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Lester Zick wrote:
> On Sat, 28 Oct 2006 09:30:02 +0100, "George Dishman"
> <george@xxxxxxxxxxxxxxxxx> wrote:
> >"Lester Zick" <dontbother@xxxxxxxxxxx> wrote in message
> >news:agn4k2dg2en2hg0gl38gsh07iq1q12053g@xxxxxxxxxx
> >> On 27 Oct 2006 00:26:31 -0700, "George Dishman"
> >> <george@xxxxxxxxxxxxxxxxx> wrote:
> >>>sean wrote:
...
> >> Hi George. I think c is supposed to be both independent of v for any
> >> source and independent of any spatial medium in the context of SR.
> >
> >That's true but we were discussing the "luminiferous
> >aether" on which M&M based thier experiment.
>
> Not sure there would be a difference apart from purely speculative
> considerations such as "aether drift".
There are enormous differences. I don't want to
start a string of side issues by giving examples
but virtually everything is different.
> >> ... What MM and KT actually demonstrate is that the
> >> product of relative v and frequency is constant for the crossed paths.
> >> They're frequency dependent experiments and not simply relative motion
> >> experiments.
> >
> >The frequency is fixed by the source. Since the
> >single beam is split to go down the two legs, it
> >has to be the same for both. Any difference in
> >frequency when recombined would give a constant
> >rate of drift of the fringes which doesn't occur.
>
> Well as it turns out this is the crux of the whole experiment. Yes f
> is "fixed" by the source. But no it doesn't stay fixed.
It doesn't matter even if it changes. For example
suppose the temperature in the lab varied and
caused a change of the source frequency, there
is only a single source from which the two beams
are spit so the frequency has to be the same in
both.
> There are only
> three conceivable variables in the experiment: changes in l (relative
> path length), f (frequency) and c (relative velocity of light).
>
> The conventional expectation historically is that a periodic shift
> should occur to reflect changes in l according to changes in relative
> c.
Not quite. The expectation from a Galilean aether
(which is what we are discussing, just to be clear)
is that the length stays unchanged with varying
orientation while the speed varies hence the time
taken for the two legs differs depending on the
orientation and this causes the fringe shift.
> However if the product of c and f remains constant there would be
> no fringe shift. In other words if the optical path with the longer l
> and slower relative c contains a proportionately greater frequency
> while the optical path at right angles with the shorter l and higher
> relative c combined with proportionately lower frequency, differences
> between the two will exactly offset.
Your understanding of the experiment isn't quite
right. The two path lengths are usually set to be
equal to maximise the contrast in the fringes and
the lengths are assumed not to change. Since a
single source is used, the frequency in the two
legs must be the same at any time (if it drifts
slowly, it has no significant effect) so in theory
only a change of speed can cause a fringe shift.
> The usual explanation is that there is an anomalous change in l
> instead.
No, that's the explanation for a Lorentzian aether,
not the Galilean aether we were discussing.
> However contraction is just as ad hoc an explanation as
> aether drift. And I can disprove contraction as the source of the
> effect leaving nothing but changes in c and f to explain the lack of
> fringe shift.
>
> >>>Whether it is particulate or not, if the speed is
> >>>fixed relative to the medium then the effect occurs.
> >>
> >> Only provided there is no frequency interdependence involved.
> >
> >No, the 'wind' effect from motion of the Earth
> >depends only on the difference in speeds.
>
> I don't want to overburden the conversation at this point by trying to
> explain everything at once. But the fact is that contraction cannot
> happen the way Einstein imagined.
I don't want to get sidetracked either but I doubt
you understand what contraction means in SR
so you might want to dig around a bit. In particular
see if you can understand the difference between
length contraction in SR and in a Lorentzian aether.
The effect doesn't occur in a Galilean aether so it
isn't relevant to this discussion.
> This plus the idea of dilation in
> "time" posited by Einstein is really only a dilation in f produced by
> the same mechanism as indicated above.
Again a single beam is split by a piece of glass
so there cannot be a difference in frequency
between the two beams.
> ><snip>
> >
> >> By the way, George, I haven't forgotten about your last reply to my
> >> post. I'm still considering the problem.
> >
> >Cool, I wondered what had happened.
>
> Yeah, I was getting into a reactive mode and didn't want to pursue
> that. Fact is I can't produce Kepler's Third Law from inverse square
> gravitational force and that bothers me.
You should be able to check it using the extra column
I added to the table. Change the order of the columns
to find the period rather than acceleration and it should
become clear.
> I've already looked up the
> law on the internet just to get firmly grounded in the facts but until
> I can calculate one from the other obviously I don't understand the
> problem well enough to get back to the original issue of orbital
> velocities in galaxies or anywhere else.
That's great it will make it much easier to
discuss the subject once you figure it out.
> >OK, I'm reading sci.astro so as long as you keep
> >that in the list I'll see your reply.
>
> Appreciate it. A week or so ago there was a similar topic posted to
> sci.physics.relativity and it turned into a real donnybrook over pure
> nonsense completely unrelated to the issue. Occasionally I used to
> post to sci.physics.relativity and never experienced that kind of
> problem but I guess times change.
I used to post there a lot several years ago
but I gave up when the number of cranks
went up severely to the point where it became
impossible to keep a thread to a topic long
enough to resolve even simple questions.
The subject here was using the MMX to
measure anisotropy of the speed of light in
a Galilean aether (or more accurately how
Gucharn's version is related to the classical
version) and I'd like to keep with that until
we agree it and not get sidetracked if we
can avoid it.
George
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