Radioactive decay and the myth of randomness
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From: tg on 15 Nov 2009 16:29 On Nov 15, 3:24 pm, Jim Burns <burns...(a)osu.edu> wrote: > tg wrote: > > I'm fascinated by JJ's ability to elicit responses > > with his language which closely approaches quantum > > randomness. However, there is a reasonable underlying > > language/philosophical question. > > I agree that these questions about quantum randomness > and others like them are reasonable. But the program of > consulting our intuition about their answers has expired, > has ceased to be: it is an ex-program. > > The assumptions of Bell's Theorem are that the > outcome of a quantum measurement is (i) determined > by properties of the particle and apparatus > (whether or not we can measure the properties > themselves), and (ii) /not/ affected by anything > that happens at some arbitrarily large distance > (which are often abbreviated as "local reality" > and may, for many purposes, be referred to as > "our intuition"). > > The theorem puts a limit on how strongly correlated > certain pairs of widely separated measurements > can be. Quantum mechanics claims that some of these > measurements will break those limits. It turns out > experimentally that quantum mechanics is right and > "local reality" (AKA "our intuition") is wrong. > > > We believe that there is no cause that can effect > > the lifetime of the decay of a particle. So it seems > > to me that we could attribute a label of > > 'hidden variable' to that information itself. IOW, > > while we do not claim a cause, we could argue that > > the lifetime could as easily be *determined* at the > > instant of creation of the particle as at the instant > > of decay. So there would be a piece of information > > about the particle which is inaccessible rather than > > non-existent. > > I'm afraid I don't find your description of this > whatever-it-is (that does not cause the particle's > decay but does determine it) to be very coherent. > I wrote rather quickly but I thought it was understandable; let me try again: 1) I do not claim that something causes the particle's decay. 2) That nothing causes the particle's decay does not mean that the lifetime is not determined at the creation of the particle. By determined I only mean that it is inevitable, that there is nothing that can change it. 3) If you believe that this would violate QM, then you should be able to describe a hypothetical experiment whose outcome would be different if my proposed conjecture is incorrect. It seems to me that the best argument against what I am suggesting is that it is not parsimonious, but I'm not even sure that such a position holds up. As I said in the first place, this is a question of language and philosophy, not physics. I find the use of decay as the knee-jerk example to explain randomness to be facile. -tg > If the time of the decay of the particle is a function > of this 'hidden variable', then the conditions > of Bell's Theorem are met and there is a limit on > correlations between widely separated measurements > which is at least sometimes broken by our measurements. > I take this to mean that there is, in fact, no such > hidden variable, whether or not we can access it. > > Someone might object that we don't know that the > results of the intuition-destroying experiments > apply to decaying atoms as well as pairs of > gamma rays. Personally, I find experimental > results that dodge our constraints but only > when we can't see them doing so to be considerably > less intuitive than the loss of local reality. > > Perhaps a better answer would be to point out > that the way physics proceeds, the way science > proceeds is to generalize alleged laws to the > utmost extent ("Energy is conserved everywhere > in the universe.") and then wait for contradictions > to pour in from the experimentalists. ("But, wait! > I've got some radium that behaves very oddly.") > Is there some contradiction, some troubling > experimental result that makes it necessary to > suppose there is this 'hidden variable'? > > Jim Burns > > http://en.wikipedia.org/wiki/Bell%27s_theorem#Importance_of_the_theorem
