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Post by speakertoanimals on Feb 11, 2011 15:40:31 GMT 1
If you KNOW it went through only one (by measuring which one it goes through), you destroy the interference fringes.
Hence what is happening when you get fringes is a different thing. Okay, according to your interpretation of quantum theory, could be one photon in this universe interfering with itself and being two places at once, or it could be photon in one universe interfering with all those other photons in alternate universe.
BUT the fact that you still get the interference fringes when there is ever only ONE photon in the apparatus at a time is an experimental fact. The photon somehow 'knows' about the presence of the other slit, that is unassailable.
And it certainly doesn't fit in with our usual classical ideas as to a thing always having a definite position at every time, and what it then does depending only on that previous position. something weird is going on, and the SIMPLEST way to talk about it is that a single photon manages to be in two places at once.
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Post by abacus9900 on Feb 11, 2011 16:09:20 GMT 1
I think fundamentally we haven't got a clue what is going on in this experiment but I suppose it is incumbent on those who are supposed to know to offer any old bull that sounds interesting as a solution. Hi Abacus Penrose 'explains' the phenomenon in terms of -1 0.5. Although this odd number and its manipulations are quite elementary, it is difficult going following his explanation. I will attempt to understand what he is saying and get back. It seems that the wave function of a photon can be split into two complex vectors that each go through the separate slits which then modifies the vectors so that they add to a different resultant (positive or negative) (You can see from that that quite a lot more than ability with -1 0.5 is required!) naymissus, the problem I have with this is that 'i' (in common with all mathematical systems) is self-referential. We define i as the sqrt 1 fine, but then we have to work out all the logical consequences of that so although the concept of i was a new idea brought in to resolve some problems it is still inevitably embedded within the main logic of maths and therefore is limited in trying to provide an answer to something as mysterious as the double slit experiment. It seems to me, naymissus, that the people who try to understand such mysteries are forced to conjure up imaginary worlds that have no real meaning aside from what our imaginations imbue to them.
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Post by Progenitor A on Feb 11, 2011 16:30:56 GMT 1
It just does, get used to quantum theory, and stop wasting everyones time with these inane posts. STA, that a single photon 'goes both ways' through the two slits is a deduction, it is not as such a fact, and therefore could be wrong. Precisely Robin
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Post by Progenitor A on Feb 11, 2011 16:45:05 GMT 1
naymissus, the problem I have with this is that 'i' (in common with all mathematical systems) is self-referential. We define i as the sqrt 1 fine, but then we have to work out all the logical consequences of that so although the concept of i was a new idea brought in to resolve some problems it is still inevitably embedded within the main logic of maths and therefore is limited in trying to provide an answer to something as mysterious as the double slit experiment. It seems to me, naymissus, that the people who try to understand such mysteries are forced to conjure up imaginary worlds that have no real meaning aside from what our imaginations imbue to them. Yes I have that problem too. Penrose takes the probabilities of an electron or photon appearing at any of the positions behind the two slits. Then by doing some mathematical jiggery pokery (that I am still trying to get on top of) comes out with a complex number that he then demonstrates as describing the path ogf a photon as a helix. All very mysterious He does say that the particle as a wave-function (which is never how we measure a particle [my interjection]) acts as a local wavefront that extends across the two slits, going through both of them and then when it leaves the slits, interfering with itself to produce the probability characteristics that result in the classic 'fringeing' Of course (I think) the particle-as-wave-function (that we never see) is invoked by QM as a way of explaining these mysteries. In other words this mathematical tool is an application that might explain what is going on. Then again it might not QM is in need of a good kick up the arse in the form of a coherent understandable explanation. Still I will keep at Penrose to see if I can understand what he is talking about, then when (if) I come to unerstand than I will explain it all to you in my extraordinarily pellucid way that leaves no room for misunderstanding
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Post by abacus9900 on Feb 11, 2011 17:11:48 GMT 1
You know, I am really inclined to think at times that despite Penrose's brilliance he is really expressing a personal opinion here.
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Post by Progenitor A on Feb 11, 2011 17:16:47 GMT 1
You know, I am really inclined to think at times that despite Penrose's brilliance he is really expressing a personal opinion here. You mean like STA?
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Post by abacus9900 on Feb 11, 2011 17:25:48 GMT 1
You know, I am really inclined to think at times that despite Penrose's brilliance he is really expressing a personal opinion here. You mean like STA? Well, I wouldn't quite put her ramblings on a par with his, but essentially, yes.
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Post by speakertoanimals on Feb 11, 2011 17:44:30 GMT 1
Well that's a bloody stupid remark! What ELSE do you think anyone working at the very speculative end of theoretical physics IS doing. They are giving their own personal opinion as to what they think might be a worthwhile way forward.
It is their personal scientific opinion though, which is a world and more away from such transitory and insubstantial personal opinions as your opinion as to which premier league team is the best................
That's just standard quantum theory, no mystery there! Actually, isn't even that, just standard cklassical waves gets you a long way there.
