Light as an Electric Field A friend of mine insists that light must have an electric field medium through which it travels.  I told him that light creates its own electric field, but an additional 'medium' field is not necessary.  Which statement (if any) is correct?
 A: Light does not need a medium to propagate through, simply because electric and magnetic fields can permeate free space. 
The medium that you would be describing was historically known as the aether. It was constructed as a model to explain why the vacuum speed of light was constant. In 1887, the Michelson-Morley experiment falsified this model by using an interferometer to measure the speed of light with and against the direction of aether wind. The negative findings brought skepticism to the model and encouraged the development of the special theory of relativity.  
A: See light have both components the electric and magnetic field perpendicular to each other and the propagation direction is also perpendicular to both.No additional field is required for it to propagate.
A: In a specific sense, your friend is right that light needs a medium. The medium is called "space", and free space has various properties in electromagnetic theory which determine the behavior of light.
To say that light "creates it's own field" as you do, is not really true, because it conceives of light as an "object" surrounded by a field. On the contrary, light is the field.
The key thing to stay away from, is to interpret this space "medium" as in any way consisting of a mass of particles - as in an analogy with water or air. A particulate conception of the EM medium has been long-falsified by experiment. 
Some of the analogy with waves which travel in water or air are still perfectly valid analogies, but the conception of the medium itself as particulate is not valid.