From: Jim Burns on 15 Nov 2009 23:39 tg wrote: > On Nov 15, 3:24 pm, Jim Burns <burns...(a)osu.edu> wrote: >> tg wrote: >>> I'm fascinated by JJ's ability to elicit responses >>> with his language which closely approaches quantum >>> randomness. However, there is a reasonable underlying >>> language/philosophical question. >> I agree that these questions about quantum randomness >> and others like them are reasonable. But the program of >> consulting our intuition about their answers has expired, >> has ceased to be: it is an ex-program. >> >> The assumptions of Bell's Theorem are that the >> outcome of a quantum measurement is (i) determined >> by properties of the particle and apparatus >> (whether or not we can measure the properties >> themselves), and (ii) /not/ affected by anything >> that happens at some arbitrarily large distance >> (which are often abbreviated as "local reality" >> and may, for many purposes, be referred to as >> "our intuition"). >> >> The theorem puts a limit on how strongly correlated >> certain pairs of widely separated measurements >> can be. Quantum mechanics claims that some of these >> measurements will break those limits. It turns out >> experimentally that quantum mechanics is right and >> "local reality" (AKA "our intuition") is wrong. >> >>> We believe that there is no cause that can effect >>> the lifetime of the decay of a particle. So it seems >>> to me that we could attribute a label of >>> 'hidden variable' to that information itself. IOW, >>> while we do not claim a cause, we could argue that >>> the lifetime could as easily be *determined* at the >>> instant of creation of the particle as at the instant >>> of decay. So there would be a piece of information >>> about the particle which is inaccessible rather than >>> non-existent. >> I'm afraid I don't find your description of this >> whatever-it-is (that does not cause the particle's >> decay but does determine it) to be very coherent. >> > > I wrote rather quickly but I thought it was > understandable; let me try again: > > 1) I do not claim that something causes the > particle's decay. > > 2) That nothing causes the particle's decay does > not mean that the lifetime is not determined at the > creation of the particle. By determined I only mean > that it is inevitable, that there is nothing that > can change it. Here is my understanding of /randomness/: the outcome of an experiment (like rolling a die) is /random/ if, in all the possible worlds that are /identical/, there is more than one outcome (more than one face lands up). By /identical/ I mean that /everything we know/ about all the causal paths leading to our experimental outcome is the same in each possible world. My understanding of /quantum randomness/ is that we consider all the possible worlds where /everything/ is identical, instead of /everything we know/, but there is still more than one outcome of the experiment. I see two interpretations that you might intend (and a third option -- that I just don't get it). (1) If we draw a box around the space-time just before the decay of the atom, we can look at all the possible worlds where the contents of the box is identical. Because the decay of the atom has quantum randomness, there are still different times of decay for the atom in different possible worlds. HOWEVER, if we, in our imaginations, mark the time of the decay on the box (our hidden variable -- hidden because it plays no part in the physics, being imaginary), then we can further subdivide the possible worlds so that boxes marked with the same time are grouped together. Presto! The outcome is no longer random, because these groups of possible worlds all have single outcomes (the atom decays at the same time in each possible world -- /within each subgroup/, that is). Under this view, I suppose there is no quantum randomness, but there is no randomness either, nor any probability except 0 and 100%. There are no uncertain outcomes because every outcome will be what it will be, tautologically. I don't know, but this view may be logically consistent, but it seems to me completely useless. It certainly isn't physics. (2) We have almost the same situation as before: a box around the space-time just before the decay of the atom, a collection of all the possible worlds where the contents are identical. Except that, under this view, in stead of marking the time of decay on the outside of the box, it's placed inside the box, inside a lockbox, let us say, so that we know it can't be used in the processes leading to the outcome. I think this might qualify as a physical theory, but this is also the sort of situation that Bell's theorem applies to. It doesn't matter that the decay time written inside the lockbox does not participate. The theorem does not ask whether a particular parameter /participates/, just as the theorem does not ask whether /we know the value of/ a particular parameter. > 3) If you believe that this would violate QM, > then you should be able to describe a hypothetical > experiment whose outcome would be different > if my proposed conjecture is incorrect. I think the experimental verification of quantum mechanics over local reality are what you are asking for. If you are considering scenario 2 above, then you are trying to fix local reality by partitioning the possible worlds finely enough that the outcome appears non-random. I don't think local reality is fixable. > It seems to me that the best argument against > what I am suggesting is that it is not parsimonious, > but I'm not even sure that such a position holds up. > As I said in the first place, this is a question > of language and philosophy, not physics. I find > the use of decay as the knee-jerk example to explain > randomness to be facile. If what you describe is only a question of language and philosophy, then maybe my first interpretation is the correct one. If that is so, then the point you are making is that it is possible to change the meaning of "quantum randomness" so that what you have turned it into does not exist. I don't find that a very interesting point. Jim Burns
