[geeks] Re: Watch prescision

[Gavin Hubbard]

<<We were discussing all the subtleties of calibrating atomic clocks
for altitude and such, and I asked if they adjusted for latitude,
based on the fact the objects closer to the equator should be
experiencing subtle relatavistic effects due to the rotation of
the Earth.

This led to a two month argument about whether or not the periphery
of a rotating object "counts" as movement from the frame of reference
of the axis, in relativity.

(We eventually concluded that it does.)

But it's apparently too subtle an effect for the atomic-clock
crowd to care about. Since they account for *EVERYTHING* it
must be damned subtle! :-)
>>

I know this is tangental...but in my last year of school we watched a documentary for a physics lesson. I don't remember all of it, but one of the interesting things the documentary makers did was to synchronise two atomic clocks in the UK then load one onto an aircraft so it could be flown to the USA. 

When they got to the USA it was clear that the two clocks were slightly out of sync (by an extraordinarily small amount). The disparity was in agreement with the predictions of the general theory of relativity. Although obviously contrived, this seemed to be a fairly straightforward example of an observable relativitic effect (time dilation).

Regards,

Gavin