Re: The Impossibility of Measuring the Velocity of Light

In sci.physics, Uncle Al
<UncleAl0@xxxxxxxxxxxxx>
wrote
on Fri, 29 Apr 2005 10:31:55 -0700
<42726F8B.1FF1D866@xxxxxxxxxxxxx>:
> Traveler wrote:
>>
>> In article <4272590C.A30935FC@xxxxxxxxxxxxx>, Uncle Al
>> <UncleAl0@xxxxxxxxxxxxx> wrote:
>>
>> >Weiv wrote:
>> >>
>> >> The Impossibility of Measuring the Velocity of Light
>> >[snip lines of ignorant crap]
>> >
>> >Hey fuckwad, c = 299,792,458 m/s EXACTLY.
>>
>> The problem is, you ***-sucking sack of ***, is that measuring c is
>> like using a ruler to measure itself. Whether or not the ruler expands
>> or shrinks makes not difference: it's always the same result. Why?
>> Because c is an inherent part of the mechanism used by our measuring
>> instruments. Don't you dare deny this, fuckface.
> [snip crap]
>
> Lightspeed is a defined constant. No measurement.
>
> DING!!! Savain DING!!!
>

It should be noted here that the prior definition of the
meter (using wavelengths of Kr-86) had an error of about
4 * 10^-9, which turned out not to be accurate enough.

Perhaps Savain can explain the logic behind the
scientists' rather interesting decision sometime
in 1983 to just say "the heck with it" and define
the meter to be exactly the distance traveled in
1/299,792,458th of a second (said second itself being
defined to be 9,192,631,770 complete oscillations
of a certain Cs-133 state transition)? Obviously,
they had to have a reason...

However, just to be slightly pedantic, there can
be measurement involved -- if only to count off the
oscillations of that cesium atom and to establish the
length of the meter. But one needn't do that measurement
just to get lightspeed, nowadays.

(For the record, 9192631770/299792458 = 656616555/21413747.
Darn those inconvenient units. When can we use
kilonils? :-) )

--
#191, ewill3@xxxxxxxxxxxxx
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