(May 7, 2013 at 9:10 am)Chuck Wrote: Current thinking is particles are effected by gravity if they interact with the messenger particle of gravity, called gravitons, similar to how the other three elementary forces - the electromagnetic, the nuclear weak, and nuclear strong forces - excerts their effects through their respective messenger particles.
I think it is important to highlight the fact that the "graviton" has not been observed empirically; it only exists in mathematical form, and could ultimately prove to be untestable. Some theoretical physicists believe that adding the graviton, a hypothetical elementary particle, to the Standard Model of particle physics and certain quantum field theories would help particle physicists to make more sense of they have observed empirically with other elementary particles. In essence, the ultimate goal is to unify general relativity and quantum field theory.