Re: NASA Gravity Probe B mission enters science phase, ready to test Einstein's theory (Forwarded)

From: Joseph Lazio (jlazio_at_adams.patriot.net)
Date: 09/16/04 

Date: 16 Sep 2004 17:46:31 -0400

>>>>> "JG" == Jim Greenfield <greenfield_7@hotmail.com> writes:

JG> If time passes differently under changed gravity, then time passes
JG> differently at the earth's center, than at the surface, (or a
JG> point above the surface). Hands up all those who think the
JG> earth's center takes a different amount of time to complete an
JG> orbit of the sun, than the surface???????????????

My hand is up.

As Steve Willner has pointed out already, gravitational fields do
affect the rate at which time passes. A hypothetical observer fixed
out in space over one of the Sun's poles will measure a different
number of seconds for the Earth to complete one orbit than would an
observer on the surface of the Earth. The reason is because the
observer on the Earth is in a larger gravitational potential than the
one out in space.

This is a well-known effect and has to be taken into account in order
that the GPS system works. 

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