[time-nuts] Measuring speed of light or reproducing a metre

[Jim Lux]

On 6/24/13 5:21 AM, Brian Alsop wrote:
> The time issue was effectively eliminated by the Michaelson-Morley
> interferometer.  One used a monochromatic light and an array of mirrors
> which split the light in opposite directions around the track.  The two
> beams were recombined and an interference pattern resulted.  One counted
> the number interference fringes passing by  while moving one mirror in
> one path.
>
> Knowing the number of fringes, wavelength of light and the mirror
> movement, one could compute c.

There are easier ways to measure wavelength of an EM wave (Young's 
double slit experiment, for instance), or measuring the voltage along a 
transmission line carrying a reflected wave.

BUT, then, an interferometer (or melted marshmallows in the microwave 
oven) tells you the wavelength of the EM radiation.  But you need to 
know the frequency of that signal in order to calculate c from that 
measurement.

and we're back to the "what can be done simply to measure time/frequency"

(I guess.. it's all really arbitrary.. a meter is so many wavelengths of 
the light from a Krypton lamp)




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