What Is a Photon?

This is a continuation on previous posts on the concept of photon.  It was Einstein who in 1905 introduced the idea of a photon as a little packet of energy or light quanta of size $hf$ with $h$ Planck's constant and $f$ a frequency, to give a heuristic explanation the photoelectric effect. The idea was picked up by leading physicists elevating the photon to be an elementary particle of the Standard Model of particle physics as a gauge boson as force carrier of the electromagnetic force. 

But Einstein did not get along on that train and confessed in 1954 just before his death:

• All these fifty years of conscious brooding have brought me no nearer to the answer to the question, "What are light quanta?" Nowadays every Tom, Dick and Harry thinks he knows it, but he is mistaken.

So what is then a photon? What properties does it have? We read:

1. A photon is stable.
2. A photon has zero mass.
3. A photon has zero charge:
4. A photon mediates electromagnetic interaction.
5. A photon moves at the speed of light in vacuum. 
6. A photon has spin angular momentum $-h,0,+h$.
7. A photon has orbital momentum $0,1,2,3,...$.

We note that in Maxwell's wave equations describing all of electromagnetics including electromagnetic interaction, there is no role for photons. The properties 1- 5 are thus empty by Ockhams Razor and one may then ask what meaning 6 and 7 can have starting from emptiness. 

Here is a supposedly illuminating picture of photons as little wave packets  traveling SouthEast at the speed of light:

Do you get the idea? Do photons really exist? Does black body radiation consist of a shower of photons?

Check out What, exactly, is a photon or specifically a single photon:

• A photon is the click registered by a single-photon resolving detector.

We learn that a (single) photon is a click of a (single) photon detector, but understand that the click says more about the detector than about the photon, so we are left in mystery. 

An explanation of the photoelectric effect without photons is given on Computational Black Body Radiation.  There you also find the real physical phenomenon of resonance as mediator of electromagnetic interaction instead of unphysical photons.

PS Is there maybe a connection to this picture: