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

On Sun, 10 Jul 2005 16:33:25 +0100, "George Dishman"
wrote:


"Henri Wilson" H@.. wrote in message
.. .
On Wed, 6 Jul 2005 20:04:37 +0100, "George Dishman"

wrote:


"Henri Wilson" H@.. wrote in message
...
...
The concept of 'light wavelength' is a bit obscure.

Not really, it's the distance between points
of equal phase measured in the directon of
propagation.

You can say that about generated radio waves
but not individual photons.

Another interesting subject.

Consider Young's slits illuminated by a laser.
If the setup is symmetrical you get a bright
line in the centre with fringes either side.
Conventionally the high brightness at a
location ten fringes to one side is due to the
signal interfering such that the peak through
one slit coincides with a peak ten wavelengths
later that has travelled a longer path having
come through the other slit.

If you reduce the brightness of the laser and
add a shutter, you can allow single photons
into the setup.

That is a pretty tricky operation.

At the same location as above,
you still get a peak of probability of photons
arriving while half a fringe either side, the
probability is zero because a peak through one
slit interferes with a trough 9.5 or 10.5
wavelengths later. That must apply to each
photon individually.

How about using parallel light from a very dim star instead of a laser.
If single photons reach the slits, the spacing should give an indication of
photon cross section.


If light changes speed in flight, does the distance between
wavecrests change or not?

Unless wavelength = speed / frequency, you
need your "tick fairies" at every change of
refractive index. Think of light passing
through a sheet of glass, there must be the
same number of wavefronts passing a point
within the glass as points outside in any
given time.

No doubt about that one, George.

Now, if light speed relative to a particular observer changes due to the
observer's motion, what would you expect happens to the 'wavelength' in
his
frame?

In Ritzian theory I would expect the wavelength
to change according to the classical formula
for a moving observer while if SR is right, it
should change according to the relativistic
formula.

I would not expect the wavelength to change at all.


George



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.

On Sun, 10 Jul 2005 11:56:23 -0400, "sue jahn"
wrote:


"George Dishman" wrote in message ...

"Henri Wilson" H@.. wrote in message
...
On Wed, 6 Jul 2005 20:04:37 +0100, "George Dishman"

wrote:


"Henri Wilson" H@.. wrote in message
. ..
...
The concept of 'light wavelength' is a bit obscure.

Not really, it's the distance between points
of equal phase measured in the directon of
propagation.

You can say that about generated radio waves
but not individual photons.

Another interesting subject.

Consider Young's slits illuminated by a laser.
If the setup is symmetrical you get a bright
line in the centre with fringes either side.
Conventionally the high brightness at a
location ten fringes to one side is due to the
signal interfering such that the peak through
one slit coincides with a peak ten wavelengths
later that has travelled a longer path having
come through the other slit.

If you reduce the brightness of the laser and
add a shutter, you can allow single photons
into the setup.

If you do this by reducing the brigtness of the
laser you allow a single *absorbed* photons to eject a
photoelectron.

Quantum dot emitters that will measure out a single
photon are now available.
The experiment and Results
This experiment proved that the following two things were possible in an
open photonic network environment such as the Internet.

1. A single photon can interfere...
http://www.physorg.com/news4536.html

IOW a single *emitted* photon goes through
both slits.

That doens't look favorable for BaT or
particle propagation models.

Why not?
Photons have an effective cross section that stretches to infinity. It does off
very rapidly with distance from the central axis, though.

Sue...



At the same location as above,
you still get a peak of probability of photons
arriving while half a fringe either side, the
probability is zero because a peak through one
slit interferes with a trough 9.5 or 10.5
wavelengths later. That must apply to each
photon individually.

If light changes speed in flight, does the distance between
wavecrests change or not?

Unless wavelength = speed / frequency, you
need your "tick fairies" at every change of
refractive index. Think of light passing
through a sheet of glass, there must be the
same number of wavefronts passing a point
within the glass as points outside in any
given time.

No doubt about that one, George.

Now, if light speed relative to a particular observer changes due to the
observer's motion, what would you expect happens to the 'wavelength' in
his
frame?

In Ritzian theory I would expect the wavelength
to change according to the classical formula
for a moving observer while if SR is right, it
should change according to the relativistic
formula.

George





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.

