User talk:Brews ohare/Speed of light (Example)

Brews just for the record may I point out that your proposed method of measuring the "actual" distance in terms of the wavelength of some atomic transition has exactly the same dependence on the speed of light as measuring it in transit time of light. Your definition defines the meter as:

(some numerical constant)*c/h*(the energy difference between two atomic levels)

While time of flight definition of the meter can be expressed as:

c*s = c*(some numerical constant)/h*(the energy difference between two other atomic levels)

If by some form of magic the 'real' value of c would change, then both definitions of the length would change equally. Now, you will probably respond by saying, then we take a definition that does not depend c, but that might not actually as easy as you might think. (not trying to assume what you think) In the end any definition of the meter by relating to something physical will amount to:

(some function of various dimensionless constants)*(the planck length)

Since the planck length relates to the planck time by

(planck length) = c*(planck time)

the definition will always depend linearly on c. (TimothyRias (talk) 10:33, 4 September 2009 (UTC))