system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can something (ie. light) have volume and energy, but no mass?

I've watched multiple YouTube videos and read a couple things online and now I have a headache. It still doesn't make sense to me.
If photons have volume, then there can only be a finite number of photons in a given space, right? And once that limit is reached, why can't I squeeze in one more photon? What is stopping me, the "walls" or "shell" of the photons? What are the walls/shells made of?

Every source I've looked at agrees that light is BOTH a wave AND a particle. I can understand why waves don't have mass, but then what the hell is a "particle"? Every other elementary particle like quarks have mass, right?
gpt
>If photons have volume, then there can only be a finite number of photons in a given space, right?

That's wrong, actually. Photons are a type of particle called a boson, and two (or more) bosons can occupy the same space.

The counterpart to a boson is a fermion. Fermions obey the Pauli exclusion principle, meaning they cannot occupy the same space or energy state.