrinked or stretched. We sees the object shrink is because the light cannot travel faster than Light speed constant, physically the object does not shrink unless there is seriously heavy gravity working on it like the black hole.
CORRECT ME IF I AM WRONG... TQ...
collision near speed of light will cuase nuclear fusion...
Yeah but this is a theoretical studyl
@@aoe9015 more like theoretical bullshit
@@MrGodofcar the theory is weird and unintuitive, but experiment after experiment has shown it to be true.
@@jetison333 No experiments have shown it to be true.
@@MrGodofcar denial
As always, great videos. Thanks for going into the different scenarios. ..?.. If it is worthy of a video, may I ask for examples explaining where and how Einstein's equations break down in quantum mechanics and on up to large scales such as neutron stars and black holes? I'm sure you are plenty busy, so Its no biggie if you don't. its just that thru all I have studied in the last few years none of any sources have ever shown any work. Not that there are answers but examples of where unifying gravity and quantum mechanics doesn't work...is there a "Line in the sand" if you will?
+Andrew Karpinen The reason why no one shows the work is because the break between QM and GR is rooted pretty much completely in mathematics. And really difficult mathematics at that. I don't think there's much to visualize about it.
Wished I was your friend in real life Eugene, I would probably be a pesky friend but a grateful one if you unconditionally answered all my questions. Anyway... thank you for sharing thru the inter-web :)
Thanks!!!
To get the correct visual appearance you have to do special relativistic ray tracing, i.e. use light paths, not a calculation of a supposed length on a non observable spacelike interval . The language you used of what Sara "sees" is incorrect. No one sees the calculated "Lorentz contraction."
The problem is that Special Relativity has accepted Minkowski's space-time. I, on the other hand, continue to believe the Lorentz Transformations to be true.
I consider the two Lorentz transformations:
a) x_1 = gamma * (x - v * t)
b) x = gamma * (x_1 + v * t_1)
With gamma I obviously indicated the Lorentz factor, and I do not consider the other two Lorentz transformations because they depend on a) and b).
If two distances are in relative motion to each other at speed v, the distances overlap. In my opinion, if we denote with t the time spent in the frame of the tunnel and if we denote with t_1 the time spent in the frame of the train,
it is t = t_1. (and the distances overlap, no problem)
If x_1 = - x, then t = t_1 (and the two distances overlap because x_1 = - x, do not consider x = v * t and do not consider x_1 = - v * t_1)
The Pole and Barn Paradox is not a paradox! (The tunnel Paradox is not a paradox!)
Now consider a spaceship moving with uniform rectilinear motion at speed v in the frame of the Earth, in this case we know that x = v * t.
If x = v * t, then t_1 < t. (the spaceship's clock slows down relative to the Earth's clock)
If x = v * t, then x_1 = 0.
If x_1 = 0, then v * t = gamma * v * t_1, t_1 = t / gamma, t_1 < t.
The twin paradox is not a paradox!
Special Relativity is a paradox!
x = v * t, x_1 = - v * t_1 and x_1 = - x are mutually exclusive.
He can't refute this because he only parrots from his book.
Brian Greene, Neil DeGrass-Tyson, Jim Al-Khalili, Max Tegmark - great hosts of science documentaries and science conferences (all on RUclips) !
Walter Lewin - his lectures (all on RUclips) can make everybody love science !
Chris Bishop and Andrew Szydlo - their experiments in front of audience can make all children on this planet want to become scientists (again, see RUclips) !
Eugene Khutoryansky - I have watched lots of visual representations of natural laws and occurencies, but I have never seen a better way to present and explain (!) them than the way Eugene does it in his clips. All thumbs up and fingers crossed that he will keep up the good work !
And the voice of Kira Vincent is really the best choice for the clips - she speaks in a slow and very understandable manner, so that non-native speakers can hear clearly.
+Milen Cenov, thanks for that really great compliment. And yes, lots more videos are on their way.
+Milen Cenov I second that. As a non-native speaker, I would highlight the quality of both the animations and the voice narration. Keep up the good work guys !
Ps: Mind to share the song list ?
+Florent_ATo, thanks for the compliment on the video. All the music is from the free RUclips Audio Library, and the names of the songs are the following: Ride_of_the_Valkyries_by_Wagner, Renaissance_Castle, Moonlight_Sonata_by_Beethoven
I just love the weird off style of these videos. The terrible music and the weird animations are somehow perfect for learning this mysterious stuff.
This video is 5mins long but my friend thinks it is 11mins long? Whaaat?
It's your point of view
pett pette if you watch this video at 2x then its actually 5 minutes long.
