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I Did Answer Him...

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Posted by Bruce on June 6, 2004 09:01:08 UTC

I told him to stuff it and find out for himself. Maybe you think I should prove Cahill's theory wrong? I'm pretty familar with the experimental tests for GR and how the theory predicts what has been measured. I know that the theory hasn't been falsified as Cahill claims. I also know that the rotation of spiral galaxies isn't the only experimental result which implies dark matter. I also know that folks who invoke 'absolute motion through the quantum foam' and the results of Dayton Miller's experiments to support the falsification of GR and to prop up their nonsense are full of Language Removed. Read these comments about Dayton Miller's experimental results and the stuff about bias.

"Miller, Rev. Mod. Phys. 5 (1933), p203.
This is a laborious repetition of the Michelson-Morley experiment (MMX), with observations taken over a
decade. He reports a net ether drift of about 10 km/s, and describes the variation in velocity and direction in
terms of the motions of the sun and the earth combined with a net ether drift.

This experiment was re-analyzed in: R.S. Shankland, S.W. McCuskey, F.C. Leone and G. Kuerti, "New
Analysis of the Interferometric Observations of Dayton C. Miller", Rev. Mod. Phys. 27 167-178 (1955). They
re-examined Miller's original data logs and explained his non-null result as partly due to statistical fluctuations
and partly due to local temperature conditions. Their re-analysis is consistent with a null result at all epochs
during a year. They gave no justification for any correlation with sidereal time such as Miller reported.

Miller's "signal" is actually composed of points that are an average of several hundred measurements each, and
the magnitude of the signal is more than 10 times smaller than the resolution with which the measurements
were recorded. See Experimenter's Bias below."

"Experimenter's Bias
Experimenter's bias is a phenomenon caused by the inability of human participants in an experiment to remain
completely objective, in which the human experimenter directly influences the experiment's outcome based upon his
or her personal desires or expectations. It is most commonly a concern in medical and sociological experiments, in
which "single-blind" and "double-blind" protocols are usually required. But some physical experiments in which a
human observer is required to round-off measurements can also be subject to it. In the experiments here the
conditions for this are basically the combination of a signal smaller than the actual measurement resolution and an
over-averaging of the data used to extract the "signal" from the measurements.

In principle, if a measurement has a resolution of R, then if the experimenter averages N independent measurements
the average will have a resolution of R/sqrt(N) (this is the central limit theorem of statistics). This is an important
experimental technique used to reduce the impact of randomness on an experiment's outcome. But note that this
requires that the measurements be statistically independent, and there are several reasons why that may not be true -- if
so then the average may not actually be a better measurement but may merely reflect the correlations among the
individual measurements and their non-independent nature.

The most common cause of non-independence is systematic errors (errors affecting all measurements equally, causing
the different measurements to be highly correlated, so the average is no better than any single measurement). But
another cause can be due to the inability of a human observer to round off measurements in a truly random manner. If
an experiment is searching for a sidereal variation of some measurement, and if the measurement is rounded-off by a
human who knows the sidereal time of the measurement, and if hundreds of measurements are averaged to extract a
"signal" which is smaller than the apparatus' actual resolution, then it should be clear that this "signal" can come from
the non-random round-off, and not from the apparatus itself. In such cases a single-blind experimental protocol is
required; if the human observer does not know the sidereal time of the measurements, then even though the round-off
is non-random it cannot introduce a spurious sidereal variation.

Note that modern electronic and/or computerized data acquisition techniques have greatly reduced the likelihood of
such bias, but it can still be introduced by a poorly-designed analysis technique. Experimenter's bias was not well
recognized until the 1950's and 60's, and then it was primarily in medical experiments and studies. Its effects on
experiments in the physical sciences have not always been fully recognized. Several experiments referenced above
were clearly affected by it."

Text from Tom Roberts 'What is the experimental basis of special relativity' of the Speed of Light

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