
Re: Metric Time (was Re: Why not 13 months? (Was La Systeme Metrique))
jrhodes@pupgg.princeton.edu
10 Oct 1995 17:23:56 GMT
In article <45e44t$laf@driene.student.utwente.nl>, otterw@utctu8.ct.utwente.nl (Wouter den Otter) writes:
>What do you mean, 'the meter is known to a very high precision'?
>It is DEFINED with a very high precision.
>
>Groetjes,
> Wouter.
I meant exactly what I said. The meter is DEFINED in terms of
two other constants the speed of light and the second. The
speed of light is defined exactly in meters per second. The
second is defined exactly as how long it takes a certain atom
(Cesium, I think) to make a certain number of oscillations.
Then, of course, any measurement we make of the speed of light in
vacuum will help us FIND a value for the meter. The value for a
meter is known to a very high precision, as I said. This is the
current convention (since 1983). For an explanation or
confirmation, pick up any introductory physics text published
since then. The metal bars kept in Paris and elsewhere are
relics of the past.
Jason
