Ok, I was walking around today thinking about this…
A photon is a tangible thing – extraordinarily small, but it does exist. Light moves very fast – nearly the speed of light, minus a little for the medium it’s traveling through. Momentum is mass * velocity. If a photon exists, it must have mass otherwise it’d just be a concept not an actual thing. So, very small mass * very high veolcity = some momentum / kinetic energy. Now, when we see things it’s because light (photons) gets reflected off of them. Darker things reflect less because they absorb some light. Does this mean that a dark body is constantly gaining mass?
Is the earth constantly gaining mass? I suppose not, because hydrogen atoms do escape to space and their mass is huge compared to a photon, plus we raiate some heat off, which is light in the infra red portion of the spectrum which is just less energetic photons.
I wonder how many photons you’d have to hit something with before noticing the effect of M1*V1 = M2*V2 (conservation of momentum).
Think about that for a while.
Photons do not have mass.
– Mitch
I stand corrected…
I made the mistake of assuming that since they have momentum (which they do) they have mass, which is contrary to the normal way of thinking about it, not true.
Apparently there is more to than p=m*v to the equation for momentum. Who knew.