Re: satellite clock gravitometer

[John Denker <jsd@MONMOUTH.COM>]

At 02:33 PM 1/27/01 -0800, Bernard G. Cleyet & Nancy Ann Seese wrote:

>  An aeroplane is a "product?"

Sure.  Why not?

At 03:56 PM 1/27/01 -0800, Bernard G. Cleyet & Nancy Ann Seese wrote:

> Are there gravitometers other than mass oscillators (pendulum and spring)?

Yes;  see below for an existence proof.

> Does a satellite separate the effects? (Do compared clocks (time dilation)
> measure only that due to mass?)

The equivalence principle applies to satellites.

For starters, compare
  a) a clock at sea level at high latitudes, where it is relatively close
to the center of the earth, and
  b) a clock at sea level at the equator, where it is relatively far from
the center of the earth and where there is a lot of outward centrifugal
acceleration.

Do you think the clock rate of the two clocks is the same?  Or is there a
correction due to General Relativity?  This is very messy to calculate for
those who add up all the contributions;  meanwhile it is trivial for those
who decide that whatever is an equipotential for water is an equipotential
for clocks.

Note that for GPS satellites in orbit, the relativistic contributions are
very significant, necessary corrections.