Re: michelson morley experiment

Harry wrote:
<vern@xxxxxxxxxxxx> wrote in message

[snip]

The experiment is based on the
assumption that when a laser pulse is in the air between the source and
target, the target continues to move along with the Earth in the
essentially linear motion of the Solar System towards the constellation
Leo. The target will have moved about 4 inches before the pulse hits
it. So the reference frame for the whole experiment is the CMBR frame.

OK

Does the target move in the reference frame of the Earth's surface in
the time the pulse is in the air? I guess the answer is "no" because
both the source and target are stationary during the length of time
starting when the pulse is fired from the source and ending when the
pulse hits the target in the reference frame of the Earth's surface.

Right - apart of a negligibly small rotation.

But that can't be used as a reason that there is no aberration of
terrestial light, since in the reference frame of the CMBR, the Earth
is moving and that resulting aberration of terrestial light should be
evident in any experiment using light on the surface of the Earth.

What do you think needs to abberate, and why? What makes you think that the
light should change its course when it exists the laser? (Note how the path
inside the laser is when mapped to the CMBR frame).

I think this is more of an issue and question about absolute motion.
If you take as a fact that the measurements using the CMBR establish
that the Earth is moving essentially linearly at approximately 370 km/s
towards the constellation Leo, then a consequence of that fact is that
when a laser beam is shot from a laser on the surface of the Earth to a
target also on the surface of the Earth such that the laser and target
are aligned perpendicularly to the direction towards Leo and the
distance between the laser and the target is approximately 300 feet,
then from the time the beam leaves the laser the target will have moved
approximately four feet in the direction towards Leo (obviously, the
laser would have moved too, but that's immaterial since what happens
to the laser after the beam leaves it has no effect on where the beams
goes or what happens to the target). I have made no statement about
the light changing course when it exits the laser. That involves
whether the movement of the source imparts momentum to the beam. Tom
Roberts has already said that it does not and the beam does not leave
at an angle. But that does not have a bearing on whether the target
moves during the transit time of the beam. Whether the target moves or
not is a statement about absolute motion. If it is accepted that the
Earth is moving as stated above, then it doesn't matter that motion
is not apparent if electing to use an Earth-surface reference frame.
Your choice of frames does not stop the Earth from moving. Therefore,
the experiment outlined above has to account for that movement in
determining the outcome of the experiment. That's where aberration
(or perhaps you could say a lack of aberration) comes into play. Since
the movement of the Earth towards Leo does not have any effect on the
beam, the beam would be expected to strike the target approximately
four inches behind (opposite the direction towards Leo) where it was
aimed because that's how far the target moved towards Leo in the
transit time of the beam. Arguments concerning not knowing where the
laser was originally aimed are negated by shooting a beam every hour
over a 24 hour period. An ellipse pattern should be evident on the
target with the center of the ellipse being where the laser was aimed.

Vern

.

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