[ntp:questions] Re: Extracted fom comp.risks - What Time Is It?

Dale Worley worley at dragon.ariadne.com
Mon Aug 18 19:40:37 UTC 2003


"David Schwartz" <davids at webmaster.com> writes:
> I don't believe anyone corrects for gravitational effects. Time dilation
> definitely requires compensation when you have to fly an atomic clock from a
> standards lab to your radiotelescope observatory.

The clocks in the GPS satellites are (I've read) corrected for the
gravitational red shift.  But I would expect that for clocks on the
surface of the Earth, the gravitational red shift effects would be
negligible.

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/gratim.html says
that the dilation factor is 1 + g h / c^2.  I get that the difference
is about 3.3E-13 for 10,000 feet vertical distance, or 3.3E-15 for 100
feet.  That would build up to 100 ns within some days, if I've done
the calculation right.

Dale



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