1. If photons have no mass does that mean that they can't bend space? That their trajectory is affected by other objects' mass but that they don't affect other objects' trajectories in return?
2. Does the coherence length of a laser beam give a measure of the spatial extent of the individual photons of that beam?
3. Acceleration is supposed to be equivalent to being in a gravity field. Accelerated charges give off electromagnetic radiation. Does that mean that charges in two heavy objects in space will give off radiation just because they are in each others gravity fields? Will the two heavy objects give off gravity waves even if they are just sitting there pressed together by gravity?
Posted by fugu13 (Member # 2859) on :
1. Photons have no rest mass. However, they are always moving, so they have mass.
2. Well, I'd guess the answer is yes and no. A photon doesn't exactly have a spatial extent, it has a probability cloud. Coherence likely is relatively correlated with probability cloud extent, but I could easily be wrong.
3. Good Question Posted by handle (Member # 8509) on :
fugu is a bright man.
1. So if an extended laser beam in free space were intense enough it would self-focus due to its own gravity?
2. Yeah, say field quantum unit or something instead of photon because photon sounds two partically.
3. Good link. Didn't achieve clarity but now I know I am not alone on the question.