On Sun, Aug 05, 2018 at 04:56:42AM -0400, Richard Aiken wrote:
> Of course, not that many real world scientists support VSL, but it appears
> to solve a lot of basic problems.

Such theories solve some minor concerns with models of the almost
unobservable early universe, while throwing out practically everything
else we already model in the current universe.

> [As I understand it, while the speed of light varies over time, the scale
> of time involved is so massive relative to the change in velocity that -
> for all practical purposes for us living people - the speed of light is
> effectively constant.]

All the theories I've seen so far have to explain why even small
variations aren't observed in modern times, since we do have rather
precise measurements with a wide variety of methodologies.  That
usually means radically redefining what is meant by "distance".

In short, they're the sort of theories that cause more problems than
they solve.  They aren't necessarily wrong, but they're mostly
complicated, ad-hoc matched to sketchy data, and there's no real
reason to believe them.  What's more in all of the theories of this
type proposed seriously by physicists, the constraints and symmetries
of relativity still hold for all practical purposes.

- Tim