8:50 _If we start the following reasoning not from Sarah, but from Adam, then logic will lead us to the opposite result:_
*From Adam’s point of view, the train is much longer than the section of the missing bridge, and will, therefore, cross the hole successfully. From Sarah’s point of view, the hole is much longer than the train. However, since Adam saw the train cross the hole, Sarah must also see the train cross the hole. This is possible if we keep in mind that the train can consist not only of many rectangles that are connected through flexible connections but can be a rigid object as well. Therefore, Sarah will see the whole train cross the hole as shown* _(a different movie)._ *In this way, Adam and Sarah will both agree that the train has crossed the hole without violating Einstein’s Theory of Relativity.*
Does this mean that these two scenarios where adam or sarah is right are equally likely? if we repeat the experiment several times with the same initial conditions (same speed and hole). Will the train pass the hole in 50% of experiments and fall into the hole in the other 50% of experiments. if no reference frame is preferred.
@@josip_giuseppe As I see, nobody can answer your question because of the ‘if.’ “What will happen IF…?” we can know only in case of having such an experience. So, let’s experiment as many times as you’d like, and then we may get an answer - that’s the only thing I can offer you trying to honestly answer your question.
i love how you refering to the speed of light by using the slowest train of all times
8:20 - Now let us consider how nice Sarah's legs are!
That is a nice pair of get-away sticks!
@@dartvader7335 get away?
The gown of sarah was short in toms view, bur long in mine
RIP Adam you will be missed
Adam will be alive and well for the next video.
8:22
Sarah: "A train! Let's stand in it's way and see what happens."
SPOILER ALERT: the train fell off the bridge from every perspective. R. I. P. Adam.
I didn't like how it's always Adam who dies. It's just unfair.
Just found this video at the right moment. Was struggling with the HW. Thanks,
Eugene!
Thanks.
I regret that I can't donate becoz I m only 16 years old. But pls make more video for visualisation of Relativity and quantum mechanics , your efforts are really appreciatiable.🙏🙏🙏🙏
Thanks. I understand that many of my viewers are students and don't have any money to donate. That is OK. I am simply glad that my videos are useful. You can always help by encouraging your classmates to subscribe to my channel, and sharing links to my videos. Thanks.
Your parents paid enough for the taxes to promote this nonsensical propaganda. These people rob you of more than any money can amount.
Ah. I dont get it.
After watching the whole video, - yes it can be ...............
After seeing comments here RIP my brain😣
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Thanks.
If the both are blind...what happened.?
@@ShyaMKumAr-bo1ji nothing will happen in absense of observer.
Just added portuguese-brazilian subtitles. Portugal's portuguese may differ a little bit, but yet, still understandable to the european side of the atlantic.
If adam, knew sarah belive he is short, he would jump out and show he is normal.
Good
Where Einstein erred was his thought that nothing else can go faster than light. He was wrong and that limited his possibilities. The fact is that we cannot calculate or apply theories based on something we cant measure, That is a huge flaw in theoretical science.
5:50 etc The slice analogy of the (contracted!) train body works only for pushing forces. It breaks down for pulling forces which would instead 'elongate' the train. Slicing up is not the way to illustrate length contraction. What's needed is detailing the force transmission information 'protocol' through the train body. A protocol with EM signals being sent to and fro, in other words, with the help of arrays of adjoined light clocks. And light clocks do length contract, in fact they are used to explain length contraction! So the body matter regulated by light clock signals will length contract with them.
So the train becomes liquid?
No, it just got affected by a huge acceleration.
Luis Calderari I mean the one with the rail gap part.
Your Waifu Sucks Not that it became liquid. The train has always been considered as a not perfectly rigid object. So that when the train is falling down, the acceleration that caused the trajectory you observed must be huge in both frames of reference since it was moving at very high speed. Therefore, the train gets deformed, even though from Sarah's point of view is hard to notice such thing.
Luis Calderari but when adam sees the train, will the train look like those blocks with gaps in the middle. I mean adam will still see it as a rigid material right?
+Rocksmith Pdl
No, they both agree that the train is not a rigid object. But in Sarah's frame of reference the train looks very short, so it's harder to notice the train is not rigid.
Skip the train- we want to see more of Sarah.
In a POV pron flick ;D
8:01 moonlight sonata
Excellent video illustrating the "pole in a barn" "paradox". Thank you for making it. Two points of interest:
1. The video clearly implies, but does not state directly, the Principle of Relativity: The laws of physics are the same for all observers. All observers will agree on the physical outcome of an event, even if they disagree on measured quantities like space and time (and velocity).
2. Did you notice what happened when the tunnel doors closed, as shown from Adam's point of view? They stretched in a strange way. This correctly reflects the fact that length contraction occurs only along the axis of motion and not along a perpendicular axis. Thus the "door/track" was shorter when it lay flat, parallel to the track than when it was folded up. Kudos to Dr. Khutoryansky for getting this subtlety right.
Thanks. The reason I didn't directly state the principle of Relativity is because I had already covered it in my main video on Relativity at ruclips.net/video/ev9zrt__lec/видео.html
Your videos are wonderful. Been a fan of your channel for years now
Thanks for the compliment.
Let's forget relativity; let's think about how hot Sarah is.
In my experience, trains ARE actually rigid objects.
