# [time-nuts] FW: Pendulums & Atomic Clocks & Gravity

Dr Bruce Griffiths bruce.griffiths at xtra.co.nz
Wed May 30 19:33:02 EDT 2007

```Bill Beam wrote:
>>> Assume satellite in circular orbit.  (Not really necessary.)
>>> Assume test mass's released at rest wrt satellite center of mass.
>>> Inner test mass released closer to Earth and outer released farther
>>>
>> >from Earth.  Also assume no air currents, no relativity, no luminiferous
>>
>>> ether, no static, no s- -t.
>>>
>
>
>>> It helps if this problem is solved in a proper (Earth based) inertial frame
>>> and to consider the total energy (kinetic plus potential) of the test masses.
>>>
>>>
>> But there are no strictly inertial frames based on the Earth.
>> The earth rotates around its axis (neglecting precession, nutation etc),
>> it also orbits the sun which in turn ...
>> An actual test of these predictions would be somewhat expensive to carry
>> out.
>> The damping due to the air in the shuttle or ISS (as well as a host of
>> other small effects) would tend to damp out such motion.
>> The question is how quickly?
>>
>
> This contradicts the last assumption stated above.
>
Yes, but if one wishes to experimentally test the predictions it is not
always practical to use an SV with an internal vacuum.
The question is really could this be done on the ISS or shuttle or would
the effects of the internal atmosphere disturb/damp the motion too quickly?
In other words what would actually happen to 2 such test masses within
the space shuttle, for example?
The other question is how large would the interior of the SV have to be
to avoid the test masses colliding with internal surfaces?

The other point that in practice the frames in which virtually all
measurements are made are non inertial.
Sure one can correct the results to an Inertial frame if one can
find/identify one that is inertial to a sufficient approximation.
However this is an elusive target which keeps shifting around as the
precision of measurement increases.
General relativity surely indicates that the concept of an Inertial
frame has a strictly local existence/validity?
> Bill Beam
> NL7F
>

```