bangstrom

Why would more than one atom need to be involved?

I see light as a wave and never as a particle. Light is quantized for certain but that does not mean it is a particle. Light is emitted and absorbed by electrons in discrete amounts representing the many differences in energy levels from one electron orbital to the next and that is why light waves appear as quanta. The photoelectric effect converts light energy into a stream of electrons but counting electrons thinking that each electron represents a photon is not a valid assumption. BTW it is not "my" discussion or even my OP. I am just another butinski.

I remember Marshall but I will have to look into what Rovelli has to say. My answer is at the bottom. In my view of the double slit experiment, the slits are detectors of nothing when light is involved. This may be a different matter with electrons. Light as a wave should pass through both slits so there is no which-path information because the light wave took both paths. The which-path information must be indicating something different. In experiments modeled after the Wheeler Delayed-Choice experiment there is a beta barium borate crystal (BBO) directly behind the double slits. The purpose of the BBO crystal is to generate pairs of entangled photons...No, forget the photons. The crystal generates entangled pairs of wavelets of light energy. In Wheeler’s Delayed-Choice, light enters the BBO crystal as an extremely powerful laser beam of UV light and it passes directly through the crystal. On extremely rare occasions, a quantum of UV energy is absorbed by a BBO molecule and an electron in one of the atoms is boosted to a much higher energy level. Instead of dropping back down to its original energy level in one big jump, the electron drops down in two steps releasing two entangled photons wavelets. If the two wavelets are of equal energy, they are called “parametric” and the whole process is called “spontaneous parametric down conversion” SPDC. I think SPDC is largely a distraction from what else is happening. The original UV light from the laser and any light except for the feeble red light having half the energy and twice the wavelength of the UV light is used for the rest of the experiment. Everything else is removed by color filters. BBO crystals are used because they are the only birefringent crystals that can survive the heat of the UV laser. The BBO crystal is a nonlinear, birefringent crystal with optical properties nearly identical to calcite. When a light wavelet enters a birefringent crystal it can take one of two paths. It can go straight through the crystal on the “p” path or it can take a slight jog to the side on the “s” path. Also, when light travels through a nonlinear crystal as an electromagnetic wave, the wave is slowed upon entry more on the electro plane than on the magnetic plane. This gives the wave an apparent spiral called circular polarization. Light can be both circularly and linearly polarized at the same time and this is the condition of light when it emerges from a birefringent crystal. I suspect the which-path information that is determined later is more likely to indicate which path the light wave took as it passed through the BBO crystal (the p or s path) than which path it took through the double slit. Other than myself, I don't know of anyone who has looked into the effect of circular polarization on the simple double slit experiment but I have read some hear-say accounts that orthogonol beams of circularly polarized light will not interfere. If they do interfere that would give you which-path information and interference at the same time which is claimed to be impossible. I have tried it and it works for me.

The double slit is evidence of light waves but it also works with particles. Small particles also have a wave nature so the two properties are not mutually exclusive. The presence of which-path information is characteristic of the particle nature of light and the presence of which-path information destroys the interference, so in experiments where which-path information appears to be critical to the outcome, light is considered to be to be acting as a particle. A wave should not be expected to demonstrate which-path information. Yes, the screen is a detector. The Wheeler Delayed-Choice experiment uses two electronic versions of a screen looking for interference. One receives light from both slits and indicates the presence or lack of interference. The other is a Mach-Zehnder interferometer that looks for both interference and which-path information. The second is located meters behind the first so interference is noted first and the which-path information is determined later.

