On 23 Sep, 21:15, HW@....(Dr. Henri Wilson) wrote:
On Wed, 19 Sep 2007 22:16:11 +0100, "George Dishman" wrote:
"Henri Wilson" HW@.... wrote in message ...

Incidentally, ANTU and MELIPAL are only 102m apart
if you check the diagram, but the point remains, the
inteferometer is still capable of detecting individual
photons and intereference results from the _two_
telescopes.

You are not making it clear whethr the result is a normal image or an
interfrence pattern. All I would expect to get from this greater
resolution is a normal image.

The system was used to measure L Car. Using just one of
the two telescopes, you get an image which is basically
a point, the size of the imaged star will be less than
the PSF (point spread function) of the scope which is
set by the diameter of the dish. If you could make a
reflector 100m across, that diffraction limit would be
less than the image diameter so you could resolve the
star as a disc. the system goes part way there by
combining the light from the two telescopes. If the
star were static, the interference would modify the
detector output like putting a photocell at a fixed
point in a Young's Slits experiment, say 50%. However,
the earth rotates and as it does so it sweeps across
the star so essentially the interference pattern is
swept over the detector as the star's image appears
to moves across the sky. That allows the contrast
ratio between the dark and light fringes to be seen
as a variation in the signal from the detector and
the contrast ratio depends on the star's diameter.

If as you claim, individual photons DO spread themselves out...or
disperse.. as
they travel, then this fact would give a litttle more information to work
on in
constructing a photon model. It doesn't really conflict with my traveling
wave
idea. It simply means the whole crossection becomes larger.

You have to think of your diagram as a sort of cross
section. The spherical wavefronts you mentioned would
look like alternate red and blue umberellas if you did
a 3D version of your program.

...but I cannot see how a gamma paticle can end up similarly dispersed....

Photons hit one atom on a detector but never that
next to it. They usually behave like bursts of
wavefronts in optical systems and zero-size
particles in detectors.

That is not an acceptible theory.

It is not a theory of any kind Henry. A theory
consists of a set of eqations that make
quanititative predictions of observed measurable
values.

What I said is a statement of what is observed,
any valid theory has to predict that behaviour.

explain how you can get interference effects with
single photon sources like dim stars. You don't
seem to appreciate that many advanced telescopes
work in this low photon rate mode these days.

Well you can't produce an interference pattern that way.

But they do Henry, a lot of astronomy is done that
way now. Take your EM program, think of it like
a string of umberellas and if one red umberella
wavefront passing through one telescope arrives at
the same time as another later red umberella
wavefront via the other telescope then you get
constructive interference. You have drawn the
pattern along a 1D 'ray' and the wavefronts are
normal to that but imagine what a 3D view would
look like. Who's to say how wide it could be?
The evidence is they cover the whole sphere at
emission.

Well I say the conclusions are a complete misinterpretation of the facts.

What I have written above are the facts, it is
up to you to interpret them. Photons only ever
cause a single detection in a sensor (perhaps
multiple electrons if avalanche technology is
used) and individual photons are subject to
all the normalrules of interference and
diffraction.

Regardless of your lack of understanding of that
point, even with classical waves, it should be
obvious that only the speed from x to y affects
the relative phase at the detector provided the
speed from the mirrors to the detector is the same
in both cases.
George, you are referring to a photon that acts over a distance of at
least 120 metres and somehow creates fringes.
Where does 'wavelength' come into this?

You also said once before that the interference is cause byinteraction
between photons emitted from the two sides of the star.

No Henry, you said that. I said that was impossible
because they are uncorrelated. I think you spend
too much time inventing strawmen and forget what I
really said.

George, if the pattern is NOT caused by photons from both sides of the star,
how can it possibly privide information about radius change?

I explained that before. Photons(idividually) from
one side of the star create a pattern of intensity.
Photons from the other also create their own pattern,
again behaving individually, but the patterns are
displaced by a small amount, essentially the size
of the "image" formed by the telescope. Because one
is shifted relative to the other, the nulls don't
occur in the same place which affects the contrast
ratio of the fringe pattern. The actual analysis is
much more complex, involving limb darkening and lots
of other stuff but those are the basics.

snip lots not commented

I doubt
if single photon that has traveled 1700 LYs will be detectable on both
sides of
a 600 metre circle.

The longest baseline used by the GSI setup is 12400.5 km
so photons have to be bigger than that :-)

It is possible...but you wont produce any interference involving photons
emitted from both sides of a star in this way.

No Henry, you get interference when a single photon
is received at both ends of the antenna and combined.
If the path length difference is a multiple of the
wavelength you get constructive interference as usual.
That applies to each photon individually. The path
length difference for the phtotn includes a term that
depends on which side it came from since that slightly
changes the angle of the wavefront since it is
perpendicular to the line of site.

George, no matter how you try to wriggle out, a single photon from a star
cannot tell you anything about the star's radius.

Of course not, as I told you before, it is the
superposition of the displaced interference
patterns that carries the information.

Do you think I have all day...

I don't think your have that much life left, but
that's what proper models do, you can find the
result all over the web. "How long does it take
for light from the Sun's core to reach us?"

they say it takes thousands of years....

Right, that's from the core. In Cepheids, most
of that time is reaching the unstable region
but it still takes some more time to reach the
photosphere hence there is a lag.

I don't accept that cepheids are really huff puff stars.

Tough, the radius is observed to vary and the
interferometric, photometric and integrated
velocity measurements are all similar.

I hope you are impressed George.

No, ballistic theory is wrong as shown by Sagnac
but I am pleased that you have learnt a little
local astrophysics, that's what this game is all
about ;-)

Sagnac disproves SR. ...

Don't waste your time with stupid word games, it would
be better spent if you learned some schoolboy calculus.

George