Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: sciconoclast on 10/03/2010 19:35:37
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I have performed about a dozen or so experiments that I feel may contradict quantum theory. My equipment is rudimentary and the experiments tertiary. I realise thta before these experiments can change scientific theory they need to be refereed and duplicated by an accredited lab. My question is, if that ever happens for the sample experiment described here, would the sames results be a contradiction to quantum theory?
In this experiment light from a 630-680nm laser is first passed through a 0.65mm horizontal slit at 0.120m from the laser. Next, after traveling another 0.45m it passes through a 0.50mm vertical slit. The two single slits eliminate any radial paths. At 3.795m further a barrier with 0.30mm double slits, separated by 2.30mm, is positioned so that the right slit is in the dark space between the first and second peripheral bans in the left side of the pattern from the vertical slit and the left slit is in the light of the adjacent second peripheral ban. When the illuminated left slit is blocked no light passes. When the dark right slit is blocked there is the expected single slit pattern. Howevere, when both slits are open there is a double slit pattern! Is my assertion, that changing an interference pattern by blocking a path that is not available to photons a contradiction to quantum theory, correct? Do you think that this is what is happening?
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There's a few things going on in the experiment.
First, a double slit experiment is designed to show that whatever forms an interference pattern is acting like a wave. The reason is that only waves show interference patterns, not particles. What your showing (and what Thomas Young initially showed) is that light behaves like a wave, which is a classical theory.
Second, I think part of the problem is with your understanding of how light propagates.
In this experiment light from a 630-680nm laser is first passed through a 0.65mm horizontal slit at 0.120m from the laser. Next, after traveling another 0.45m it passes through a 0.50mm vertical slit. The two single slits eliminate any radial paths.
I don't know how wide the laser beam you're using is, but when you pass light through a narrow silt, the beam tends to spread out after the slit due to a property of wave propagation called diffraction. By passing it through two slits like this, you're actually making the beam spread out in both directions, so its not surprising that both slits are hit by the beam.
Lastly, light must be hitting them both in order for the system to behave in the way you say, but you also say the dark slit has no light reaching it. (Also, diffraction theory says that light should be reaching the dark slit.) Have you tested to see that no light reaches the dark slit? If so, how? Also, do you have any measurements of the contrast of the fringes--how bright are the bright fringes and how dark are the dark fringes? That would tell you how much light should be reaching the dark slit.
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At 3.795m further a barrier with 0.30mm double slits, separated by 2.30mm, is positioned so that the right slit is in the dark space between the first and second peripheral bans in the left side of the pattern from the vertical slit and the left slit is in the light of the adjacent second peripheral ban.
Ain't Louis De Broglie proved that light is, in propagation, waves?
And ain't you doing the thing called Young's double slit experiment.
If you are, then congratulations, you proved that light diffracts and creates an interference pattern!
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Thanks for the input!........JP: If understand quantum theory correctly (which I very well may not)a photon materialises when it is tested for at points of highest probability for photon occurrence, which in so called interference patterns, is at the convergence of the greatest number of probable paths. Nothing actually passes through the slits as they only represent mathematical possible paths within the quantum field. The photons at the target screen represents photons for which the probable paths are through the slit openings (the quantum field does not collapse into a photon at the slit barriers where the probable path is through the openings). The dark slit lies within the quantum field but the single slits create points of high probability where the possible diffraction paths overlap. This alters the quantum field to where the path through the dark slit has a nearly zero probability. In contrast the path through the lighted slit and the convergence of its diffraction paths have an increased probability. Therefore, the dark slit path should not be a factor in the target screen pattern; but it is!........As for the method of testing for light I used a digital camera with a 30 second exposure focused on the screen and also placed directly behind the dark slit; I mentioned my equipment was rudimentary. However, there is a history of experiments detecting every photon hit or experiments where only the dark lines were tested for photons that demonstrate how efficient slits are at consolidating photon paths into bans..........Tintin_Triton:.. The difference between my double slit experiment and that of Thomas Young is that in mine light may only have a possible path through only one slit.
