My FQXi Essay About the Quantum Measurement Problem is Now Available!
The Foundational Questions Institute (FQXi, the "X" is there perhaps to represent the unknown, or maybe extra effort to try and find out what this is all about) promotes independent research into the ultimate scientific "why" questions. One of the reasons we need FQXi is given below from their summary, from http://fqxi.org:
EXPLORING THE FOUNDATIONS AND BOUNDARIES OF PHYSICS AND COSMOLOGY
FQXi catalyzes, supports, and disseminates research on questions at the foundations of physics and cosmology, particularly new frontiers and innovative ideas integral to a deep understanding of reality, but unlikely to be supported by conventional funding sources.
The money quote as they say: "... but unlikely to be supported by conventional funding sources." Such sources are not likely to be much help to those like me who are"amateurs" in practical terms, whatever their abilities. (I do note there are other helpful groups, like the Society for Amateur Scientists.) One of the ways FQXi supports quality inquiry that is open regardless of professional affiliation, is through their periodic essay contests. The current FQXi Essay Contest wants answers to the question: "Is Reality Digital or Analog?" My submission to this contest was just accepted. The title: Our Non-Deterministic Reality Is Neither Digital Nor Analog: Experimental Tests Can Show That Decoherence Fails to Resolve the Measurement Problem. The paper itself is IMHO too long and maybe hard to format into this space, but here's the abstract and a link to the article (pdf download):
Is reality best described in digital or analog terms? In proper context, we are asking: what type of math is best for that purpose? However, I argue that our universe is genuinely non-deterministic, as conventional notions of quantum mechanics imply. Since mathematics is by nature deterministic, reality is not fully describable by any true mathematical model. The best answer to the original question is then, “neither – reality transcends mathematics.” It is argued that some popular attempts to avoid the quantum measurement problem, such as the decoherence interpretation, are flawed. The logical case for DI is flawed by the circular argument at its core. More importantly: some experiments are described, which could falsify the DI. If successful, they would show that we can recover superpositions supposedly lost to decoherence. Hence our finding definitive experimental outcomes instead of superposed results is not due to the effects of decoherence. Those definite, exclusionary results show a genuinely indeterminate character of the universe.
The complete paper is available here.
Previous visitors to this blog will recognize that this paper deals with one of my controversial pet peeves: the idea that decoherence helps solve the quantum measurement problem. My previous post about the subject, Decoherence Interpretation Falsified?, generated lots of intense discussion. Please, hop on over to FQXi and tell me what you think.
EXPLORING THE FOUNDATIONS AND BOUNDARIES OF PHYSICS AND COSMOLOGY
FQXi catalyzes, supports, and disseminates research on questions at the foundations of physics and cosmology, particularly new frontiers and innovative ideas integral to a deep understanding of reality, but unlikely to be supported by conventional funding sources.
The money quote as they say: "... but unlikely to be supported by conventional funding sources." Such sources are not likely to be much help to those like me who are"amateurs" in practical terms, whatever their abilities. (I do note there are other helpful groups, like the Society for Amateur Scientists.) One of the ways FQXi supports quality inquiry that is open regardless of professional affiliation, is through their periodic essay contests. The current FQXi Essay Contest wants answers to the question: "Is Reality Digital or Analog?" My submission to this contest was just accepted. The title: Our Non-Deterministic Reality Is Neither Digital Nor Analog: Experimental Tests Can Show That Decoherence Fails to Resolve the Measurement Problem. The paper itself is IMHO too long and maybe hard to format into this space, but here's the abstract and a link to the article (pdf download):
Is reality best described in digital or analog terms? In proper context, we are asking: what type of math is best for that purpose? However, I argue that our universe is genuinely non-deterministic, as conventional notions of quantum mechanics imply. Since mathematics is by nature deterministic, reality is not fully describable by any true mathematical model. The best answer to the original question is then, “neither – reality transcends mathematics.” It is argued that some popular attempts to avoid the quantum measurement problem, such as the decoherence interpretation, are flawed. The logical case for DI is flawed by the circular argument at its core. More importantly: some experiments are described, which could falsify the DI. If successful, they would show that we can recover superpositions supposedly lost to decoherence. Hence our finding definitive experimental outcomes instead of superposed results is not due to the effects of decoherence. Those definite, exclusionary results show a genuinely indeterminate character of the universe.
The complete paper is available here.
Previous visitors to this blog will recognize that this paper deals with one of my controversial pet peeves: the idea that decoherence helps solve the quantum measurement problem. My previous post about the subject, Decoherence Interpretation Falsified?, generated lots of intense discussion. Please, hop on over to FQXi and tell me what you think.
posted by Neil Bates at 13:32
37 Comments:
Hi, Neil. I don't see any replies to your nice short paper yet. Would they be right beneath your abstract? If so, it's been less than 12 hours since it was posted so that may be the reason. They should be reading it in Europe right now though, and 29 hours after it was posted (noon on the US East coast) Californians should be starting to read it, so let's give it till say 9 pm tonight Friday for the world to have ingested this and commented, with all due respect to Hawaii. :-)
Genral question: WHOSE toes would be stepped on the hardest if you are correct? Yes, I want names. :-)
I hate politics, in gets in the way of progress so darn much.
