[time-nuts] UTC and leap seconds

Tom Van Baak tvb at LeapSecond.com
Fri Jun 11 15:37:56 UTC 2010

> Beside the general theoretical considerations as of what answer is more 
> acceptable (sincerely I agree so far)  and  what method could be used to solve 
> the matter, can anybody out there point me please to any article on actual 
> measurements of the variation rate of the earth's rotational speed, not based 
> on clocks?


Consider that you need at least two clocks before you can
make a rate measurement. One is the DUT; the other the
REF. So it is not possible to measure the earth (DUT) without
using some other clock (REF). Make sense?

> (Speculative hint: We accept that the universe is expanding. Might this affect 
> the fine structure of matter, including cesium atoms? Is there any adverse 
> proof? What is easier to think? a) the expansion of the universe doesn't affect 
> at all the properties of matter. b) it might.).

There is no small amount of effort being put into this question.
The results are not usually given as yes/no, zero or non-zero.
Instead they just calmly establish a new lower bound on what
the drift rate might be.

Whether the answer is (a) or (b) doesn't change the fact that
the earth day is a poor clock compared with other clocks now
available. Besides tidal friction effects which might be hard to
imagine, or lunar effects which you already know about, note
that every time it rains or glaciers form and melt it changes the
angular momentum of the poor spinning planet. Then again,
many OCXO are also affected by humidity...


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