From: tg on 16 Nov 2009 06:42 On Nov 15, 11:39 pm, Jim Burns <burns...(a)osu.edu> wrote: > tg wrote: > > On Nov 15, 3:24 pm, Jim Burns <burns...(a)osu.edu> wrote: > >> tg wrote: > >>> I'm fascinated by JJ's ability to elicit responses > >>> with his language which closely approaches quantum > >>> randomness. However, there is a reasonable underlying > >>> language/philosophical question. > >> I agree that these questions about quantum randomness > >> and others like them are reasonable. But the program of > >> consulting our intuition about their answers has expired, > >> has ceased to be: it is an ex-program. > > >> The assumptions of Bell's Theorem are that the > >> outcome of a quantum measurement is (i) determined > >> by properties of the particle and apparatus > >> (whether or not we can measure the properties > >> themselves), and (ii) /not/ affected by anything > >> that happens at some arbitrarily large distance > >> (which are often abbreviated as "local reality" > >> and may, for many purposes, be referred to as > >> "our intuition"). > > >> The theorem puts a limit on how strongly correlated > >> certain pairs of widely separated measurements > >> can be. Quantum mechanics claims that some of these > >> measurements will break those limits. It turns out > >> experimentally that quantum mechanics is right and > >> "local reality" (AKA "our intuition") is wrong. > > >>> We believe that there is no cause that can effect > >>> the lifetime of the decay of a particle. So it seems > >>> to me that we could attribute a label of > >>> 'hidden variable' to that information itself. IOW, > >>> while we do not claim a cause, we could argue that > >>> the lifetime could as easily be *determined* at the > >>> instant of creation of the particle as at the instant > >>> of decay. So there would be a piece of information > >>> about the particle which is inaccessible rather than > >>> non-existent. > >> I'm afraid I don't find your description of this > >> whatever-it-is (that does not cause the particle's > >> decay but does determine it) to be very coherent. > > > I wrote rather quickly but I thought it was > > understandable; let me try again: > > > 1) I do not claim that something causes the > > particle's decay. > > > 2) That nothing causes the particle's decay does > > not mean that the lifetime is not determined at the > > creation of the particle. By determined I only mean > > that it is inevitable, that there is nothing that > > can change it. > > Here is my understanding of /randomness/: the outcome of > an experiment (like rolling a die) is /random/ if, in all > the possible worlds that are /identical/, there is more > than one outcome (more than one face lands up). By > /identical/ I mean that /everything we know/ about > all the causal paths leading to our experimental > outcome is the same in each possible world. > > My understanding of /quantum randomness/ is that we > consider all the possible worlds where /everything/ > is identical, instead of /everything we know/, but > there is still more than one outcome of the experiment. > > I see two interpretations that you might intend (and > a third option -- that I just don't get it). > > (1) If we draw a box around the space-time just before > the decay of the atom, we can look at all the possible > worlds where the contents of the box is identical. > Because the decay of the atom has quantum randomness, > there are still different times of decay for the atom > in different possible worlds. HOWEVER, if we, in our > imaginations, mark the time of the decay on the box > (our hidden variable -- hidden because it plays no > part in the physics, being imaginary), then we can > further subdivide the possible worlds so that boxes > marked with the same time are grouped together. > Presto! The outcome is no longer random, because > these groups of possible worlds all have single outcomes > (the atom decays at the same time in each possible > world -- /within each subgroup/, that is). > > Under this view, I suppose there is no quantum > randomness, but there is no randomness either, > nor