Yes, the experiment is about which-path information and there is no evidence from the experiment to indicate that light is a particle. Light appears as a wave through out the experiment. The results that are said to be lacking interference are diffraction patterns which are just a less elaborate demonstration of wave interference. The conventional interpretations of the double slit experiments is to consider light as a particle and that approach leads to a dead end. The conventional interpretation of the Wheeler Delayed-Choice experiment is that an observer can decide the outcome of the experiment by determining the which-path information even if the determination is made after the experiment is completed. The retroactive nature of which-way information is a problem for physics. Yes, that is the way it works. There is an interference pattern when there are no detectors of which-way information but the interference pattern is lost when the detectors are present. This makes it suspicious that the detectors are causing the loss of interference. In one test of the double slit experiment, the detectors were placed behind the double slit and recorded the which-path information. This destroyed the interference pattern. The test was then repeated with the detectors active but unplugged from the recorders and the interference returned. The interference pattern is destroyed whenever the which-path information is “out there” but the interference pattern is present even when the detectors are present and active but there is no record of which-path information. This places the suspicion on the presence or absence of which-path information as a cause for the loss of interference.

This is a quote from Anton Zeilinger. “Thus, even though a sub-quantum amount of light is received at a detector, the probability of a detection event occurring at the detector increases with the amplitude of the received light signal. Thus, even sub-quantum amounts of light can cause detectors to trigger and generate “click” events. It is sufficient to destroy the interference pattern, if the path information is accessible in principle from the experiment or even if it is dispersed in the environment and beyond any technical possibility to be recovered, but in principle still ‘‘out there.’’ The absence of any such information is the essential criterion for quantum interference to appear.” A. Zeilinger Zeilinger is saying that even if the light level is so low that you have only one light event at a time passing through the double slit, a “click” of the which-path detectors is sufficient to prevent the formation of the interference pattern for as long as the “which-path” information is “out there”. However, if the which-path information is destroyed beyond recovery before you observe the results of the experiment, then an interference pattern appears. The results suggest that a person has free will to determine the outcome of the double slit experiment. If he chooses to learn the which-path information before observing the results of the results he will see no interference. If he has no means of learning the which-path information, then there will be interference. The results suggest that the interference pattern is not possible if someone has access to which-path information but interference is only possible if the which-path information is unknown and unknowable. The obvious explanation is that the which-path detectors are interfering causing the loss of interference but that possibility has been ruled out. The detectors were moved from the front of the double slit to the back with no change in the results. They were even moved all the way back so the which-path information was not determined until after the interference should have taken place but the interference pattern does not appear whenever the experiment is observed while the which-path information is “out there.” This is the difficulty behind the question in the OP. I agree with both statements. The Wheeler Delayed-Choice Double-Slit experiment is a good example to consider because it contains all the elements that are interpreted as having observer involvement- not necessarily human but possibly just sentient. I think this is the sort of explanation the OP is asking for so let it run. Sorry about the confused quotes, I am new to this forum and haven't figured out the editing yet. That short quote from "swansont" should have been at the beginning.

One question is, How do the objects that follow 'know' where to land in order to produce an interference pattern characteristic of a wave? With light, it is said that the wave becomes a particle when observed and it will no longer produce an interference pattern. This same scenario continues to say that the photon 'knows' it is being watched when a 'sentient'? observer discovers which path it took when going through the double slit and alters the outcome of the experiment accordingly. This is the interpretation of the Wheeler Delayed-Choice Double Slit experiment and it brings us back to the question in the OP. "Does the ability of an observer to affect an outcome simply by choosing to observe it mean that the choice had to have been made outside of all universal conditions?" One problem with scenario above is that, if the photon passed through just one slit, a single photon can't produce an interference pattern. If it split and passed through both slits or if it passed through both slits as a wave, there could be no which-path observation since it went through both. Also, if the wave has become a photon particle, it should produce a pattern characteristic of a particle like this || . Instead, it produces a diffraction pattern which is a long horizontal line with a few horizontal lines to the side. This is also characteristic of light as a wave. There is no evidence in any tests of the double slit experiment where light is behaving as a particle. That only happens in the cartoon illustrations of the experiment. If the above part is clear, i think I can explain how the experiment works with no human involvement.

The delayed choice double slit quantum eraser has EVERYTHING to do with optics. What happens when you send an electron through a BBO crystal or a C-60 molecule through a polarizing filter? It only works with light.