Nice ending with the dodecahedron bird. I never read Penrose's book but it does sound similar to the Myth of Sisyphus.
Good luck sir!
Btw your timestamp is set that it says by last reply was made at 11:20, when it fact it is 6:22 am EST
Thanks, Steven. I thought it better to work up a piece for this FQXi contest than ViXrA, both for publicity and because it is easier for me to write semi-popular stuff (but I have done the real deal, look up the pieces from Physics Essays if you like, from that Scitation link here.) Please comment if you haven't already, that gets it started at least. Tell friends and colleagues. Even more congrats in order if I win a prize for this.
Dodecahedron-bird: Just for the record, that's an actual dream I had, some years before reading about Penrose's "magic dodecahedron" of quantum mystery published in 94. I think late 80s. Note also, when the Platonic solids are used to represent elements:
cube: earth
tetrahedron: fire
octahedron: air
icosahedron: water
and the dodecahedron is "quintessence" - the mystical fifth element of the heavens, and sometimes "the universe" as a whole. Since I knew that when I had the dream, I think it really did symbolize that whole issue of fruitlessly chasing after the ultimate nature of reality.
Some physicists do refer to a special stuff or field they call quintessence. Wikipedia says: "In physics, quintessence is a hypothetical form of dark energy postulated as an explanation of observations of an accelerating universe."
More answers and thoughts in short order.
PS: for that global-citizen feel I use UT (old GMT) for this blog.
Neil, you know I love ya brah, but I'm not really qualified to write about your essay, not yet anyway.
For starters, I gave up on QM when I explored Entanglement, which is either trivially obvious, or implies a 5th dimension being a 4th spacial one (although NOT "hidden variables" ala Bohm). Since R-sub-4 (you know what that is right?) can't support matter/space as we know it ala Simon Donaldson, I got stuck. Backed up, Looked at Gen Rev and Spec Rev, never been happier. Except I don't know/forgot the math, so I'm studying that now.
Anyways, I like Decoherence. BUT, I like your experiment too. I wish someone would run it. Doesn't look that expensive. The worst it can do is fail. If so, that would teach us something, ala Michelson-Morley. Also, the one paper I wrote based on the one experiment I did was on a Mach-Zehnder Interferometer. I can blow up those rubber tires and align beam splitters and lasers with the best of them. I'd like to help, but unless you're independently wealthy and can hire me, well ....
If your name was Witten and you had a PhD you'd get funding tomorrow. I hate Politics. All the IQ and Mensa membership in the world doesn't matter vs Politics.
Steven, about toes: First of all, I'm not looking to make Chad O. look particularly bad or continue our feud (such as it is, he seems to have mellowed but still won't address me directly.) I know I bungled the way I introduced my critique of DI, making it seem like a rub against him. And AFAICT he deserves no special "blame" for being a promoter of DI. (In my essay, I refer to his demonstration example as "illustrative, its author is aware of the limitations of DI.") He was basically just illustrating it and going along with the popular flow like so many do, and not being critical enough. But he does merit some later blame for not getting my point right in his big infamous rebuttal: in my proposal (at Decoherence Interpretation Falsified? here and "TE2" in my essay), it was crucial that the first beamsplitter be asymmetrical (unequal reflection and transmission), but he wrote it up as equal. That ruined the whole effect. My proposal depends on getting the asymmetrical split out later, at BS3, in a way that only interfering superpositions can do, but not mixtures. Chad admitted that late, in comments only, and it was too late for readers to really appreciate what I was trying to do. He and most commenters didn't think my TE proved anything of interest, yet my experiment TE2 proves that the output from an ostensible mixture-machine like his ("TE1" in my essay), really is not. Furthermore, we could do without those digs at what "amateurs" are capable of. Well, our heated discussions and cross-linkings did propel me back into top search for "quantum measurement paradox" ...
The biggest promoter of DI is W. Zurek, who apparently thinks that decoherence really does explain why we don't see macroscopic superpositions. Well, it doesn't. Decoherence happens, but should just muddy up WFs that continue to be superposed all in "one world." Without some special intrusion, there's nothing to turn coherent waves into nice patterns of hits that indicate interference, or to turn messy waves into sloppy patterns that misleadingly seem to indicate prior "mixtures" in and of themselves.
You can add Andrew Thomas, with a big site "What Is Reality?". Also, our old quasi-buddy LuMo ("a great teacher", but mean to Bee etc.) defends the idea and considers it a genuine answer, see for example LuMo. But so many others have followed the DI pied piper's disingenuous path ... I'm not the only one who is suspicious, for example read more of the page that Nick Herbert quote came from. Penrose gets down on it too. I want this piece of mine to be noticed, and to create a ruckus. There needs to be a big "airing of dirty laundry" about this whole thing. DI should never have been accepted as a reasonable alternative, nor its related post-bongian indulgence the MWI (see my little nibbles on that, too.)