And measurement is a separate problem, hence no bloody surprise it isn't referred to here. We can't MEASURE the wavefunction directly in any one case, but we can INFER the amplitude squared of the wavefunction from repeated measurements on identical copies of a system.
ANd the usual bollocks from the great unwashed and those that don't understand the first thing about quantum theory!
We have THE most accurately tested theory in the WHOLE OF PHYSICS. We are talking about an agreement at the level of ten parts in a billion for QED. Yet these numpties keep 'complaining' because according to their little minds, it is neither coherent nor understandable. Which is bollocks. As I've said before, WHY should the universe agree with your preconceptions as to what is coherent, or to your limited ability to understand?
Quantum physics is mostly very understandable. The measurement problem is a bit of a bugger, but the main 'problem' is that it doesn't agree with out intuition -- and that's as far as these supposed objections go. Just the same as for cosmology or relativity -- what is not immediately obvious to the man in the street is seen by some, rather than one of THE great intellectual achievements of humanity to date, but instead as some sort of confidence trick run by mathematicians and researchers keen to keep their jobs, so rather than coming up with a PROPER explanation, they instead go wittering on about complicated maths in a deluded attempt to fool that same man in the street.
Which always looks to me like the man in the street having a very frail ego, and assuming that what he cannot easily understand is not worth understanding, or even worse, a great con. And a little commonsense ought to be able to see that it is nonsense! Two places at once, curved space, expanding space, they must be having a laugh at my expense....................
As Wells knew, in the country of the blind, they try to put out the eyes of the one/few who can see...........................
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Post by abacus9900 on Feb 11, 2011 18:07:19 GMT 1
Well that's a bloody stupid remark! What ELSE do you think anyone working at the very speculative end of theoretical physics IS doing. They are giving their own personal opinion as to what they think might be a worthwhile way forward. It is their personal scientific opinion though, which is a world and more away from such transitory and insubstantial personal opinions as your opinion as to which premier league team is the best................ All it means is that they are telling more elaborate fables because they have more 'myths' to use. Fact is dearie, the more remote such ideas are from good old commonsense the more absurd they become and BTW harder to prove!
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Post by abacus9900 on Feb 11, 2011 18:11:22 GMT 1
How many more times have you got to be told that NOBODY understands quantum theory? Richard Feyman said this a long time ago yet you keep insisting the opposite is true. Do you really think we are that gullible?
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Post by Progenitor A on Feb 11, 2011 18:23:26 GMT 1
How many more times have you got to be told that NOBODY understands quantum theory? Richard Feyman said this a long time ago yet you keep insisting the opposite is true. Do you really think we are that gullible? There is no point in even reading her posts abacus She is disturbed and not worth the bother Simply go to the IDIOT SCIENCE thread and read just how preposterous her ranting is. Do Remeber this is the person 'That doesn't give a fig what Einstein says' (in writing his 'Theory Of Relativity'). A bigot
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Post by robinpike on Feb 11, 2011 20:28:10 GMT 1
BUT the fact that you still get the interference fringes when there is ever only ONE photon in the apparatus at a time is an experimental fact. The photon somehow 'knows' about the presence of the other slit, that is unassailable. something weird is going on, and the SIMPLEST way to talk about it is that a single photon manages to be in two places at once. STA, your statement: 'The photon somehow 'knows' about the presence of the other slit, that is unassailable' - the 'know' is a conclusion - and therefore may be incorrect. For example, there could be other explanations, such as when a photon passes near atoms, the atoms affect the path of the photon. Now, when atoms 'are removed' to create the second slit, the configuration of the atoms has changed, and therefore how they affect the photon can change. This could also explain how the 'interference pattern' is altered when we try to measure which slit the photon goes through - the atoms in the measuring equipment have changed the configuration of the atoms that the light passes. This could also explain how changing the thickness of a piece of glass can change how much light is reflected, in a cycle from 0% minimum to 16% maximum as you go through different thicknesses. At no point would the light have to go to the back of the glass to 'know' how thick the glass is and therefore work out what percentage it should 'interfere with itself' to give reflection.
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Post by abacus9900 on Feb 11, 2011 21:06:25 GMT 1
naymissus I seriously do think that STA has some serious issues and this is not based on any personal enmity between us but on several years of experience both on here and the old BBC science MB. I did put it down to a bit of eccentricity but I really do wonder if it is a symptom of a much deeper problem. I do not say this to be vengeful or hateful, it's just the case, as you will probably agree.
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Post by Progenitor A on Feb 11, 2011 22:16:44 GMT 1
Best ignored and do not, ever , reply.
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Post by abacus9900 on Feb 11, 2011 22:58:16 GMT 1
Best ignored and do not, ever , reply. I keep telling myself not to naymissus but then I begin to feel a bit sorry for STA because I feel she needs this place to compensate for something or other. Am I just too soft? I would say she has poor social skills which is why she keeps posting here.
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