General Relativity IS an aether theory. The meaning of this claim is simple, the only way to resolve the problem of forces felt by rotation is to referance space-time as an aether that things move through. This is not the same aether as was thought of in the early 1900's whoose sole purpose was to mediate the propogation of light, but has a small differnace. It doesn't resist mass moving through it at constant velocity, but does resist matter moving through it at changing velocities. Newton argued that the only way to resolve the forces felt by rotation was to referance each object to an absolute space, but we know better today, and referance an absolute space-time (which can be expressed as absolute, ie. Lorentz invariant). Mach argued that the forces felt by rotating objects arises from all the matter that surrounds them. Rather than referancing matter to space, he referanced matter to matter. Since GR claims that there is no absolute rest, there is no absolute rest frame to referance an object's rotation relative to it, but there is such a thing as absolute space-time, and the use of this idea resolves the "forces felt by a rotating object" problem. To get even more in depth, space-time is affected by the presence of matter, and so there will be a configuration of matter that makes space-time rotate in some local area in the universe relative to some other local area. This forces us to claim that the "forces felt by a rotating object" problem is resolved by GR in a hybrid of Mach's and Newton's resolution, that only in a local neighborhood, space-time is absolute and can be referanced to determine the rotation of a body in that local space, but it is determined by the local effect of matter on that local space. Is this an acceptable argument? going further: SR states that light emitted by a moving body moves independantly of the object moving through space. It still looks like it's moving through space at c when measured from a moving body, but that's because the moving body is lorentz transformed relative to the absolute space-time which is determined by the local bodies in the area. We can tell something is moving relative to us because of the local matter around us, when you see a car drive by, it is moving relative to you, but more importantly, it feels accalarations when it changes velocity, not you. Therefore there is a local absolute space-time that you are in, determined by the majority of the matter around you, and things that accelerate linearly or rotate relative to that aether feel forces internally (as long as thier mass is miniscule relative to the local mass determining the configuration of local space-time). Photons move independantly of the speed of the car moving on a highway, they move at c through absolute space-time, and the car is lorentz transformed relative to local absolute space-time. So in this respect, we can go back to the early 1900's and say that light does travel through an aether, the local absolute space-time, which is determined by the majority of the local mass. In a way, gravity is the aether of light. It makes me wonder, if there is no local gravity (theoretically, no situation like this can exist in the universe), can light travel locally?