[... comment continued below, because of that damn 4096 character limit.]
...
Yet, I don't want anyone to look dumb or dishonest here. DI is an appealing salve to comfort worries about the measurement problem. The QMP and the "collapse" idea seem so absurd and distasteful, that even (otherwise) good thinkers are drawn to something, almost "anything," that seems to provide a way out. But it's a false promise and false premise. DI is based on the fallacy of circular argument, and experimentally disprovable as well. I don't even consider DI worthy of being a great but failed theory: a worthy attempt that just turned out short. It is just bogus, not even a good-faith and worthy effort. I say of it, "the Jester has no clothes." Finally, it wouldn't hurt for you to vote for my essay on the basis you think I made a good effort. Tommaso Dorigo already said my article was "Beautiful" at his Facebook page. REM these are semi-popular essays, and an intelligent and reasonably science/math-literate person can get my point. Also, you can leave comment/s. I'm afraid my piece won't get much notice, for as you suggest, unless fans vote and comment.
PS: heh, yeah; I'll put something about this in a forthcoming issue of our local Mensa newsletter M-Tides.
BTW, in case not clear from context: by "the way I introduced my critique of DI" and the wrangle-off thereof, I meant the post here: "Decoherence Interpretation Falsified?" The later quote etc. is from my recent essay, now posted at FQXi as noted.
BTW another way to dig at DI is that it's an expression of "truthiness" in scientific theorizing.
Hi Neil,
Time flies. I have only been into Math Phys since Feb/March 2009. Anyway, in Dec. 2008 there was a big thing about Christoph Schiller's "Motion Mountain." Bee gave him a guest post then. You wrote a long post at the end, then he replied, disagreeing with you, here.
So, what do you think of that Physics text download, and how would you response to his criticism?
Well Steven, he basically just reiterated a claim that he explained his point without a circular argument. But I looked, and it was indeed the same fallacious and circular argument (something that can be *demonstrated* by analysis of its logical structure, whatever nature does ...) that I disemboweled in my earlier blog post and recent essay. He just doesn't want to believe that.
As for "experimental evidence" - DI proponents can't say, "Look, we find a specific outcome to the measurement after there was decoherence." Well, we already knew that a specific exclusive outcome was what we *always* find in an authentic measurement (altho it is sometimes possible to know that certain states are still in superposition), but most thinkers used to accept that we couldn't say why. All decoherence can do by itself, is make for a messy and complicated superposition.
And sure, we can't find "interference" after decoherence, but interference is a red herring. Interference is just a vivid consequence of having orderly WFs in interaction, it's absence doesn't change the logical facts of there being an extended combination rather than a localized, singular "hit."
BTW, I went ahead and submitted a belated reply there! I don't know if Bee will pass it, it's been so long. Last time, I just got tired of arguing with people who wouldn't be convinced that the whole thing was flim-flam.
She hasn't passed it up at the time of this writing.
Btw, I guess you're not abig fan of this guy, are you? From Wiki...
Heinz-Dieter Zeh (usually referred to as H. Dieter Zeh) (born 8 May 1932 in Brunswick), is a Professor Emeritus of the University of Heidelberg and theoretical physicist. He is one of the developers of the many-minds interpretation of quantum mechanics and the discoverer of decoherence, first described in his seminal 1970 paper.
I just found about this guy, by surfing Wiki re quantum jumps, or as I look at them, very very fast CONtinuous jumps, not discontinuois ones.
For the record and not that my opinion counts, I'm pretty anti-MWI myself, then again I'm pretty anti-Metaphysics discussion in general, and that's where I personally characterize all QI discussions.
So I came across this paper titled There are no Quantum Jumps,
nor are there Particles!.
Haven't read it though.
Yeah, I haven't time to read that (or much else) through. So far from skimming and significant statements, Zeh makes the usual circular argument in principle. Furthermore, there are the same silly problems of MWI: the two-way split (or any simple n-way from the available choices) doesn't reproduce amplitudes squared actual frequentist probabilities, and there is no real answer to the charge that it violates conservation laws for the particle to end up in "both" destinations as final "observation." This is answered by arm-waving about thinner slices, as I noted.
tx for your enthusiasm.
BTW Steven, I only got a 7.0 rating from Phil Warnell, because he likes the Bohmian scheme and is disappointed I didn't even mention it. (Well, I'm just not real impressed, and it tends to slip my mind since I don't reflect on it much. But if you're reading this, Phil - I appreciate your interest and comments, and would here as well.) It would help to get a better rating, hint ...(and to anyone else who thinks I did well.)
