Re: Time dilation and expanding space
- From: "Robert Karl Stonjek" <stonjek@xxxxxxxxxxxxxx>
- Date: Wed, 28 Feb 2007 12:06:56 GMT
The term nuclear-resonance is used by Pound-Snider
to describe a Mossbauer shift with altitude.
Hi Sue,
I assume the paper to which you refer is the famous:-
"Effect of Gravity on Gamma Radiation
R. V. POUND and J. L. SNIDER
Laboratory of Physics, Harvard University, Cambridge, Massachusetts
(Received 26 May 1965)
Recoil-free resonant absorption of the 14.4-keV [gamma] ray in Fe^57 has
been employed to measure the effect of gravity over a 75-ft vertical path in
the Jefferson Laboratory, in an improved version of the experiment of Pound
and Rebka. A Co^57 source, initially 1.25 Ci, large-windowed proportional
counters, and an enriched
absorber foil 15 in. in diameter permitted a much increased counting rate.
The employment of temperatureregulated ovens for source and absorbers and a
redesigned monitor system to detect variations in waveform of the source
velocity effected a reduction in systematic uncertainties. The result found
was (0.9990±0.0076) times the value 4.905X 10^-15 of 2gh/c^2 predicted from
the principle of equivalence. The range given here is the statistical
standard deviation set by the number of counts involved. An estimated limit
of systematic error is 0.010."
They refer to 'time scales' and 'clocks' toward the end of their paper vis:-
"The possibility, a priori, of a discrepancy between the simple theory and
experiment in the domain between a few tenths and one percent does not
appear large. One aspect that may be worthy of mention is that g includes
the effect due to the earth's rotation amounting to a reduction from the
purely gravitational acceleration by about 0.3%. Agreement at that level
would then compound the effects of gravitation and of central acceleration.
These latter have, of course, been observed directly, in their own right, in
experiments with rotating systems.
The view that the local time scale depends on gravitational potential
appears to require a coherent source for confirmation. The present
experiment is unable to distinguish between frequency changes and velocity
changes, for example. It appears as if an experimental comparison of clocks
at different potentials would make
a useful complementary contribution to the over-all status of confirmation
of theory."
They also refer to the Mössbauer effect (page one of the paper, P 788 of the
journal)
I don't think using the term 'Time Dilation' is confusing too many people -
we mean that interval between the clicks of a clock dilate at the source of
red shift as measured by the observer whom also measures the red shift.
--
Kind Regards
Robert Karl Stonjek
.
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