Talk:Interpretation of quantum mechanics

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[edit] Semiotic Interpretation of Quantum Physics

I'd like to see the semiotic interpretation of Quantum mechanics added to the list.

In the semiotic interpretation a quantum particle is more like an "event" (in both space and time) rather than a "thing" travelling in space over time. To ask where this event is, other than where it takes place, is like asking where London is other than where it is.

But a quantum particle is also more than just an event. It is also a "signifier", like the letter "X" or the letter "R". On their own letters doesn't mean much - but in combination with other signifiers (particles) they start to signify something. For example, the letters X, R, A, and Y, when combined, form a word ("xray") which starts to mean something - if only to us humans. In semiotics this meaning is called the "signified".

By applying semiotics to physical processes we can ask what the combination of particle-like events signify. Although this is somewhat peculiar it is also strangely effective.

The particle-like events that occur in an interference experiment can be regarded as signfying an interference pattern.

Note how this is a reversal of the "normal" questions. Instead of asking what the interference pattern means we ask what the particle-like events mean? And instead of looking for their meaning in the "cause" of such we look for what they mean in the effect they produce.

In the semiotic interpretation the "cause" of A is anything which signifys A. The effect of B is anything signified by B.

How does the wave function fit into this?

The wave function is a generalisation of interference patterns. It is that which is specifically signifed (or rendered) by particle like events in an interference experiment. For any given experiment the wave function can also be signified (or rendered) by appropriate transforms of classical measurements - of slit widths and screen distances etc.

A characteristic of the wave function - or an interference pattern (which is much the same thing) is that the wave exists over space and time. This contrasts with a particle which exists in space and time.

This is why one can not simultaneously measure both a particle and a wave at the "same time". Because the meaning of "at the same time" is inconsistent with the measurement of waves which are measured over time (and space).

By analogy we do not measure the distance between A and B at point A, or at point B. We measure the distance between A and B.

Anyway, there is a lot of stuff in quantum physics that makes sense when interpreted in terms of semiotics. This is but an introduction.

Carl Looper 11 January 2006

[edit] Landé's interpretation

Is it a good idea to add the interpretation of Alfred Landé to the set of interpretations? I guess it would need a page of its own too where his interpretation is explained. INic 23:20, 16 January 2006 (UTC)

Umm, good question. I think the goal of this article was to list the "major" interpretations; I know that there are dozens of variants and "minor" interpretations (i.e. not widely accepted/discussed). I am not sure how we should go about treating these variants. Can you provide a summary of the Lande interpretation here? Is your intent to describe this as a piece of physics history, or to present this as something that has modern adherents? linas 00:26, 17 January 2006 (UTC)

Neither, more as showing the logical possibility of a different approach to the interpretations problem altogether. In the same way as Bohms interpretation always is mentioned, not because it has (or ever have had) many adherents, but because it shows an interesting possibility. Landé's interpretation never did a big impression, as far as I know, so I'm afraid it's historical import on physics history is very limited too. It has been a while since I read his books, but I'll re-read them and write a short summary here. (His opinion is closest to my own opinion in these matters, so I remember that I liked what I read.) INic 01:30, 24 January 2006 (UTC)

[edit] Prowave interpretation

I was recently very favourably impressed by the "Prowave Intepretation" by Dan R. Provenzano.

From: http://www.quantummatter.com/wave.html
Abstract:
It is widely accepted in Quantum Mechanics that measurements reveal the particle nature of elementary quanta, but there are many interpretations on how these ``particles move from the emitter to the point of measurement. This paper introduces in the ProWave (for ``Propagating Wave ) Interpretation of Quantum Mechanics, The basic idea is that elementary quanta always exist in the form of a wave, and always travel in the form of a wave, described by Schrödinger evolution, but are always measured each at a single location. This concept replaces all interpretations based on quanta traversing a particle path with the notion of a propagating wave coupled with a new concept of ``Quantum Energy Localization. It is argued in this paper that the ProWave Interpretation explains all known experimental results in a ``realistic way that would have pleased Einstein, Schrödinger, deBroglie and all those who are currently looking for a sensible way to understand the implications of Quantum Theory. As examples, the 2-slit experiment, and EPR experiment, and a quantum eraser are interpreted in the ProWave picture.