any probability except 0 and 100%. There are no > uncertain outcomes because every outcome will be what > it will be, tautologically. I don't know, but this > view may be logically consistent, but it seems to > me completely useless. It certainly isn't physics. > > (2) We have almost the same situation as before: > a box around the space-time just before the decay > of the atom, a collection of all the possible worlds > where the contents are identical. Except that, under > this view, in stead of marking the time of decay > on the outside of the box, it's placed inside the > box, inside a lockbox, let us say, so that we know > it can't be used in the processes leading to the outcome. > > I think this might qualify as a physical theory, > but this is also the sort of situation that > Bell's theorem applies to. It doesn't matter that > the decay time written inside the lockbox does > not participate. The theorem does not ask whether > a particular parameter /participates/, just as the > theorem does not ask whether /we know the value of/ a > particular parameter. > > > 3) If you believe that this would violate QM, > > then you should be able to describe a hypothetical > > experiment whose outcome would be different > > if my proposed conjecture is incorrect. > > I think the experimental verification of quantum mechanics > over local reality are what you are asking for. If you > are considering scenario 2 above, then you are trying > to fix local reality by partitioning the possible worlds > finely enough that the outcome appears non-random. > > I don't think local reality is fixable. > > > It seems to me that the best argument against > > what I am suggesting is that it is not parsimonious, > > but I'm not even sure that such a position holds up. > > As I said in the first place, this is a question > > of language and philosophy, not physics. I find > > the use of decay as the knee-jerk example to explain > > randomness to be facile. > > If what you describe is only a question of > language and philosophy, then maybe my first > interpretation is the correct one. If that is so, > then the point you are making is that it is > possible to change the meaning of > "quantum randomness" so that what you have > turned it into does not exist. > I don't find that a very interesting point. > > Jim Burns Yeah, option 3, and I also think you have been over-consuming caffeinated beverages or something. I always wonder about people who can't read through a couple of short paragraphs before rambling on with a reply that is nowhere near the point. -tg
From: haiku jones on 16 Nov 2009 10:04 On Nov 14, 8:20 pm, John Jones <jonescard...(a)btinternet.com> wrote: > haiku jones wrote: > > On Nov 13, 1:19 pm, John Jones <jonescard...(a)btinternet.com> wrote: > >> haiku jones wrote: > >>> On Nov 13, 7:56 am, John Jones <jonescard...(a)btinternet.com> wrote: > >>>> Quantum mechanics says that there is no way to predict when an atom will > >>>> decay radioactively. > >>>> This doesn't mean that the decay is random. We wouldn't, for example, > >>>> claim that a person who suddenly appears from behind a bus is exhibiting > >>>> a new, mysterious, physical state called randomness. > >>>> So! - why would we say that the appearance of an outcome of hidden > >>>> quantum events is random? Quantum events are necessarily hidden because > >>>> physical space itself hides very small objects - but they are still only > >>>> "hidden", like the man behind the bus. > >>> I take it you didn't really read my post, in which I discussed exactly > >>> this idea -- what physicists call "local hidden variables" -- > >>> and how the general consensus among quantum physicists > >>> is that the experimental investigations of Bell's inequality > >>> have led to the conclusion that local hidden variables -- > >>> again, exactly the sort of thing you suggest -- are not > >>> possible. > >>> Could this change some day? Is our current conception > >>> of such things not final? > >>> I am utterly open to such new insights. But until then, > >>> your pitching an idea which had been debated for > >>> the better part of a century, and is currently considered > >>> to be bogus by most (but not all) workers in the field, is not > >>> the sort of thing that will change my mind. > >>>> I rest my case. But ponder this...wasn't the scientific term "random" > >>>> invented to support a verbal fantasy world created by the quantum > >>>> physicists? > >>> Given that the OED gives examples of "random", meaning > >>> exactly what it does today, dating back to the mid 17th > >>> century, I'm going to say "no". > >>>> It's understandable. > >>> Not to mention "bogus". > >>> Haiku Jones > >>>> After all, every discipline, including > >>>> maths, likes to have its own non-religious menagerie