Phil is big on Bohm and John Stewart Bell. These are not the worst people to be big on. Bohmian mechanics is like .... mm-m-m, PROVE it! They're actually quite useful in Quantum Hydrodynamics, I believe as a teaching exercise as to what is NOT good enough.
I haven't read any of those submissions Neil, can I rate them if so, or is Phil part of the "club"?
Also, I think you should very much read Zeh because apparently he is THE guy who started all this decoherence stuff. Read his Wikipedia page, for example.
My enthusiasm for you Neil is based on the fact that rather than philosophize or metaphysicize (is that even a word?), you have an experiment that would give a thumbs up or thumbs down to your idea, and I think experiment is damned important. Is that wrong?
Bohmian mechanics: I left the following comment at my essay thread, which also illuminates about my basic point:
First, to its enthusiasts in general: I regret not mentioning Bohmian mechanics in my article. Note restriction to 25,000 characters which made the piece shorter than I wanted. I had to ditch some extra discussion about other alternatives etc. I also needed a definite declarative point to grab attention. I also just don't think BM would work out. For example, I still don't see how a deterministic process could make nuclei decay in true random manner. Note that a remaining portion after many trimmings still has to show the same statistical behavior. I don't think any "mechanism" whatsoever can do that.
Thanks Phil for the consideration and effort you put into essays and comments. Let me say in my defense, as elsewhere: I noted simply that we don't have any answer right now in the sense of knowing the answer, nor do we have a right to *assume* that there *must be* a reasonable answer to the QMP - not that in Nature there really can't be such an answer, and/or that we can never find it, and/or that BM cannot possibly be such an answer. I acknowledge that Bohmian mechanics is an option that avoids either the decoherence fallacy, or the inscrutability of collapse; however I am not otherwise impressed with it. Finally, regarding DI: It is wrong in any case to use fallacious methods and conceptualizations, to attempt to achieve the goal of understanding fundamental quantum reality - whatever is there to be attained. I hope that my experimental proposals will transcend just having to argue over these issues.
Zeh: Yeah I remember more now, couldn't think of him at first. And sure it's great to want and to like proposals for experiments. Read that Feynman quote again. My philosophizing there is more about showing errors in other philosophy. I don't know how to "rightly think" about evolution of the wave function, since indeed it gets into troubles. The DI people can't seem to stand that.
Steven, you or anyone can read and rate essays as part of the "public" ratings (ie, not a submitter/FQXi member yourself), just put an email addy it seems (and have chance to be on their mail list too.) I would appreciate your checking and the support per as you already expressed.
Hi Neil,
First I’d like to say that despite what you might believe I’m extremely happy that your essay was accepted by FQXi. Also I do think you make a good case for having DI being dismissed as on its own being able to resolve the measurement problem. Your point in respect to the circular argument as I said in my comment regarding your paper at FQXi is essentially the same line of thinking following that of Goldstein’s concerning the measurement problem in respect to QM.
Now as to what you refer to as my disappointment that you didn’t acknowledge the deBoglie-Bohm pilot wave picture, I would like to have it made clear it has nothing to do with me being a fan of Bohm or Bell, yet rather with you saying the measurement problem hasn’t been resolved. To thoroughly explain why I find this as the central issue would take much commentary and exchanged dialogue at bare minimum and yet I’ll attempt to give you a sense for it with stating the following.
To begin Bell’s eventual discover of his famous inequality was inspired by his first reading of Bohm’s paper on it surfacing in 1952, as he was previously lead to believe during the course of earning his doctorate what Bohm had achieved was impossible, with that being that no hidden variable theory could possibly be consistent with the phenomenological demonstration(s) and consequence(s) of QM’s formalism. The indisputable truth being however is that the deBoglie-Bohm pilot wave model does this precisely and thus serves as a counterexample to a claim first made by von Neumann, with his so called and yet proven as totally fallacious impossibility proof.
Now as for the reason for Bell’s inequality theorem is him realizing that entanglement as demanded by the formalism of QM was and still is for a large part treated as an artefact such that spooky action at a distance could be ignored as the nature of the quanta itself would preclude it from ever being able to be distinguished to it being a demonstratedly ‘real’ phenomena. That is in a way one could consider non localness as QM’s dirty little secret. On the other hand Bell’s theorem showed that any hidden variable theory, to be consistent with QM, did require it to be intrinsically non local, which Bohmian Mechanics from the outset was so admittedly. It has also been argued by Bell that this also required orthodox QM to be the same, which was at first denied by many and yet now is accepted by most. The point being although such outcome is demanded by way of its formalism it is not dealt with in respect to its interpretation as something to be expected and/or dealt with as phenomenologically significant.
..... sorry continued in next post
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...this is the continuation post.
Now as a final point the measurement problem, as QM’s non local aspect was largely ignored in the case of orthodox QM, with requiring putting in arbitrary and inconsistent rules in respect to having the wave function to collapse, which as you pointed out doesn’t serve as an explanation at all; even with the added action of decoherence. On the other hand, although decoherence is part of the Bohmian interpretation description it only works in respect to its metaphysical/ontological framework and not that of QM’s.