Peter Morris Adelaide 220.238.50.102 13:11, 12 February 2006 (UTC)

This is not appropriate for this article. linas 01:08, 14 February 2006 (UTC)

[edit] About decoherence

The table contains "decoherence" under the title "interpretations" but decoherence (as you can read in the article's page) is not an interpretation it is "a process". So what is it doing there on that table?!?--Pokipsy76 21:15, 28 May 2006 (UTC)

Quite right. The decoherence entry should be merged with the consistent histories entry -- despite that they disagree about many of their properties! I'll merge them if no-one else wishes -- let me know. PS I've updated the MWI entry, which had some misleading values. --Michael C Price 20:59, 12 June 2006 (UTC)
Couldn't wait, I've merged the decoherence tag into both the Many Worlds and Consistent Histories comparison. Note: I've made some properties indeterminate - which seems appropriate for a quantum table!! --Michael C Price 21:22, 12 June 2006 (UTC)
I think that yellow color has too much visive impact...--Pokipsy76 14:07, 13 June 2006 (UTC)
Pick any new colour except black :-) --Michael C Price 14:14, 13 June 2006 (UTC)

Are these two really the same? I was very surprised to read this article, and find that there was no decoherence picture (which I would ascribe to Zurek, and personally I think that a large number of physicists subscribe to). I would say that the consistent histories interpretation is a different interpretation (which I would ascribe to, among others, Omnes and Griffith)... Do people agree or not? --138.253.77.57 19:16, 6 October 2006 (UTC)

An interpretation is something people argue over; no researcher disputes the utility of decoherence as a mechanism: hence decoherence is not an interpretation itself. Zurek says he subscribes to the existential interpretation. --Michael C. Price talk 19:38, 6 October 2006 (UTC)

[edit] Many worlds and consistent histories

As a footnote to the consistent histories entry in the table at the bottom of the article there is the comment

If wavefunction is real then this becomes the many-worlds interpretation.

I don't think this is true. The mathematical formalism of MWI and consistent histories are different.--CSTAR 14:17, 13 June 2006 (UTC)

In what way? I'm fairly sure they are the same. Whether you deal with density matrices (Consistent Histories) or universal wavefunctions (MWI) is irrelevant, the maths is isomorphic and they both evolve in a unitary fashion. Which is why Gell-man and Zurek are sometimes cited as Consistent Histories advocates, some times as Many Worlders. Everett used what we now call decoherence (building on Bohm, who is largely unrecognised in this context, I believe) to explain the loss of interference between worlds. --Michael C Price 14:25, 13 June 2006 (UTC)
Indeed both formalisms have "histories". In MWI however, a history is a sequence of measurement outcomes and the universal state is a superposition of these measurement histories; in consistent histories a history is a sequence of projections (each projection corresponding to a projective measurement at some time). A family of histories which satisfies a "consistency property" (it's defined in the consistent histories article but not very clearly -- that article needs work). As the article state "The consistent histories approach can be interpreted as a way of understanding which sets of classical questions can be consistently asked of a single quantum system". But I don't know that the state can be obtained as a superposition of "histories". There might be some way of obtaining formal equivalence of the two approaches, but as far as I know, this hasn't been done.--CSTAR 15:56, 13 June 2006 (UTC)
The theories -- MW & consistent histories with real wavefnctn -- have to be the same since they agree about the state of the wavefunction (uncollapsed) and its reality. Every thing can be deduced from the wf. Classical, decohered probabilities are additive (=consistent) in both approaches. Zurek describes the consistent histories approach as post-Everett for this reason -- it's just that the role of the various density operators is the focus with Zurek, the u'wavefunction with Everett; switching between them is trvial. --Michael C Price 16:40, 13 June 2006 (UTC)

[edit] "Many worlds"

I read in Penrose that "many worlds" is (about) the same as what I have been calling a direct interpretation, but I did not catch that from this article. Suppose we substitute "Many classical worlds" or "Superposition of classical worlds" and spell out "multiverse" as quantum universe or quantum reality? That doesn't really describe the point of view, but it may be clearer than "Many worlds", which sounds mystical.

This whole disagreement seems unreal to me, because I have never had any problem with, or heard any serious objection to, the idea that matter is a wave since I first read it when I was about ten years old. David R. Ingham 03:14, 28 August 2006 (UTC)

Your proposed use of "many worlds" would be WP:OR. "Many worlds" is what it is called in the literature and is in wide usage. The "direct interpretation", by contrast, is a minority term used by who? --Michael C. Price talk 03:58, 28 August 2006 (UTC)

How about "Quantum reality" for the name of this subsection? There is only one world, but it is most accurately described by a state vector, not by classical coordinates. David R. Ingham 04:20, 28 August 2006 (UTC)

No, there is NOT only one "world" according to MWI. If you think this you shouldn't be editing the article. Please stop inserting your own original terminology everywhere. That's not what Wikipedia is about. Use standard terms. Read WP:OR. --Michael C. Price talk 05:19, 28 August 2006 (UTC)

What I am saying is that the article is not clear as it stands, even to an expert. I should be able to get some idea of whether or not I am interested in "Many Worlds" before reading about it in other places also.