I am saying the which-path information is not telling us which way the photon went through the double slit but something else. Most likely it is telling us which slit the transverse light wave went through on the dielectric plane. I am also saying the absence of an interference pattern was explained in classical physics by Fresnel and Aragon and it has nothing to do with our observation of which-path information. I have not yet explained how the electrical observation of the photon path applies, but similar to observations with polarized light, the Delayed Choice Quantum Eraser can be explained as involving the combined effects of both linear and polarized light emerging from the birefringent crystals. This is no different from the technology used for the modern type of 3D movies.

OK And I see no collapse of the wave function. A paper by Fresnel and Arago (see Fresnel-Arago Laws) published two centuries ago explained why orthogonal polarized lights do not produce an interference pattern. The two beams collide in such a way that the interference is so rapid and random that the light is no longer coherent and the interference is no longer discernible. This has nothing to do with which-path information. I have found that light “marked” with circularly polarized light does produce an interference pattern so it is possible to have which-path information and an interference pattern both. This is consistent with the observations of Fresnel and Arago. There is no indication of a collapse of the wave function at any point in the double slit experiment,so even at low light levels where the light signal becomes intermittent and is observed as quanta of energy, there is no evidence to support the idea that light has become a particle. A quantum of energy can have the form of a wave packet and is not necessarily a particle. The classical view of the double slit experiment holds that light passes through both slits and both beams fan out and produce an interference pattern on the back side. The photon theory of light offers a more speculative view where a photon particle splits in two and passes through both slits and then both particles become waves that interfere with each other on the other side. Neither of these scenarios is consistent with the later determination of which-way information where the photon is observed to pass through only one of the two slits. So what can be passing through one slit but not the other? Light waves are transverse electromagnetic waves as discovered by Fresnel. One wave lies on the dielectric plane and the other is on the magnetic plane. When light passes through a birefringent crystal it is refracted upon entry into two divergent paths. One path is diverted more strongly than the other because the light wave on that path is slowed more on the electric plane than on the magnetic plane. This gives the transverse wave an apparent spiral. The two light paths that emerge from a birefringent crystal are oppositely polarized both linearly and circularly. In the “Wheeler Delayed Choice Double Slit Experiment” there are two color filters and three birefringent crystals directly behind the double slit. The first birefringent is the BBO crystal and the other two are found in the Glen-Thompson prism. These are usually calcite crystals. I suspect that the later determination of which-path information in the Wheeler DCE is not telling us which slit the photon went through but which path the light went through on the dielectric plane. And since the light in the experiment is second hand light generated within the BBO crystal, (not the UV light from the laser) it may not even be telling us which slit the original light from the laser went through. Sorry about the font size. I don't know how to change it or why it didn't go to default size.

I am interested in knowing if anyone can repeat my modification of the "DIY Quantum Eraser Experiment". Directions for how to perform the experiment can be found on YouTube. My modification involves replacing the two linearly polarized films in the experiment with two circularly polarized films to see what happens. I have observed that marking the two light paths with circularly polarized light does not erase the interference pattern contrary to the which-path theory. Ordinary clear cellophane tape "Scotch tape" serves well as a circular polarizing film and the tapes become orthogonal at a 45 degree angle. The tapes can be applied to glass for support. A microscope slide is ideal. The correct polarizing angle can be verified by examining the films sandwiched between two linear polarizing films or better by examining the films through polarized glasses when backlit by light from a flat screen LCD monitor. Quote from wiki: “However, in 1982, Scully and Drühl found a loophole around this interpretation.[11] They proposed a "quantum eraser" to obtain which-path information without scattering the particles or otherwise introducing uncontrolled phase factors to them. Rather than attempting to observe which photon was entering each slit (thus disturbing them), they proposed to "mark" them with information that, in principle at least, would allow the photons to be distinguished after passing through the slits. Lest there be any misunderstanding, the interference pattern does disappear when the photons are so marked. However, the interference pattern reappears if the which-path information is further manipulated after the marked photons have passed through the double slits to obscure the which-path markings. Since 1982, multiple experiments have demonstrated the validity of the so-called quantum "eraser"” I have always been more than a little dubious about the theory that "which-path" information can alter the results of an experiment and the Fresnel-Arago Laws explain the experiment so much better without the quantum woo.

