Invutil said:
Since an electron generated a negative charge around itself and can push other electrons around itself, waves can travel through electrons. These are electromagnetic waves. But quantum theory proposes that the pushes between electrons happen in discrete packets. Electromagnetic packets called photons. Are photons imaginary particles then?
Quantum theory is a tool that we use to very accurately predict what we are and are not likely to measure. To that end, we need "photons", and "electrons" to accurately predict measurement results of optical experiments.As far as the difference between photons and electromagnetic waves go:
Photons are what we use to describe electromagnetic waves at the quantum level.
To quantum mechanically describe an electromagnetic wave, we break up a wave as a sum of many basis waves, one for each frequency. The energy in each basis is some integer number (of [itex]\hbar \omega[/itex] up to a constant zero point) just as a consequence of solving Schrödinger's equation for the electromagnetic field.
We can use quantum optics (the quantum mechanics of light coming from these equations) to predict optical interactions at the atomic level. And an accurate description of these phenomena seems to require "photons", "electrons", and "atoms" for the time being.
In short, photons are no more or less real than electrons, as far as theory goes.
Experimentally, what counts as a single photon is a bit murky, but we can generate and detect single photons, which is good enough for me.