Re: michelson morley experiment

As you have read below (you did, right?), such an analogy is no good for
questions relating to momentum conservation. The analogy was only intended
(but never proved!) to be valid for calculating the propagation *speed* of a
wave that propagates through a moving medium.
Assuming that it's indeed valid for a wave that is skewed relative to the
medium, then you get the factor gamma for the total time delay, and gamma^2
for 0/180 degrees. The difference is a factor gamma, and that's what M-M
expected to be able to measure.

Harald

It's not my analogy.   Judging by the URL, the University of Virginia
physics department is responsible for the analogy.

Since I didn't get an answer to my question about the siwmmers and the
river that made any sense to me I will assume that the analogy with
the swimmers and the river is meaningless and the crucial details
about the MM experiment are not explained on that web page.

Darkknight.

Do you think you need to aim a flashlight up stream to hit a target
perpendicular to your direction of motion?  Light doesn't work that
way, so your analogy is flawed.

Take a friend and a couple of megaphones out to a field on a windy day.
Use your megaphone to shout to your friend while he uses his to
determine the direction the sound comes from.  You will find that he
does not hear the sound come from up wind or down wind but straight
from you.  You will find it is best to aim straight at him, not up wind
or down wind.  So sound, which is carried by a medium, does not behave
the way you predict either.

It's not so easy to disprove the aether when you use what really
happens as opposed to poor analogies.

Bruce Richmond

So if I calculate the phase relationship between the two swimmers that
are described here
http://galileoandeinstein.physics.virginia.edu/lectures/michelson.html
will I find any change if I "rotate the apparatus" i.e. if the
direction of the current in the river is changed?

If I change the direction of the current in the river, the two
swimmers won't make it back to the original starting point unless I
also change the direction they swim, but if I change the direction
they swim, this is no longer the equivalent of the MM experiment, so
the fact that the two swimmers make it back to the starting point at
different times when the river is flowing parallel to the river bank,
proves nothing ??

Since the MM apparatus doesn't change the direction the "swimmers"
swim in, won't this produce a fringe shift as the apparatus is
rotated, according to the ether theory being tested?

Thanks

They originally set it up that way. Of course, one can not have
*exactly* same lengths but within error bars was the same length. Then
other similar setups were done with different arm lengths. See
Kennedy-Thorndyke.

It did not *rely* on that fact. I was setup to find what would happen
if rotated.

It (as was already known) showed that the TWLS was constant.
It did not disprove (modern) ehter theory because ether theory predicts
that there would be no fringe shift. But the 'earlier' ether theory was
badly interpreted and was thought that it it predicted a fringe shift.

---
If you want to be sure, then always doubt
}:-)

Hi

In the MM experiment, was the length of the two light paths set
exactly equal.  If so, how was this done?  If not, did the experiment
"rely" on the fact that there was no change in the interference
fringes when the apparatus was rotated?

Did the MM experiment demonstrate anything about the constancy of the
speed of light or did it merely "disprove" the aether theory?

Does this website have any credibility in mainstream physics?
http://home.iprimus.com.au/longhair1/page1.html

Thanks.