So, I have been watching a lot of videos on physics, and a few of them have eluded to the fact that light has momentum. For instance, minutephysics video "E=MC2" is incomplete states that the full equation to describe objects with momentum and mass is E^2= (mc^2)^2 + (pc)^2 and he also says "The energy of a massless particle is the same as it's momentum". What I don't understand is this: The equation for an objects momentum is P=(mv)/(sqrt(1-(v^2/c^2))) which is basically just p=mv but because of gamma you have to do that annoying thing in the denominator. But EITHER WAY when mass=0, momentum equals zero. And light is massless. So... I'm confused. Please help.