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Simon Bridge
21st January 2006, 06:30 PM
http://physics.prodos.org/
http://www.yankee.us.com/TEW/TEW96paper.html

On surface, it seems to be a bit of a mixed metaphore with nothing actually new... a photon is a partical because it has a return wave as well as a transmittion wave? Come on - is it a wave or a partical.

I'd personally like to see the TEM (also means Tunneling Electron Microscope BTW) explaination for the double slit experiment.

Something like this comes up every now and again ... there is a tendancy to forget that a new theory has to make some prediction which is not accounted for in the old one as well as account for everything in the old one. So, it seems what we have here may be yet another metaphore - way of imagining what is going on.

Simon Bridge
21st January 2006, 06:33 PM

I showed you a support forum in the last post. Now a debunking page. It's only fair.

21st January 2006, 06:34 PM
If the predictions are the same its another stupid metaphor for what's going on.

Note: there are no non-stupid metaphors for QD.

Simon Bridge
21st January 2006, 07:00 PM
hah - I got my wish, I guess... perusing the essay:

The basic youngs-interference setup is shown, and the following observation:if the screen is moved to position B, clearly the particles from each slit, and still following those same trajectories, will no longer arrive at the same points on the screen; the particles from one slit will fall somewhere between the points of impact of the particles from the other slit. The pattern would then be washed out. And yet a similar wave pattern is observed at all screen distances.

If the particles are assumed to be particles, and if they follow straight lines between the slits and the screen, there is only one conclusion that can be drawn: the trajectories depend on the screen position. If one moves the screen the particles follow different trajectories. I think this shows a fundamental misunderstanding of the phenomina.

While the particals would arrive at different points on the screen, it is easy to show that the pattern wuld not be "washed out". This isn't like focusing an image wth a lense - you'd just get a different pattern. In this case, the maxima (the regeons on the screen where the most particals arrive) will be more closely spaced.

Simon Bridge
21st January 2006, 07:03 PM
If the predictions are the same its another stupid metaphor for what's going on.

Note: there are no non-stupid metaphors for QD.The word "stupid" comes from you. I just said it is a metaphore.

Of course, a theory that describes everything known, but nothing extra, from a different standpoint may still be useful. Even ideas that are demonstrably wrong can be interesting and generate insights.

I'm having trouble believing that this is one of them.

It turns out I didn't need to look quite as hard as I thought to find the "stupid" part though. Have you read the essay?

sionep
21st January 2006, 08:41 PM

I showed you a support forum in the last post. Now a debunking page. It's only fair.

Here is a response from the TEW newsgroup moderator Dr. Stephen Speicher to the author of the article above:

http://groups.yahoo.com/group/TEWLIP/message/494

sionep
21st January 2006, 08:54 PM

I showed you a support forum in the last post. Now a debunking page. It's only fair.

I have seen the video of Dr. Lewis Little doing a presentation of TEW at Caltech. The paradox mentioned in the essay shown above, about gravitational lens is decoded very clearly by Dr. Lewis in his Caltech lecture, since he was answering a similar question originated from the audience. I would not be surprised if it was Tom Radcliffe from the audience who asked that question, since there was no microphone for the audience, the quality of the sound from that question was not that clearly heard. Anyway, Dr. Little, was on the board detailing of how TEW solve that problem.

I believe that the video is available at Caltech Department of Physics, it may be available at the general library for borrowing. I would find out more if it is available in the general library or not.

I saw this video in 2000, so I have to ask my 'Objectivist' friend , to borrow the tape so I can see it again and try to understand more on TEWs reply to gravitational lens.

Soapy Sam
22nd January 2006, 12:02 AM
'However, if the screen is moved to position B, clearly the particles from each slit, and still following those same trajectories, will no longer arrive at the same points on the screen; the particles from one slit will fall somewhere between the points of impact of the particles from the other slit. The pattern would then be washed out. And yet a similar wave pattern is observed at all screen distances. '- Quoted from "The Theory of Elementary Waves" , by Dr.L.Little.

Can I ask an elementary question. I have read much about the two slit experiment, but like weighing a goldfish in water, I have never seen it actually done. Nor have I met anyone who has actually seen it done, so far as I know.
Who here has actual, personal experience of performing the two slit experiment? Can any such person confirm that the result on the screen is always the same, whatever the position of the screen?

Also- and I apologise for the banality of these questions-
"Suppose further that the particles, once emitted in response to the wave from a particular point on the screen, are causally determined to follow that wave to that point on the screen. "
1. If the quantum wave arriving at the emitter stimulates the emission of the particle, how can the particle "follow" it? The wave has already arrived and in any case following is impossible as the wave and particle move in opposite directions. Does the wave somehow create a path for the particle to take? If so what form does this path take and in what does the path exist?
2. What is actually waving when a quantum wave travels? Are we back to the ether?
3. Surely if we fire photons through the slits, they are generated by a finger on a button, not by the arrival of waves from the far side of the slit. Is Little saying that no matter how much energy we pump into a light bulb, if it's not possible for anywhere to be lit by the bulb it simply won't emit any light, because no qwaves will arrive from anywhere able to be reached by the photons? If the bulb is inside the Schwarzchild radius of a black hole, can it receive quantum waves from outside the black hole or from inside? In which direction then can it emit photons?
ETA-

1a."The wave is present at all times, and not only when the particle is emitted. There is thus no problem in explaining why the wave is present when the particle `needs' it."
How can a wave be present at all times? Is this Tennyson's "wave that runs for ever?" A wave is a dynamic entity, defined by movement- or is this some sort of standing wave? So how does it get from the screen to the emitter ?(Sorry if this is explained later in the article. If I don't note it now, I will become more befuddled as I go on.)

Gah! I see all my queries are indeed addressed later. I'll shut up till I've read the whole thing.

sionep
22nd January 2006, 04:05 AM
[I][B]

Can I ask an elementary question. I have read much about the two slit experiment, but like weighing a goldfish in water, I have never seen it actually done. Nor have I met anyone who has actually seen it done, so far as I know.
Who here has actual, personal experience of performing the two slit experiment? Can any such person confirm that the result on the screen is always the same, whatever the position of the screen?

I did the double slit experiment using germanium-doped laser, however the experiment was an Optics experiment rather than a 'Quantum Mechanics' one. The experiment was to measure the following parameters:

- double slit grid space,
- slit to screen distance
- source to slit distance
- distance between max interference (usually first and second)

By measuring the parameters described above, you are then able to calculate the frequency of the laser source and its half-width bandwidth. The frequency of the source is clearly labelled on the laser by the manufacture, however the aim is for the student to find this out by conducting experiment. So, the experiment is purely a geometrical OPTICS rather than testing Schrodingers Cat. I did this more than 10 years ago, so I can’t remember about the double slit whether it was distance independent or not.

A classmate of mine did the one that confirms the duality of photon. The apparatus set-up for that one is a bit complicated because it involved 2 laser sources, with one is a multiple source (shooting many photons continuously) and the other one is a single source (shooting a single photon pulse one at a time). This apparatus was also housed in the same dark room as the experiment that I was doing. There were 6 different apparatuses in the dark room. I chose the easiest one of them all (two 3-hour lab sessions) as compared to the others that took three to four 3-hour lab sessions to complete.

My classmate experiment's aim was to use the multiple source laser to observe the diffraction pattern on the screen, which confirmed the wave-property. Then the single source laser source was used to fire a single photon per unit time through the double slit. The rate of photon emission here was tuneable, but it was set at one photon per every 50 milliseconds. The screen was a fluorescence detector that glows whenever a photon impinges on it, which it is quite clear in the dark room. This is left to run for about an hour, where the build up on the screen shows interference pattern (maximum & minimum). Here is how QM interprets the result. Since there is interference observed, the photon is a wave. This is strange since only one photon at a time that was shooting through the double slits. This implies that the photon did interfere with itself and formed the observe patterns on screen. It follows that the particle went through hole A and hole B simultaneously to account for the interference observed. How absurd is this, that a material object say for example, can be in England and Paris at the same time (simultaneously).

The second part was to position 2 transparent semi conducting films in front of each holes from the double slit, which were connected into a photo counter, that would register if the single photon went through hole A or hole B of the double slits. The experiment is repeated then run for another hour. The amazing thing is that the interference patterns disappears and thus form the classical bell-shaped (gaussian distribution) pattern. That is maximum in the middle and faded away to both sides of the middle. In fact this is what pattern you would expect if you were shooting billiard balls through big double slits, so you are observing particles here. Here is what QM says, since you the observer (experimenter) decides what to measure (decide what to look for), you are then creating reality yourself. If you want to measure wave, all you do is remove the 2 transparent semi conducting films and run the experiment, then observe waves ( interference pattern on screen). If you want to measure particle, then all you do is position the 2 transparent semi conducting films in front of the double slits, run the experiment, then observe the bell shape distribution of the intensities on screen which is property of being a particle, that is the interference pattern disappears. All of these are that the observer creates reality rather than reality existed independently of the observer. In QM the photon is suppose to exist as a particle and wave simultaneously until you (the observer) measure it (or look) and then only one possibility materialise, either a wave or a particle. Take note that the observer is running the show; he/she is the one creating reality. This is what haunted Einstein, which prompted him to look if QM is incomplete.

