Everything in our universe is made up of waves. Does it really matter whether it's an oscillation in one field or another? Photons are discrete systems, can you clearly differentiate why anything else in the universe is "physical"?
How so? My understand is that a photon is a discrete packet of energy. Why can't I count those? If there is an excitation in the electromagnetic field, and then there is not, and then there is one - why are those not separate, countable photons?