Now that I have some idea what is meant by it, the term "Many World" sounds to me somewhat as though it has been made up to be derogatory. On the other hand, if it does mean that there are really many worlds, then the impression I got from Penrose is wrong, and the point of view I learned in school and used to do research is missing here. David R. Ingham 16:37, 28 August 2006 (UTC)

You're being vague. If you have a specific criticism of the many worlds article take it to its talk page. That an "impression" you got from Penrose is confusing is not really newsworthy or surprising, although I see no conflict between what he said about ascribing reality to the wf and the existence of many worlds. --Michael C. Price talk 08:29, 29 August 2006 (UTC)

[edit] One universe

The table contains the column "One universe?" and all the interpretation have "Yes", so what is the function of this colums if there is always one possible answer?--Pokipsy76 17:44, 13 June 2006 (UTC)

The many worlds interpretation uses many universes, something which is often counted against it by its detractors (a violation of Occam's razor). The table has that column so that the comparison can be made between interpretations that use many universes and those that do not posit other universes. However, the column currently reads "Yes" for MWI, I suppose because to say that MWI has extra universes is almost misleading enough to be wrong. See the footnote attached to that entry. -lethe talk + 17:48, 13 June 2006 (UTC)
So why don't we erase the column or why don't we change the title of the column so that the difference can be expressed more clearly?--Pokipsy76 18:05, 13 June 2006 (UTC)
The fact that people use this property of MWI to compare it to other interpretations means that we ought to keep the column, in my opinion. As for changing the title, what do you have in mind? Another solution would be to change the "Yes" to a "No", which would make the purpose of the column clearer. -lethe talk + 18:11, 13 June 2006 (UTC)
I think we could change "yes" to "no" and explain better in a note in order to be not too much misleading.--Pokipsy76 18:16, 13 June 2006 (UTC)
That's one possibility, but "universe" has become such a loaded term that there would be a need for a big footnote. Here's another possibility: that we retitle the column "multiple histories" or something similar? The two decoherent approaches would say yes, and the others no, with a qualified no for Bohm, since it contains multiple wave histories and a single particle history. --Michael C Price 18:29, 13 June 2006 (UTC)
I suggest to name the column "single history" because the "No" in the other part of the table denote something strange. Moreover there should be added a note to explain what does "history" mean in the context. But what if we call the column "One world"?--Pokipsy76 08:20, 14 June 2006 (UTC)
World, like universe, is rather interpretation-specific and just enough POVish to raise hackles in some quarrers. I suggest "unique history" .....? I'll change it and see what you think. --Michael C Price 10:20, 14 June 2006 (UTC) Done, and table re-ordered into a more natural grouping with a few extra clarifications.--Michael C Price 10:56, 14 June 2006 (UTC)
That's OK for me, now we need a note to explain what is a "history"!--Pokipsy76 11:23, 14 June 2006 (UTC)

[edit] Relational Quantum Mechanics and Modal Interpretations of Quantum Theory

We need some people who are comfortable with this topic to describe these interpretations of QM. RK 19:14, 17 June 2006 (UTC)

I can do Relational QM...for a start I am rewriting the Stanford quote, and providing a link to the published paper on the subject (which is stored at the arXiv). How long should this be? I am also going to write a full article on RQM, but that'll be a while coming.--Byrgenwulf 11:29, 15 July 2006 (UTC)

[edit] Removed passage

Hi, I'm new to Wikipedia and so if I made an editing mistake or am breaking any rules please let me know. I have deleted the following section from this article -

'Though interpretation continues to be a current topic in the philosophy of science, from the viewpoint of many physicists, the question it poses is meaningless, since answers to it are untestable. Likewise many philosophers see this interpretational quest for meaning as representing a simple category error, since philosophical arguments are clearly not empirical, and thus not "testable" in a scientific sense, though they are open to the criticism of logic.'

The author has cited no evidence for his suggestion that many physicists think the question it poses (regarding the conceptual foundations of quantum theory) is meaningless. Moreover, the assertion that the reason for this is 'since answers to it are untestable' reflects a misunderstanding of the nature of the philosophical investigation of theories. What would it mean for an interpretation to be 'testable'? The philosophy of science isn't science, but whether this is a point against it is irrelevant to this article. In bringing up issues regarding the meaninglessness of non-empirical statements etc. the author has strayed from the point of the article, which is to discuss interpretations of quantum mechanics.