Henri Wilson wrote:
On Sun, 10 Jul 2005 16:33:25 +0100, "George Dishman"
wrote:
"Henri Wilson" H@.. wrote in message
.. .
On Wed, 6 Jul 2005 20:04:37 +0100, "George Dishman"

wrote:
"Henri Wilson" H@.. wrote in message
...
...
The concept of 'light wavelength' is a bit obscure.

Not really, it's the distance between points
of equal phase measured in the directon of
propagation.

You can say that about generated radio waves
but not individual photons.

Another interesting subject.

Consider Young's slits illuminated by a laser.
If the setup is symmetrical you get a bright
line in the centre with fringes either side.
Conventionally the high brightness at a
location ten fringes to one side is due to the
signal interfering such that the peak through
one slit coincides with a peak ten wavelengths
later that has travelled a longer path having
come through the other slit.

If you reduce the brightness of the laser and
add a shutter, you can allow single photons
into the setup.

That is a pretty tricky operation.

True but it is done.

At the same location as above,
you still get a peak of probability of photons
arriving while half a fringe either side, the
probability is zero because a peak through one
slit interferes with a trough 9.5 or 10.5
wavelengths later. That must apply to each
photon individually.

How about using parallel light from a very dim star instead of a laser.

A laser is monochromatic, a star isn't. The
linewidth is important in this case. A laser
will show interference with single photons
even if the difference in the path length
is many wavelengths. This abstract mentions
a choerence length of 50m for one laser and
is nothing special, just the first that came
out of Google:

http://www.ingentaconnect.com/conten...00008/art00003

If single photons reach the slits, the spacing should give an indication of
photon cross section.

That's a different subject, I was responding to
your comment on the applicability of wavelength
to single photons.

If light changes speed in flight, does the distance between
wavecrests change or not?

Unless wavelength = speed / frequency, you
need your "tick fairies" at every change of
refractive index. Think of light passing
through a sheet of glass, there must be the
same number of wavefronts passing a point
within the glass as points outside in any
given time.

No doubt about that one, George.

Now, if light speed relative to a particular observer changes due to the
observer's motion, what would you expect happens to the 'wavelength' in
his
frame?

In Ritzian theory I would expect the wavelength
to change according to the classical formula
for a moving observer while if SR is right, it
should change according to the relativistic
formula.

I would not expect the wavelength to change at all.

You are right, I was thinking it would be reduced
by the distance the observer had moved but that is
not correct. There is still a difference between
the two theories.

George

On 12 Jul 2005 05:10:05 -0700, "
wrote:



Henri Wilson wrote:

If you reduce the brightness of the laser and
add a shutter, you can allow single photons
into the setup.

That is a pretty tricky operation.

True but it is done.

At the same location as above,
you still get a peak of probability of photons
arriving while half a fringe either side, the
probability is zero because a peak through one
slit interferes with a trough 9.5 or 10.5
wavelengths later. That must apply to each
photon individually.

How about using parallel light from a very dim star instead of a laser.

A laser is monochromatic, a star isn't. The
linewidth is important in this case.

Single photons should be monochromatic, should they not?
A filter could be used anyway.

A laser
will show interference with single photons
even if the difference in the path length
is many wavelengths. This abstract mentions
a coherence length of 50m for one laser and
is nothing special, just the first that came
out of Google:

http://www.ingentaconnect.com/conten...00008/art00003

If single photons reach the slits, the spacing should give an indication of
photon cross section.

That's a different subject, I was responding to
your comment on the applicability of wavelength
to single photons.

You know my 'sawblade model' of a photon. It has a spatial regularity that
shows up as 'frequency' when it passes an observer. The wavelength is fixed.
It is the nature of this 'spatial pattern' that is of interest.
One explanation is that the 'wave package' itself features a standing
oscillation from back to front as it travels along.

If light changes speed in flight, does the distance between
wavecrests change or not?

Unless wavelength = speed / frequency, you
need your "tick fairies" at every change of
refractive index. Think of light passing
through a sheet of glass, there must be the
same number of wavefronts passing a point
within the glass as points outside in any
given time.

No doubt about that one, George.

Now, if light speed relative to a particular observer changes due to the
observer's motion, what would you expect happens to the 'wavelength' in
his
frame?

