[time-nuts] Detecting gravity with optical atomic clocks

[Anders Wallin]

on the subject of pendulum vs. optical:
please don't mix sensitivity to "g" directly with sensitivity to the
gravitational potential "g delta-h / c**2" that the optical clocks can now
measure.

changes in g seem to be at 1e-8 level according to [1].
the gravitational redshift is "g delta-h / c**2" or 1e-16 per meter of
height.
if optical clocks were really sensitive to "g" we would be in the same
(horrible) boat as the kibble-balance experimenters who need a map of "g"
in the lab before building the kibble balance and then need to re-measure
that map every now and then... . Instead what optical clock labs need is a
height measurement from the geoid to the experiment (where the cold atoms
are).

"accelerometer" (something that measures "g") is a poor word-choice IMO for
the latest optical clock results...

AW

[1] http://www.leapsecond.com/hsn2006/pendulum-tides-ch3.pdf


On 2018-12-01 06:17, Tom Van Baak wrote:
> >> Surely, this is nothing new?
> >> I thought standard pendulum clocks were quite good at detecting
> >> gravity as well!
>
>