I have contacted Stephen Speicher who maintained the TEW discussion group to comment on your other questions.

Soapy Sam
22nd January 2006, 07:16 AM
Thanks you for that, sionep. As with boats vanishing hull down over the horizon, this is one of those iconic tests of scientific thinking which we tend to take for granted that someone else has actually done.

I copied Simon's first linked reference above to a USB stick and am working my way through it offline.
Right up front, let me state my maths & physics is high school level, forty years old and not great even when I was there, so my understanding of it relies wholly on the text. I've read many popular science writers on the subject of QM and have a decent popsci grasp of the matter, but no more.
I must say I am therefore impressed by the comprehensibility of Dr.Little's verbal explanation. It covers a great deal of ground and is remarkably understandable to this lay reader. I remain puzzled about much of it, but I have a lot still to read.

I'd be keen to know if a double delay experiment has been done incorporating his suggested alteration to Alain Aspect's timing parameters.

I have always found "explanations" of quantum uncertainty, entanglement and wave-particle duality disturbingly unsatisfying. It feels wrong. I don't think the writers believe it, even as they trot out the dogma.

A local , causal model would be far more emotionally satisfying to me. Still I prefer ugly facts to beautiful theories, so I will be interested also by the refutation Simon posted. This could take me a while...

Fascinating thread. Thank you too, Simon.

Incidentally, Tennyson's line is from "The Lady of Shalott" I always thought it would be a good title for a John Gribbin book.

Wire
22nd January 2006, 01:49 PM
The amazing thing is that the interference patterns disappears and thus form the classical bell-shaped (gaussian distribution) pattern. That is maximum in the middle and faded away to both sides of the middle. In fact this is what pattern you would expect if you were shooting billiard balls through big double slits, so you are observing particles here.

Maybe a bit silly question, but does it mean that diffraction also disappears?

Dilb
22nd January 2006, 07:02 PM
Here is what QM says, since you the observer (experimenter) decides what to measure (decide what to look for), you are then creating reality yourself. If you want to measure wave, all you do is remove the 2 transparent semi conducting films and run the experiment, then observe waves ( interference pattern on screen). If you want to measure particle, then all you do is position the 2 transparent semi conducting films in front of the double slits, run the experiment, then observe the bell shape distribution of the intensities on screen which is property of being a particle, that is the interference pattern disappears. All of these are that the observer creates reality rather than reality existed independently of the observer. In QM the photon is suppose to exist as a particle and wave simultaneously until you (the observer) measure it (or look) and then only one possibility materialise, either a wave or a particle. Take note that the observer is running the show; he/she is the one creating reality. This is what haunted Einstein, which prompted him to look if QM is incomplete.

That's rather different then the way I'm learning it. The wave-particle duality says that for any event, the "wavicle" (not a popular term, as I understand) behaives either as a particle or a wave, depending on the event. What is happening is that you can't observe a photon without destroying it, although you might create a new photon which is very similar. By observing the photon as it comes through the slits, you collapse the probability function of the photon and observe it like a particle. The leftover energy that continues on as a photon then propegates as a wave from it's source, which is after the slits, and therefore doesn't interfere with anything.

And I don't think Einstein was bother by wavicles, especially as he won the Nobel prize for his work on the particle nature of light, despite the fact that at that time the double slit experiment was well known, and proved light behaived like a wave. What bothered Einstein was the fact that QM, out of a necessity of the mathematics, discribes the real world as lacking information, which means that quantum physics is limited to statistical, rather than deterministic, results.

sionep
22nd January 2006, 11:50 PM
By observing the photon as it comes through the slits, you collapse the probability function of the photon and observe it like a particle.

Do you think that "Probability function" is a PHYSICAL construct or MATHEMATICAL construct ? It is a purely MATHEMATICAL construct and has no physical meaning at all. It is not like physical properties as spins, momentum, energy, which are REAL PHYSICAL constructs.

The leftover energy that continues on as a photon then propegates as a wave from it's source, which is after the slits, and therefore doesn't interfere with anything.

How about if your source is not photons (as in lasers) but a beam of protons or a beam of electrons? You know that these are real particles. If you use the same double slits set-up as described above , what do you expect to observe ? Exactly , the same thing. You will still see the interference on screen when you (observer) don't know which hole (slit hole A or slit hole B) that each particle (proton, electron, alpha, etc...) has gone through. This means that the beam of protons particles is wave , wave property is observed here. If you then place some counters in front of both slit holes , i.e., hole A and hole B, so as the counters do not disturb (do not altered its momentum or its kinetic energy) into a substantial amount, so that the observer know exactly which hole that each proton traverses, the screen interference patterns disappear all of a sudden. The only thing you observe on screen is a bright spot aligning directly between the mid-point of the slit holes, and fades exponentially either sides of this maximum spot (intensity). Suppose that the observer (experimenter) slows the rate of proton emissions to one/per second, then shoot each through the double slits with photo-counters in place that a beep sound is set off if the proton goes through hole A or hole B. Lets say that the observer runs the experiment for a while that the total number of protons (particles) emitted by the generator is 1000. Assume that following sequence is what the counter detected of which hole each particle went through. The following sequence is one I made up, but it is enough to make you understand of what the diffraction pattern of a single particle emission source is all about.

A,B,B,B,B,A,A,B,B,A,B,B,B,.... 1000

The fact that the observer now knows which slit holes each particle traversed because of the counters, the protons are now particles. If the slit hole detectors are now removed, then you observe interference on screen which means you are detecting waves. PROTON WAVES ? YES for the reasons of particle wave-duality. NOW, what happens if we replace our proton or electron emission source with atoms such as helium source ? Use the same experimental set-up as described previously. Say the rate of the source emission is set at one helium atom per second. Repeat the experiment by shooting helium atom through the double slit one at the time with no detectors to tell which slit holes each atom went through. Allow this to build up on screen for a while, then finally the interference pattern is observed. HELIUM atom interfering with itself ? Now, the same procedure is again followed by positioning the slit hole detectors in front of the holes (hole A and hole B). Run the experiment again and allow enough time to build up on screen. AND now what ? The interference pattern has just disappeared. You only observe the classical distribution of the gaussian bell-shaped of intensities on screen. The atom version double slits has been done, but not exactly the same set-up as described here. On top of my hat, I am not sure whether it has been done with molecules yet, BUT the result would be exactly the same as has been with photons or protons or helium atoms. Property of a particle in Newtonian Physics is that it must traverse a defined trajectory. This is what happened when the observer knows exactly which hole (A or B) that each particle went through when he placed slit detectors to tell if particle 1 went through hole B, particle 2 went through hole B , particle 3 went through hole A, ..., particle 1000 went through hole B. The fact that the observer is observing particles as when he placed counters at slit holes, MAKE the observer decides that the helium atoms are? He decides that they should be particles and therefore his experiment gave him exactly that. If he then removed the slit detectors, which also made him lost his knowledge of which hole A or B that each particle went through. The minute that he does not know the trajectory of how each helium particle made their way to the screen (did it go thru hole A or B?), the OBSERVER is deciding to see WAVE. Now the observer is now telling (bossing) nature of what he/she wants it to be.

And I don't think Einstein was bother by wavicles, especially as he won the Nobel prize for his work on the particle nature of light, despite the fact that at that time the double slit experiment was well known, and proved light behaived like a wave.

Einstein was not bothered about the photon particle properties, UNTIL the technology had advanced from his 'Photo-electric Effect' paper in 1905. When sub-atomic particles had started been discovered (late 1920s), the use of particle source other than photons, such as protons, electrons beams, became common then. He thought that protons must be a particle at all time and not be a wave, however scattering experiments in early days, showed that they also have wave properties.

What bothered Einstein was the fact that QM, out of a necessity of the mathematics, describes the real world as lacking information, which means that quantum physics is limited to statistical, rather than deterministic, results.

Einstein bothered most by the absurdities philosophy of QM. Einstein and Bose (Indian Physicist) developed the so called Bose-Einstein quantum statistics. This statistics is obeyed by all Boson particles, which are particles with integral spins (0,1, 2, 3, 4, …). The other statistics is called Fermi statistics, which is obeyed by Fermion particles, which are particles with half integral spin (1/2, 3/2, 5/2, …). This was developed by Enrico Fermi (Italian Physist). The universe contains only bosons and fermions. So it is not the statistics of QM that Einstein was worried about , but about the assertion of QM that reality is observer dependent rather he thought that reality ought to be independent of the observer.

Simon Bridge
23rd January 2006, 02:49 AM
I have done the double-slit experiment many times. It is a standard experiment given to students at all levels - much like rolling things down planks and timing pendulums (pendulae?)

I have done it with water waves, photons from sodium lamps, photons from He-Ne lasers, and protons from a partical accelerator.

The whole thing is a solid experiment. The results are not contraversial. However, I find that the QM description given to the lay public is very unsatisfactory. Basically, the writers are more interested in impressing the reader that this is sooo strange and mysterious.

The best description of this thing I've seen comes from Richard Feynman in his lecture tour. I had the priviledge of attending some of his lectures when he visited Auckland (forget the date) when I was a very young student.

You can do the experiment yourself:

Get a small bit of glass (think microscope slide here) stick one of your own hairs across it. This is your target - you don't need actual slits.