I think we are saying the same thing. I understand the evolution of the universe as a several billion year emergence from a gravity well with the BB at the very bottom.

No, it is still possible to use rotation to create artificial gravity. The point is that an object floating free in the depths of space is still within the effects of the gravity originating from the sum of all the massive bodies in the universe. This gravity determines our perception of distance and time. There is no place in the universe that is free of gravity.

I suspect the general enlightenment about gravity is little better now than it was in Einstein’s time and the popularity of the flat earth theory makes me wonder if has gone the other way. Einstein’s delight in the Equivalence Principle was in knowing that he had discovered two ways of thinking about the same problem so he could test his theories about gravity against his understanding of free fall looking for consensus between the two. More importantly, the Equivalence Principle gave him simple examples he could use to explain his ideas to others. Everyone knows that astronauts are weightless in space but it is my impression that popular opinion holds that there is no gravity in space and I don’t think it is generally understood that astronauts are subject to much the same gravity as we are on the surface of the Earth. The difference between us and the astronauts is that they are in continuous free fall. There is also an erroneous impression that there is no gravity in deep space far from any massive bodies. Einstein’s Equivalence Principle seems to be less difficult to comprehend than what Einstein called Mach’s Principle which deals with universe wide influence of gravity and it is the latter that is the most enlightening about gravity.

It may be sloppy semantics but I equate inconsistency with uncertainty so the Uncertainty Principle self identifies as inconsistent. Here is a quote from Wiki” "Which-way" experiments and the principle of complementarity “A well-known thought experiment predicts that if particle detectors are positioned at the slits, showing through which slit a photon goes, the interference pattern will disappear.[6] This which-way experiment illustrates the complementarity principle that photons can behave as either particles or waves, but cannot be observed as both at the same time.” Contrary to many experts such as Don Lincoln at Fermi Labs, whom I cited in my previous post, the interference pattern never disappears and becomes a particle pattern. An interference pattern bears no resemblance to a particle pattern so it should be impossible to confuse the two but many do. I find it unambiguous to say that there is no evidence of complementarity in the double slit experiment so we should be able to interpret the experiment as a straight forward classical experiment with light waves.

This is an account of the double slit Delayed Choice Quantum quantum Eraser experiment that I have been trying to understand. https://en.wikipedia.org/wiki/Delayed-choice_quantum_eraser Here is a concise explanation of the Yoon Ho-Kim et al experiment described in the wiki article. https://video.search.yahoo.com/yhs/search;_ylt=Awr9NVWc2F9h4F0AFzg0nIlQ;_ylu=c2VjA3NlYXJjaAR2dGlkAw--;_ylc=X1MDMTM1MTE5NTcwMARfcgMyBGFjdG4DY2xrBGNzcmNwdmlkAzZsVDY3REV3TGpJS185VkZXNkh5Z2dENU5qY3VOZ0FBQUFDLi5PZ2EEZnIDeWhzLXRycC0wMDEEZnIyA3NhLWdwBGdwcmlkA3hOVDVab3JTUzE2QWkwWm1rQXQyOUEEbl9yc2x0AzYwBG5fc3VnZwMwBG9yaWdpbgN2aWRlby5zZWFyY2gueWFob28uY29tBHBvcwMwBHBxc3RyAwRwcXN0cmwDBHFzdHJsAzQ0BHF1ZXJ5AyUyMGRvbiUyMGRlbGF5ZWQlMjBjaG9pY2UlMjBxdWFudHVtJTIwZXJhc2VyBHRfc3RtcAMxNjMzNjcxNDI3?p=+don+delayed+choice+quantum+eraser&ei=UTF-8&fr2=p%3As%2Cv%3Av%2Cm%3Asa&fr=yhs-trp-001&hsimp=yhs-001&hspart=trp&type=Y167_F163_202037_052821#id=18&vid=44c8973728d6255afd71e2d1effc7cd3&action=view This is a crude demonstration of the double slit experiment that I have found key to understanding the more elaborate experiment above. https://video.search.yahoo.com/yhs/search?fr=yhs-trp-001&ei=UTF-8&hsimp=yhs-001&hspart=trp&p=you+tube+diy+quantum+erasers&type=Y167_F163_202037_052821#id=1&vid=0e2094e2c615986a3d91004bbf995aba&action=click In later posts I hope to explain how this last double slit experiment works and how it exposes errors in the convention thinking about the double slit experiment that make it so impossible to understand.

