1) We draw the classic light wavetrain as a sine(x) function, but is it possible (even classically) for a 'single' wavetrain of light to exist. By 'single' I mean a varying electric/magnetic field occurring only along a one dimensional line in space. Or is there a fundamental reason why light must always exist as a wavefront over an extended region of space? 2) If it could exist, what would the electric field be on points just to either side of the line? zero? I normally think of electric fields being 'caused' by a charged particle. In this case the electric field reduces as you move away from the particle, in other words the particle is the source of a field that extends some distance away. For a light wave though, it would seem that the fields exist only 'along' the one dimensional line itself? Is this true? 3) In fact, for a single wavetrain (or photon of light), what is 'causing' the electric magnetic fields to vary exactly? Is it simply an unexplained physical phenomena on which we base other physics or is the existence of the varying electric/magnetic fields explainable in more fundamental terms. I imagine a magnetic field being produced by an accelerating charge. When we think of a 'single' light wave, do we imagine a more fundamental charged particle wiggling up and down somehow to produce the magnetic field?Does this have any relationship to quantum spin or not?