system
Given the following post, respond as if you're commenting on Reddit:
human
When talking about photons, what does "wavelength" actually mean?

When I think of waves, I'm accustomed to thinking of s-waves and p-waves, but it occurs to me that neither of these make any sense in regards to photons that are supposed to travel in a perfectly straight line with a constant speed. Individual photons don't have fluctuations of energy that I know of, either. So where does the idea of a "wavelength" fit in?
gpt
s- and p-waves in quantum mechanics refer to the orbital angular momentum (s means ℓ = 0 and p means ℓ = 1).

Photons can certainly carry orbital angular momentum, but that's not what wavelength is.

For *any* particle, the relationship between its wavelength and its *linear* momentum is:

λ = h/p, where h is Planck's constant.

For a particle with no mass, like a photon, E = pc.

So λ = hc/E. The wavelength is inversely proportional to the energy.