Get one of those laser pointers - you may need a lense to get a parralell beam - let me know and I'll tell you how to do that, but it should work well without it. If you cannot get a laser pointer (they are illegal in some countries) then a bright lamp and a lense will work just as well.

In a very dark room, shine the beam through the glass (so the hair is pretty dead on) and look at a distant wall (about 2 meters should do it).

You'd expect to see a spot of light with, maybe, a line through it right? What you actually see is a row of spots. It goes right across the wall, getting fainter and fainter.

This sort of intereference is called Youngs Interference. It occurs when the object in the way of the beam has a size comparable to the wavelength of the light.

There is always a big bright spot in the middle. The other spots are numbered from here (counting the bright spot as zero). The separation between the spots (x) is related to the wavelength of the light (L, written on the laser) and the width of the hair (w) and the distance from glass to wall (d) ... the relationship is typically written as follows:
$\frac{L}{w}=\frac{x}{d}$

However, diffraction happens at any edge where you get a shadow. This is Frauenhoffer diffraction. There is a diffraction pattern through big slits like doorways - it shows up as a slight bleeding of light into the classical (Newtonian) shadow regeon. Careful measurements will show a ripple-effect between light and dark bands right at the edge of the light.

If you have never done the experiment before, go do it.

In the QM (Wave Mechanics) description we have to be very careful about what we say we are doing. The distinction between what is a convenient bit of math and what is actually going on is very fine indeed.

The "wave-partical duality" does not exist. It is a convenient bit of fudging for journalists and it sounds cool. To illustrate - get a coin out of your pocket. Is it heads or tails?

Well - depends which side you look at right? But would you say the coin exhibits head-tail duality?

This is illustration only - but you get the idea right?

You could divide coins into type:heads and type:tails, but this wouldn't be useful. It is much more useful to divide them by currency and value right? Similarily it is not useful to describe fundamental stuff as classical particles or classical waves.

The usual thing, since we have to call them something, is to talk about QM particles. This is what Dirac and Feynman and all the rest are talking about.

These are described quantum-mechanically. This is a whole different ballgame, though it includes all Newtonian mechanics and is mostly compatable to relativity. You have to get your head around some concepts that seem pretty way out at first.

But it is a bit like when you first learned Newton's laws... objects keep going unless they are forced to do something else? This is not obvious - surely you gotta keep pushing things to keep them moving? Push that big roller along a level feild and I'm not doing any work? But how come I'm tired? And what do you mean "I can't tell if I'm the one moving or not": I still get a speeding ticket!

After a while you get used to the POV.

So I get a little tired when people tell me that QM is mysterious or difficult. That's just an excuse for not trying.

The main trouble is the Wave Mechanics is fundamentally statistical. People commonly misunderstand probability, as many threads on this site attest to. That is actually the main set of concepts you need to get a handle on.

What we do with Wave Mechanics is we work out the probability of detecting a partical at a given spot in space. We do this by working out all the ways the partical could have got from the source to the point.

Each possible pathway works out to a particular "phase" for the particle's "wave" at that point. What we do is we add up all the waves. The square of the result is the probability of finding the particle at that spot.

We can do this for all possible spots and then build a picture - though usually we are only interested in particular spots... like on a screen.

In the two-slit experiment, there are (ideally) only two possible paths from source to screen. So the maths is nice and easy.

Pass one particle through the equipment and you will only get one "hit" on the screen. As far as the screen is concerned, the momentum and energy of the photon arrives as a single blip.

However, the distribution of hits is the same as the probability distribution calculated previously.

If there is only one slit - the previous method of calculation produces the pattern for a classical particle.

We can even use the same apparatus - cover a slit - and we get the classical result fair enough.

The question is - how does the particle know there are two slits in the first place?

So the theory successfully describes both the classical and the non-classical behaviour. So it is a successful theory. However, it is ambiguous about how the particles actually do this trick. It is even ambiguous whether the question actually means anything in terms of empiricle science.

It can help get some idea about how things go if we consider something everyone has experienced. Reflection.

This is non-contraversial and non-ambiguous. We've all done the experiments about the law of reflection right? Angle of reflection is equal to the angle of incedence. If we measure angles from the norm, it even works for curved mirrors.

However, in QM, we have to look at all the possible ways a photon can get from the source to the detector. If the source and the detector are fixed, then it would appear there is only one path right? (draw the picture.)

Oh no - because we consider paths where the angles are not equal.

The phase of the photon's wave is worked out for each (im)possible path, the total squared, and you get the result you know and love. Only, in this picture, you need all the wave from all the paths to get the right (classical) result ... so, while the vast majority of the photons follow paths close to the classical one, some photons must be travelling wildly unclassical paths.

But but but ... because of the way waves add together, some of them add constructively and some destructively. Since the condition of the wave depends only on the path, which depends only on the point of reflection, then we can figure out all the points of reflection where the destructive waves come from and physically remove the mirror! In which case, we would get only constructive waves - and the intesity of the light at the detector would be increased!

It has been done - and it worked. By removing a bit more than half the actual mirror, you can get a brighter reflection (though only for one wavelength).

This is very clear: the law of reflection is wrong.

Now to get to where this is understandable and not weird takes a while.

Simon Bridge
23rd January 2006, 03:29 AM
How about if your source is not photons (as in lasers) but a beam of protons or a beam of electrons? You know that these are real particles. If you use the same double slits set-up as described above , what do you expect to observe ? Exactly , the same thing. You will still see the interference on screen when you (observer) don't know which hole (slit hole A or slit hole B) that each particle (proton, electron, alpha, etc...) has gone through. This means that the beam of protons particles is wave , wave property is observed here. If you then place some counters in front of both slit holes , i.e., hole A and hole B, so as the counters do not disturb (do not altered its momentum or its kinetic energy) into a substantial amount, so that the observer know exactly which hole that each proton traverses, the screen interference patterns disappear all of a sudden.Yes... the detectors are in the way. The only thing you observe on screen is a bright spot aligning directly between the mid-point of the slit holes, and fades exponentially either sides of this maximum spot (intensity). Really? Do you have a reference for this? It would have to be a very special detector to figure which hole is passed thorugh "exactly" and not disturb the momentum "significantly". Suppose that the observer (experimenter) slows the rate of proton emissions to one/per second, then shoot each through the double slits with photo-counters in place that a beep sound is set off if the proton goes through hole A or hole B. Lets say that the observer runs the experiment for a while that the total number of protons (particles) emitted by the generator is 1000. Assume that following sequence is what the counter detected of which hole each particle went through. The following sequence is one I made up, but it is enough to make you understand of what the diffraction pattern of a single particle emission source is all about.

A,B,B,B,B,A,A,B,B,A,B,B,B,.... 1000

The fact that the observer now knows which slit holes each particle traversed because of the counters, the protons are now particles.No they're not - they will still exhibit wave behaviour. (provided you didn't stop them completely when you got your "beep".) This is easily demonstrated by putting them through another double-slit apparatus. If the slit hole detectors are now removed, then you observe interference on screen which means you are detecting waves. PROTON WAVES ? YES for the reasons of particle wave-duality. Well, you are observing wave-like behaviour. The wave is from the wave-function. There is a confusion with classical waves which require a medium... like with water waves.NOW, what happens if we replace our proton or electron emission source with atoms such as helium source ? Use the same experimental set-up as described previously.Adjusted of course for the deBroglie wavelength of the helium :) Say the rate of the source emission is set at one helium atom per second.Can you show how you would arrainge this? You can have, say, a chamber with He gas inside and a valve. The valve can be set to dribble helium through... but the position of any He atom in the chamber is statistical (in the classical sence), it's speed et al random, so the best you could manage is to turn the dribble down so that it is very unlikely that more than one He atom traverses the apparatus at a time. The 1Hz frequency will not happen. Repeat the experiment by shooting helium atom through the double slit one at the time with no detectors to tell which slit holes each atom went through. Allow this to build up on screen for a while, then finally the interference pattern is observed. HELIUM atom interfering with itself ? Now, the same procedure is again followed by positioning the slit hole detectors in front of the holes (hole A and hole B). Run the experiment again and allow enough time to build up on screen. AND now what ? The interference pattern has just disappeared. You only observe the classical distribution of the gaussian bell-shaped of intensities on screen. Well of course - the detectors have interfered with the symmetry of the experiment.Property of a particle in Newtonian Physics is that it must traverse a defined trajectory. This is what happened when the observer knows exactly which hole (A or B) that each particle went through when he placed slit detectors to tell if particle 1 went through hole B, particle 2 went through hole B , particle 3 went through hole A, ..., particle 1000 went through hole B. The fact that the observer is observing particles as when he placed counters at slit holes, MAKE the observer decides that the helium atoms are? He decides that they should be particles and therefore his experiment gave him exactly that. If he then removed the slit detectors, which also made him lost his knowledge of which hole A or B that each particle went through. The minute that he does not know the trajectory of how each helium particle made their way to the screen (did it go thru hole A or B?), the OBSERVER is deciding to see WAVE. Now the observer is now telling (bossing) nature of what he/she wants it to be.This is very bold... telling nature what it is going to be! What a powerful person you must be ;)

The "observer" in QM is a technical term and need not refer to a sentience of any kind. In this case, the detectors and the screen are "observers". They interact with the photons/atoms/etc. Particles go from one interaction to another describing a complex web in space-time. They can do this without the intervention of a single human being.

