Why would'nt this work?
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Sound is air vibration
Sound is not exclusive to air, it can be generalized to vibrations in any media. Whale song and dolphin echolocation are certainly sounds, and we're almost always talking about them propagating in water rather than air.
which has to travel from one place to the next
No, that isn't how sound works. In air this would be a description of wind, not sound.
just transfer kinetic energy to the adjacenct atom
This is actually a good description of how sound waves propagate.
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Perfectly rigid sticks don't exist.
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Because of relativistic effects, from your point of view on the train you would just walk forward. But you would notice a strange effect while the trains were accelerating: your atomically synchronized wristwatch has slowed down and stopped counting time. So it seems that your journey to the front of the train takes no time at all.
From someone standing on the side of the tracks catching a glimpse of you and the train as you whizz by, the front of the train is moving at light speed. You're at the back of the train completely frozen still, unable to move forward because the front of the train is moving away at light speed.
Weird things happen when you're talking about the limits of physical reality.
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your atomically synchronized wristwatch has slowed down and stopped counting time.
Wait, surely time would move at a normal speed within your own reference frame. The act of you walking to the front of the inner-most train you are in would be a normal occurence to you, but if you looked out of the window you would see a completely frozen scene.
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I would liken it to a long freight train starting to move. Once the front starts moving, it will still be a minute before the back starts moving. The space between the train couplings is like the spring effect between atoms, or something.
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Relativity would prevent this. If the train moves at the speed of light, then nothing inside it will move because time will stop. The amount of trains inside trains doesn't really change much except the effect of time dilation (slowdown) on each train. You can't actually accelerate to the speed of light.
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You are correct, I should have said there was an atomic clock out the window that the walker looked out at.
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There's no such thing as a perfectly rigid object.
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In a "perfectly rigid" stick (a fictional invention), the speed of sound is the speed of light.
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That's a great guess when you try to answer the problem with traditional (Newtonian) physics. However, space and time do not behave in a way we would expect when we go nearly at light speed. So Newtonian laws do not apply in the same sense anymore.
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There was, but now I'm getting older and more tired
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That's where time dilation will kick in
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Thank you for sharing--that was a really neat demonstration, and I enjoyed seeing all the troubleshooting as well. Will definitely be subscribing and checking out more of their videos!
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as a software engineer that watches too much youtube, this is the first time it’s clicked for me:
If the train moves at the speed of light, then nothing inside it will move because time will stop.
the pieces of information:
- time moves slower the faster you travel, and
- nothing can travel faster than the speed of light
have never been concretely connected in my head, but this makes a lot of sense now: time moves slower (for you) the faster you travel BECAUSE that’s the thing that stops you from moving faster than the speed of light… AND that holds true from all perspectives because it’s like… a trade-off?
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The idea that the velocity of a person walking forward on a train is simply the velocity of the train plus the velocity of the person walking with respect to the train is called “Galilean relativity”.
Einstein realized that Galilean relativity has a big problem if you take for granted the idea that the speed of light is the same for all observers, regardless of reference frame, and people had a lot of reasons at the time to suspect this to be true.
In particular, he imagined something like watching a train passing by him, but on board the train is a special clock which works by shooting a pulse of light at a mirror directly overhead which reflects back down and hits a sensor. Every time the light pulse hits the sensor. The clock ticks up by one and another light pulse is sent out. People usually call this the “light clock thought experiment” if you want to learn more about it.
Anyway, Einstein realized if he was watching the light clock as the train passed by him while he’s standing on the station, the path the light beam traces out will take the form of a zigzag. Meanwhile, for a person standing on the train, it will just be going straight up and down. If you know anything about triangles, you will realize that the zigzag path is longer than the straight up and down path. So if everyone observes the speed of light to be the same exact thing, it must be the case that it will take the light a longer amount of time to reverse the zigzag path. And so the person standing on the platform will see that clock ticking slower than the person on the train will. This phenomenon is called “time dilation”.
From this point, you can apply some simple trigonometry to figure out just how much slower things would be appearing to move on the train. And it turns out that the velocity the person watching the train observes the person walking on the train to have is not the velocity of the train plus the velocity of the person walking on the train. But rather, it’s something like that velocity, but divided by 1 + (train velocity)•(walking velocity)/c^2, where c is the speed of light (and this is called “Lorentzian relativity” if you want to read more about it).
It’s important to notice that since trains and walking come nowhere close to the speed of light, the value you’re adding to one is very small in these kinds of situations, and so what you’re left with is almost exactly the same thing you would get with Galilean relativity, which is why it still is useful and works. But when you want to consider the physics of objects that are moving much much faster. All of this is extremely important to take into account.
And lastly if you wanna read more about this stuff in general, this is all part of “the theory of special relativity” and there’s probably helpful YouTube videos covering every single thing that I’ve put in quotation marks.
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Have you spoken to your healthcare provider about Viagra^tm^? It may be able to help with your issue. (Please seek immediate medical help with an erection lasting more than 4 hours).
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Dang there goes my patent
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Think of it like this. If our universe is a simulation, then the speed of light is the maximum speed at which information can propagate through reality. We know that for anything to move through space, it must move from one adjoining position to another, then another, then another, incrementally. Each one of those increments takes, at minimum, one 'tick' of the universe. That's one tick to increment each bit of information, that is, the position of something moving at light speed from position x,y,z to x+1,y,z. Light moves as fast as the universe allows; if there was a faster speed, light would be doing it, but it turns out that our universe's clock speed only supports speeds of up to 299,792,458 meters per second.
What you have here is sound. Motion propagates through material, at its fastest, at the speed of sound in that material. That's part of the reason why moving large scale objects quickly gets weird.