In Ritzian theory I would expect the wavelength
to change according to the classical formula
for a moving observer while if SR is right, it
should change according to the relativistic
formula.

I would not expect the wavelength to change at all.

You are right, I was thinking it would be reduced
by the distance the observer had moved but that is
not correct. There is still a difference between
the two theories.

Under BaT, diffraction is explained in terms of frequency, not wavelength.


George


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.

"Henri Wilson" H@.. wrote in message
...
On 12 Jul 2005 05:10:05 -0700, "
wrote:



Henri Wilson wrote:

If you reduce the brightness of the laser and
add a shutter, you can allow single photons
into the setup.

That is a pretty tricky operation.

True but it is done.

At the same location as above,
you still get a peak of probability of photons
arriving while half a fringe either side, the
probability is zero because a peak through one
slit interferes with a trough 9.5 or 10.5
wavelengths later. That must apply to each
photon individually.

How about using parallel light from a very dim star instead of a laser.

A laser is monochromatic, a star isn't. The
linewidth is important in this case.

Single photons should be monochromatic, should they not?

Frequency is a measure of momentum so an
accurately known momentum implies a single
frequency, but the bandwidth of a tone burst
is inversely proportional to the duration.
The uncertainty of the value of the momentum
therefore relates inversely to the 'length'
of the photon but it is hard to say where a
'long' burst of sine wave is located. This
is basically another way of looking at the
uncertainty principle, dx * dp has a minimum
value.

A filter could be used anyway.

A laser
will show interference with single photons
even if the difference in the path length
is many wavelengths. This abstract mentions
a coherence length of 50m for one laser and
is nothing special, just the first that came
out of Google:

http://www.ingentaconnect.com/conten...00008/art00003

If single photons reach the slits, the spacing should give an indication
of
photon cross section.

That's a different subject, I was responding to
your comment on the applicability of wavelength
to single photons.

You know my 'sawblade model' of a photon.

No, I haven't seen you post that that.

It has a spatial regularity that
shows up as 'frequency' when it passes an observer. The wavelength is
fixed.
It is the nature of this 'spatial pattern' that is of interest.
One explanation is that the 'wave package' itself features a standing
oscillation from back to front as it travels along.

What is it reflecting off at the ends?

You are right, I was thinking it would be reduced
by the distance the observer had moved but that is
not correct. There is still a difference between
the two theories.

Under BaT, diffraction is explained in terms of frequency, not wavelength.

I'm not quite sure what you mean, are you
talking of a diffraction grating rather
than diffraction itself?

George

On Wed, 13 Jul 2005 08:05:58 +0100, "George Dishman"
wrote:


"Henri Wilson" H@.. wrote in message
.. .


At the same location as above,
you still get a peak of probability of photons
arriving while half a fringe either side, the
probability is zero because a peak through one
slit interferes with a trough 9.5 or 10.5
wavelengths later. That must apply to each
photon individually.

How about using parallel light from a very dim star instead of a laser.

A laser is monochromatic, a star isn't. The
linewidth is important in this case.

Single photons should be monochromatic, should they not?

Frequency is a measure of momentum so an
accurately known momentum implies a single
frequency, but the bandwidth of a tone burst
is inversely proportional to the duration.
The uncertainty of the value of the momentum
therefore relates inversely to the 'length'
of the photon but it is hard to say where a
'long' burst of sine wave is located. This
is basically another way of looking at the
uncertainty principle, dx * dp has a minimum
value.

What if the intensity of a well filtered beam was so low that only single
photons were passing at any time?


A filter could be used anyway.

A laser
will show interference with single photons
even if the difference in the path length
is many wavelengths. This abstract mentions
a coherence length of 50m for one laser and
is nothing special, just the first that came
out of Google:

http://www.ingentaconnect.com/conten...00008/art00003

If single photons reach the slits, the spacing should give an indication
of
photon cross section.

That's a different subject, I was responding to
your comment on the applicability of wavelength
to single photons.

You know my 'sawblade model' of a photon.

No, I haven't seen you post that that.

It has a spatial regularity that
shows up as 'frequency' when it passes an observer. The wavelength is
fixed.
It is the nature of this 'spatial pattern' that is of interest.
One explanation is that the 'wave package' itself features a standing
oscillation from back to front as it travels along.