You are not telling a photon (say) to be a wave or a partical. It is just that you are looking at it differently.

When you look at a coin, you don't tell it wether it is heads or tails. The coin is telling you. If you looked at it differently you would get a different answer - but it is the same coin. A coin can exhibit heads-like behaviour and tails-like behaviour. It is not one or the other. It is not even both together. The coin dosn't care if you like this or not. It is a coin.

Einstein bothered most by the absurdities philosophy of QM.[snip]it is not the statistics of QM that Einstein was worried about , but about the assertion of QM that reality is observer dependent rather he thought that reality ought to be independent of the observer.Mostly it was the wave mechanics picture of quantum statistics. The Bose-Einstein statistics are classical statistics associated with thermal populations of quantum energy levels in solids. Classical statistics describe what we know about the state of the system. Einstein had no trouble with the idea that humans may not know everything. However, he felt that there was an underlying order to the universe, and it is only our imperfect knowledge that gives rise to randomness. However, as his famouse argument with Neils Bohr attest, the very ideas he helped to popularise seemed to be showing that the universe was fundamentally random.

However - the saught to demonstrate flaws in the quantum theory. He argued one side and Bohr the other of simply ages. No firm conclusion was reached. You can read their letters and see for yourself.

He wasn't the first scientists whose discoveries disturbed him. Newton had trouble with the mechanistic/deterministic universe his theories seemed to show. Where was free will? Where was divine intervention?

But you are right in that his objections were at heart philosophical ones. He didn't like it. Unfortunately, the theories persist in being very good at describing the universe. The universe dosn't care if Einstein likes it or not. It just is.

Simon Bridge
23rd January 2006, 03:41 AM
That's rather different then the way I'm learning it. The wave-particle duality says that for any event, the "wavicle" (not a popular term, as I understand) behaives either as a particle or a wave, depending on the event. What is happening is that you can't observe a photon without destroying it, although you might create a new photon which is very similar. By observing the photon as it comes through the slits, you collapse the probability function of the photon and observe it like a particle. The leftover energy that continues on as a photon then propegates as a wave from it's source, which is after the slits, and therefore doesn't interfere with anything.That is pretty much it. These days nobody seriously uses the ideas of wave-particle duality. Particles are particles are particles. If we want to make a distiction, we refer to classical behaviour - which occurs only on average. Basically, what you see depends on how you look.

Talking about "events" is useful. An interaction is a "measurement" and any measurement is and "observation".

And I don't think Einstein was bother by wavicles, especially as he won the Nobel prize for his work on the particle nature of light, despite the fact that at that time the double slit experiment was well known, and proved light behaived like a wave. What bothered Einstein was the fact that QM, out of a necessity of the mathematics, discribes the real world as lacking information, which means that quantum physics is limited to statistical, rather than deterministic, results.

Einstein got the Nobel Prize for his work on the photo-electric effect... well done. Most people think it was for relativity.

What you say bothered Einstein is pretty much what he told Bohr. (This is where I'd have liked to have a searchable source of the Bohr-Einstein letters.)

Simon Bridge
23rd January 2006, 03:49 AM
Here is a response from the TEW newsgroup moderator Dr. Stephen Speicher to the author of the article above:

http://groups.yahoo.com/group/TEWLIP/message/494That's no good. The responce is only to say that there will be no responce.

Tom's article was entirely a critique of the essay. It was not a formal refutation of the theory. The strongest point was that the essay did not make a strong case for TEW as a worthwhile theory.

Having peer-reviewed articles for other publications, I'm rather surprised the essay made it into print. However, I note that the journal says they give a lot of leeway to authors. Authors are given the peer-review notes and the option to use any, all, or none of them to improve the article. The editors do not say if the article is re-submitted for peer-review or what. Presumably (hopefully) yes. I wonder who reviewed it? Practically anyone would come up with the same objections using the text of the essay alone.

Sorry - TEW proponents will have to do better than that.

sionep
23rd January 2006, 04:03 AM
I have done the double-slit experiment many times. It is a standard experiment given to students at all levels - much like rolling things down planks and timing pendulums (pendulae?)

I have done it with water waves, photons from sodium lamps, photons from He-Ne lasers, and protons from a partical accelerator.

The whole thing is a solid experiment. The results are not contraversial. However, I find that the QM description given to the lay public is very unsatisfactory. Basically, the writers are more interested in impressing the reader that this is sooo strange and mysterious.

The best description of this thing I've seen comes from Richard Feynman in his lecture tour. I had the priviledge of attending some of his lectures when he visited Auckland (forget the date) when I was a very young student.

You can do the experiment yourself:

Get a small bit of glass (think microscope slide here) stick one of your own hairs across it. This is your target - you don't need actual slits.

Get one of those laser pointers - you may need a lense to get a parralell beam - let me know and I'll tell you how to do that, but it should work well without it. If you cannot get a laser pointer (they are illegal in some countries) then a bright lamp and a lense will work just as well.

In a very dark room, shine the beam through the glass (so the hair is pretty dead on) and look at a distant wall (about 2 meters should do it).

You'd expect to see a spot of light with, maybe, a line through it right? What you actually see is a row of spots. It goes right across the wall, getting fainter and fainter.

This sort of intereference is called Youngs Interference. It occurs when the object in the way of the beam has a size comparable to the wavelength of the light.

There is always a big bright spot in the middle. The other spots are numbered from here (counting the bright spot as zero). The separation between the spots (x) is related to the wavelength of the light (L, written on the laser) and the width of the hair (w) and the distance from glass to wall (d) ... the relationship is typically written as follows:
$\frac{L}{w}=\frac{x}{d}$

However, diffraction happens at any edge where you get a shadow. This is Frauenhoffer diffraction. There is a diffraction pattern through big slits like doorways - it shows up as a slight bleeding of light into the classical (Newtonian) shadow regeon. Careful measurements will show a ripple-effect between light and dark bands right at the edge of the light.

If you have never done the experiment before, go do it.

In the QM (Wave Mechanics) description we have to be very careful about what we say we are doing. The distinction between what is a convenient bit of math and what is actually going on is very fine indeed.

The "wave-partical duality" does not exist. It is a convenient bit of fudging for journalists and it sounds cool. To illustrate - get a coin out of your pocket. Is it heads or tails?

Well - depends which side you look at right? But would you say the coin exhibits head-tail duality?

This is illustration only - but you get the idea right?

You could divide coins into type:heads and type:tails, but this wouldn't be useful. It is much more useful to divide them by currency and value right? Similarily it is not useful to describe fundamental stuff as classical particles or classical waves.

The usual thing, since we have to call them something, is to talk about QM particles. This is what Dirac and Feynman and all the rest are talking about.

These are described quantum-mechanically. This is a whole different ballgame, though it includes all Newtonian mechanics and is mostly compatable to relativity. You have to get your head around some concepts that seem pretty way out at first.

But it is a bit like when you first learned Newton's laws... objects keep going unless they are forced to do something else? This is not obvious - surely you gotta keep pushing things to keep them moving? Push that big roller along a level feild and I'm not doing any work? But how come I'm tired? And what do you mean "I can't tell if I'm the one moving or not": I still get a speeding ticket!

After a while you get used to the POV.

So I get a little tired when people tell me that QM is mysterious or difficult. That's just an excuse for not trying.

The main trouble is the Wave Mechanics is fundamentally statistical. People commonly misunderstand probability, as many threads on this site attest to. That is actually the main set of concepts you need to get a handle on.

What we do with Wave Mechanics is we work out the probability of detecting a partical at a given spot in space. We do this by working out all the ways the partical could have got from the source to the point.

Each possible pathway works out to a particular "phase" for the particle's "wave" at that point. What we do is we add up all the waves. The square of the result is the probability of finding the particle at that spot.

We can do this for all possible spots and then build a picture - though usually we are only interested in particular spots... like on a screen.

In the two-slit experiment, there are (ideally) only two possible paths from source to screen. So the maths is nice and easy.

Pass one particle through the equipment and you will only get one "hit" on the screen. As far as the screen is concerned, the momentum and energy of the photon arrives as a single blip.

However, the distribution of hits is the same as the probability distribution calculated previously.

If there is only one slit - the previous method of calculation produces the pattern for a classical particle.

We can even use the same apparatus - cover a slit - and we get the classical result fair enough.

The question is - how does the particle know there are two slits in the first place?

So the theory successfully describes both the classical and the non-classical behaviour. So it is a successful theory. However, it is ambiguous about how the particles actually do this trick. It is even ambiguous whether the question actually means anything in terms of empiricle science.

It can help get some idea about how things go if we consider something everyone has experienced. Reflection.

This is non-contraversial and non-ambiguous. We've all done the experiments about the law of reflection right? Angle of reflection is equal to the angle of incedence. If we measure angles from the norm, it even works for curved mirrors.

However, in QM, we have to look at all the possible ways a photon can get from the source to the detector. If the source and the detector are fixed, then it would appear there is only one path right? (draw the picture.)

Oh no - because we consider paths where the angles are not equal.

The phase of the photon's wave is worked out for each (im)possible path, the total squared, and you get the result you know and love. Only, in this picture, you need all the wave from all the paths to get the right (classical) result ... so, while the vast majority of the photons follow paths close to the classical one, some photons must be travelling wildly unclassical paths.

