Ballistic Theory, Progress report...Suitable for 5yo Kids

The program relies on the concept of 'closing speed of light', as defined by
SR.
How COULD it be wrong?

See? :-)

Henri Wilson won't tell us what the result was
the one time he tested his program with measured data
of a known binary.

All that beer hasn't cured your tendency to rave.

And you still REFUSE to answer the question. Are you a politician?
You sure duck questions like one.

"bz" wrote in message
98.139...
"George Dishman" wrote in
:
"bz" wrote in message
98.139...
"George Dishman" wrote in
:

....
Yes, but it also affects single photons.

How?

I don't know how, I only know it does for the
reason above, interference effects affect the
probability of photon distribution even with
multi-wavelength path differences.

I thought that the distribution of the double slit pattern depended on the
wavelength of the photon, not the coherence length of the laser.

The spacing between indiviual fringes depends
on the wavelength. The extent of the screen
over which the fringes have good contrast ratio
depends on the coherence length. I found this:

http://marcus.whitman.edu/~beckmk/QM/inter/inter.html

You might find the link to the presentation
interesting, but the red graph on that page
illustrates what I mean, the variation from
peak to trough reduces as you go further from
the zero difference point. Eventually, when
the path difference is much more than the
coherence length, the two beams are unrelated
and you get uniform illumination.

One can even
get a double slit pattern from an incoherent source, such as a lightbulb
with
a band pass filter.

Yes, and the narrower the filter, the wider
the region showing fringes.

I know of one place that coherence length is important: laser holography.
I
wanted to build a color holographic camera, using 3 laser diodes. During
the
research I did on that project I found that it would be useless for taking
holographic pictures of anything at a distance greater than the coherence
length of the diodes. This ruled out a portable color camera.

The key factor is path length difference. If
you send the reference beam through a coil of
fibre, the coherence length would affect the
distance but the depth of field. You will get
good contrast if the difference betwen the coil
length and twice the distance to the subject is
less than the coherence length.

I still am not sure that the coherence length effects interference
patterns
for single photon experiments.

See the link above.

http://www.holo.com/holo/book/book6&7.html

Thanks, another useful link.

By the way, did you know that you [anyone] can build a lensless, laser
that
uses the nitrogen in the air at atmospheric pressure?
http://repairfaq.ece.drexel.edu/sam/lasercn2.htm

I haven't seen it done with N2 but the guys on the
next bench to me in my final year were doing the
same with CO2. They got the basics working by
breathing through a tube into the cavity :-)


[quote restored]
However I also know that a single photon in
the double slit experiment has a negligible
probability of hitting a point where the
path difference is 10.5 wavelengths if the
coherence length is 1000 wavelengths.
....
Is your statement from experimental data? I would like to read about
the experiment.

Nothing special, this is the first hit I got
on Google:

http://tinyurl.com/cknu7

a good dual slit, single photon experiment but I see nothing about
coherence
length having an effect on the pattern.

No, I was just saying that a photon cannot be
considered to be like a small train of waves
(e.g. less than a few wavelengths) if it can
interfere with itself with a path difference
of many wavelengths. Coherence length only
creates an upper limit which is specific to
the experiemnt.

I think that there may be some effect due to the thermal phonons of the
slits interacting with the electron clouds at the edge of the slit and
deflecting photons passing close to the edge.

Could be, I'm not saying I know the mechanism
but experiments like that above tell us
something about single photons that seems to
contradict the idea that it can be a single
cycle or something close to that.

Unless, in passing through the slit, it influences the various vibrations
in
the structures of the slits, kind of like seismic waves, passing through
the
earth, cause measurable effects at a distance.

Again, I will decline to speculate. I think
QED would provide an answer but I don't know
what it is.


Single photon RF experiments should produce similar results to single
photon
light experiments. A single photon, at say 100 GHz, is 0.3 cm in
wavelength.
It has 6.6e-23 joules of energy (making it hard to detect one, but perhaps
in
a cryogenic chamber, it could be done).

A 5 mW transmitter puts out 7.5e19 photons per second. In a single cycle,
7.54e8 photons are emitted at that power level.

Assuming we could switch the transmitter on and off (or switch antenna and
dummy load) at zero crossing, fast enough to pass only 1 cycle to the
antenna, we would need to switch at a 10 ps interval.

That should be possible. At 5 mW, it should give us 7.5e8 photons that are
frequency and phase coherent, and, I predict, no keying transients.

In any case, we should be able to determine the maximum length of a
photon.