So the bottom line is although Bell established two points of distinction between BM and QM should have been enough to form a straight line as to be reasonably sure of a conclusion; with the added case of decoherence this forms to be yet a third point having all three having not only the Bohmian view as demonstrated straight thinking, yet as time progresses a strong indication, if nothing else, as to where theorists should be looking in their quest in understanding the nature of the quanta. Now I’m not insisting that Bohmian Mechanics is the end all and be all, rather all I’m saying is despite what many have thought or worse never even bothered to seriously consider, it stands as clear evidence there being more wrong with current thinking then there is right with it.
"The Heisenberg-Bohr tranquilizing philosophy--or religion?--is delicately contrived that, for the time being, it provides a gentle pillow for the true believer from which he cannot very easily be aroused. So let him lie there."
-Albert Einstein, letter to Erwin Schroedinger (May 31, 1928)
Best,
Phil
I already voted on it, Neil, the day you asked me. But, I did not comment and I won't. Simply not my field, man. Also, take a guess what value I assigned? Did you notice you rating went from 7 to 8.5 in one fell swoop?
Listen, if anything, I do like "decoherence", but I see so many different definitions for that word I often wonder if any two people are talking about the same thing. It confuses me. In any event, your experiment will either prove or disprove, and that's grand. And it won't cost much, either.
Funding, funding, always a problem, funding, sheesh.
Neil,
Ran into your paper by accident. Well done, I hope this gains your ideas some attention. You have some interesting thoughts on the whole topic.
Here's a question I had and was hoping you could help me out with is a pretty fundamental one. I've heard the twin-slit experiment framed like this: You set up a detector that tracks and records which-way information about the two slits. If the detector tracks but doesn't record (Say it instantly erases the record), you get one pattern. If the detector tracks but records, you get another pattern.
The orthodox treatment of this question (as I understand it) is that the availability of which-way information plays the central role in determining which pattern shows up. If someone 'can find out' the which-way information, you get one pattern. If they cannot, you get the other pattern.
Is this accurate? Sorry to bother you with such a mundane question.
Steven: Thanks for your support, you're a mensch. And I understand someone "liking decoherence." It surely affects the quantum world, but it just can't get rid of the unobserved superposition partners. The argument that it does is semantic gamesmanship, it's like a SNL skit caricaturing a really bad, "post-modern" Wittgenstein argument. And I see more and more, the misleading claim that "decoherence explains why we don't see macroscopic superpositions" or "it destroys superpositions" etc. (since I subscribe to "decoherence" Google alert and others: try it.)
I thought the definition of decoherence was fairly consistent (disturbing of wave function such as to destroy interference) - but of course there is a difference as I noted, between the odd habit of comparing phase relations between different instances versus the scrambling of the WF in a given instance. As for my experiment proving or disproving, it won't be accepted that easily. Even though the expected result definitely shows that the BS2 output is not nor is "like" a mixture, the attraction of this Pied Piper's way out of the supposed horror of quantum mystery will motivate so many to double talk their way out of trouble, just like they did into the swamp in the first place. And will enough people even pay attention? If I win a prize I have a chance, otherwise an uphill battle.
Crude, thanks for dropping back in after a spell. I should have been back to yours too, so I checked it out again. Your latest, "Blinded with science!" is typically clever and with pithy intellectual skill yet guy-in-the-street informality and chattiness. Once you appreciate what happened with the "decoherence scam", you'll be shocked that such a bogus notion and semantic slight-of-hand could have taken such a hold and become so popular. They just can't stand real mystery and will "do anything" to stop it. See also my reply to Steven and visit his blog (and vice versa, might as well network.) It's like a cult, truly depressing.
As for your specific question: yes, the attempt to measure which slit does ruin the interference effect (which is supposed to depend on the wave going thru both slits, so ...) But it isn't that simple or utterly assured, because of challenges like the Afshar experiment (easier for you to look that up than for me to try and summarize.) I have my own challenge involving polarized light, maybe for another post.
Now, even if fully true that doesn't violate my argument against the DI. I'm saying, the confusing of phase relations doesn't isolate superpositions, which is not the same as deliberately picking out one or the other before a measurement.
Neil,
Thanks for the reply. A followup question, though. One reason I find this interesting is because to me - a layman who may be missing something - it seems as if it makes "information" fundamental.
Meaning, it seems like someone would be committed to saying that in measuring device that's recording which-way information, the information is not observer-relative - it is intrinsic. (By this I mean, a note on a piece of paper that reads 'Movies tonight' may mean 'I'm going to the movies tonight' or 'I want to make some movies tonight' or 'I want to talk about movies tonight' or mean nothing at all, etc. The information is relevant to the mind of whoever wrote it or is reading it, or it's otherwise lacking. If that's rejected in the QM case - and I think it would have to be if one wants to avoid 'consciousness causes collapse' speculations - then it seems like someone is committed to saying that no, the state of the measuring somehow has intrinsic meaning. But that's going to go down almost as bad as CCC.)
