Think about this for a second, think how truly odd this is

Einsteins special theory of relativity says that for every observer, the speed of light stays the same. The laws of physics is the same for any given observer.

so, imagine you take two torches turn them on, and point them in the opposite direction. Now if you sat on the the beam of light travelling one way looking back at the beam of light travelling the other way. What would you see? Ignore the fact we cant actually travel at the speed of light :). Well, light stays the same speed no matter what, since we have been travelling at the speed of light we would observe that the other beam has done nothing, moved no where. Yet, if we are the person holding the torches we see two beams stretching off into the distance both ways. Whys this? Time is relative. This is quite a heavy concept! Time changes depending on the speed we are going relative to other things! Mostly people just see time marching on in a pretty straighforward manner, yet its worth considering time is not constant! It took some smart thinking to let go of the notion that time is this constant distinct definable flow of everything.

And whats really interesting is if you looked back on your beam of light the only thing you'd see is that instant of the torch being turned on. Meaning for a beam of light time effectively stands still.