Alan McDougall Posted July 9, 2012 Share Posted July 9, 2012 Can you poke something that’s far away with a stick faster than it would take light to get there? If you had a really long (about 500,000 km) stiff stick, say made up of the stuff of a neutron star would one be able to hypothetically send information faster than light by moving it quickly by 1 cm and poking someone on the other side by pushing a button instantaneously on the other side. I know! I know! a silly question , but many uninformed people ask this question all the time, so let the forum put their confused minds to rest Alan Link to comment Share on other sites More sharing options...
swansont Posted July 9, 2012 Share Posted July 9, 2012 Not silly. The answer is no. There is no infinitely rigid material, even the stuff of neutron stars. The compression from the push would be limited to be below c; the electromagnetic interactions involved do not propagate any faster than that. Link to comment Share on other sites More sharing options...
Cap'n Refsmmat Posted July 9, 2012 Share Posted July 9, 2012 The force of your push is transmitted through electromagnetic interactions between the atoms in the stick, and the interactions only travel at the speed of light. Realistically I think the push would travel at the speed of sound through the material, since the speed of sound is by definition the speed at which a push like that would be transmitted. Think about pushing on the end of a spring. It takes a moment for the push to propagate through the spring, since the compression wave has to travel through it. A stick is just an incredibly stiff spring. 2 Link to comment Share on other sites More sharing options...
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