Hal Murray wrote:
iov...@inwind.it said:
I was wondering, why we assume that Earth's rotation is slowing down,
instead that clocks are speeding up?
The quick answer is that there is a mechanism that explains why the Earth is
slowing down: tidal effects. There is no corresponding way to explain why
atomic clocks are speeding up.
How many different timekeeping mechanisms are there that are accurate enough
to notice changes in the Earth's rotation?
Wikipedia says 2 ms/100 years and that it was noticed by Halley in 1695 and
confirmed by Dunthorne in 1749. I assume they were using the Earth's orbit
around the sun as their reference clock.
how exactly would that work? Are they measuring the number of "days" in
a "year"? How would one do that? See when the sun crosses in front of a
specific star (to get the "day") (or an equivalent measurement at night
of some sort)
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