I hope I'm making myself clear here.
Crude, your question is very pertinent and interesting, and I'm sorry I took so long to get back. (Er, I wonder if any question about QM can be "clear" ;-) Indeed, information in QM is very important and can be controversial and vexing. I wanted to dig into the issue and not just answer with what I had at the time, so I read up and ruminated on things like the Afshar Experiment. The AE says we can find "which way" information even when an interference pattern has formed, so clearly relates to my challenge to the claim that decoherence breaks wave superpositions into literal separate and localized outcomes by itself. I took awhile longer than I intended, but came up with IMHO an improved version of the AE that I will post about in due course.
But experiments have already shown, that whether interference v. which way is found, does depend on what and how the system is being measured. Some information apparently really does ruin the interference pattern (like having a detector at slits to see which one an electron goes through) but other times, it's contextual. I want to find the cites (sic!), but in the case of polarized light researchers were able to take away interference and then bring it back. So it's tricky. Some of the nostrums that seemed so obvious (like, there must be an interaction to detect something) proved wrong, as with interaction-free measurements (like, put the bomb in the path of the interferometer, and even when not hit the bomb makes it possible to a photon to come out a channel it otherwise could not - Elitzur and Vaidman.)
To sum up for now, information is very important in QM and that means that the world is "thought-like" to an extent inexplicable with classical physics. But, it is not a simple matter and can mislead. This is the fundamental mistake made by the DI proponents. They think that changing the information in the direct sense of what kind of measurement you get at a given stage, in effect creates a new reality. But instead, the original wave functions are still there but just in hidden form - I show how to recover them later. It's hard to say how that fits into your question about being "intrinsic." It seems that the wave nature of things remains intrinsic up until it is forced to do something else, but: there are already ways to manipulate that with context, and then if so we still don't understand the original mystery of how that WF finally does turn into a click etc, why that detector and not the other, "where does the rest of it go" etc.
PS for final perplexity look up "Renninger measurement." The RM shows that the WF doesn't always collapse into a given outcome, but that a null return (like, no click from one leg of a split path) means the WF is rearranged to fit the other space the particle can now possibly be in.
Thanks, Neil. Still trying to absorb your explanation. I guess it seems to me that even with the 'decoherence' explanation, we're still left with some fundamental weirdness re: information.
An uphill battle is better than no battle at all.
Aside, one thing we both agree on is that Everett III's original MWI is crap! Or if it is true, kill me NOW, LORD! Because if it IS true, most of mes will live on elsewhere, right? Also, I don't want to live in such a cheesy Universe. I object! :-)
I have since done the smallest amount of research, and discovered you and I may be talking about two difference kinds of decoherence, so maybe I agree after all. The two kinds as far as I can tell are MWI decoherence and Copenhagen with Consistent Histories decoherence. Garbage to the first one, not sure on the 2nd. Is that right?
Well, right or wrong, let's talk turkey. How much would this experiment cost to run? Perhaps a private e-mail exchange is called for here. Thanks to my experience with MZI experimentation I could be of help, combined with my business school education which taught me among many other things how to write a killer business plan and cost analyses.
Call me, and be sure the mini-bike tires are properly inflated, in a very quiet room, somewhere other than the Ring of fire.
By the way, Neil - is this at all relevant to what you're outlining in your paper?
http://www.physorg.com/news137245970.html
Steven, thanks for your offer. I'll get to you soon more directly on that. Meanwhile: I got behind trying to digest the consistent history concept, and still don't really appreciate if it avoids the deficiencies of other attempts to end-run around the perplexing twilight zone of the collapse problem. Sometimes I work so much on an answer, yes to "just a blog comment" and etc. going on, that I get bogged down in delay. And sure, MWI is a bad idea. No, I don't hate weirdness or the multiplicity per se, but it's so contrived because of the (perhaps deliberately obscure) problem of how to get various probability ratios out of a split into two streams. (And how to keep the mass-energy all accounted consistently, etc.) BTW here is a nifty critique of DI from awhile ago: ArXiV...-ph/0112095, "Why Decoherence has not Solved the Measurement Problem: A Response to P. W. Anderson" by Stephen L. Adler
(Submitted on 17 Dec 2001 (v1), last revised 10 May 2002 (this version, v3))
See also that link Crude provided (which got truncated, it is http://www.physorg.com/news137245970.html.) It's of related interest, but pertains more to my "proposal summary" about repeated measurement of a photon's polarization than to the decoherence issue.