'Likewise many philosophers see this interpretational quest for meaning as representing a simple category error, since philosophical arguments are clearly not empirical, and thus not "testable" in a scientific sense, though they are open to the criticism of logic.'

Again the author has not cited evidence that many philosophers support such a view. Although incidental to my argument for removing the passage, I do not think he could find any evidence for this view. He is using the terms 'category error', 'empirical' and 'testable' out of context and is obviously not familiar with the terminology. In any case, the passage is merely speculation on the views of physicists and philosophers without citation.

I think I agree with your opinion, the section as it was couldn't stay. Surely the point of view it describes actually exists but we need some reference. Remember to sign your messages using the "sign" button on the edit box or the "sign your name" link below it.--Pokipsy76 08:45, 27 June 2006 (UTC)
I added that line: "Likewise many philosophers see this interpretational quest for meaning as representing a simple category error, since philosophical arguments are clearly not empirical, and thus not 'testable' in a scientific sense, though they are open to the criticism of logic." The reason is that the preceding line was already present, and it seemed to tell only one side of the story. As you rightly stated, it displyed a misunderstanding of the nature of philosophical investigation (the conclusions of which are in no way testable), so I added my line in the interest of balance. I think you are right that both of the sentences should be removed. The reason I'm writing now is because I find your criticism curious (you said: "I do not think he could find any evidence for this view. He is using the terms 'category error', 'empirical' and 'testable' out of context and is obviously not familiar with the terminology.") I find this odd, given that YOU seem to agree with my view (you also said: "Although incidental to my argument for removing the passage" and "Moreover, the assertion that the reason for this is 'since answers to it are untestable' reflects a misunderstanding of the nature of the philosophical investigation of theories," which is another way of saying what I said). I find it even more curious that you claimed I could not find "evidence" for that view. But this is precisely what we've been talking about! These kinds of philosophical arguments are not based on evidence, and they are not testable! Rather, it should be seen solely by the natural light of reason that a philosophical conclusion is subject to different methods of "verification" and refutation than scientific conclusions. Which brings me to my last point: In what way did I misuse the terms "category error," "empirical," and "testable" so as to exhibit my blatant ignornace? Your claim here is a rather biting one, so I should hope you would have some sort of argument. First, I used "category error" here to refer to the error of some physicists in criticizing philosphical conclusions for being untestable. Philosophical conclusions do not fall under a category of expressions which have the property of "testable," hence the criticism is in error. This fits perfectly with the definition of a category error, which is "when one mistakes the logical type or category of a certain expression" (http://plato.stanford.edu/entries/categories/). Second, I used "empirical" here to refer to those things which are testable (http://dictionary.reference.com/search?r=8&q=empirical). Third, I used "testable in a scientific sense" (which is, admittedly, a sloppy way of putting it, but by no means wrong)to refer to a property which philsophical conclusions do not have, namely that of being testable or verifiable. We've already established that you are aware of this truth. Well, I'm finished standing up for myself intellectually. Anyone who sees that I am in need of correction is invited to point it out to me. Agondie 13:41, 30 November 2006 (UTC)


Yes, the point of view that the author is trying to describe is roughly verificationist positivism regarding non-empirical propositions. However, the author doesn't describe it at all accurately and I would guess is not familiar with the relevant literature. Nor does the author provide support for his claims regarding the popularity of the view. I can't speak for physicists but I know that virtually no one holds to an unreformed verificationism in philosophy currently.

In any case, the point is that even if described properly it would be irrelevant to the article. If it is acceptable to make claims regarding what physicists and philosophers think about foundational epistemological issues in this article, then we would be justified in adding similar ones to every article concerning specific topics in the philosophy of science. It would be as irrelevant as commenting on what falsificationists think of scientific method at the start of every article on, say, the biology of dogs.

--Camcolit 10:32, 27 June 2006 (UTC)

The author? This is WIkipedia for heaven's sake. Are you imagining the "author" sitting doing in a room and actually writing this? Writing for WP is like trying to doing scholarly work crouched in a foxhole in the middle of a battlefield - between four armies.
You should look at the history list, to see how this evolves.
In particular, look at these edits to the article

--CSTAR 15:39, 27 June 2006 (UTC)

[edit] Direct interpretation

[edit] Penrose

Here is some source material, from The Road to Reality" by Roger Penrose, 2004, section 21.6, (top of p. 508 in my copy):

If we are to believe that anyone thing in the quantum formalism is 'actually' real, for a quantum system, then I think that it has to be the wavefunction (or state vector) that describes quantum reality. (I shall be addressing some other possibilities later, in Chapter 29; see also the end of 22.4.) My own viewpoint is that the question of 'reality' must be addressed in quantum mechanics—especially if one takes the view (as many physicists appear to) that the quantum formalism applies universally to the whole of physics—for then, if there is no quantum reality, there can be no reality at any level (all levels being quantum levels, on this view). To me, it makes no sense to deny reality altogether in this way. We need a notion of physical reality, even if only a provisional or approximate one, for without it our objective universe, and thence the whole of science, simply evaporates before our contemplative gaze!

