When I think of the speed of light, I imagine something moving really fast. Everyone knows that something moving fast hurts more than something moving slow. So why is something said to have "infinite" mass when traveling at the speed of light if the speed of light is a finite "measurable" speed? Why is this even considered "impossible"? If E = mc(squared) then doesn't it simply make energy proportianal to mass "since the speed of light doesn't change for the equation". Or does the E stand for "potential energy". Does anyone else relate to how I feel about this? Can't you just as justifiably take the speed of a train, write it down, and use that as an absolute? "which would produce a representation of energy that is only practical for use in a relitive sense, and cannot be applied as a number on it's own"