In special relativity it is often claimed that light does not need a medium to propagate. In quantum field theory, particles (and thus also photons) are excitations of fields. The the position is not a dinamical variable as such anymore, but just a label for each of the field excitations in space. Does then QTF tell us that light, as quanta of EM waves, propagates indeed over a medium (the electromagnetic field permeating the whole space)? Thanks.