So his interpretation is direct: it is reality. (I assume that the other possibilities he considers later would be no more pleasing to the classical mind.)

[edit] Weinberg

I put this into two articles' discussion some time back, but it is also relevant here.

Physics Today, April 2006, "Weinberg replies", p. 16,

... but the apparatus that we use to measure these variables—and we ourselves—are described by a wave function that evolves deterministically. So there is a missing element in quantum mechanics: a demonstration that the deterministic evolution of the wave function of the apparatus and observer leads to the usual probabilistic rules [Copenhagen interpretation].

So the "Copenhagen interpretation" and its competitors are not philosophy nor basic physics. They are empirical rules, that have not yet been fully justified theoretically, for using the classical approximation in quantum experiments. David R. Ingham 05:01, 16 August 2006 (UTC)

Hi, I hope someone at interpretations of quantum mechanics (where I see you have already posted your comments) can answer. But briefly, MWI is deterministic (Weinberg) and classically realist (Penrose). --Michael C. Price talk 07:31, 16 August 2006 (UTC)

[edit] "Hidden variables"

In section 23.2, while introducing entanglement, Penrose (above) points out that there being one wave function for all the particles in a quantum system makes the number of dimensions depend on the number of particles as an exponent, instead of as a multiplier. This vastly increases the number of variables needed to specify the state of a system. Since the number of particles always greatly increases during an experiment, the instruments, etc. becoming part of the system, it is hard to imagine why anyone would want to introduce more "hidden" variables not to know either. David R. Ingham 00:05, 23 August 2006 (UTC)


[edit] Introduction

Hi,

I've rewritten the introduction section which did not seem adequate to me, although I admit that what I put down does seem a little clunky. - Rafaelgr 16:15, 7 September 2006 (UTC)

[edit] Copenhagen interpretation / Consciousness causes collapse

From Consciousness_causes_collapse: "Consciousness causes collapse is the theory that observation by a conscious observer is responsible for the wavefunction collapse in quantum mechanics."

From Copenhagen_interpretation: "The act of measurement causes an instantaneous "collapse of the wave function"."

I guess the consciousness part makes the difference between this and (part of) the Copenhagen interpretation. However, is it not so that a conscious observer is necessary to do the measurement? The question I pose is: why is the 'Consciousness causes collapse' interpretation regarded as separated from the Copenhagen interpretation? Seems to be part of it... Info D 10:12, 29 October 2006 (UTC)

It can be regarded as part of it, I believe. The distinction (I think) is that Copenhagen (some variants) says the wavefunction collapses somewhere along the measurement chain (observed microsystem at one end, conscious observer at the other) whereas the 'Consciousness causes collapse' POV says collapse happens only at the conscious endpoint of the chain. Other CI variants says it happens at the first irreversible interaction in the measurement chain -- consciousness is presumed to be irreversible, but is not necessarily the first such step encountered in the chain. So CI is a somewhat broad umbrella. --Michael C. Price talk 11:48, 29 October 2006 (UTC)
According to Bohr we need to describe the experiments we perform in purely classical terms, i.e., according to classical physics, as our measuring apparatus are of necessity "macroscopic." What he didn't explain was where exactly the boundary between "macroscopic" and "microscopic" should be drawn. Thus, this is a problem in itself within the Copenhagen interpretation. One of the proposed solutions to this sub-problem is to say that it's our "consiousness" that causes the collapse. As this twist of the problem never was what Bohr had in mind (for him the collapse was caused by the macroscopic instruments) it's separated from the Copenhagen interpretation in the literature. INic 12:06, 29 October 2006 (UTC)
However, you are absolutely right that the "cosiousness interpretation" shouldn't be treated as an interpretation of QM standing on its own. It's just a twist on the Copenhagen interpretation. Oddly enough this isn't usually stressed in the literature. In fact, most of the different "interpretations" are just different twists on the Copenhagen interpretation. I'm not sure, however, if the wikipedia article should stress this logical point of view or stick to how this is commonly treated in the literature. I personally think it's such a simple observation as it shouldn't qualify as "original research" even if we can't support this with an explicit reference. INic 12:06, 29 October 2006 (UTC)

[edit] consistent histories - vandalism? i'm no physician...

