Let me preface this question by saying that it might be silly because I might have the facts wrong, but I'll ask anyway. If a photon is a "little packet/bundle of energy", the photon (energy) should contain some mass, even if it is tiny, since Einstein stated mass and energy are interchangeable. Now when this mass is accelerated toward the speed of light it needs energy to "push" it to a higher speed. When the photon starts getting closer to the speed of light, the energy that it takes to get it there starts to cause the particle to gain mass until it reaches a point where the energy it takes to overcome light speed would be infinite. My question is that if the photon has so much energy how come when a photon hits a human it doesn't "knock him/her out cold"? Like I said this may be a stupid question. I think I am just missing something really easy that I should know, so feel free to rip my statement apart and add any new info I am missing.