[time-nuts] Re: LTC

[Attila Kinali]

On Fri, 12 Apr 2024 12:09:26 -0700
Hal Murray <halmurray at sonic.net> wrote:

> Attila Kinali said:
> > I guess the "off by 58.7µs" is just someone incorrectly stating the
> > difference in relativistic shifts between a clock running on earth and on the
> > moon.
> 
> What do people on Earth do if they live in someplace like Denver that isn't at 
> sea level.

We do correct for gravitational redshift already.

Until recently, a simple using the simple geo-potential survey
we had, was enough. The gravitational redshift on earth is
approximately 1.1e-16/m. It hasn't been very long that the
uncertainties in the realization of the second got below 1e-15.
So, an uncertainty in the geopotential of a few meters was ok.

I know that in the last decade quite a few labs measured their
local gravitational potential. But I guess, with the upcoming
redefinition of the second, the proliferation of optical
clocks, and the progress we had in gravitational sensors
(quite a few of them coming out of SYRTE in Paris), there is
likely to be a new campaign to measure gravitational potentials
more accurately again, in the next decade.


			Attila Kinali
-- 
The driving force behind research is the question: "Why?"
There are things we don't understand and things we always 
wonder about. And that's why we do research.
		-- Kobayashi Makoto