But roughly so far: First, I think we need to distinguish two different sorts of "decoherence" that are apparently not properly differentiated by most writers, esp. the popularizations like Chad's MZI ("TE1" in my own essay.) First there is cross-instance decoherence. Note that the "Confuser" in his decohered MZI (and the analogous spin example I referenced in my FQXi essay) work by changing relative phases from instance to instance. That means, for example the relative phase in a run using many photons might be, in degrees: -7, 20, 105, -44, -12, 73, ... etc. Well, then of course when we just look at counter stats out of BS2 channels, we don't "see the interference" (using that very pernicious phrasing, which makes assessing a bunch of click patterns sound like actual experience of seeing any unique detector reading at any one time versus literally seeing the superposition of outcomes together!) I made arguments against such "decoherence" making the output to be, or to be like, a mixture. (Look, a real mixture is sometimes one thing and sometimes another.)
Note also, in any one case we do have "interference" at that odd angle, it just isn't pure bright or dark fringe. So like I said before: anticipation of some plan to change phase in the future will not create a current condition, of things being classically distinct versus a concurrent superposition. But more important, I have an experimental setup ("TE2") that can prove that the output is not a mixture - because we can recombine BS2 output in such a way, to show that output remained as superpositions. So somehow the detectors past BS3 have to pin down the output into definite, exclusive clicks.
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(I have to continue next comment because of the idiocy, "Your HTML cannot be accepted: Must be at most 4,096 characters." Well, I would allow 32k.)
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Then there is the decoherence that consists of a given WF getting disorderly, during the instance of its evolution. That would be from the environment scattering it, etc; as in the case of my TE3. In that proposal, the WF of a given photon is scrambled across space so we can't get an interference pattern (sure, we have to use many photons to get that, but the point is: the scrambling happens to each photon, rather than the circumstance varying from case to case.) Again, that is still a spread out WF, it contains all the superpositions, and some collapse or whatever has to pin it down somewhere.
Above all, remember that the density matrix starts with the probabilities of various WFs being present, then adds the quantum probabilities by applying the squared-modules projector, so it puts collapse in "by hand" - and then wielders of it promptly just take that for granted. Excuse me, but ... . (Both kinds of disorder could be combined, too. I can't crack that one yet but it still doesn't help the other cases.)
So the CH concept, which I don't really get well in particular as distinction from the ordinary fallacious argument, must deal with that issue. As best I can tell from e.g. reading the Wikipedia article, it's psychobabble and evasive in like vein to what I've been criticizing. Really, go back to the core dilemma: you split a photon, it goes to two separated detectors. One clicks, the other does not; no way to get a rational handle on that as is. What are they going to do with it any better than anyone else? So, is that what you meant by "decoherence"? I think my explanation is pretty commonplace, and I wonder if you've seen proper acknowledgment of the two ways to work it.
Experiment: well, OK I can send you an email and will start by forwarding this comment. It would be great for someone to do this, I only hope enough of the "right people" will care. I'm already peeved and deflated that I got a low rating from the FQXi Community. Well, it's atrocious overall: the highest CR for any essay was 5.4! I really wonder, how can they not even notice something with an offer to experimentally disprove a popular interpretation of quantum measurement.
Maybe worse, how could none of the Raters even leave any rebuttals or critique explaining why they weren't happy with my argument? I don't think so much of them anymore. That's depressing because I thought FQXi represented a way out of the swamp, like one of those academies or boxing teams out in the inner city. What am I going to do now? I will email the director/s with a complaint about how it went. See the complaint comment at my essay, from "basudeba" on Mar. 20, 2011 @ 06:14 GMT.
BTW, you should find my latest post interesting. Again, imagination used to poke pedantry.
PS, I changed to use my full name.
Crude - see my first reply to Steven. You need not digest the whole thing, just find where I reference that link (BTW, text dump will be truncated so use HTML to be sure.)
BTW I saw you at David Heddle's blog. I met him and correspond some. He's very clever, and more "religious" than me but I'm easy as they say, both ways.
Hi Neil,
All in all, considering the overall score from the community being so low and not many public rankings over a six yours fares quite well. I would be careful before raising much of a fuss and yet like you said it would be at least helpful if more of the FQXi members left some comments as it could be known how they made such assessments.
I myself have a slightly different take on all this and have voiced my opinion over at Bee’s and Strefan’s blog in a reply I made to Plato. That was essentially I found very few submitters wrote essays actually addressing the question, yet rather used it as a platform to expound their own theories regarding one thing or the other with very few being directly relevant. I would argue even your essay, although it does deal with the DI proposal as whether or not it be a solution to the measurement problem still doesn’t offer a clear answer to the question at hand, yet leaves things pretty much as Neil Bohr and gang did so many years ago.
I would agree however there are very few members of FQXi who are actually qualified enough to weigh such a question. The few I do feel so qualified would be David Albert, Harvey Brown, David Duetsch, Lucien Hardy, Roger Penrose, Robert Spekkens and Antony Valentini.
However there are others out there I feel so qualified, among them being Travis Norsen. He is a Professor at Marboro college who you might like to write to and ask him to look over your essay. I haven’t corresponded with him for years yet found him accessible and one who is very serious and knowledgeable regarding the foundations. In as your essay has been accepted by FQXi and deals with decoherence he might be inclined to read it. You can drop my name if you wish as I’m pretty certain it at least won’t have a negative effect.
