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I just had this idea one day and I decided upon a thought experiment to verify it. Imagine 2 people A & B sitting on two sides of a pipe which is stretched to a length of 3x10^8 m. The pipe is hollow and has a rectangular block on the inside. person A sends a radio message to person B which takes approximately 1s to cover the distance while person B pushes the rectangular block on the inside to tell A that he has received the message. Now a push on the block should show instantaneous results on the other side of the block which would move forward. While this movement is detected by A who gets the message that B has received his message. But while the message transferred by EM waves takes 1 second the other message transferred via the pipe takes no time at all. though this is hypothetical it violates the fact that speed of light is the fastest speed of anything in the universe as message is being sent faster than light. Is their a solution to this paradox or it is something that is no what it appears

Qmechanic
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Suhrid Mulay
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1 Answers1

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There is one proposition you assumed on your experiment that is driving you to a false conclusion: the hypotesis that the block, on the A side, would move forward instantaneously.

Every interaction in the universe occurs, ultimately, only locally. This is not always taken in account because the minimalistic point of view (that is, the point of view that ignores this fact) is, specially on classical theories, sufficient, but it's not in this case since it involves comparisons with relativistic velocities (that from the light itself).

In your experiment what happens is that the mechanical interaction (fundamentally eletromagnetic) take its time to travel across the block. Roughly speaking: the distance between the "planes" of molecules (perpendicular to the pipe) would stretch and come back to normal as the other side would return until the whole block was translated by certain distance, which the person in A would perceive. The outline being: it would take some time until the "I got your message" sign reached the other side.

The (refuted) hypothesis that interactions could occur at a distance without any propagator carrying the information between the point is what is what is sometimes called "spooky action at a distance", term that Einstein invented dealing with quantum entaglement (completely different thing).

Hope I've helped and I apologize for my English, not my native language.

GaloisFan
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