I think I would be tempted to switch a current
through a communications laser diode to do this
at reasonable cost. The higher energy reduces
the number of photons per mW and current can be
easily controlled. The harder part would be the
detector, PMT's are expensive.

George

"George Dishman" wrote in
:


"bz" wrote in message
98.139...
"George Dishman" wrote in
:
"bz" wrote in message
98.139...
"George Dishman" wrote in
:

...
Yes, but it also affects single photons.

How?

I don't know how, I only know it does for the
reason above, interference effects affect the
probability of photon distribution even with
multi-wavelength path differences.

I thought that the distribution of the double slit pattern depended on
the wavelength of the photon, not the coherence length of the laser.

The spacing between indiviual fringes depends
on the wavelength. The extent of the screen
over which the fringes have good contrast ratio
depends on the coherence length. I found this:

http://marcus.whitman.edu/~beckmk/QM/inter/inter.html

You might find the link to the presentation
interesting, but the red graph on that page
illustrates what I mean, the variation from
peak to trough reduces as you go further from
the zero difference point. Eventually, when
the path difference is much more than the
coherence length, the two beams are unrelated
and you get uniform illumination.

Interesting, for sure.


One can even
get a double slit pattern from an incoherent source, such as a
lightbulb with
a band pass filter.

Yes, and the narrower the filter, the wider
the region showing fringes.

Sounds like it should be related to information theory and s/n ratios

Narrower bandwidth, better signal to noise ratio.

I know of one place that coherence length is important: laser
holography. I
wanted to build a color holographic camera, using 3 laser diodes.
During the
research I did on that project I found that it would be useless for
taking holographic pictures of anything at a distance greater than the
coherence length of the diodes. This ruled out a portable color camera.

The key factor is path length difference. If
you send the reference beam through a coil of
fibre, the coherence length would [not] affect the
distance but the depth of field. You will get
good contrast if the difference betwen the coil
length and twice the distance to the subject is
less than the coherence length.

hmmmm. Path length difference. Interesting.

Still, most laser diodes have rather short coherence lengths (on the order
of a few hundred micrometers), giving a rather shallow depth of field. In
1997 'Long coherence length Laser diodes' meant 'several centimeters'.
http://omlc.ogi.edu/news/dec97/pclaser.html

I still am not sure that the coherence length effects interference
patterns for single photon experiments.

See the link above.

http://www.holo.com/holo/book/book6&7.html

Thanks, another useful link.

By the way, did you know that you [anyone] can build a lensless, laser
that uses the nitrogen in the air at atmospheric pressure?
http://repairfaq.ece.drexel.edu/sam/lasercn2.htm

I haven't seen it done with N2 but the guys on the
next bench to me in my final year were doing the
same with CO2. They got the basics working by
breathing through a tube into the cavity :-)

I was in college in the mid 60's and tried to help a kid with his high
school science project, he built a HeNe laser but we never could get it to
lase. That was my first experience with lasers.

[quote restored]
However I also know that a single photon in
the double slit experiment has a negligible
probability of hitting a point where the
path difference is 10.5 wavelengths if the
coherence length is 1000 wavelengths.
...
Is your statement from experimental data? I would like to read about
the experiment.

Nothing special, this is the first hit I got
on Google:

http://tinyurl.com/cknu7

a good dual slit, single photon experiment but I see nothing about
coherence
length having an effect on the pattern.

No, I was just saying that a photon cannot be
considered to be like a small train of waves
(e.g. less than a few wavelengths) if it can
interfere with itself with a path difference
of many wavelengths. Coherence length only
creates an upper limit which is specific to
the experiemnt.

Minimum pulse lengths of ~ 1 cycle and single photon, dual slot
interference patterns present an interesting challenge to the models for
photons.

I think that there may be some effect due to the thermal phonons of
the slits interacting with the electron clouds at the edge of the
slit and deflecting photons passing close to the edge.

Could be, I'm not saying I know the mechanism
but experiments like that above tell us
something about single photons that seems to
contradict the idea that it can be a single
cycle or something close to that.

Unless, in passing through the slit, it influences the various
vibrations in
the structures of the slits, kind of like seismic waves, passing
through the
earth, cause measurable effects at a distance.

Again, I will decline to speculate. I think
QED would provide an answer but I don't know
what it is.

I have reservations about Feynman's multipath theory.

Single photon RF experiments should produce similar results to single
photon
light experiments. A single photon, at say 100 GHz, is 0.3 cm in
wavelength.
It has 6.6e-23 joules of energy (making it hard to detect one, but
perhaps in
a cryogenic chamber, it could be done).

