There's a question I've come across that often sparks some debate, and I feel I'm in a position to give some clarification.
The question in hand pertains to the cosmic speed limit - that of light. As I'm sure most (if not all) of you know that no object can travel faster than light, which has an astounding speed of 300000000 metres per second. That's pretty fast.
It is also accepted that information cannot travel faster than light. Let's say a coin is tossed, and if it lands on heads a red light will immediately activate, or green for tails. Since information cannot travel faster than light, there is absolutely the no way an observer at any distance could know the result of the coin toss before the light emitted reached them.
The question is this - Two people are at a great distance from each other, holding a long rod between them. If someone at one end pushes the rod, will the other person feel the push before any light could have traveled between the two?
At first, the answer seems to be yes. For instance, let's imagine the distance is a lightyear (the distance light will travel exactly 1 year). It appears illogical that it could possibly take the recipient one year to feel the push.
However, information CANNOT travel faster than light. When the rod is pushed, the entire object does not move at once. Instead, a pressure wave is formed at one end of the rod which travels through the entire object. Imagine a slinky. Holding it horizontally, should you push one end quickly while keeping the other end still, you would see a wave travel from one end to the other. This is what is happening in our rod. You don't seen this on an everyday level, for objects like pencils and rulers this takes place in under nanoseconds.
The wave in the rod will travel slower than the speed of light, and Physicists can sleep easy knowing that the laws of relativity remain intact.