Yeah let's tell these these theoretical physicists to stand in front of the train, let's see how those flexible tiles really work in the real world. xD
@@BillAnt That's not the point. Of course the train is "solid" in our common definition, but nothing is actually 100% solid, meaning impossible to deform.
Look at buildings like skyscrapers, for example: we can all agree that they are pretty solid, but when they are built one of the factors that has to be accounted is how much wind is going to bend the top.
The deformation of the train due to its speed is just too small to be measured, unless it's traveling at near lightspeed. And of course every person standing in front of it would just be obliterated in a fraction of a second regardless of deformation...
@stefano olivotto < Given the buildings example, I can see your point. Thanks.
@@BillAnt Thanks to you for not just insulting me as most of the people on the internet would have done at this point! That was really nice, for a change.
@stefano olivotto < No problem man... respect towards other goes a long way, whether you agree or not with their point of view. By the way anytime someone personally insults me, I never waste my time on them, simply press the report button next to the message, and let RUclips handle it. ;D
from sarahs point of view ...adam looks like a standing pancake...because he has skrunk
Questions for the bridge thought experiment
1. Why is the consequence of Sarah is any more prefferable than Adam?
2. If Sarah isnt there to observe, will Adam train pass the small hole on the bridge?
3. Why the slides model and its effect (each slide falling) only appear when the speed approaching C? Why our everyday experience dont see this ?
1. The consequences for one observer are not preferrable to any other observer.
2. If Sarah is not present to observe, the results will still be the same.
3. Relativistic effects are always present. It is just that they are so small that we don't notice them until the relative speeds are close to the speed of light.
@@EugeneKhutoryansky
Does this mean that these two scenarios where adam or sarah is right are equally likely? if we repeat the experiment several times with the same initial conditions (same speed and hole). Will the train pass the hole in 50% of experiments and fall into the hole in the other 50% of experiments. if no reference frame is preferred.
@@josip_giuseppe The Theory of Relativity is not probabilistic. If we repeat the same experiment, then in Relativity we will always get the same result. (This is different in Quantum Mechanics.) Also, Adam and Sarah must always agree on whether or not the train falls through the hole.
1. Does this mean that if the train indeed not moving and the earth indeed moving against the train at the speed close to C, the train will still fall into a hole that is much smaller than its size?
Also if take into consideration that the hole moving at close to C would make it even smaller?
Appreciate all your answers. Ive been watching for your vids since 10 years ago and still occasionally going to be make sense of knowledge more and more.
@@vuhoangbiz
A scenario where the train passes contracted(small) hole is impossible. Because Adam feels inertial forces while accelerating the train, but Sara does not. Therefore, both will agree that Adam is accelerating relative to Sarah. I watched a video about the twin paradox. If one twin in a rocket feels inertial forces as it turning back, but other twin from earth does not. They will agree that the one in the rocket is moving.
This is incredible and A true beauty of physics. ....Einstein a genius human being. ..
why always adam is sacraficed? poor guy.
Don't worry. Adam will be alive and well again for the next video. No pixels were harmed in the making of this video.
Physics Videos by Eugene Khutoryansky relieved...
弗航 sexism.
suppose Einstein did actual experiments and not thought experiments. maybe science wouldn't be in the predicament it is in these days.
what predicament are you talking about? countless experiments have been done validating relativity.
The lens of my glasses bend light also, yet, no one will say they have a gravitational influence. So does gravity actually bend light or is it the atmospheres of the bodies that refracts it.
Einstein was to cool for that, he had other people do his Experiments for him. And the Experiments support his conclusions, so what's the problem.... Oh right... The problem is people not taking the time to learn advanced physics concepts and instead insist that their junior high school understanding of physics is where physics Stops and that people that put the time and energy into science that Beethoven would put into music is just silly.
@@CeriusDeluge so, I see that you have no understanding of these concepts. Great. Of course no one would say that, that makes no sense. And you're still thinking of gravity as a force, instead of it being the shape of the space time continuum. It's not that gravity pulls on light. It's that things with mass change the shape of the spacetime continuum. The shape of spacetime is like the track of a roller coaster for light. It simply has nowhere else to go, because it's the shape of the surface it's traveling on.
If in case of train crossing a section of bridge missing..if the missing section is so small that ,train passes even it is moving faster from sara's point of view...but in adam's point of view train is considered as small pieces and these pieces will fell down ,because even it is a small hole it is a hole to provide a gap for segments of train to fall down.here both situations are not same..how can we explain this..
If the doors at the end permanently close the train must stop.
the last example would need to assume that they are under extreme acceleration due to gravity, something only possible near a singularity as far as I know. This is because the train is going forward near the speed of light, which means for every unit distance forward only an extremely tiny moment of time has occured. For the train to then be pulled through the hole and under the track in that same small moment of time it took for the train to move forward that small distance relative to the train's motion, extreme acceleration would be necessary. This would also cause spaghettification on the train, in the same way that being near a black hole's event horizon would, since it is not a rigid body.