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 JREF Forum Theory of Elementary Waves: QM revolution?

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 21st January 2006, 06:30 PM #1 Simon Bridge Critical Thinker     Join Date: Dec 2005 Location: Waiheke Island (NZ) Posts: 346 Theory of Elementary Waves: QM revolution? http://physics.prodos.org/ http://www.yankee.us.com/TEW/TEW96paper.html comments? 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.
 21st January 2006, 06:33 PM #2 Simon Bridge Critical Thinker     Join Date: Dec 2005 Location: Waiheke Island (NZ) Posts: 346 http://enlightenment.supersaturated....liffe/tew.html I showed you a support forum in the last post. Now a debunking page. It's only fair.
 21st January 2006, 06:34 PM #3 Dr Adequate Banned   Join Date: Aug 2004 Location: Waiting Long Enough By The River Posts: 17,897 If the predictions are the same its another stupid metaphor for what's going on. Note: there are no non-stupid metaphors for QD.
 21st January 2006, 07:00 PM #4 Simon Bridge Critical Thinker     Join Date: Dec 2005 Location: Waiheke Island (NZ) Posts: 346 hah - I got my wish, I guess... perusing the essay: http://enlightenment.supersaturated....liffe/tew.html The basic youngs-interference setup is shown, and the following observation: Originally Posted by L Little 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.
 21st January 2006, 07:03 PM #5 Simon Bridge Critical Thinker     Join Date: Dec 2005 Location: Waiheke Island (NZ) Posts: 346 Originally Posted by Dr Adequate 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?
 21st January 2006, 08:41 PM #6 sionep Scholar   Join Date: Jan 2006 Posts: 103 Originally Posted by Simon Bridge http://enlightenment.supersaturated....liffe/tew.html 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
 21st January 2006, 08:54 PM #7 sionep Scholar   Join Date: Jan 2006 Posts: 103 Originally Posted by Simon Bridge http://enlightenment.supersaturated....liffe/tew.html 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.
 22nd January 2006, 12:02 AM #8 Soapy Sam NLH   Join Date: Oct 2002 Posts: 25,885 '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. Last edited by Soapy Sam; 22nd January 2006 at 12:40 AM.
 22nd January 2006, 04:05 AM #9 sionep Scholar   Join Date: Jan 2006 Posts: 103 Originally Posted by Soapy Sam [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.
 22nd January 2006, 07:16 AM #10 Soapy Sam NLH   Join Date: Oct 2002 Posts: 25,885 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.
 22nd January 2006, 01:49 PM #11 Wire Scholar     Join Date: Jul 2002 Posts: 81 Quote: 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? __________________ Cosmologists are often in error, but never in doubt. L.L.
 22nd January 2006, 07:02 PM #12 Dilb Muse   Join Date: Oct 2004 Posts: 738 Originally Posted by sionep 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.
 23rd January 2006, 02:49 AM #14 Simon Bridge Critical Thinker     Join Date: Dec 2005 Location: Waiheke Island (NZ) Posts: 346 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. So what about this two-slit thing? 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.
 23rd January 2006, 03:41 AM #16 Simon Bridge Critical Thinker     Join Date: Dec 2005 Location: Waiheke Island (NZ) Posts: 346 Originally Posted by Dilb 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". Quote: 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.)
 23rd January 2006, 03:49 AM #17 Simon Bridge Critical Thinker     Join Date: Dec 2005 Location: Waiheke Island (NZ) Posts: 346 Originally Posted by sionep 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 That'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.
 23rd January 2006, 04:03 AM #18 sionep Scholar   Join Date: Jan 2006 Posts: 103 Originally Posted by Simon Bridge 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. So what about this two-slit thing? 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.
 24th January 2006, 03:46 PM #20 Simon Bridge Critical Thinker     Join Date: Dec 2005 Location: Waiheke Island (NZ) Posts: 346 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
 25th January 2006, 03:42 AM #23 sionep Scholar   Join Date: Jan 2006 Posts: 103 Originally Posted by Soapy Sam 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.
 26th January 2006, 09:14 AM #24 Soapy Sam NLH   Join Date: Oct 2002 Posts: 25,885 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.
 3rd September 2011, 09:31 PM #28 Simon Bridge Critical Thinker     Join Date: Dec 2005 Location: Waiheke Island (NZ) Posts: 346 Sorry for the long delay - I got distracted... Quote: 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.)
 3rd September 2011, 11:14 PM #29 quarky Banned   Join Date: Oct 2007 Posts: 20,454 I read the whole thread. 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.
 4th September 2011, 05:17 PM #30 Reality Check Penultimate Amazing   Join Date: Mar 2008 Location: New Zealand Posts: 10,783 Originally Posted by Simon Bridge 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. Originally Posted by Simon Bridge 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. __________________ Real Science: NASA Finds Direct Proof of Dark Matter (another observation) (and Abell 520) "Our Undiscovered Universe" by Terence Witt: Review 1; Review 2
 4th September 2011, 09:01 PM #31 Reality Check Penultimate Amazing   Join Date: Mar 2008 Location: New Zealand Posts: 10,783 Back to the OP: The Theory of Elementary Waves by Lewis E. Little which is fairly well debunked by Problems with the Theory of Elementary Waves 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 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:quant-ph/0610241v1. __________________ Real Science: NASA Finds Direct Proof of Dark Matter (another observation) (and Abell 520) "Our Undiscovered Universe" by Terence Witt: Review 1; Review 2

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