the sentence "According to this interpretation, the purpose of a quantum-mechanical theory is to predict probabilities of various alternative histories." is a joke/bullshit/vandalism/callitwhatyouwant, or is it real?-- ExpImptalkcon 22:56, 19 November 2006 (UTC)

No, I think that is for real. Admittedly it might be a bit clearer, although how, I'm not sure! --Michael C. Price talk 01:07, 20 November 2006 (UTC)
Other voices? Perhaps a quote of an actual Ph. D. in Physics saying that? Sorry, but i cant imagine hard-nosed physics buffs suddenly wandering off to lala-land to think about alternative histories.... can you?-- ExpImptalkcon 23:17, 20 November 2006 (UTC)
Murray Gell-Mann hard-nosed enough for you? --Michael C. Price talk 02:02, 21 November 2006 (UTC)

[edit] Theory of Incomplete Measurements

The "incomplete measurements" approach derives quantum mechanics axioms from properties of the physical processes we are willing to call measurements. It does not require a conscious observer, but rather a selection among physical processes to isolate those that can legitimately be used as measurements. An noteworthy consequence is the suggestion that the normalization condition for the wave function needs to be restricted to whatever the measurement process can legitimately return as a result. It also gives a physical interpretation not just to the amplitude, but also to the phase of the wave function.

The original paper is at http://cc3d.free.fr/tim.pdf. It's very recent, has not been published in print, and it did not receive much scrutiny. If the case of Afshar's experiment is any indication, Wikipedia accepts references to very recent work. —The preceding unsigned comment was added by Descubes (talk • contribs) 09:08, 4 December 2006 (UTC).

[edit] Objective/Spontaneous Collapse Theories

This article makes no mention of a class of approaches to QM, the Objective (or spontaneous) collapse theories, of which the most famous example is the Ghirardi, Rimini and Weber theory).

As the Sanford Encyclopedia of Philosophy [3] article states..

'...this approach consists in accepting that the dynamical equation of the standard theory should be modified by the addition of stochastic and nonlinear terms. The nice fact is that the resulting theory is capable, on the basis of a unique dynamics which is assumed to govern all natural processes, to account at the same time for all well-established facts about microscopic systems as described by the standard theory as well as for the so-called postulate of wave packet reduction (WPR). As is well known, such a postulate is assumed in the standard scheme just in order to guarantee that measurements have outcomes but, as we shall discuss below, it meets with insurmountable difficulties if one takes the measurement itself to be a process governed by the linear laws of the theory. Finally, the collapse theories account in a completely satisfactory way for the classical behavior of macroscopic systems'.

1Z 15:52, 11 January 2007 (UTC)

Looks like a good addition. Worth also pointing out that this approach is not really a new interpretation of the standard laws of quantum dynamics. Rather it is a new set of postulated dynamics, since they are modifying the canonical equations. --Michael C. Price talk 01:21, 12 January 2007 (UTC)

[edit] Merge?

The merge tag needs to be addressed. Does it make sense to split this article at all, or to address philosophy/"controversy" in another article? -Ste|vertigo 05:28, 5 February 2007 (UTC)

I would strongly suggest a Vote for Deletion. This is riddled with original research--or free-wheeling speculation, if you like--and is a distant cousin to anything encyclopedic in tone. —Preceding unsigned comment added by 136.142.21.213 (talk)
Oops, that looks unclear. I meant that I support the delete of the "QM, phil., and controversy article." Not the "Interp of Q.M." article, which I think is altogether nifty. —Preceding unsigned comment added by 136.142.21.213 (talk)
I also support the delete of the 'philosophy and controversy' article. Even the title seems out of place - I don't think it's an area unto itself, unlike 'interpretations of quantum mech'. I will start a discussion on the other page with a move to delete it. Mogudo 05:23, 13 April 2007 (UTC)

[edit] Transactional Interpretation - really indeterministic?

Hi,

in the comparison table of the various interpretations of quantum mechanics, John Cramer's Transactional Interpretation is indicated as an "INDETERMISTIC" one. Is this classification really feasible or does it have to be changed to "determistic"? After all, the transactional interpretation has to presuppose a blockworld scenario with a prexististing future to allow a handshake between past and future events. This would of course imply determinism, because past and future are already fixed.

If there is no rational argument in suport of an indetermistic transcational interpretation, I will chgange this point in the table.