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If the dark slit has absolutely zero light passing through it, then you shouldn't get an interference pattern. (Zero light is the same as covering the slit.) If it has some light passing through it, then you would expect to see an interference pattern. As you increase the light through the dark slit, the interference pattern should become more pronounced up until you have equal amounts of light passing through both slits.
Again, you're not testing quantum theory here. What you're testing is classical electromagnetic theory that describes light as waves. If you want to test quantum theory, you would need to send only one photon at a time through the slits.
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Scic, if you have the equipment try this. With two polarizing lens placed at half a meter apart. Place both lens in the vertical position. Set a laser beam to pass through both lens. At the mid point of the beam between the two lens place one pole of a magnet as close as possible to the beam. What does the Laser look like on the screen?
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I have posted another experiment which may be relevant and which you may want to view. Your opinions are appreciated
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Where did you post it?
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Ron Hughes: I didn't mean that the second post was relevant to your proposed experiment. Although I am curious and may try it later. The second post was relevant to my first post and posted in this forum under "Is this second experiment a contradiction to quantum theory".
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Ok, but if you try mine please let me know your results. Any deviation from expected result would demand new thinking.
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Still hear.
Now that JP has shown me how to place diagrams and pictures on this site I thought that I should add them to this tread.
Diagram of Experiment
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Picture with Both Slits Open
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Picture with Lighted Slit Only
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Picture with Dark Slit Only
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I hope this helps clarify the experiment. JP: I still do not understand how an unobservable, if any, quantity of light can alter the pattern of a copious amount of light. But that doesn't mean that you are incorrect as there are a lot of things I don't understand.
In posting experiments in the future I will try to post diagrams and pictures at the beginning of the tread.
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Apparently, JP did not do a very good job [;D]
Focus people. We really need to focus!
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As I said before, zero light is different that some light. If there is truly zero light passing through the dark slit, then the pattern would look the same as with the dark slit covered, since no light is no light either way. If it's a small amount of light, you expect to see a small amount of interference, which is what you get.
In other words, current theory explains this if a small amount of light is getting through the dark slit. If you want to convince people that your work is overturning mainstream physics, then you need to do very precise measurements of the interference patterns (or darkness) to prove that no light is making it through at all.
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Sciconoclast: I don't think you're contradicting quantum theory, but instead are challenging the Copenhagen interpretation of quantum theory.
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Sciconoclast: I don't think you're contradicting quantum theory, but instead are challenging the Copenhagen interpretation of quantum theory.
Aren't the Copenhagen interpretation and all the other interpretations (that have matched with experiment) identical in this case? None of them are supposed to produce experimentally different results that I know of.
The bigger problem is that this isn't limited to quantum mechanics. If no light is passing through that slit and it's still effecting the pattern, then it's overturning classical electromagnetic theory as well!
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Taking a stab at explaining this.
A small wave passing through the dark slit would interfere with all the waves or a large single wave passing through the lighted slit. However, ever since Albert and Neils the dominate view is that light is not a wave. Although, quantum theory does mimic classical wave theory and it is still used for convenience by optical engineers.
In quantum theory there is a separate, expanding, abstract probability field for each potential photon ( in some cases each pair of mirror photons ) which does not affect the probabilities of other photons ( there are some exceptions though ). If there is a photon with a path through the dark slit within its probability only that photon alone is affected by that possibility.
Only a photon with probable paths through both slits will appear at their point of convergence, or in other words within a double slit ban. Such photons could produce a faint double slit pattern on top of the lighted single slit pattern by adding their numbers on top of the others and increasing the total number of photons in the double slit ban areas. However, it seems unlikely that if the number of photons, if any, when only the dark slit is open, are insufficient to create an observable single slit pattern for the dark slit, that they would be sufficient to create an observable pattern overtop of the more intense lighted slit single pattern.