But but but ... because of the way waves add together, some of them add constructively and some destructively. Since the condition of the wave depends only on the path, which depends only on the point of reflection, then we can figure out all the points of reflection where the destructive waves come from and physically remove the mirror! In which case, we would get only constructive waves - and the intesity of the light at the detector would be increased!

It has been done - and it worked. By removing a bit more than half the actual mirror, you can get a brighter reflection (though only for one wavelength).

This is very clear: the law of reflection is wrong.

Now to get to where this is understandable and not weird takes a while.

Simon,

Obviously, you are another Kiwi ? I assume you went to Auckland, perhaps way before I enrolled in my first year? I was there at Auckland when Prof. Alan Polleti (Nuclear Physics) , Prof. Orange , Prof. Dan Walls (Quantum Mechanics) , Dr. Bold (Acoustics & Signal Processing) , Prof. John Harvey (Laser Physics & Optical Electronics), Prof. Garret (Nuclear Physics), Prof. Paul Barker (Nuclear Physics), Prof. Yolk (Astrophysics) . Only Harvey, Barker, Yolk and Bold are still at the Department. I noted that you have done the water waves experiment. I did that one too. The dark room has been relocated to the ground floor, however the advanced laser projects has to be done at the Opto-electronics lab (6th floor), a completely clean room (no dust or anything like that up there which might diffract laser light beams that are pointing everywhere). First floor, which used to be Physics lab is now occupied by computer science department. AURA-2 (the nuclear accelerator building) has been demolished to make way for the computer science department's new building. Paul Barker told me recently that students who are doing research in nuclear physics have to travel to Mt. Albert to use the government's linear accelerator over there, because the University has none. Great experience at AURA-2 in doing the proton scattering experiment , where a group of 4 people (including myself) did the experiment , which ran for 3 weeks.

Where are you based ? I am in Ponsonby. I came to know this forum (JREF) via the NZ Skeptics newsletter.

If you are in Auckland, then please send me a mail using the forum's private message.

I have made contact with an objectivist friend of mine who has the TEW video if we can run through it again. We did see the video in 2000 with most of the Libertarians in Auckland attended. They are all Ayan Rand followers apart from me, who truly believe in causality. They are thinking of running a series of Physics lecture tapes title ‘Philosophical Corruption in Physics’ by a Physicist named David Harriman perhaps in about the kick off of the rugby super-14 (mid-February) , on every second Saturday of the month. It is BBQ and drinks, plus debating Physics. If you want to attend then please let me know. It would be good to have another Physicist, in the debate since I find myself debating on my own facing a whole platoon of objectivists who put more emphasize on philosophical grounds and less on experimental physics evidence. Their point is always, ‘philosophy engulfs the whole of physics’.

Cheers,
Sione.

Soapy Sam
24th January 2006, 08:31 AM
Simon gave an intro and location in the Community Introductions thread a few weeks ago.

I agree with Simon's comment that popular explainers of QM seem too satisfied with leaving the whole business as a mystery. I never yet read an account that "felt right"(whatever the blazes that means).
I have to say that Little's essay has a strong intuitive appeal to me , because once I accept the existence of these "waves" - and he admits they are waves only insofar as they have certain wavelike properties- an awful lot of things which never made any sense to me suddenly seem rather obvious.
This is not a claim that I suddenly understand QM, merely a statement that it no longer sounds like a lot of nonsense, which until now, it has.

(That the evidence for QM is quite evidently not nonsense merely makes the traditional explanation even sillier in my opinion, but my opinion is uninformed mathematically, so I have tended to keep it to myself. I'm just glad to read that someone who appears to understand the maths shares my own view- namely that things are things and don't change shape because I'm moving towards them - and that anyone who can seriously talk about "curving"empty space is using a different dictionary from the one I use.)

I was reminded of the Polynesian navigators who claimed to be able to detect the presence of an island at long range in the open Pacific, by the way wave patterns were altered by it's existence.

Now to tackle the rebuttal from Simon's second post.

OK- I had expected that to be longer. Even I had heard of retarded waves, so I would suppose Little felt he hardly had to mention them to any likely readers of the essay. The time question over long distances is one I wondered about too,as it seems it should take twice as long for anything to happen as it actually does, unless the elementary wave moves backward in time.Can anything travelling at c move backwards in time , I wonder? but (I'm guessing) the answer to the gravity lens example would be along these lines:-
Little says several times that a photon need not cover an entire journey uninterrupted. Particles are described as "jumping "waves- and that this can be seen as the annihilation of a photon and creation of a new one in response to a reverse wave from a local detector.
(Where "detector"can mean anything that interacts with the particle via the wave system- in this case, the massive body-. The word "detector" is confusing).
This is how he explains an experiment in which the slits are altered after the emission of a particle. In principle, adding 300 million years to the flight time makes no difference.
So the particle passing the massive body would be locally following a wave which did have properties affected by that body. The photon , accordingly would be deflected. By the time the photon reached a telescope, it might be following a very different wave and might indeed be a quite different photon. How much time passes for a photon in flight after all?

Hah! I like it . I'm not for a minute saying this model is right. I'm interested though by why it feels (to me) much more likely to be right than the "conventional" explanations.

Simon Bridge
24th January 2006, 03:46 PM
O Soapy One: I've been checking somwhat into the background of this.

1. The journal: Physics Essays
This is not actually a physics journal - striktly speaking - but a philosophy journal. The editors have a deliberate policy of encouraging essays which are quite speculative. Little knows this, and he argeted his essay to this journal rather than something more heavyweight like Physics Review or Nature. If he really felt he was doing something groundbreaking, then this is what he would have done.

In this light alone, the essay is nothing to get all that excited about.

2. The essay itself contains conceptual errors - the representation (in the diagram) of young's interference in the form of ray-optics is just an example.

In optics, you often cast an image on a screen. You get ray diagrams strikingly similar to the one Little draws for Young's interference. In optics, if you move the screen, the image gets "washed out". With Young's interference, this does not happen (but Little claims that it "should".). This is because different things are happening. These systems are well understood in terms of classical optics as well as the regular interpretation of QM.

3. The meat of the essay, in so far as it has any, is that the wave-function(s) collapse at state preparation.

Here's how it normally goes:

I set up an initial system by some means. Lets say I want to shoot a particle across the room. I want to know as accurately as possible where the partical is at the start so I create a "minimum uncertainty wave-packet". This is to have a well-defined position and momentum. This wave packet will be restricted in space and it will be dynamic (it's gotta move).

However, I can represent this wave-packet as a sum of stationary states - provide I have a complete set of stationary states for the containment. If I rig things so the partical cannot leave the room - then this is easy: this is the set of energy eigenstates for an infinite square well.

In the mathematics now, the wave-packet is time-evolved. This is easy to do - each component eigenstate is a stationary harmonic wave - it's amplitude varies sinusoidally in time with the frequency depending on the energy eigenvalue (energy level) of the state.

The time-evolving wave-packet is the sum of it's component time-evolving stationary waves.

(The wave-functions are described here in terms of a distribution in position. however, the momentum distribution of this is the fourier transform of the position distribution. So you see right away they are related in a non trivial, non-arbitrary manner.)

The effect is that the mean of the wave packet travells to the far wall of the room, bounces off, and returns. This is also what the classical partical does.

However, the individual waves in the packet make nice shifting patters which are constantly changing. There is always a "hump" where the classical partical would be though.

(You can actually do this on a computer - you should have enough information for a simple simulation...)

Now: we don't actually see the partical in this process ...

If the wave packet is the function Y(x,t), then the probability of detecting the particle at time t=T in regeon: a<x<b is the integral along x between those limits of Y*(x,T)Y(x,T)dx

That is, we multiply the function with itself. The "*" indicates that we need the complex conjugate (all the i's become -i's where i^2=-1).

Bear in mind now, all we actually know about the partical is the where it was released (in terms of position and momentum) and that it is in the room.

If we want to find it, we need to use a detector. Sensible right?

The probability of finding the partical at a particular point (so a=b=x) is zero. You may want to take a moment to check this. It's not an issue. In normal statistics, adult human height are distributed accrding to a probability density function - a Gaussian, or "normal" distribution - the probability of finding someone in a range of heights is the area under the graph inside that range. The probability of finding a particular height is zero. This is fine because we cannot actually measure an exact height. (Note: this is not Heisenberg - more on him later.)

Detectors always have an aperture, a regeon where they are sensitive. The probability calculation is done over that regeon.

The detector only records if it was hit or not. A chain of ones and zeros. All it tells us is that the particle was detected at a given time.

If we want to detect patterns, we need more than one detector, and more than one particle.

A detection even does not tell us anything about the particles flight. Intuitively we feel that if a particle is released at point A and is detected later at point B, that the particle must have travelled from A to B in a line. A moment's thought tells you this is nonsence... it may have bounced off a wall somewhere, or zipped right through the detector with being noticed and only detected on the second, third or nth pass. There is no way to know.

Once detected, we have some information about the particle. We have a distribution of possible positions and momenta. This can be represented as the square of a wave-packet just like the initial states.

We would intuitively expect that the detected wave packet would just be the initial wave packet at time T (detection time).

