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Okay so according to my high-school knowledge I know about inertia and momentum. Now I have a question regarding the photon which my teachers say that is to be learnt in higher classes(and thus not answering my question so).
So the question is, why does a photon have momentum and no mass? I mean $p=mv$, right? If $m=0$ then it shouldn't have any momentum. Considering it to be a 0-dimensional the answer could be yes, it could have momentum without mass but if I had to add more to the question, I would say, what if you've got like a million-billion photons which stacked together very closely and moving as a single thing, then it would have a volume and thus, according to Newton, anything with a volume has a mass. Now photons is energy, you may say, but then there is the mass-energy equivalence, i.e., $E=mc^2$.
I know it's a sort of a childish but a question.