As for the faint appearance of the double slit pattern in the picture; I am sure you are aware that interference patterns oscillate or move and that the longer the exposure the more muddled the pattern. In this experiment the light has been separated into small bans by two single slits and one double slit. It takes a long exposure to get these pictures.
Anyway that is how I presently see it but I am open for correction.
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Taking a stab at explaining this.
A small wave passing through the dark slit would interfere with all the waves or a large single wave passing through the lighted slit. However, ever since Albert and Neils the dominate view is that light is not a wave. Although, quantum theory does mimic classical wave theory and it is still used for convenience by optical engineers.
Quantum theory doesn't mimic classical theory. Quantum theory should be the underlying principles of the classical theory. However, just because there is a quantum theory of light doesn't mean the classical theory doesn't work. It does work for highly accurate predictions in many instances, including the kind of experiment you're conducting here. If this experiment can be explained by classical theory, then it should also be explained by quantum theory.
As for the faint appearance of the double slit pattern in the picture; I am sure you are aware that interference patterns oscillate or move and that the longer the exposure the more muddled the pattern. In this experiment the light has been separated into small bans by two single slits and one double slit. It takes a long exposure to get these pictures.
They shouldn't be moving at all unless some piece of your experiment is moving. The light waves move, but the interference pattern should be stationary.
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Hello JP:
Thanks for the correction that the interference pattern does not move. I had been missinformed by a statement in an outdated text book. The problem in my case is still real ( even straight on simple double slit patterns bleed out with long exposures). Perhaps I should be using a more finely tuned laser.
Is my other statement about the quantum wave function applying separately to each possible photon correct?
When using the short cut formula, probability equals the square of the modulus of the total amplitude, doesn't it only apply to the wave function for a single photon or photon pair? Otherwise wouldn't their be two photons occurring at the same point where their crest overlap?
Farsight is correct in that this experiment would only be a challenge to the Copenhagen interpretation and not to quantum mechanics and theory in general. Even some Nobel laureates that are strong supporters of quantum mechanics have questioned this interpretation. There are other interpretations, which altough not the predominate theory, are still well within main stream physics.
For the sake of discussion; if it is assumed that my tertiary experiment lacks sufficient control and precision to demonstrate anything, wouldn't it still be an important experiment to duplicate under better conditions? For example if it was found that opining a truly dark slit did not create a double slit pattern, it would confirm positivism and the group of theories such as Neils Bohr theory that photon occurrence is dependent only on abstract probabilities. On the other hand if opening the dark slit does create a double slit pattern, it would confirm realism and theories such as David Bohms in which an actual photon would pass through the lighted slit and the pilot wave would pass through bot slits.
Looking forward to your answers
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If you're convinced that you're observing new physics, then the next step would be to fine tune everything, repeat the experiment and publish.
But as I said, you're almost certainly not observing new physics. This isn't a purely quantum effect, so I still don't understand why you keep trying to explain it with a quantum model. From what little I know of Bohmian mechanics, it also doesn't distinguish between that theory and the Copenhagen interpretation--you can't force the particle to travel through one slit while the pilot waves go through both slits. There is even a Bohmian mechanical version of classical optics, by the way, which I believe is called the hydrodynamic model of light propagation. So even there, you don't have to appeal to quantum mechanics.
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Greetings J.P.
I have been waiting for someone else to jump in an explain that the photon passing through one slit and the pilot wave passing through both slits is the Broglie-Bohm explanation for the single photon double slit experiment; but I ques it is not going to happen [ "In de Broglie-Bohm theory, the wave function travels through both slits, but each particle has a well-defined trajectory and passes through exactly one of the slits." from Wikipedia ].
As for upgrading my equipment and redoing experiments; before I go to that expense I would first like to get as much credible input as possible. Which is why I am posting on forums. Your comments have been helpful and given me a lot to think about.
Thanks!