I’ve been working on a simulation at work that includes, among other things, interplanetary travel. One of the things I frequently deal with is that things are not currently where they appear to be – due to the finite speed of light. However, orbital mechanics requires that the current position of the gravitational bodies be used – not the positions they will be in (or were in) when the light-travel time is considered. Another way of saying this is that gravity travels at infinite speed. But viewing it this way is flawed. The curvature of space time is linked to the body (mass or energy) as it moves. There is no separation between the action/motion of the body and the reaction of space time. They are essentially one and the same. So, the question I’d like to pose here is whether they are in fact the same. Is the fastest speed attainable by a body, the speed of light, actually limited by the fastest speed at which space time can change?
Extending this thought a bit, is inertial mass a manifestation of the ‘momentum’ of 4-D volume of space time? I’m thinking here (in 2-D space) of visualizing the motion of a body as a traveling ripple in the fabric of space time. Without a force acting on it, the ripple (and therefore the body) travel at constant speed and direction. There is no way to prove that mass exists without trying to exert a force on a body. There is no direct measurement of mass, only through the measurable forces created by a mass-determining apparatus. Such an apparatus invariably tries to push or pull on the body in order to determine its mass. The property of mass might not be intrinsic to the body, but rather to the curvature of space time the body’s existence creates. I’m not sure there is anything useful in thinking of things this way. It may, however, free one to think about the mechanisms by which matter and energy interact with space time. What role does the Higgs Boson play in all of this? How does the Higgs relate to the photon (or any other form of energy) having a mass? I guess I’m a little rusty on my General Relativity.