I wrote: I get the impression that relativity fits the known facts to within a very > small error, and that any thought experiments concerning corner cases that > are far removed from everyday experience nonetheless remain internally > consistent. >
I should add one qualification. Mainstream physics describes a universe that is currently expanding rapidly, one in which some galaxies are receding from us faster than the speed of light. This is what Wikipedia says [1]: The expansion of the universe causes distant galaxies to recede from us > faster than the speed of light, if comoving distance and cosmological time > are used to calculate the speeds of these galaxies. However, in general > relativity, velocity is a local notion, so velocity calculated using > comoving coordinates does not have any simple relation to velocity > calculated locally. This notion of "local" versus "comoving" coordinates, and a lack of any simple relation between them, to explain away an apparent faster-than-light violation of special relativity has the hallmarks of a fudge. I think physicists should be allowed to fudge things here and there when in order to keep the obvious stuff pinned down, so it's not a bad thing that has been done, necessarily. This example, however, it seems to me, does not highlight an apparent violation of special relativity that must be explained away (using a fudge about local versus comoving coordinates), but rather, it highlights an assumption that should be revisited about galaxies receding away from us faster than the speed of light. That would require a reassessment of the redshift. Eric [1] http://en.wikipedia.org/wiki/Faster-than-light#Universal_expansion