A 5 mW transmitter puts out 7.5e19 photons per second. In a single
cycle, 7.54e8 photons are emitted at that power level.

Assuming we could switch the transmitter on and off (or switch antenna
and dummy load) at zero crossing, fast enough to pass only 1 cycle to
the antenna, we would need to switch at a 10 ps interval.

That should be possible. At 5 mW, it should give us 7.5e8 photons that
are frequency and phase coherent, and, I predict, no keying transients.

In any case, we should be able to determine the maximum length of a
photon.

I think I would be tempted to switch a current
through a communications laser diode to do this
at reasonable cost.

But up in frequency mean the time resolution/switching speeds need to
increase.

The higher energy reduces
the number of photons per mW and current can be
easily controlled. The harder part would be the
detector, PMT's are expensive.

CCD detectors, such as in a video camera, are very sensitive now.




--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap

bz wrote:
"George Dishman" wrote in
:

much snipped
The key factor is path length difference. If
you send the reference beam through a coil of
fibre, the coherence length would [not] affect the
distance but the depth of field. You will get
good contrast if the difference betwen the coil
length and twice the distance to the subject is
less than the coherence length.

hmmmm. Path length difference. Interesting.

Still, most laser diodes have rather short coherence lengths (on the order
of a few hundred micrometers), giving a rather shallow depth of field. In
1997 'Long coherence length Laser diodes' meant 'several centimeters'.
http://omlc.ogi.edu/news/dec97/pclaser.html

It doesn't seem to have improved much but it
would perhaps allow 3D filming of say insect
flight with a depth of field of a few cm at
a range of say 1m.

more snpped
Again, I will decline to speculate. I think
QED would provide an answer but I don't know
what it is.

I have reservations about Feynman's multipath theory.

It illustrates well how science need not provide
understandable explanations. It works, just turn
the handle and get the numbers, but thinking about
the philosophical implications can be hazardous!

I think I would be tempted to switch a current
through a communications laser diode to do this
at reasonable cost.

But up in frequency mean the time resolution/switching speeds need to
increase.

Higher carrier frequency means a lower photon
rate for the same power hence lower switching
speeds to select a single photon. It would be
possible to measure the bandwidth of a laser
diode with coherence length in the cm range
going through a shutter which was open for say
1 microsecond at a repetition rate of 10 kHz
with a photon rate of a few hundred per second.
The chances of getting two photons during an
opening would be low but the shutter would be
open for a time much longer than the "duration"
of a single photon.

Then change to a shutter open time around 10ps
and see if the bandwidth increases. The photon
"length" should be 30ps per cm of coherence so
selecting only part of the photon should increase
the bandwidth if I am right.

The higher energy reduces
the number of photons per mW and current can be
easily controlled. The harder part would be the
detector, PMT's are expensive.

CCD detectors, such as in a video camera, are very sensitive now.

That and a decent diffraction grating would do it
but I guess the CCD would need to be cooled.

George

" wrote in
ups.com:



bz wrote:
"George Dishman" wrote in
:

much snipped
The key factor is path length difference. If
you send the reference beam through a coil of
fibre, the coherence length would [not] affect the
distance but the depth of field. You will get
good contrast if the difference betwen the coil
length and twice the distance to the subject is
less than the coherence length.

hmmmm. Path length difference. Interesting.

Still, most laser diodes have rather short coherence lengths (on the
order of a few hundred micrometers), giving a rather shallow depth of
field. In 1997 'Long coherence length Laser diodes' meant 'several
centimeters'. http://omlc.ogi.edu/news/dec97/pclaser.html

It doesn't seem to have improved much but it
would perhaps allow 3D filming of say insect
flight with a depth of field of a few cm at
a range of say 1m.

That would be interesting, especially in color.


more snpped
Again, I will decline to speculate. I think
QED would provide an answer but I don't know
what it is.

I have reservations about Feynman's multipath theory.

It illustrates well how science need not provide
understandable explanations. It works, just turn
the handle and get the numbers, but thinking about
the philosophical implications can be hazardous!

I have a hard time integrating it into my personality.

I think I would be tempted to switch a current
through a communications laser diode to do this
at reasonable cost.

But up in frequency mean the time resolution/switching speeds need to
increase.

Higher carrier frequency means a lower photon
rate for the same power hence lower switching
speeds to select a single photon.

The way to test the photon 'length' is by switching times on the
order of the expected time for the expected number of cycles per photon.

