Hey folks. I was reading this odd explanation for why the bottom of a hanging Slinky appears to defy gravity when the top is released. As the comments note, there is a simpler explanation involving how the spring under tension reacts when it becomes a free-falling object. But the attempt at an informational explanation made me think of a question I'm not sure how to answer: Instead of a hanging slinky, consider a vertically hanging metal bar of infinite rigidity, length=l. It is released from the top at t=0. Does the bottom begin to move at t=0? I'm guessing it would not, because this would involve superluminal information transfer from the top to the bottom. If I am right, then the soonest it could move would be at t=l/c. But then the falling bar would be longitudinally compressed, which -- combined with its infinite rigidity -- seems to produce a paradox. Is this just the universe's way of saying that the finite speed of light forbids infinitely rigid bodies?