Kind regards, Dr. Guenter Bechly —Preceding unsigned comment added by 193.197.147.9 (talk) 08:34, August 24, 2007 (UTC)

I think you are confusing predestination with determinism. --Michael C. Price talk 08:38, 24 August 2007 (UTC)
Is it possible that you confuse predestination and predictability? Can you conceive of a deterministic universe without predestinated future (or of an indeterministic universe with predestinated future)? I think both are strictly correlated like two sides of a coin. What is not correlated is predictability, thus a deterministic universe could be inpredictable even though the future is predetermined, but this is not an issue of ontology but of epistemiology (e.g. Chaos theory is based on determinism but explains unpredictability). Therefore, I still raise the initial question: Does the transactional interpretation imply indeterminism or determinism, or is it at least compatible with both indeterminism and determinism? —Preceding unsigned comment added by 193.197.147.9 (talk) 10:35, August 24, 2007 (UTC)
Can you conceive ..... of an indeterministic universe with predestinated future - Yes. Different words mean different things. --Michael C. Price talk 10:39, 24 August 2007 (UTC)
According to the definition of "determinism" by Van Inwagen (1983): Determinism may also be defined as the thesis that there is at any instant exactly one physically possible future. Enough said!? And if this is accepted: Is the Many World Interpretation really a deterministic interpretation in the strict sense (like Bohmian mechanics for example), or rather a stochastic causal interpretation: All outcomings are causally defined by the wavefunction, but there is no internal causal reason for a particular eigenstate in a particular branch of the multiverse (e.g. no causal reason for a specific quantum fluctuation or radioactive decay which is still stochastic in the Many Worlds Interpretation). Kind regards, Dr. Guenter Bechly (p.s. sorry if my physical understanding is only layman like, but I am biologist and geologist, no physicist) —Preceding unsigned comment added by 84.56.182.65 (talk) 18:46, August 24, 2007 (UTC)
That's a nice definition of determinism, but does it mean the same as predestination? I don't think so, simply because predestination is slippery religious concept (see predestination). So let's not talk about predestination in a physics article.
The MWI is deterministic, because it is the deterministic wavefunction that defines reality. Same with Bohmian mechanics, where the particle's course is deterministic. Copenhagen is indeterministic since we have wf collapse. Even Cramer admits that the TI is isomorphic to Copenhagen; ergo it is indeterministic. --Michael C. Price talk 19:03, 24 August 2007 (UTC)
Michael, it was you (not me) who introduced the notion of predestination to our discussion. I am talking about determinism in the sense of a block universe and block time view. If you compare this with a religious concept of predestination you are free to do that, but nevertheless block time and block world are purely scientific corolloraries of Minowski's spacetime interpretation of Einsteinian relativity. Myself, I am an atheist and Bright and I am not interested in metaphysical aspects of any kind of predestination. My point is: Is there really an ontological difference (whatever you might call it) in the world view of TI and MWI, and I am still not sure about this. It still looks to me that TI ist more deterministic, because it implies a single blockworld history (thus, endorsing counterfactual definiteness, contrary to MWI), while MWI does not imply a particular blockworld history but all possible ones, and therefore is rather indeterministic. There is no open future in TI, but well in MWI. Could you please elaborate on this crucial point instead of semantics? —Preceding unsigned comment added by 84.56.182.65 (talk) 09:40, August 25, 2007 (UTC)
I still think you're confusing predestination with determinism. Anyway I am not going to continue to debate flakey original research here. As I've already said -- and which you completely ignored -- Cramer says TI is mathematically isomorphic to CI (which is indeterministic). The MWI is deterministic, because it is the deterministic evolution of the wavefunction that defines reality. Same with Bohmian mechanics, where the particle's course is deterministic. End of story. --Michael C. Price talk 18:06, 29 August 2007 (UTC)
John Gribbin's take on TI is that future events are "already there", which is almost, but not quite, determinism. However, that is contested by some. 1Z 10:32, 29 August 2007 (UTC)
As I've said, "already there" is predestination, not determinism. --Michael C. Price talk 18:06, 29 August 2007 (UTC)
Saying it again does not make it correct. Predestination is a religious concept, but block universe is a physical concept which has nothing to do with predestination at all. Predestination does involve a notion of destiny which again involves a notion of teleology in the sense of destiny predetermined by a higher power, while block universe is just another term for fourdimensionalism and eternalism in the spacetime worldview of modern physics. —Preceding unsigned comment added by 84.56.203.190 (talk) 18:18, August 29, 2007 (UTC)
And denying it again doesn't make it false either. --Michael C. Price talk 18:28, 29 August 2007 (UTC)
