Imagine that in the future we had the technology to create a pole that could reach from the Earth to the Moon. I can't think of any reason why future man would build this completely pointless pole, other than to poke people with it.
Building the pole itself would be a pretty impressive feat considering the Moon is 384,000km away from Earth.
But what would happen if someone on Earth pushed the pole to poke someone. Would the person on the Moon feel the pole move towards them instantaneously?
Its very easy to visualise this scenario. The pole is a solid object, the effect of being pushed should be felt straight away?
The short answer is no. Thats because it takes a noticeable amount time to transmit information over large distances. The Moon is 1.28 light seconds away, so it would take 1.28 seconds to transmit a signal to the Moon at the speed of light, which is the universal speed limit. It's no different for a solid object either.
But what happens to the pole when it's being pushed?
Push one end of the pole and the information is passed atom to atom. The pole would act like a spring sending a compression wave pushing atoms one by one towards the unsuspecting poke victim. One atom is pushed, it moves, then the next atom and so and so forth.
In all it would take about 18 seconds for the person to receive the poke, by then they may have moved scuppering your poke.
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