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”?

592 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

The push would propagate along the rod at the speed of sound in that material. That speed is waaaay less than the speed of light. Why the speed of sound? Well, that is the speed that happens when the atoms push on other atoms which then push on other atoms and so on down the rod. For steel, that speed is about 6,000 meters/second. If you try to push faster than the speed of sound, the metal just bends.

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