In sci.math message <earle.jones-0C430F.firstname.lastname@example.org >, Tue, 30 Jul 2013 16:16:34, Earle Jones <email@example.com> posted:
> >The permittivity and permeability of a vacuum are well known. These are >constants. Therefore c (speed of light in a vacuum) is a constant. >
Incorrect. The speed of light, in metres per second, is constant by definition, and it is that definition which determines the length of a metre, the duration of a second being already exactly defined already.
The speed of light is 299 792 458 metres per second. The permeability of vacuum is, by definition, 4 pi 10^-7 henries per metre. The permittivity of vacuum is therefore, from the formula given earlier, 8.854 187 817 ... 10^-12 farads per metre.
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