If I were to take a really really really (light years) long stick and push something on the end of it, would it happen “instantly”?

604 viewsOtherPlanetary Science

Obviously theoretical but if I took a light year long stick and say pushed a button at the other end would that button be pushed at the same time for me as say someone standing at the button? How does the frame of reference work when physically moving something? And could that “work” as a method of instant communication?

In: Planetary Science

34 Answers

Anonymous 0 Comments

No, because materials are not infinitely stiff. When you push the stick, you actually only push on the first layer of atoms in the stick. The atoms have to wiggle/move a little bit to propagate the push to the next layer of atoms etc…

This all takes a bit of time, so the speed is not infinite. Specifically, the push will propagate through the stick with the speed of sound.

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