This is actually nuts. The initial packet could extend through the entire lab, while detector-apertures are quite small (or they are not useful).

What happens is, by interacting with the detector apparatus (always some physical process, which is why it is very important to understand your meters and rulers when you use them) changes the statistics of the particle. Thus it changes the shape of the wave packet.

The way the initial wave turns into the detected wave is called "collapse". We say the detection collapses the wave-function. Sometimes, like if we measured energy, the wave function collapses to a stationary state. In this case, it collapses to another dynamic one.

The new state can be time-evolved again, and future detection events predicted. (This sort of experiment has been done).

The picture just presented is the "Wave Mechanics" picture.
The experiment has three main stages:
1. state preparation (where the initial states are formed)
2. time evolution
3. detection

You cannot have a detection without collapsing the wave function. Fair enough. In the standard description the collapse occurs at detection. There are physical reasons why this is sensible ... and it is general. When a bullet hits the sand-bag, it has been detected and it's state has been changed by the detection process.

Mathematically - this is not the only way of doing it.

Mathematically, it dosn't matter where the collapse occurs, or even how long the collapse takes. The physical predictions are the same regardless.

In Little's essay, the collapse occurs at the state preparation stage.

This immediately suggests the question: how does the particle know it's going to be detected? (Or - how does the wave-packet know to collapse in exactly that particular way?)

The actual mechanism is not important to the mathematics you realise. The consequences are the same. But it is important to the physics.

Little suggests that a variation on advance waves are the reason.

Now, collapsing the wave at the very start has some advantages, mathematically. These mathematical advantages are described (somewhat) in Little's essay.

However, for this to be other than a purely mathematical process, TEW requires postulating additional waves not needed in the standard approach. Is that an Occam's razor I see before me? :)

The addition is justified, within the essay, by pointing out that without them things are very weird indeed but with them things are only a little weird. Which is not really an answer - the universe could just be very wierd. After all, why should nature care about our ideas about what is sensible or not?

Can you see now why this idea should be considered suspect?

That's enough for this post ... more next time.

Simon Bridge
24th January 2006, 04:40 PM
Simon gave an intro and location in the Community Introductions thread a few weeks ago.Whew - someone noticed :) I made some effort to make a splash...I agree with Simon's comment that popular explainers of QM seem too satisfied with leaving the whole business as a mystery. I never yet read an account that "felt right"(whatever the blazes that means). The "mystery of science" angle makes better copy. It sells better and helps people feel comfortable in their ignorance. However, this "culture of ignorance" is exactly what JREF is set up to fight.

There's a political side too ... if people are used to being kept in the dark, then maybe they will sit still long enough to be governed?

I have to say that Little's essay has a strong intuitive appeal to me , because once I accept the existence of these "waves" - and he admits they are waves only insofar as they have certain wavelike properties- an awful lot of things which never made any sense to me suddenly seem rather obvious. Which things?

Excuse me, but I see the same statement from creationists ... but not from evolutionists. And surely - it is obvious that the Earth is flat isn't it?

(That the evidence for QM is quite evidently not nonsense merely makes the traditional explanation even sillier in my opinion, but my opinion is uninformed mathematically, so I have tended to keep it to myself. I'm just glad to read that someone who appears to understand the maths shares my own view- namely that things are things and don't change shape because I'm moving towards them - and that anyone who can seriously talk about "curving"empty space is using a different dictionary from the one I use.)That's relativity, not QM. And the shape changing has been observed.

The "curve" in space-time (not just empty space) is an analogy which comes from an observation that our universe does not follow Euclid. For eg. Parallel lines will eventually intersect. (This is what happens if you draw parralell lines on a curved surface - hence the analogy: "space is curved".)

I was reminded of the Polynesian navigators who claimed to be able to detect the presence of an island at long range in the open Pacific, by the way wave patterns were altered by it's existence.Neetoh - can you provide a reference for that?

Now to tackle the rebuttal from Simon's second post.Cool - thanks for collapsing the wave... I wasn't sure if I'd reply :)

OK- I had expected that to be longer. Even I had heard of retarded waves, so I would suppose Little felt he hardly had to mention them to any likely readers of the essay.Actually, the similarity of Little's theory to retarded waves is striking. Little must have known about them. He needed to mention it, if only to point out the similarity (and maybe that the similarity is superficial). That he did not is an important ommission, but not a fatal one.

I don't know how much experience you have had in reading peer-review journals... but there are good articles and there are bad ones. This is a bad one. This dosn't mean he's wrong though - only that he has communicated poorly. In fact, the article is written in a way that would create automatic dismissal in most physicists.

He must have known this (though I havn't had a look at his previous publications .... yet.) and yet he constructed his essay in the way he did. Maybe he dosn't want to be taken seriously? Maybe he is deliberately courting controversy - thus sell more books? Who knows.

but (I'm guessing) the answer to the gravity lens example would be along these lines:-
Little says several times that a photon need not cover an entire journey uninterrupted. Particles are described as "jumping"waves- and that this can be seen as the annihilation of a photon and creation of a new one in response to a reverse wave from a local detector.
(Where "detector"can mean anything that interacts with the particle via the wave system- in this case, the massive body-. The word "detector" is confusing).
This is how he explains an experiment in which the slits are altered after the emission of a particle. In principle, adding 300 million years to the flight time makes no difference.
So the particle passing the massive body would be locally following a wave which did have properties affected by that body. The photon , accordingly would be deflected. By the time the photon reached a telescope, it might be following a very different wave and might indeed be a quite different photon. How much time passes for a photon in flight after all? But it cannot do this and be deterministic along the entire flight path - which Little claims.

Anyway - do you know what Little's actual rebuttal was? Better see if you can find the reply before making your own assumptions.

I think the main point of this example (grav-lensing) is the question: "How does the detector know it's going to detect anything? (It must have some advance knowledge of the photon (in this case 300 million years advance) in order to know when to emit the detector wave. So long ago, the detector didn't even exist! The Earth wasn't even at the place where the photon was due to arrive! (Remember, we can use these terms because Little claims to be deterministic... in the statistical model this is not a problem.)

Hah! I like it . I'm not for a minute saying this model is right. I'm interested though by why it feels (to me) much more likely to be right than the "conventional" explanations.

I am reminded of when an audience member approached Feynman after a lecture and announced "I don't like it." in reference to QED. Feynman promptly told him to move to a different universe.

You should be suspicious of what "feels" right. After all, it feels right that the Earth is flat.

What feels right depends on the kinds of things that make sence in your experience. This is OK, normally, except you should not generalise from personal experience if you can help it. Your experience is different from another's experience.

You admit you are poorly informed - this is good. Take care you don't get caught out by people taking advantage of that.

For my part - I try not to tell anyone anything they cannot check out for themselves. Like the little experiment described earlier.

For another POV: have a look at:
http://cnqo.phys.strath.ac.uk/Research/QuantOpt/Retro/

This is a discription by people who believe what they are saying. Spot the difference from how popular science books et al relate stuff. I'm sure you'll find it matter of fact and sensible.

In the case where the collapse happens at state preparation - you see we start with a wave at the detector, time evolve it (backwards?) and the average position travells back to the source. We can then do the calculation in terms of the probability that the particle was created at the source.

This is useful because, in general, it is hard to actually create a particular combination of stationary states. But easy to measure final states. So we can "predict" likely initial states from known final states.

Turns the problem on it's head.

From the point of view of space-time, this is legit because everything has already happened. Taken literally, there are causality problems.

There are other POVs - like the wave can slowly collapse during the time-evolution stage. This can be seen as the particle become gradually more and more aware of the detector.

In Little's case, he seems to have the detected packet somehow interfering with the initial packet. Both packets travel forward in time.

In the end, the fatal flaw in the article is that the mathematical basis for the theory is absent. With it, he has a falsifiable idea. Without it, he has waffle.

All the descriptions I've seen have been qualitative. They have involved terms which have ambiguous meaning - sometimes changing their meaning at some point without notice. Now, all this occurs in legit articles - but usually because the math is there to back it up. You can work out what is meant by looking at the numbers. This is what I mean when I say Little's essay os poorly written.

Scientifically, I cannot really say if he's on to something or not. But I can say it looks doubtful.

Soapy Sam
25th January 2006, 01:28 AM
Simon - I appreciate the trouble you have taken here.

I find several quite different aspects of interest here , which probably differ significantly from your own.
1. The physics - if this really is a different model to explain QM. (And relativity- I appreciate the difference, but Little does claim both).
As I said, I am wholly unqualified to comment on this.
2. Understanding of QM (etc) to the layman.
3. Perception of understanding. (Of anything) by the layman.

Items 2 and 3 actually interest me more than the correctness or lack of it of the model. It's the psychology of belief which first brought me to this forum. Why people believe things interests me. ( Including why I myself believe things).

You should be suspicious of what "feels" right. After all, it feels right that the Earth is flat
Oh absolutely, no argument on that. Mind you - the Earth feels flat, because, to the level of accuracy available to human senses, it is flat. the degree of curvature is tiny.
(ETA-Asimov wrote a lovely essay on this entitled "The Relativity of Wrong"well worth a read.)
Humans understand things through sensory input, because evolution has so wired us that the hardware and software work together to produce an integrated picture of reality. We then confuse the issue with cultural and verbal issues. A staple assumption of popular science books is that this fails us when dealing with the very large, small or fast, - and that we therefore need mathematical models to grasp QM or relativity.