Best,
Phil
It's a good thing i didn't submit to that essay contest, because while it's a good question, my answer would have been short, sweet, accurate, and to the point. It would have been:
"Is Reality Digital or Analog?"
Both. Neither. Maybe there's a 4th Dimension of Space which presents itself as the cosmological constant and/or "dark energy." And then again, maybe not.
In short: Nobody knows, because we lack the energy to explore at the smallest length and time scales, and will always lack the same, so the closest we can ever get is through speculative extrapolation of the Universe-imposed experimental limits, the only thing we can be sure of being we will never be sure, unless the aliens land and tell us, and I wouldn't hold your breath on that happening anytime soon, or, ever.
Have a nice day.
Love,
Steve
P.S. Where do I pick up my winnings?
Hi Neil, I'm sorry you didn't do better. I gave you a 10, so don't blame me. But don't give up, either.
Hi Phil,
I'll see your Travis Norsen, and raise you a Sheldon Glashow. Or Peter Woit if Glashow is too busy.
Hi Steven,
I think you underestimate human ingenuity and besides how do you know Roger Penrose isn’t an alien:-) As for those you raised me with they are about as qualified to weigh in on foundational matters as Charlie Sheen is able to becoming monogamous :-)
More seriously, I truly think Travis Norsen can give Neil some expert feedback as far as his DI experiment is concerned. I’m afraid however he may be told that it just doesn’t serve to prove what he thinks it does, even though recording the results he suspects. I’m not sure if Neil has ever read J.S. Bell’s selection of papers called “Speakable and Unspeakable in Quantum Mechanics” yet there is one paper called “de Boglie-Bohm, Delayed Choice Double-Slit Experiment, and the Density Matrix” (paper 14) which besides showing why from the Bohmian perspective there is no backwards in time decisions being realized, yet also has a good discussion about the role of decohernce more generally ; although as like in Bohm’s original 1952 paper its not referred as such.
Anyway there was a time I was quite up to speed on it all and had many discussions with Norsen regarding such matters on the Yahoo Bell_Bohm forum. In fact you could say I revitalized it for about a year. If interested you can look at some old discussions we had regarding decoherence along with other concerns. However as since my focus has turned to other things I just don’t feel up to the time and amount of concentrated effort it takes to have such things to be made clear as they are quite subtle.
Best,
Phil
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Thanks guys for keeping up. Phil, I will look at those links etc. However, I just don't get why you and some other people think that the result of my experiment would not be significant, and would not falsify the usual presentation of DI. But it does, and the case is basically a syllogism:
1. DI claims (such as it is - their conceptualization is so flawed and post-modernish it can be hard to grasp their claim as to the state of affairs and its interpretation) that the output from a confused (decohered) MZI will be or is equivalent to, a mixture. That means, sometimes a photon goes out one channel, sometimes another instead; but not both at the same time. The latter would be continued concurrent state evolution (continued superpositions) in "the same world." I have seen literal statements to the effect that the decoherence "turns [such decohered] superpositions "into mixtures."
2. Well, claim #1 has consequences. If a mixture is directed on to BS3, the BS3 output *would be* equal intensity clicks from both channels. But if the superposition is always still present despite decoherence, we get the output b² from the lower channel and a² from the upper channel. That is a direct falsification. Maybe you didn't think DI could be falsified like that (like many didn't appreciate that the Bell inequality was subject to experiment), but it is a falsification of the "mixture" claim, period.
I suppose some DI advocates will waffle and say that they're just saying the WF evolves anyway, it just isn't accessible or whatever (it's hand-waving), but then there's no point in saying it makes a difference or explains anything. If one, like Chad, is trying to give any insight into why we find exclusive outcomes after BS2, that person is implying some mixture like output (because the whole point is to avoid special powers of the detectors that can be put there.) Guys, you can and should get this - and so should anyone else with enough chops to get the issues at all.
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Hi Neil,
I wasn’t insisting that your experiment wouldn’t have implications in respect to decoherence for conceptualizations of QM having a singular ontology. What I was implying it would have no such effect on conceptualizations having a dual ontology, such as Bohmian mechanics. That being it is here I take issue with your position that QM will forever be found as a mystery in respect to demonstrations such as yours or those of Wheeler’s with his delayed choice experiment, as they have long been adequately accounted for as to be explained.
”By contrast, if, like Einstein, we regard the description provided by the wave function as incomplete, the measurement problem vanishes: With a theory or interpretation like Bohmian mechanics, in which the description of the after-measurement situation includes, in addition to the wave function, at least the values of the variables that register the result, there is no measurement problem. In Bohmian mechanics pointers always point.”
-Sheldon Goldstein, “Bohmian Mechanics” Stanford Encyclopaedia of Philosophy
Best,
Phil
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