Photons as fundamental particles Is there any theory, current or debunked, that considers the photon to be a non elementary particle?  That is to say, is the photon just the photon or is there possibly more to the photon than just the photon? In theory, of course.
I would like to make a tuxedo for my cat out of photons.
 A: In all the theories for which we have experimental verification the photon is a fundamental particle. However it's a different type of particle to the electrons that quarks that make up the matter around us, so you can't make a tuxedo from it.
Particles are divided into fermions and bosons. Matter (e.g. tuxedos) is made up from fermions, while bosons create the forces that hold the matter together. The key thing about fermions is that their number is conserved. At low energies if you start with one electron you finish with one electron so the number of electrons you have doesn't change. At higher energies you can create electron-positron pairs, but a positron counts as -1 electrons so the total number of electrons (add up all the electrons and subtracting the positrons) stays constant. At even higher energies you have to use a more general rule that the number of leptons is conserved.
By contrast the number of bosons is not conserved. Photons can be created and destroyed willy-nilly (though obviously conservation of energy still applies). For example your body is continually creating and emitting photons due to black body radiation, and likewise it's continually absorbing and destroying photons from the world around you.
This makes bosons a poor choice for making tuxedos.
A: One serious proposed theory that is now not widely held to be correct ("debunked") is the neutrino theory of light, wherein the photon was postulated to be a neutrino/anti-neutrino pair. This was taken seriously in the 1930s by people like Max Born and Ralph Kronig. See the Neutrino Theory of Light Wikipedia Page.
One reason for beliefs along these lines is the high likeness between Maxwell's equations (which describe the first quantised propagation of the lone photon) and the Dirac equation for a massless particle. They can be written to be identical (although the spinors fields that define the wavefunction are of different rank). At the time the neutrino was thought to be massless, and so was assumed to propagate by a Dirac equation with a zero mass term. The Dirac equation for the electron written in a particular way: we write the equations for the so-called Weyl spinors, which are a kind of circular polarisation for the electron:
$$\begin{array}{lcl}\partial\!\!\!/ \psi_L &=& -m\,\psi_R\\\partial\!\!\!/ \psi_R &=& +m\,\psi_L\end{array}$$
Maxwell's equations written in the same form are:
$$\begin{array}{lcl}\partial\!\!\!/ \psi_L &=& 0\\\partial\!\!\!/ \psi_R &=& 0\end{array}$$
which are the same as the Dirac equation for zero mass.
A: You can consider the photon as being a quantum mixture of the "more fundamental" V-photon and the neutral W to produce the photon and the Z instead.


*

*Electroweak

*mixing
Keeping with standard model, particles are not fundimental at all — fields are.  And elecromagnetism isn't a primary field, but arises out of the more abstract B and W fields which represent underlying symmetries of nature.
In string/M-theory (a workmin progress) all particles are strings, and that's more fundimental than just saying that the same photon is 1-dimentional rather than a point.  Rather, the same string can be different particles depending on its state.
If space and time are not fundimental either, then stings vibrating in spacetime won't be, either.
Speculative thinking has produced various preon models where the particles we know are made of smaller things.
Of course if our universe is a simulation than particles are rows in a database table.
But really, though,  things are real only in that they are useful abstrations for prediction.  Photons are a handy encapsulation that make the rules come out nice, but so are phonons (quasi-particles) which are not real in the same way.  So what is fundimental and what is ezplained in terms of the fundimental depends on our choice of factoring up the rules.  Think of them as basis vectors in the space of physical law.
