system
Given the following post, respond as if you're commenting on Reddit:
human
What exactly "gives" a particle its mass?

In other words, what exactly does the electron have that a photon does not? Is there a fundamental particle that gives it mass?

And how can a photon have no mass, but still have momentum? I know it has something to do with relativity but I still can't visualize how a beam of light is able to bend around massive objects.

And finally, is energy/heat itself affected by gravity? I know this sounds stupid, but if a photon can bend around a star, why can't a free blast of heat in outer space do the same?
gpt
Congratulations. You just asked one of the hottest questions in particle physics today.

The smart money is on the Higgs mechanism. Massive bosons couple to a scalar field; massless bosons don't. (No idea what the rules are for fermions; a subject-matter expert will have to chime in there.)

Momentum is *related to* mass, but you can have momentum without mass no problem.

"Heat" isn't anything. Heat is a property of matter. And yes, matter is affected by gravity, obviously.