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From: Jonah Thomas on 21 Oct 2009 01:13
HW@..(Henry Wilson DSc). wrote:

> Now getting back to the main point, WHY wouldn't the above
> configuration produce the same kind of interference?

Has anybody said it wouldn't? I'm going to stick my neck out and say
that from everything I've seen so far, it would produce that kind of
interference provided the path length was short enough that the two
beams were still sufficiently mutually coherent. To make it work for a
longer distance you get a better laser, and I don't yet know of any
theoretical upper limit on how good that can be. (But if you send the
light through air or water or glass etc it will get less coherent
because of that, and there might be an upper length limit under those
conditions.)
From: Jonah Thomas on 21 Oct 2009 03:51
HW@..(Henry Wilson DSc). wrote:
> Jonah Thomas <jethomas5(a)gmail.com> wrote:
> >HW@..(Henry Wilson DSc). wrote:
> >
> >> Well, without dispersion there would be no path length differences
> >and> no fringe pattern.
> >>
> >> Try this arrangement then, which is what I really meant:
> >>
> >> S------->----------/\----------<---------M
> >>
> >>
> >>
> >>
> >> O
> >>
> >> Now the observer receives light from both the source and the mirror
> >> via the two half silvered mirrors.
> >> If the source beam is coherent and parallel, why shouldn't
> >> interference occur. The fact that the path lengths are different
> >> shouldn't matter.
> >
> >http://skullsinthestars.com/2008/09/03/optics-basics-coherence/
> >
> > * well-stabilized laser: coherence time, 10^-4 seconds, coherence
> >length = 30 km
> > * filtered thermal light: coherence time, 10^-8 seconds,
> > coherence
> >length = 3 m
> >
> >3 meters is enough to do a lot. But some lasers have a shorter
> >coherence length than that.
> >
> >> I'm asking this because of claims here that two similar but
> >> independent laser beams can interfere.
> >
> >http://skullsinthestars.com/2008/09/12/interference-between-differen
> >t-photons-never-occurs-not-1963/
> >
> >"Coherence" is basicly a measure of how well the light interferes.
> >Over time and distance laser light from a single source interferes
> >with itself less well. To get laser light from two sources to
> >interfere you have to tune them carefully, and presumably the better
> >that's done the longer they'll interfere. This link describes the
> >first experiment that showed interference between two different
> >lasers. The interference was weak enough that it had to be detected.
>
> My idea uses only one laser so one problem is overcome, at least over
> reasonably short distances.

Sure, I gave you the link because you'd said you were interested.

> Can you see any reason why it shouldn't work just as well as
> Michelson's? With a good laser source, there should be no real need
> for the full cross beam. Actually, the mirrors in my interferometer
> would have to be slightly out of line so the two beams would end up
> traveling together towards the observer....but that presents no real
> problem.

I think one laser might interfere better if you compare the light that
leaves the laser at one time against itself, instead of comparing the
light that leaves at one time against the light that leaves much later.
But if it interferes well enough for you to measure whatever it is you
want to measure, then that's OK.

> >"Thanks to the weakness of the fringe pattern and the poor photo
> >reproduction of the era, the photograph is a bit of a Rorschach test
> >of a scientific result. the microphotometer tracing below it,
> >though, is unambiguous: the fields from the two independent lasers
> >produce a fringe pattern!"
> >
> >You might be interested in another experiment described in the same
> >link. They did low-intensity interference studies, and found that
> >light from the two different lasers interfered even when almost
> >always one photon would have been absorbed before the next photon
> >from either laser arrived.
> >
> >That is, the two lasers were doing interference but it was not two
> >photons interfering. It was something that does not make sense.
>
> It wouldn't to a relativist because their view is that a photon is a
> 'point particle'.
>
> As you might know, my model photon has both 'length' and 'cross
> section'....(maybe considerable length)....so that might partly
> explain it. Also, if you read my reply to Huang today, about points
> and other dimensions, you might consider the possibilities that idea
> opens up.

I'm not sure I understand about 'cross section'. But length? Somebody
claims that it takes an electron in an atom about 10^-8 seconds to emit
a photon.

That could be like firing a gun -- you pour in the powder, you ram in
the casing and shot, you prime the firing pan, you aim, you apply the
glowing punk to the pan, you rest the butt of the gun on the ground
while you pour in more powder -- and the shot spends only a very little
time actually leaving the gun. But it could go the other way, it could
take 10^-8 seconds between the time the front of the photon and the back
of the photon leave, which would give you a photon about 3 meters
long....
From: Androcles on 21 Oct 2009 10:57

"Henry Wilson DSc ." <HW@..> wrote in message
news:m3otd5ldht67g13880lmc6jrgtjv2pakp3(a)4ax.com...
> On Wed, 21 Oct 2009 01:13:04 -0400, Jonah Thomas <jethomas5(a)gmail.com>
> wrote:
>
>>HW@..(Henry Wilson DSc). wrote:
>>
>>> Now getting back to the main point, WHY wouldn't the above
>>> configuration produce the same kind of interference?
>>
>>Has anybody said it wouldn't? I'm going to stick my neck out and say
>>that from everything I've seen so far, it would produce that kind of
>>interference provided the path length was short enough that the two
>>beams were still sufficiently mutually coherent. To make it work for a
>>longer distance you get a better laser, and I don't yet know of any
>>theoretical upper limit on how good that can be. (But if you send the
>>light through air or water or glass etc it will get less coherent
>>because of that, and there might be an upper length limit under those
>>conditions.)
>
> It should work as well as a conventional interferometer and would have one
> less
> mirror to worry about. .....Much less bulky and considerably easier to
> manage
> all round.

In Wilson theory it should work. In practice it won't.




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