Thursday, May 24, 2018

special relativity - Is it possible for information to be transmitted faster than light by using a rigid pole?


Is it possible for information (like 1 and 0s) to be transmitted faster than light?


For instance, take a rigid pole of several AU in length. Now say you have a person on each end, and one of them starts pulling and pushing on his/her end.


The person on the opposite end should receive the pushes and pulls instantaneously as no particle is making the full journey.



Would this actually work?



Answer



The answer is no. The pole would bend/wobble and the effect at the other end would still be delayed.


The reason is that the force which binds the atoms of the pole together - the Electro-Magnetic force - needs to be transmitted from one end of the pole to the other. The transmitter of the EM-force is light, and thus the signal cannot travel faster than the speed of light; instead the pole will bend, because the close end will have moved, and the far end will not yet have received intelligence of the move.


EDIT: A simpler reason.
In order to move the whole pole, you need to move every atom of the pole.
You might like to think of atoms as next door neighbours If one of them decides to move, he sends out a messenger to all his closest neighbours telling them he is moving. Then they all decide to move as well, so they each send out messengers to to their closest neighbours to let them know they are moving; and so it continues, until the message to move has travelled all the way to the end. No atom will move until he has received the message to do so, and the message won't travel any faster than all the messengers can run; and the messengers can't run faster than the speed of light.


/B2S


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