# How the effect travel's? [duplicate]

Let us assume that we placed lot's of ball touching each other in a hollow cylindrical tube, now if we push one ball at the end the ball at the other end move's instantly. So how do the information from one side of the tube travel's to the other side of the tube instantly. and at what speed at it travel's. If it travels at the speed of light so if make a long tube of the length of about $3*10^8$m it would take 1 second to see the effect at the other end assuming that nothing will bend or compress all thing's are ideal? I have read other related question but it didn't contained what I actually wanted to know. So it is not a duplicate.

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## marked as duplicate by Qmechanic♦Mar 8 '13 at 21:51

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Possible duplicates: physics.stackexchange.com/q/2175/2451 and 13 links therein. – Qmechanic Mar 8 '13 at 21:53

## 1 Answer

A similar famous example of this, is to point with some laser ray from earth to moon, moving the laser with very small angle will make the spot on moon surface to move with extremely fast speed, much faster than light speed!

Note that the photons here will need some time to reach moon surface anyway, so transferring information between Earth and moon, or between two points on the moon (through earth) will not violet relativity at all.

Similarly to your example, the balls are actually a collection of atoms, which are "glued" together with electromagnetic forces, and any two balls of them are actually not touching each other, there is some tiny space between them determined by the electromagnetic forces that arise between atoms of the neighbor balls (this is friction), and electromagnetic waves (the impulse that happens when you pushing the balls, is actually those waves) still moves at speed of light, so the pushing signal will be transmitted from one ball to another at speed of light anyway, not instantaneously!

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