Questions of Light and Space (Introduction)

by Balance_Maintained , U.S.A., Saturday, October 09, 2010, 09:37 (5137 days ago)

Recently, after watching a documentary on Einstein, I was puzzled by what at first seemed to be a very basic question. So, I asked a physicist:-> QUESTION: 
>I was watching a documentary on Einstein, and contemplating his theory of relativity(and the recent debates on the speed of light being constant) and came up with a question, which while I am sure it is non-sense, still begs to be asked. Has/Can the speed of light in a vacuum, free of electromagnetic/gravitational anomalies ever been measured by two items that are truly at rest? This would seem, by its nature, to have to occur in space, with two items that are not moving with our solar system relative to the universe. It would also seem to need to occur between two man made items since all other objects in the universe are inherently in motion. Feel free to correct me if my assumptions on the requirement of the experiment are wrong. It would seem, though, that this would be the ultimate test of the speed of light being constant.
>
>ANSWER:
>Your whole idea does not hold water for one simple reason�there is no such thing as "truly at rest". (See earlier answer.) There is something called an inertial frame of reference where the laws of physics as we know them are true (things like Maxwell's equations, Newtonian mechanics, thermodynamics, etc.). Any other frame of reference which moves with constant velocity with respect to that one is also an inertial frame of reference, the laws of physics are exactly the same. There is therefore no experiment you can perform which distinguishes any of these as the "truly at rest" frame. The "ultimate test" of the constancy of the speed of light is that special relativity, for which that constancy is the cornerstone, works perfectly. Nobody feels any need to further test this; see FAQ page for more on why the speed of light must be the same to all observers.-
Now right off the bat, a couple of parts of his answer struck me as rather odd. ->There is therefore no experiment you can perform which distinguishes any of these as the "truly at rest" frame.-Working with applied geology and geophysics in surveying, there is something about this answer that just seems plain wrong. When you design a survey, you have to determine an origin. From that origin, you can extend your X,Y,Z axis as far as you like, in which ever direction you like. Without this origin, nothing makes sense mathematically. In a universe that is (supposedly) expanding, there would by necessity need to be a central point. This point could be in fact determined using standard surveying tricks coupled with physics. Basically, you would define the number of axis that you wished to use to make your coordinate system. For simplicities sake, I will use 3 for this discussion, the standard X,Y,Z. If you measure the time it takes for readings from the CMRB to reach a given point, then work backwards to a point where the time from CMRB X+,Y+,Z+ = X-,Y-,Z- you should have origin=X,Y,Z =0 which gives you a universal frame of reference. At that point, it no longer matters if the universe is or is not expanding, as any expansion would happen at the outer edges of your grid. -From this point, you would be able to determine a single 'resting' frame of reference by which to measure all other movement in the universe. By setting your test points static in reference to that point, you have created a true resting frame of reference in which you could perform the proposed experiment.->The "ultimate test" of the constancy of the speed of light is that special relativity, for which that constancy is the cornerstone, works perfectly. Nobody feels any need to further test this-The theory of GR and SR are still theory, not fact, and thus deserve to be tested. They do not work perfectly, as is more than exemplified by the satellite clocks, whose timing errors come from absolute velocity, not relativistic motion.