🚀 go-pugleaf

In article <1992Nov8.174608.24504@CSD-NewsHost.Stanford.EDU> pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt) writes:
>With regard to bar length, assume you were carrying a variety of meter
>bars of different stable materials (I have no idea what materials are
>sufficiently stable for billions of years).  With regard to clock
>frequency, assume you were carrying a variety of atomic clocks based on
>hyperfine transitions of various elements.  And assume that the
>observed change was the same to within 10% of the change for all
>combinations of bars and clocks.
>
>Given these circumstances, which parameter would you prefer to say had
>changed, light speed, bar length, or clock frequency?  Or would you
>prefer to say that there was no basis for choosing among these?
>-- 
>Vaughan Pratt

I would call for further experiments to measure the speed of light in
terms of purely *nuclear* quantities (some strong interactions have already
crept in because the hyperfine transition involves the nuclear magnetic
moment).  My first hunch would be to say that the bar lengths and 
the clock frequencies all changed because of a change in the electromagnetic
coupling constant.  It's a matter of economy, really; if the speed of light
seems to have changed in exactly the same way with regard to all physical
processes, it seems absurd to say that all of the other physical constants
got twiddled in such a way as to produce this effect.  But if the speed of
light only seems different when you measure it with bulk matter dependent
on electromagnetic couplings, I would tend to implicate the coupling of
electromagnetic fields to matter, and I would start writing down theories
in which the charge on the electron is determined by a field...
-- 
Matt McIrvin