I read on a post that photons have 0 rest mass. This made me wonder if this meant (and this could be ludicrous) that any propulsion applied to them, no matter how small, would accelerate them to c meaning that all photons would either be at c or at rest (if even that is possible).
Also an entirely different question that I didn't think was worth creating another whole topic for; Is there such a thing as a unit of space so small that it could be said to be an "elementary" unit of space? I guess you could define this as nothing other than a boson could fit more than one of itself into it. I do wonder if the defining an elementary unit of space nullifys the question.
To give context of where the thought rose, I was reading the "boson" page on Wikipedia and it mentioned that multiple bosons could occupy the same "quantum state" and I didn't really understand the definition of quantum state.