5 ms·
Might be totally wrong here - photons have no volume yet can exhibit mass. (I don't fully understand that particular one yet.. need to read more. Whether or not
by dedward 14y ago
Might be totally wrong here - photons have no volume yet can exhibit mass. (I don't fully understand that particular one yet.. need to read more. Whether or not photons have mass is a complex question it seems - or rather, multi-faceted)
- nilaykumar 14y agoPhotons can have momentum, which, when doing relativity, blends together with energy into the momentum 4-vector [http://en.wikipedia.org/wiki/Four-momentum http://en.wikipedia.org/wiki/Four-momentum]. Relativity also asserts that energy and mass are related [http://en.wikipedia.org/wiki/Energy%E2%80%93momentum_relation http://en.wikipedia.org/wiki/Energy%E2%80%93momentum_relatio...], so you can imagine how we could talk about the "mass" of anything with energy or momentum. Fun fact: One of the ways physicists are looking for Higgs is by looking for bumps in the "invariant mass" spectrum of LHC events with 2 photons!
- dedward 14y agoThanks - I'll read up. I've long interpreted E=mc^2 to mean not just that energy and mass are interchangeable, that energy and mass are one and the same. What I can't quite get my head around yet (just need to read up more) is how they figured out something about the rest mass of a photon - something about using superconducting rings or something like that. (Because photons aren't generally at rest, and they don't accelerate, right?)