It would be
possible to measure the bandwidth of a laser
diode with coherence length in the cm range
going through a shutter which was open for say
1 microsecond at a repetition rate of 10 kHz
with a photon rate of a few hundred per second.

That would tell us nothing about the length of the photons.
We can already get single photons by attenuating the beam intensity.

Besides, spectrum analysis is done, every day, on fiber optical lasers.
We know that for switching speeds used for gigabit data rates, the
bandwidths needed are consistent with information theory.

We need to push the envelope, so to speak, and see what happens with VERY
narrow pulses, so narrow that they can only contain a single cycle.

The chances of getting two photons during an
opening would be low but the shutter would be
open for a time much longer than the "duration"
of a single photon.

Then change to a shutter open time around 10ps
and see if the bandwidth increases. The photon
"length" should be 30ps per cm of coherence so
selecting only part of the photon should increase
the bandwidth if I am right.

Selecting only part of the photon should either (1) produce no output
or (2) produce a photon with less energy, since part of its energy has
been absorbed.

(1) is consistent with Einstein. (2) would blow all kinds of holes in
quantum electro dynamics unless it could be shown to be consistent with
the compton effect.

The higher energy reduces
the number of photons per mW and current can be
easily controlled. The harder part would be the
detector, PMT's are expensive.

CCD detectors, such as in a video camera, are very sensitive now.

That and a decent diffraction grating would do it
but I guess the CCD would need to be cooled.

We used Peltier coolers to cool the PMTubes in our NOx monitors, back when
I did instrument repair for a division of Borg Warner.

On the other hand, liquid nitrogen is pretty cheap. Liquid He is a bit
pricy. But I could 'borrow a cup' of either as we use both in our
building.

[aside: when the new superconductor magnet for our new 700 MHz NMR was
being brought up to field, they had a quench incident that boiled off 2000
litres of liquid helium in a few seconds. The fog in the air set off the
fire alarms and cleared the building.]



--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap

On Wed, 20 Jul 2005 14:10:59 GMT, Aristotle
wrote:


The program relies on the concept of 'closing speed of light', as defined by
SR.
How COULD it be wrong?

See? :-)

Henri Wilson won't tell us what the result was
the one time he tested his program with measured data
of a known binary.

All that beer hasn't cured your tendency to rave.

And you still REFUSE to answer the question. Are you a politician?
You sure duck questions like one.

I have answered Andersen's question so many times that he has even forgotten
what the question was.

Notice that he and his mates have run for cover over my proof that the mythical
'GR correction' of GPS clocks if plain nonsense from start to finish.




HW.
www.users.bigpond.com/hewn/index.htm

Sometimes I feel like a complete failure.
The most useful thing I have ever done is prove Einstein wrong.

"bz" wrote in message
98.139...
" wrote in
ups.com:
snip
It would be
possible to measure the bandwidth of a laser
diode with coherence length in the cm range
going through a shutter which was open for say
1 microsecond at a repetition rate of 10 kHz
with a photon rate of a few hundred per second.

That would tell us nothing about the length of the photons.
We can already get single photons by attenuating the beam intensity.

Besides, spectrum analysis is done, every day, on fiber optical lasers.
We know that for switching speeds used for gigabit data rates, the
bandwidths needed are consistent with information theory.

Indeed, I was outlining the control experiment.

We need to push the envelope, so to speak, and see what happens with VERY
narrow pulses, so narrow that they can only contain a single cycle.

Single cycle might be beyond the technology
but chopping within the coherence length is
achievable.

The chances of getting two photons during an
opening would be low but the shutter would be
open for a time much longer than the "duration"
of a single photon.

Then change to a shutter open time around 10ps
and see if the bandwidth increases. The photon
"length" should be 30ps per cm of coherence so
selecting only part of the photon should increase
the bandwidth if I am right.

Selecting only part of the photon should either (1) produce no output
or (2) produce a photon with less energy, since part of its energy has
been absorbed.

(1) is consistent with Einstein. (2) would blow all kinds of holes in
quantum electro dynamics unless it could be shown to be consistent with
the compton effect.

(1) A gate of 10ps at 10kHz should allow through
100 photons per billion so the intensity would
be reduced by that factor. The laser intensity
could be increased to partly compensate as long
as the probability of two photons per gate
remains negligible.

(2) My expectation is that the mean photon energy
would not change but the spread would increase.
A coherence length of say 3cm is 100ps or a
bandwidth of 20 GHz (both sidebands). Chopping
it at 10ps would widen that to 200GHz creating
photons with energies farther from the mean if
I am right.

