when is a constant not a constant?

when is a constant not a constant?

Mu, the ratio of the mass of a proton to the mass of an electron, may have decreased by 0.002% over the last 12 billion years (to a confidence level of 99.7%).

There has also been speculation that the fine structure constant (alpha) has also changed, along with other fundamental constants such as c (speed of light) and G (the gravitational constant).

Now, one of the pillars of Einstein's theory of relativity is that fundamental properties of the universe, such as the above constants, are the same everywhere. This finding, along with theories such as Inflation (which would require a much higher value for c in the first moments of the universe's existence) suggests a possible route to a Theory of Everything, which would combine relativity and quantum mechanics. If the constants are not in fact constant, then this may be evidence for Superstring or M-theory.

Technorati Tags: Physics, Cosmology, Fundamental Constants