[time-nuts] UTC and leap seconds
iovane at inwind.it
iovane at inwind.it
Fri Jun 11 16:11:03 UTC 2010
> tvb at LeapSecond.com 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
>> 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
>> 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?
To some extent, yes. I was wrong using the word "rate" in my text above. If we
remove that word, then there is no need for clocks.
"When the sun rose 100 years ago the stars looked like this. Today when the
sun rises, the stars are in slightly different positions. "
there should be a possibility of noticing a variation (not its rate) simply
looking at the sun and distant stars.
>> (Speculative hint: We accept that the universe is expanding. Might this
>> 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
>> 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...
I think the answer is in your previous post, that is the year is more stable
than the day as compared to the same clock.
And this measurement very likely has been actually made.
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