[aside: when the new superconductor magnet for our new 700 MHz NMR was
being brought up to field, they had a quench incident that boiled off 2000
litres of liquid helium in a few seconds. The fog in the air set off the
fire alarms and cleared the building.]

You guys sure have some fun :-)

George

"George Dishman" wrote in news:dbr8pg$miv$1
@news.freedom2surf.net:


"bz" wrote in message
98.139...
" wrote in
ups.com:
snip
It would be
possible to measure the bandwidth of a laser
diode with coherence length in the cm range
going through a shutter which was open for say
1 microsecond at a repetition rate of 10 kHz
with a photon rate of a few hundred per second.

That would tell us nothing about the length of the photons.
We can already get single photons by attenuating the beam intensity.

Besides, spectrum analysis is done, every day, on fiber optical lasers.
We know that for switching speeds used for gigabit data rates, the
bandwidths needed are consistent with information theory.

Indeed, I was outlining the control experiment.

We need to push the envelope, so to speak, and see what happens with VERY
narrow pulses, so narrow that they can only contain a single cycle.

Single cycle might be beyond the technology
but chopping within the coherence length is
achievable.

Single cycle is certainly not beyond the technology at lower frequencies.


The chances of getting two photons during an
opening would be low but the shutter would be
open for a time much longer than the "duration"
of a single photon.

Then change to a shutter open time around 10ps
and see if the bandwidth increases. The photon
"length" should be 30ps per cm of coherence so
selecting only part of the photon should increase
the bandwidth if I am right.

Selecting only part of the photon should either (1) produce no output
or (2) produce a photon with less energy, since part of its energy has
been absorbed.

(1) is consistent with Einstein. (2) would blow all kinds of holes in
quantum electro dynamics unless it could be shown to be consistent with
the compton effect.


Looks like people are, or think they are, making single photons.

http://ipeqwww.epfl.ch/qd/html/singleqddevices.htm
http://www.quiprocone.org/report034.pdf
http://www.mqc2.it/MQC204/Stevenson.pdf
http://cua.mit.edu/8.422/PHYSICS-vuc...omon-yamamoto-
enhanced-single-photon-emission-from-a-quantum-dot-in-a-micropost-
microcavity-apl-v82-p3596-2003-single_photons_APL_May03-1.pdf
http://www.iota.u-psud.fr/~S4P/pdf%20files/APL02865.pdf



(1) A gate of 10ps at 10kHz should allow through
100 photons per billion so the intensity would
be reduced by that factor. The laser intensity
could be increased to partly compensate as long
as the probability of two photons per gate
remains negligible.

(2) My expectation is that the mean photon energy
would not change but the spread would increase.
A coherence length of say 3cm is 100ps or a
bandwidth of 20 GHz (both sidebands). Chopping
it at 10ps would widen that to 200GHz creating
photons with energies farther from the mean if
I am right.

[aside: when the new superconductor magnet for our new 700 MHz NMR was
being brought up to field, they had a quench incident that boiled off 2000
litres of liquid helium in a few seconds. The fog in the air set off the
fire alarms and cleared the building.]

You guys sure have some fun :-)

George








--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap

"bz" wrote in message
98.139...
"George Dishman" wrote in news:dbr8pg$miv$1
@news.freedom2surf.net:


"bz" wrote in message
98.139...
" wrote in
ups.com:
snip

We need to push the envelope, so to speak, and see what happens with
VERY
narrow pulses, so narrow that they can only contain a single cycle.

Single cycle might be beyond the technology
but chopping within the coherence length is
achievable.

Single cycle is certainly not beyond the technology at lower frequencies.

No but I think measuring single photons
becomes harder.

Looks like people are, or think they are, making single photons.

http://ipeqwww.epfl.ch/qd/html/singleqddevices.htm
http://www.quiprocone.org/report034.pdf
http://www.mqc2.it/MQC204/Stevenson.pdf
http://cua.mit.edu/8.422/PHYSICS-vuc...omon-yamamoto-
enhanced-single-photon-emission-from-a-quantum-dot-in-a-micropost-
microcavity-apl-v82-p3596-2003-single_photons_APL_May03-1.pdf
http://www.iota.u-psud.fr/~S4P/pdf%20files/APL02865.pdf

We are certainly on the verge of moving to
verge of handling single photons routinely.

Thanks again for the links.

George

"bz" wrote in message
98.139...
| "George Dishman" wrote in news:dbr8pg$miv$1
| @news.freedom2surf.net:


Watch our for bz. He'll calculate 76.6c for the speed of an electron in
an accelerator and blame YOU for it.
Androcles.