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Martin Miller
#12
Mar15-04, 03:39 PM
P: 49
To 'outandbeyond2004':
Since LLR (Lunar Laser Ranging) is a one-clock measurement of the
time taken by the light signal to travel to the moon and back, no
synchronization is involved.

To fully understand what itís all about, we need a proper and
simple example, such as the following one:

[clock]---------[rod]---------[mirror]
[source]~~>ray

Imagine a rod in space which has been ruler-measured to be
1 LY long. (Ignore the hardships involved if this were actually
done.) Picture a started-and-running atomic clock at one end of
the rod, and a mirror at the other end. Imagine a light source
that is moving relative to the clock-mirror frame. As this light
source meets the clock in passing, the former emits a light ray
toward the mirror. It is at this point that we must be careful;
i.e., we must ask ourselves What are the consequences of the
relative motion between the clock-mirror frame and the light
source frame? Clearly, if the mirror moves away from the light
source, then the light ray from the source should take longer to
reach the mirror than otherwise. Similarly, it is clear that if
the mirror moves toward the light source, then the light ray from
the source should take less time to reach the mirror than otherwise.
However, if the rod is physically contracted, and if the clock is
physically slowed, then these two physical distortions will yield
an incorrect result, namely, round-trip light speed invariance.
Of course, this incorrectness could not be revealed by a ruler
because the ruler would also be physically contracted. Therefore,
an LLR measurement will always seem to obtain very accurate
results of the ('instantaneous') distance between two objects, but
this ignores the fact that (a) no one has taken into account the
objects' movements in relation to the light signals, (b) no one
has proved that the clock is unslowed, and (c) no one has proved
that the rod is uncontracted.

In other words, the Michelson-Morley experiment did not correctly
measure light's round-trip speed, and the LLR cannot correctly
measure the distance to the moon. (Given undistorted clocks and
rods, we would find that light's round-trip, one-clock speed
varies.)

Here are the differences and similarities of the Michelson-Morley
(MMx) round-trip case and the one-way case:

Round-trip Case:
The MMx null result is a law of nature; however,
the MMx result was incorrect because Nature distorted
the instruments.

One-way Case:
In the one-way case, there can be no law of nature
because Nature cannot synchronize clocks; however, man
can synchronize clocks, and if he synchronizes them
_correctly_ (absolute synchronization), then he can obtain
a _correct_ result. (Disclaimer: Of course, he would have
to mathematically correct for clock slowing and rod
shrinkage, but we have the formulas, so this is easy!)