To someone like myself , with no mathematical ability whatsoever, this sounds like a cop out. (This is itself a "gut" response to information, I appreciate). Were I paranoid, I might suspect a conspiracy to keep the secrets secret. (I don't.)
But. When someone says "This is impossible to understand, but that's just how it is", that may well be how it is, but we should not accept the word of someone we don't understand when he tells us we can't understand something. That is a cop out. (You mentioned politics yourself).

So when something makes me feel I'm understanding without all the mathematical mumbo jumbo , I'm interested to know more. Specifically I want to know;
a) Is this model correct and
b) Have I actually understood better or am I merely perceiving that I understand better?

- And question b) is- as you imply in your last post- precisely the trap that many believers in all sorts of nonsense fall into, because they fail to ask it. Fear not, I ask myself at least once a day. In this case, I'm definitely in perception mode. Nonetheless, I'm keen to know why.

The acid test is often when one attempts to explain the concept to a third party. I tried to explain Little's model to a colleague today and we quickly became bogged. But then I can't explain traditional QM either.

Little is a very clear, logical and credible writer. By comparison, I'm sorry to say I found much of the explanation in your own penultimate post all but unreadable. (I lack too many of the referents).

While reading Little's essay, questions kept occurring to me- and one or two paragraphs later, there were the answers. ( Check my post early in the thread to see what I mean.) A convincing writer. I hope to hell he never starts a church.

Re the Polynesian navigators. I do not have a specific reference. It's one of those factoids which I have encountered in several places - National Geographic articles / probably Thor Heyerdahl / books about human movement around the globe. Probably has one source (Maybe in a 19th century sailor's log?) and since repeated by every writer on the subject. It seems feasible to me . The Pacific is a large body of water. Wave patterns will have dominant attractors to which they return. It's reasonable that such patterns would be affected by seamounts in the vicinity and that a skilled seaman would recognise this.

I'll check the reference you linked to. Looks like a University of Strathclyde address. You don't expect a University of Glasgow graduate (geology) to place any faith in something from the Royal Tech, do you?
(There should be a smirk smiley after that, but I can't get the buggers to work).

sionep
25th January 2006, 03:42 AM
Re the Polynesian navigators.

In fact I am a polynesian (born in Tonga) who happened to live in Auckland , New Zealand. Yes, the way Tongans, navigated in those days (before British missionaries arrived in early 1800s ) were by means of reading the direction of the current, the position of stars, direction of the wind, etc... They sailed in rafts from Tonga to Samoa, Tonga to Fiji , Tonga to Cook Islands, back and forth with no navigational instruments at all. From what I have heard and read about those navigators there had never been any rafts that went missing . They always did navigate themselves to the target destination and back.

Soapy Sam
26th January 2006, 09:14 AM
I imagine they lost a few. They clearly got where they planned to go most of the time though. Of all the things man has achieved, I still find one of the most incredible is that a bunch of people could go to sea in a Whitby collier with neither fuel nor engines, sail around the world making accurate and detailed charts as they went and sail the damn thing right back to where they started.

Doing something similar with neither a sextant nor Harrison's chronometers seems little short of miraculous- but it shows what can be done if you pay attention to details.

Simon Bridge
27th January 2006, 03:07 AM
Simon - I appreciate the trouble you have taken here.

I find several quite different aspects of interest here , which probably differ significantly from your own.
1. The physics - if this really is a different model to explain QM. (And relativity- I appreciate the difference, but Little does claim both).
As I said, I am wholly unqualified to comment on this.If you are sincerely interested in this sort of thing, then you really should consider becoming qualified: it is easier than popularily supposed. (Bear with me, more later.)
2. Understanding of QM (etc) to the layman.
3. Perception of understanding. (Of anything) by the layman.

Items 2 and 3 actually interest me more than the correctness or lack of it of the model. It's the psychology of belief which first brought me to this forum. Why people believe things interests me. ( Including why I myself believe things).Folk seem to believe Little for much the same reason they believe in UFO abductions and the Roswel crash; urban myths etc ... there is copious literature about this. Little seems to be the little guy (sic) daring to dis the big boys. There is resentment from the lay to the scientist... etc. Generally, we would like this guy to be right. If nothing else, it makes a great narrative (read the official bio).

You should be suspicious of what "feels" right. After all, it feels right that the Earth is flat
Oh absolutely, no argument on that

....we therefore need mathematical models to grasp QM or relativity.

To someone like myself , with no mathematical ability whatsoever, this sounds like a cop out.

But. When someone says "This is impossible to understand, but that's just how it is", that may well be how it is, but we should not accept the word of someone we don't understand when he tells us we can't understand something. That is a cop out. (You mentioned politics yourself).Perhaps you've missed the point.

1. Modern physics is understandable. You just do not possess the tools to help you understand. No-one (except perhaps Dr Little) is telling you, anything is "impossible" to understand.

The interesting this about this "feeling of rightness" is that Little dosn't actually provide you with understanding at all. The entire essay is riddled with misunderstandings anyway. What he produces is a "warm fuzzy" effect. You feel comfortable.

2. If you refuse to aquire the tools to understand stuff, you have only yourself to blame. OK - you don't trust the tools, particularily the mathematical ones.

Mainly the maths is a language - if someone tells you stuff in spanish, well you have to know spanish to understand it don't you. How about if I tell you that some things are better expressed in spanish? I can translate them for you but you won't appreciate them the same. If you want to appreciate them best, you have to learn spanish. Is that a cop out?

So when something makes me feel I'm understanding without all the mathematical mumbo jumbo , I'm interested to know more. Specifically I want to know;
a) Is this model correct and
The trouble is, nobody can say for sure. However, if the model were correct, then the appropriate place to publish is Physical Review or Nature. Instead the publishing track looks more like the path taken for pseudoscience.

The essay is fraught with common misunderstandings.

It seems very unlikely that there is anything in the theory outlined in the essay. It seems likely that the author knows this too - that's the bit I don't like. He should make quite a bit of money on his book though - the book dosn't have to be true, or meet peer review, after all.

Of course I cannot tell if a full-fledged theory is before peer review for either of these journals. However, if it were, the author would certainly be telling everyone about it. (Academics advertise submitted articles in their organisation's pre-publications list ... that way you can read what the peer-reviewers are reading.)

As a point of note, there is important information missing from the official bio. Like: what did Little get his doctorate in, exactly? (I can't find him in NYU anywhere...) Where does he work now? What research has he done before?

These things normally go in a scientific bio. It's also stuff competant journalists don't miss out and yet there is nothing in the interviews and so on at all...

Perhaps you've seen some?

b) Have I actually understood better or am I merely perceiving that I understand better?

- And question b) is- as you imply in your last post- precisely the trap that many believers in all sorts of nonsense fall into, because they fail to ask it. Fear not, I ask myself at least once a day. In this case, I'm definitely in perception mode. Nonetheless, I'm keen to know why.Exactly. If you look into the bio, you'll see the pattern. Here is a guy whose ideas have been oppressed by those eggheads who want to make everyone feel stupid with their incomprehensible maths:) OK Dr Little is one of them too - but he's one of them that's on your side.

The Roswel Crash proponents have the same sort of bio.

The acid test is often when one attempts to explain the concept to a third party. I tried to explain Little's model to a colleague today and we quickly became bogged. But then I can't explain traditional QM either.First, identify what needs explaining.

You're having trouble because you don't understand either. This test should say to you that, while you "feel" you understand TEW better than QM, in fact your understanding is about the same. You are just as in the dark about the feilds as you were before - so the light of this new idea is illusory. At least in your case.

Little is a very clear, logical and credible writer. By comparison, I'm sorry to say I found much of the explanation in your own penultimate post all but unreadable. (I lack too many of the referents).I suspect you'll find the results of classical mechanics just as arcane then. Looks like you could use a primer.

Interestingly, relativity is easier to grasp in one go than QM. At least there's no statistics. The whole thing is actually a direct consequence of Newtonian relativity, and his Laws. If you can cope with Newtonian relativity you can work your way into Einstein's quite simply.

OTOH: while you lack many of the referents, you seem quite happy to avoid aquiring them. You keep saying you do not understand, yet you do not seek understanding (only the feeling of understanding). You keep saying that you are not qualified to comment, yet you keep commenting.

While reading Little's essay, questions kept occurring to me- and one or two paragraphs later, there were the answers. ( Check my post early in the thread to see what I mean.) A convincing writer. I hope to hell he never starts a church.

I noticed that too - when I checked, I noticed that the questions were planted by the author. When I treated the essay as I would something I was peer reviewing, I found myself asking different questions.

One important question for the reviewer is: has this been thought up before? The text has to be distilled to produce the core idea - tricky because Little launches right into examples without ever actually expounding directly on the central concept. (Since this is a philosophical paper, couched in lay terms, this is not actually bad by itself - it just makes the reviewers job harder.) A literature search is then in order to see if the basic ideas have been expounded and how they've been handled.

Advance waves and retrodiction seem likely candidates, as a reviewer I'd want Little to explain how these things relate to his essay.

