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Replies: 4   Last Post: Aug 1, 2013 4:56 PM

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Dr J R Stockton

Posts: 10
Registered: 4/28/13
Posted: Aug 1, 2013 4:56 PM
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In sci.math message <
>, Tue, 30 Jul 2013 16:16:34, Earle Jones <>

>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.

(c) John Stockton, near London. Mail ?.?
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