[time-nuts] UTC and leap seconds

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri Jun 11 20:09:47 UTC 2010

Tom Van Baak wrote:
>> 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?
> Antonio,
> 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. 

Surely you mean that it changes the moment of inertia of the planet???

> Then again,
> many OCXO are also affected by humidity...
> /tvb

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