Re: Speed of Light

[roger haar <haar@soliton.physics.arizona.edu>]

Hi

	Yes, the uncertainity is now in the length of the meter, BUT
if my memory is correct before the change, most of the uncertainty in c 
was from the relatively weak standard for the length of the meter.  By 
having a good time standard and defining c, the standard for the meter 
was improved.  The other reason for the change was that many other
fundamental constants depended on the value of c.  each time someone 
changed the standard for the meter or measure c better, a lot of 
other constants changed.  With a defined c, this major source of 
variation is gone.


Thanks
roger haaar U of AZ

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On Mon, 18 Nov 1996, Rauber, Joel Phys wrote:

> Of course the speed of light is now know to infinite precision, as the meter 
> is now defined as a certain fraction of the distance that light travels in a 
> second.  Namely
> 10^ (-299792458) of a second. This was adopted in 1983.  "I interpret this 
> as basically pushing all the uncertainty in c, into the uncertainty that 
>  there already is iin a meter"
>
> Joel