What is it reflecting off at the ends?

Don't know.
The 'spinning +/- charge' model is easier.
A bit like Len Gaasenbeek's helical wave idea.

One thing is certain. Photons are not 'point particles with no structure or
properties other than 'energy'..
How could they be?
What would distinguish them from anything else?




You are right, I was thinking it would be reduced
by the distance the observer had moved but that is
not correct. There is still a difference between
the two theories.

Under BaT, diffraction is explained in terms of frequency, not wavelength.

I'm not quite sure what you mean, are you
talking of a diffraction grating rather
than diffraction itself?

George



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.

"Henri Wilson" H@.. wrote in message
...
On Wed, 13 Jul 2005 08:05:58 +0100, "George Dishman"

wrote:


"Henri Wilson" H@.. wrote in message
. ..


At the same location as above,
you still get a peak of probability of photons
arriving while half a fringe either side, the
probability is zero because a peak through one
slit interferes with a trough 9.5 or 10.5
wavelengths later. That must apply to each
photon individually.

How about using parallel light from a very dim star instead of a
laser.

A laser is monochromatic, a star isn't. The
linewidth is important in this case.

Single photons should be monochromatic, should they not?

Frequency is a measure of momentum so an
accurately known momentum implies a single
frequency, but the bandwidth of a tone burst
is inversely proportional to the duration.
The uncertainty of the value of the momentum
therefore relates inversely to the 'length'
of the photon but it is hard to say where a
'long' burst of sine wave is located. This
is basically another way of looking at the
uncertainty principle, dx * dp has a minimum
value.

What if the intensity of a well filtered beam was so low that only single
photons were passing at any time?

Everything I said in that paragraph was
meant to refer to a single photon.

You know my 'sawblade model' of a photon.

No, I haven't seen you post that that.

It has a spatial regularity that
shows up as 'frequency' when it passes an observer. The wavelength is
fixed.
It is the nature of this 'spatial pattern' that is of interest.
One explanation is that the 'wave package' itself features a standing
oscillation from back to front as it travels along.

What is it reflecting off at the ends?

Don't know.

There's the rub - two point particles? ;-)

The 'spinning +/- charge' model is easier.
A bit like Len Gaasenbeek's helical wave idea.

I don't know how that differes from cirular
polarisation and to be honest I'm not that
interested, QED is entirely adequate.

One thing is certain. Photons are not 'point particles with no structure
or
properties other than 'energy'..
How could they be?
What would distinguish them from anything else?

You would be better to ask someone more
knowledgeable about particle physics but
basically the set of properties (charge,
mass, spin) is unique. In fact zero mass
is probably the main factor.

George

"George Dishman" wrote in news:db2e6u$f1u$1
@news.freedom2surf.net:

Frequency is a measure of momentum so an
accurately known momentum implies a single
frequency, but the bandwidth of a tone burst
is inversely proportional to the duration.
The uncertainty of the value of the momentum
therefore relates inversely to the 'length'
of the photon but it is hard to say where a
'long' burst of sine wave is located. This
is basically another way of looking at the
uncertainty principle, dx * dp has a minimum
value.


Photons are not tone bursts.

That we might have difficulty accurately measuring the
frequency/wavelength/energy of a single photon would not seem to require
that those values are broadened by our uncertanty.

Femto and even atto second laser pulses have been produced that are less
than two periods of the wavelength involved.

This would seem to set an upper limit on the number of cycles in a photon.

Logic says that a pulse can not be shorter than the time it takes to create
a single photon. It would also seem to say that a single photon can not "be
longer" than the shortest laser pulse.

This review of techniques will give you a bit of an overview of the field.
http://phys.strath.ac.uk/alpha-x/Ass...time-resolved-
spectroscopy-2003.pdf

--
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:db2e6u$f1u$1
@news.freedom2surf.net:

Frequency is a measure of momentum so an
accurately known momentum implies a single
frequency, but the bandwidth of a tone burst
is inversely proportional to the duration.
The uncertainty of the value of the momentum
therefore relates inversely to the 'length'
of the photon but it is hard to say where a
'long' burst of sine wave is located. This
is basically another way of looking at the
uncertainty principle, dx * dp has a minimum
value.


Photons are not tone bursts.

