Hello everyone, this is my first thread :) It all started from the perfectly rigid rod connected from earth to the moon and how fast the signal would get there if I pushed it. I understand the signal can't get there instantaneously because the inner structure of the atoms of the rod has a propagating limit. But what happens if I push a rod (can be a regular sized one) with an energy high enough to give the first atoms in one end of the rod a speed greater then the propagating speed in the rod? My answer would be: the rod would want to deform itself, or the energy would be converted to heat / radiation. But I'm not quite sure of any of these... What do you think?