AJ Bentley said:
Gravitation is mass-related not charge-related. A photon of light carries no charge and has zero rest-mass although it does possesses energy which equates to mass.
It IS affected by gravitation - that's how the General Theory of Relativity came to be verified.
The trouble with light is that it isn't matter (whatever matter is!). It's ripples in space time itself. If you wonder how ripples in space time can be the same as a photon particle - join the club!
Since the universe is curved in on itself, so is the trajectory of light. the curvature is somehow caused by the presence of mass within the universe.
This is all standard stuff that must have been covered elsewhere in the forum.
I realize this is speculative, but since the notion of charge without mass was raised, I responded by
speculating about what massless energy is (i.e. light/em-radiation) and then considering how it could have a charge. Since it doesn't have a charge, I reflected on how the concept of charge could be interpreted in a broader sense. The conclusion I reached was that charge is the ability for distinct "nodes" (these could be particles, objects, points, etc.) to channel field-force between them unidirectionally. So, for example, electric current results from a negative "node" supplying free electrons in the direction of a positive "node," which lacks and therefore received them. Presumably, the cause is that systems are seeking balance (i.e. equilibrium).
How could matter be seen as the "positive node" of light where light-emission is the negative (i.e. sending) node? If gravity is indeed the definitive form-giver to the contours of spacetime, and light can only travel according to those contours, then could it not be said that spacetime is a conduit for light/energy? How does the positive node in an electric field/current get its positive charge? By lacking enough electrons to balance the positive charge of the protons, right? Similarly, how does a black hole shrink to a volume smaller than its schwartzchild radius? It collapses after expending its energy-generating potential, right? So couldn't you say, theoretically, that a black hole is like a positive node for light, since it attracts and receives it without re-emitting it?
If black holes are the positive-nodes/receptors of light, then could it also not be said that all non-black-hole forms of matter exert gravitation in such a way that produces resistance for light, in the same sense that electric current encounters resistance, slows down, and translates its energy into other forms? Here I'm lumping together various interactions/behaviors of light/energy vis-a-vis matter/gravitation such as absorption/re-emission, chemical effects. KE generation, and directional shifts. Generally, couldn't all deviations of light from its direct path to a black hole be viewed as stops along a particular conduit of spacetime?
I realize this is very theoretical and speculative, so please let me know if it should be reposted as a new thread. The issue raised about charge without mass was an interesting and provocative one and I'm just responding by thinking about the issue. This is not an attempt to hijack the thread in any sense.