I'm responding to #2. If spacetime curvature is imagined as lines of force, they do NOT curve around matter, but rather link directly to/from the center of each and every mass body in the universe (from quanta to planets and suns). The "curving" aspect comes from the interaction of all those...
"If you use a minimum of 4, in what dimension does spacetime "bend" due to gravity? (johnnyb42)
I'm not the pro, so I'll be more prosaic. First, spacetime does not bend due to gravity. Gravity IS the curvature ("shape") of spacetime.
You can kind of think of gravity/spacetime curvature...
So when you say, is the magnitude the direction, I think (?) an EM wave exists in all directions until it interacts. If so, I don't know if "direction" applies here?
The energy an EM wave carries is Planck's constant x the wave's frequency E=hf
So yes, the momentum derives from the energy of the wave. Momentum p =(hf)/c
or momentum = wave's energy divided by light speed.
I am no scientist, but do love physics. All I could find of magnitude is that...
Light is energy, and as E=mc2 says, energy and mass each carry a "punch"
Also, light has no mass, but does have momentum. Momentum for zero-mass particles relates to their energy, not mass. Energy of a massless particle equals Planck's constant x frequency.
Momentum of a massless particle...