Meant to add to previous post: In physics, the graviton is "hypothetical" whereas the photon is real (as best we can understand 'real') but both elementary particle serve a similar function. The graviton mediates the force of gravity in the framework of quantum field theory and if it exists, the graviton must be massless like the photon (because the gravitational force has unlimited range) and must have a spin of 2 (because gravity is a second-rank tensor field) whereas the photon has spin of one.
Could this spin difference relate to a slight difference in what can be called propagation speed? i.e. in a star collapse, does the gravity wave move faster than the corresponding light wave due solely to its spin and possibly to the aether effects of spin ? It is tempting to call spin-2 "greater" than spin-1, or perhaps a "double axis" spin, but both of those descriptions are an inaccurate verbalization of what quantum spin implies. So I am told. Yet, spin-2 is "different" for sure and that could relate to a way that the graviton interacts with (or passes through with less interaction) an extra-dimensional "aether" so that it is not retarded in the same way that the photon is slightly retarded by the aether ... ... as opposed to by any imaginary level of interstellar "dust".