of supernatural > >>>> objects and processes, where infinities abound far beyond the mortal > >>>> realms of grammar and sense. > >> I don't know what this post is about. > > > You don't? I thought it was pretty straightforward. > > > You suggested that quantum events only look > > random because the tiny scale prevents > > us from seeing behind the scenes, observing > > the machinery that causes radioactive decay > > to be caused in a non-random manner. > > > I replied that quantum mechanics had, over the > > last thirty years or so, dealt with exactly that > > possibility, and the conclusion had been reached > > that it was not possible that any such machinery > > exists. Not even as a theoretical abstraction. > > You made no such argument here Sure did. See above. >. Nor was any argument forthcoming from > elsewhere. > > > > > And just for grins, I replied to your ".wasn't the > > scientific term "random" invented to support > > a verbal fantasy world created by the quantum > > physicists?" by pointing out that the word > > "random" was in use, with its present meaning, > > two and a half centuries before the discovery > > of quantum mechanics. > > > Haiku Jones > > Yes and I said that the former use bore no relation to the Quantum use. Sure did. Haiku Jones
From: haiku jones on 16 Nov 2009 10:04
On Nov 15, 2:13 pm, John Jones <jonescard...(a)btinternet.com> wrote: > Jim Burns wrote: > > tg wrote: > > >> I'm fascinated by JJ's ability to elicit responses > >> with his language which closely approaches quantum > >> randomness. However, there is a reasonable underlying > >> language/philosophical question. > > > I agree that these questions about quantum randomness > > and others like them are reasonable. But the program of > > consulting our intuition about their answers has expired, > > has ceased to be: it is an ex-program. > > > The assumptions of Bell's Theorem are that the > > outcome of a quantum measurement is (i) determined > > by properties of the particle and apparatus > > (whether or not we can measure the properties > > themselves), and (ii) /not/ affected by anything > > that happens at some arbitrarily large distance > > (which are often abbreviated as "local reality" > > and may, for many purposes, be referred to as > > "our intuition"). > > > The theorem puts a limit on how strongly correlated > > certain pairs of widely separated measurements > > can be. Quantum mechanics claims that some of these > > measurements will break those limits. It turns out > > experimentally that quantum mechanics is right and > > "local reality" (AKA "our intuition") is wrong. > > >> We believe that there is no cause that can effect > >> the lifetime of the decay of a particle. So it seems > >> to me that we could attribute a label of > >> 'hidden variable' to that information itself. IOW, > >> while we do not claim a cause, we could argue that > >> the lifetime could as easily be *determined* at the > >> instant of creation of the particle as at the instant > >> of decay. So there would be a piece of information > >> about the particle which is inaccessible rather than > >> non-existent. > > > I'm afraid I don't find your description of this > > whatever-it-is (that does not cause the particle's > > decay but does determine it) to be very coherent. > > > If the time of the decay of the particle is a function > > of this 'hidden variable', then the conditions > > of Bell's Theorem are met and there is a limit on > > correlations between widely separated measurements > > which is at least sometimes broken by our measurements. > > I take this to mean that there is, in fact, no such > > hidden variable, whether or not we can access it. > > > Someone might object that we don't know that the > > results of the intuition-destroying experiments > > apply to decaying atoms as well as pairs of > > gamma rays. Personally, I find experimental > > results that dodge our constraints but only > > when we can't see them doing so to be considerably > > less intuitive than the loss of local reality. > > > Perhaps a better answer would be to point out > > that the way physics proceeds, the way science > > proceeds is to generalize alleged laws to the > > utmost extent ("Energy is conserved everywhere > > in the universe.") and then wait for contradictions > > to pour in from the experimentalists. ("But, wait! > > I've got some radium that behaves very oddly.") > > Is there some contradiction, some troubling > > experimental result that makes it necessary to > > suppose there is this 'hidden variable'? > > > Jim Burns > > >http://en.wikipedia.org/wiki/Bell%27s_theorem#Importance_of_the_theorem > > The idea of a hidden variable is a grammatical consequence of any > quantum theory, as I argued. Alas, the universe disagrees. Haiku Jones |