I'd also ask for the mathematical treatment that he claims exists but has yet to produce. (The longer it takes to produce this, the less credibility the idea has.) Notice, you don't need to understand the math to appreciate that a fundamental breakthrough in physics as Little claims needs to have a math description.
Re the Polynesian navigators. I do not have a specific reference. It's one of those factoids which I have encountered in several places - National Geographic articles / probably Thor Heyerdahl / books about human movement around the globe. Probably has one source (Maybe in a 19th century sailor's log?) and since repeated by every writer on the subject. It seems feasible to me . The Pacific is a large body of water. Wave patterns will have dominant attractors to which they return. It's reasonable that such patterns would be affected by seamounts in the vicinity and that a skilled seaman would recognise this. It is of interest in NZ - these islands were discovered by polynesian explorers who were clearly quite good at long-distance navigation.

The dominant idea seems to be that Kupe postulated the existance of NZ by watching migratory birds. He didn't seem to have spotted the existance of Australia ... one would expect Oz's impact on currents and so on to be much greater than NZ's. So the seabird idea seem good.

Navigation seems to have been by stars - whose positions were tracked using a kind of woven frame. Waves and currents would have alerted the explorers to an imminent shore. This was very important if trip is not to be one-way.

The craft used were very big double-hulled canoes rather than rafts BTW. Some of the hulls are still here, you can walk around them and touch them.

On the whole, the voyages are on par with the vikings.

I'll check the reference you linked to. Looks like a University of Strathclyde address. You don't expect a University of Glasgow graduate (geology) to place any faith in something from the Royal Tech, do you?
(There should be a smirk smiley after that, but I can't get the buggers to work).heh heh heh :)

Soapy Sam
27th January 2006, 06:04 AM
I noticed that too - when I checked, I noticed that the questions were planted by the author
Which is fair enough, it's a technique of good explanatory writing. Of course good writing need not be factually correct . I’m also curious about the readership he had in mind- not a high level academic one it seems, given your comments about the journal.

I suspect you'll find the results of classical mechanics just as arcane then. Looks like you could use a primer.

You are right- the best I can do is get anon quantitative impression of having understood- (not sure I'd call it warm & fuzzy, but whatever). So I could be easily misled by a largely verbal explanation which appears to support the sort of commonsense universe I actually believe in. But if I told you how little of mathematics I believe has any meaning, you would probably be quite shocked. Belief and knowledge are quite different things.

You imply Little’s argument is full of holes. Can you point out a couple without resorting to mathematics?

For example- his fundamental argument is that something travels from the observer to the source. In the case of the two slit set up, he says-
consider the following additional fact about the experiment. Suppose one tries to explain the pattern on the screen with a hypothetical set of particle trajectories. The maxima on the screen might then be explained by particles following the trajectories shown in Figure 1.

However, if the screen is moved to position B, clearly the particles from each slit, and still following those same trajectories, will no longer arrive at the same points on the screen; the particles from one slit will fall somewhere between the points of impact of the particles from the other slit. The pattern would then be washed out. And yet a similar wave pattern is observed at all screen distances.
1.(If the particles are assumed to be particles), 2.( and if they follow straight lines between the slits and the screen,) 3.( there is only one conclusion that can be drawn: the trajectories depend on the screen position. If one moves the screen the particles follow different trajectories.)
4.(But this could only happen if something is moving from the screen to the oncoming particles to affect their motion.). Without some real, physical process to explain the screen dependence, one would be left with the need for a nonlocal interaction to account for the dependence. If one rejects nonlocality, then this experiment constitutes direct observational evidence of the reverse motion of something from the screen to the particles.

Note that the “would be washed out” part specifies a result which is not obtained in reality.He is setting up (Supposing the next statement is true- a similar wave pattern is obtained…etc)

How would you criticise the argument built up here, in the four numbered steps. He is building a hypothesis (1 and 2 are unsupported assumptions) , but granted those assumptions for purposes of debate, do you disagree with conclusions 3 and 4? If so, why?

The essay dates from 1996. What , if anything, has come of this since?

Can't imagine why I said "rafts". Probably thinking of Kon-Tiki . Outrigger canoes indeed.

Soapy Sam
27th January 2006, 06:12 AM
I noticed that the questions were planted by the author
Which is fair enough, it's a technique of good explanatory writing. Of course good writing need not be factually correct . I’m also curious about the readership he had in mind- not a high level academic one it seems, given your comments about the journal.

I suspect you'll find the results of classical mechanics just as arcane then. Looks like you could use a primer.

You are right- the best I can do is get anon quantitative impression of having understood- (not sure I'd call it warm & fuzzy, but whatever). So I could be easily misled by a largely verbal explanation which appears to support the sort of commonsense universe I actually believe in. But if I told you how little of mathematics I believe has any meaning, you would probably be quite shocked. Belief and knowledge are quite different things.

You imply Little’s argument is full of holes. Can you point out a couple without resorting to mathematics?

For example- his fundamental argument is that something travels from the observer to the source. In the case of the two slit set up, he says-
consider the following additional fact about the experiment. Suppose one tries to explain the pattern on the screen with a hypothetical set of particle trajectories. The maxima on the screen might then be explained by particles following the trajectories shown in Figure 1.

However, if the screen is moved to position B, clearly the particles from each slit, and still following those same trajectories, will no longer arrive at the same points on the screen; the particles from one slit will fall somewhere between the points of impact of the particles from the other slit. The pattern would then be washed out. And yet a similar wave pattern is observed at all screen distances.
1.(If the particles are assumed to be particles), 2.( and if they follow straight lines between the slits and the screen,) 3.( there is only one conclusion that can be drawn: the trajectories depend on the screen position. If one moves the screen the particles follow different trajectories.)
4.(But this could only happen if something is moving from the screen to the oncoming particles to affect their motion.). Without some real, physical process to explain the screen dependence, one would be left with the need for a nonlocal interaction to account for the dependence. If one rejects nonlocality, then this experiment constitutes direct observational evidence of the reverse motion of something from the screen to the particles.

Note that the “would be washed out” part specifies a result which is not obtained in reality.He is setting up (Supposing the next statement is true- a similar wave pattern is obtained…etc)

How would you criticise the argument built up here, in the four numbered steps. He is building a hypothesis (1 and 2 are unsupported assumptions) , but granted those assumptions for purposes of debate, do you disagree with conclusions 3 and 4? If so, why?

The essay dates from 1996. What , if anything, has come of this since?

Can't imagine why I said "rafts". Probably thinking of Kon-Tiki . Outrigger canoes indeed.

ps- I hope I'm commenting on things I'm competent to comment on- (eg the apparent understandability of a text) , as opposed to things I'm incompetent to comment on (eg the subject of the text)- but you'll appreciate it's difficult to separate the two,

Simon Bridge
3rd September 2011, 09:31 PM
Sorry for the long delay - I got distracted...

However, if the screen is moved to position B, clearly the particles from each slit, and still following those same trajectories, will no longer arrive at the same points on the screen; the particles from one slit will fall somewhere between the points of impact of the particles from the other slit. The pattern would then be washed out. And yet a similar wave pattern is observed at all screen distances.particles from each slit fan out into the region beyond the slit. What is happening is that the screen is interrupting a pattern in space. Think of it like beams of photons fanning out from the slits.

When you move the screen, the pattern changes its size - it's smaller as you bring the screen closer to the slits. Thus, the observed effect takes place without requiring individual trajectories to change with screen position. (So c and d do not follow from a and b.)

quarky
3rd September 2011, 11:14 PM

A hyper active singularity can explain everything.
As in, the big bang happened when the singularity started to move really fast.
And in the process, manages to manifest all the potential positions that we can observe.
On command.

Reality Check
4th September 2011, 05:17 PM
The best description of this thing I've seen comes from Richard Feynman in his lecture tour. I had the priviledge of attending some of his lectures when he visited Auckland (forget the date) when I was a very young student.

Videos of his lectures at Auckland University are available at the Vega Science Trust web site (http://vega.org.uk/video/subseries/8).

This is very clear: the law of reflection is wrong.
I think that the result is actually that the law of reflection is correct. It is just the the QM explanation is different as shown by the experimental result that selectively removing parts of the mirror increases the reflection.

Reality Check
4th September 2011, 09:01 PM
Back to the OP: The Theory of Elementary Waves (http://elementarywaves.com/TEW96paper.html) by Lewis E. Little
which is fairly well debunked by Problems with the Theory of Elementary Waves (http://enlightenment.supersaturated.com/essays/text/tomradcliffe/tew.html) by Tom Radcliffe .

The basic problem with the theory is that there is is only a description of it. There is little mathematics in the essay (n.b. not really a paper since it was published in Physics Essays) that is not standard physics.

The physical flaw with is its implication that the elementary waves travel at most with the speed of light (they are real and so Special Relativity applies to them). But the results of the Wheeler's delayed choice experiment (http://en.wikipedia.org/wiki/Wheeler%27s_delayed_choice_experiment#Most_recent_ experiment) shows that any communicaiton between the detector and the slits in a double-slit experiment must be faster than the speed of light.

See Jacques, Vincent; et al. (2007). "Experimental Realization of Wheeler's Delayed-Choice Gedanken Experiment". Science 315: 966-968. arXiv (http://en.wikipedia.org/wiki/ArXiv):quant-ph/0610241v1 (http://arxiv.org/abs/quant-ph/0610241v1).