I'm not suggesting they are, AFAIK they
are point particles, but those particles
seem to be subject to Heisenberg and there
appear to be parallels.

That we might have difficulty accurately measuring the
frequency/wavelength/energy of a single photon would not seem to require
that those values are broadened by our uncertanty.

QM seems to differ with that view, or you
are getting into 'hidden variable' territory.
I'm not sufficiently familiar with QM these
days to argue the point though.

Femto and even atto second laser pulses have been produced that are less
than two periods of the wavelength involved.

This would seem to set an upper limit on the number of cycles in a photon.

Certainly, but from the paper you cite

"The large bandwidth of femtosecond pulses
causes experimental difficulties."

Chopping a pure sinewave creates sidebands
hence increases the bandwidth. Think of a
Fourier analysis of the chopping waveform.
Now I would think a single photon cannot have
a bandwidth but if you take a single photon
from a stream with a wide bandwidth, then
that would translate into uncertainty about
the energy of the particular photon.

Logic says that a pulse can not be shorter than the time it takes to
create
a single photon. It would also seem to say that a single photon can not
"be
longer" than the shortest laser pulse.

I put length in quotes because IMHO a photon
is a particle, but I think this is another
aspect of duality.

This review of techniques will give you a bit of an overview of the field.
http://phys.strath.ac.uk/alpha-x/Ass...time-resolved-
spectroscopy-2003.pdf

Excellent stuff, it will take me some time
to read that but thanks!

George

"George Dishman" wrote in
:


"bz" wrote in message
98.139...
"George Dishman" wrote in news:db2e6u$f1u$1
@news.freedom2surf.net:

Frequency is a measure of momentum so an
accurately known momentum implies a single
frequency, but the bandwidth of a tone burst
is inversely proportional to the duration.
The uncertainty of the value of the momentum
therefore relates inversely to the 'length'
of the photon but it is hard to say where a
'long' burst of sine wave is located. This
is basically another way of looking at the
uncertainty principle, dx * dp has a minimum
value.


Photons are not tone bursts.

I'm not suggesting they are, AFAIK they
are point particles, but those particles
seem to be subject to Heisenberg and there
appear to be parallels.

I agree.


That we might have difficulty accurately measuring the
frequency/wavelength/energy of a single photon would not seem to
require that those values are broadened by our uncertanty.

QM seems to differ with that view, or you
are getting into 'hidden variable' territory.
I'm not sufficiently familiar with QM these
days to argue the point though.

likewise.


Femto and even atto second laser pulses have been produced that are
less than two periods of the wavelength involved.

This would seem to set an upper limit on the number of cycles in a
photon.

Certainly, but from the paper you cite

"The large bandwidth of femtosecond pulses
causes experimental difficulties."

I am not surprised. Rapidly keying a radio transmitter also creates
difficulties. Part of the problem is that a high Q circuit element tends
to 'ring'.


Chopping a pure sinewave creates sidebands
hence increases the bandwidth.

Quite true.... especially if the chopping isn't done at the time of zero
crossing.

The antenna would also need to be low Q and non reactive so that current
and voltage would be in phase.

Think of a
Fourier analysis of the chopping waveform.
Now I would think a single photon cannot have
a bandwidth

I agree.

but if you take a single photon
from a stream with a wide bandwidth, then
that would translate into uncertainty about
the energy of the particular photon.

right.

On the other hand, if you have a narrow bandwidth beam of photons and you
'chop' it, into small slices, mechanically, I am NOT sure that we would
generate sidebands, like 'normal' modulation would. [how does one photon
know that those ahead of it or behind it have been absorbed?]

If we chopped it fine enough, we should have a single photon, of known
energy/wavelength/frequency. We would almost certainly NOT know its exact
position, however. I think time would be the expresion of uncertanty.

Logic says that a pulse can not be shorter than the time it takes to
create
a single photon. It would also seem to say that a single photon can not
"be
longer" than the shortest laser pulse.

I put length in quotes because IMHO a photon
is a particle, but I think this is another
aspect of duality.

This review of techniques will give you a bit of an overview of the
field.
http://phys.strath.ac.uk/alpha-x/Ass...time-resolved-
spectroscopy-2003.pdf

Excellent stuff, it will take me some time
to read that but thanks!

Quite welcome.




--
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