Both are strange. There is speculation that we would have no free will and everything would be deterministic if it were not for the Heisenberg uncertainty of Q M giving either Nature or our consciousness a chance to role the dice and change the future. I will leave that question to the philosophers. The HUP is predictably inconsistant.

Yes, I meant absorption. Thanks for the correction.

For light, emission and adsorption are simultaneous events.

I have been searching for the answer to the question of whether either observation or consciousness can influence the outcome of the double slit experiment for several years now and I feel I have made a lot of progress in understanding the problem but I have possibly reached the limits of my expertise to come to any definite conclusion except to say that this is an extremely thorny issue with no easy answers. It is my understanding that it is nearly the mainstream conclusion that observation and consciousness can influence the outcome of the double slit experiment. I have little interest in the philosophical or psychological aspects of this issue as long as the physics is remains in doubt. My gut instinct is that there is a simple laboratory experiment involving either QM or classical optics that can give us a definitive answer but so far any answer has remained elusive. https://video.search.yahoo.com/yhs/search?fr=yhs-trp-001&ei=UTF-8&hsimp=yhs-001&hspart=trp&p=fre+will%2C+consciousness%2C+and+the+double+slit+experiment&type=Y167_F163_202037_052821#id=59&vid=e8429fb72c2e23f62b116d966d534327&action=view https://video.search.yahoo.com/yhs/search?fr=yhs-trp-001&ei=UTF-8&hsimp=yhs-001&hspart=trp&p=fre+will%2C+consciousness%2C+and+the+double+slit+experiment&type=Y167_F163_202037_052821#id=2&vid=04b26854bc21b244bfbacf0d96dec6d1&action=view

I have always found it hard to imagine how either space or time can curve. Instead, I prefer to think of gravity a region of shorter distance and slower time. Distances appear shorter and clocks tick slower in a strong gravitational field than they do in a weak gravitational field. These are the two physical effects of that increase when entering a stronger gravitational field. These effects are invisible but they can be plotted on paper as curved lines so gravity is illustrated as curved spacetime. This is what Einstein called "Mach's Principle". Every point in space is influenced by the combined gravitational effect of every massive body in the universe. This is why a gyroscope orients itself with the distant galaxies rather than the local, and far weaker, sources of gravity such as the Earth or the sun. We tend to ignore the effect of gravity from the trillion or so galaxies because it is equal in all directions but it is the total gravitational field of the universe itself that determines our measurements of space and time. Ernst Mach explained that when a train stops suddenly the passengers fall forward because their attraction to the distant stars is greater than their attraction to the train.

For an over simplified explanation, if a gas is heated until it nearly begins to glow, one atom can emit a light wave and that light wave can strike another atom stimulating it to emit a double amplitude light wave in the same direction. As the light beam continues moving through the excited gas, it grows stronger with every collision. This is light amplification by stimulated emission “LASE." What happens in a neon light and a gas laser is similar. A gas laser is different from a neon light in that it has a mirror on both ends of a straight tube. The vast majority of light that can be generated is light that can bounce back and forth between the two mirrors growing stronger with every passage. One of the mirrors is only mostly silvered, perhaps 90 percent silvered, so the light emitted from the partly silvered mirror is light that has been generated in parallel lines perpendicular to the two mirrors within. It is not random light that has been “pulled together” The light emitted by a laser is called “coherent” light.