Michael, can you please stay objective and rational, thus answering raised questions instead of contributing just short polemic statements without any arguments! Here is one question you should answer: What is the causal explanation for a particular outcome in a particular worldline in MWI? For example, how is the radioactive decay or non-decay is explained when it is measured? The wave function only gives a causal explanation for the complete set of possible outcomes, but not for a particular event or state. If MWI does not offer a causal explanation for a particular decay event or for a quantum fluctuation it must be considered as indeterministic. The second question you should answer is, is there an open future in MWI and/or TI? —Preceding unsigned comment added by 84.56.203.190 (talk) 18:32, August 29, 2007 (UTC)
I've already made some salient points which have remained unanswered: Cramer says TI is mathematically isomorphic to CI (which is indeterministic). The MWI is deterministic, because it is the deterministic evolution of the wavefunction that defines reality. Same with Bohmian mechanics, where the particle's course is deterministic. End of story. --Michael C. Price talk 18:34, 29 August 2007 (UTC)
And Deutsch says TI is isomorphic to MWI... 1Z 13:20, 30 August 2007 (UTC)
Have you a link for that? I doubt that Cramer agrees since he is quite anti-MWI. :-) (I also doubt that Deutsch regards MWI as indeterministic.) --Michael C. Price talk 13:46, 30 August 2007 (UTC)
As for your additional MWI questions, see this FAQ and in particular question 25 "Why am I in this world and not another?" --Michael C. Price talk 18:41, 29 August 2007 (UTC)
You are comparing apples with oranges: CI is not an ontological interpretation but rather the viewpoint "shut up and calculate". TI and MWI are ontological interpretations that attempt to understand and explain what QM means in the real world. Therefore it is irrelevant if TI is isomorphic to CI (by the way a viewpoint also endorsed by C.F.v. Weizäcker). All interpretations that do not modify the mathematical formalism of QM are isomorphic to eachother. You did not answer my questions. Are you aware that philosophically it is impossible that a deterministic universe produces an open future? However, MWI implies numerous possible futures (thus an open future from each subjective point of view), while TI does not. —Preceding unsigned comment added by 84.56.203.190 (talk) 18:44, August 29, 2007 (UTC)
CI can be considered as including an objective collpase process. The current article treats that as a differnt variation from shut-up-and-calculate.1Z 13:20, 30 August 2007 (UTC)
There are shades of CI according to how they interpret the collapse, ranging from objective "real" collapse to just an adjustment of subjective knowledge. --Michael C. Price talk 13:51, 30 August 2007 (UTC)
Responding to the earlier unsigned comments:
  • You did not answer my questions. I did precisely that by my pointing you to a MWI FAQ (which I wrote, BTW).
  • TI/CI and MWI are not mathematically isomorphic to each other: (i.e. (CI=TI) =/= MWI).
  • Are you aware that philosophically it is impossible that a deterministic universe produces an open future? - no, and I don't believe it either -- and I don't intend to debate non-standard OR. --Michael C. Price talk 18:56, 29 August 2007 (UTC)
I am sorry, you did not ask any questions, thus I could not answer them. But I had some questions that you did not answer yet. The viewpoint that determinism is incompatible with free will and an open future is sufficiently mainstream to consider it anything but non-standard. How would you reconcile determinism with an open future? I absolutely accept your disagreement, but I would like to hear your arguments. I am not discussing here to impose my point a view, on the contrary, I am still in the process of building up my point of view. I would consider it a real pity, if you reject further discussion because you seem to have considerable knowledge about this subject. By the way: Of course I know the Many World FAQ written by you, and I also know the anthropic point of view concerning the question why we are thinking we are in a particular world. However, I still do not see a causal explanation for particular quantum states and events in MWI, but well in TI and Bohmian mechanics. To me MWI still looks more stochastic than deterministic. —Preceding unsigned comment added by 193.197.147.9 (talk) 06:54, August 30, 2007 (UTC)
I did not ask you to answer my questions, it was my points you ignored (repeatedly). And sorry, I do not intend to broaden the discussion by including the eternal bugbear of free-will (debates about free-will never get anywhere) -- let's stick to determinism. Determinism has a precise physical meaning: no random effects, which, in the MWI view, means a deterministic evolution of the wavefunction (i.e. without collapse), since it is he wavefunction that is taken to be the fundamental entity. It's quite simple: The MWI is deterministic, because it is the deterministic evolution of the wavefunction that defines reality. - that is a sourced position that is maintained by all the founders of MWI and (as far as I can recall), every other commentator of note, whether or not they agree with MWI. If you have specific issues with determinism re MWI then I suggest you ask on the MWI talk page, after reading the MWI article, where you are likely to get a more focussed response my myself or others. I am quite happy to improve the clarity of the MWI article by debate. --Michael C. Price talk 09:22, 30 August 2007 (UTC)

[edit] Calogero hypothesis

There's been a short notability discussion for this page. See its Talk page. It's non-pseudo but as with many QM theories, noone seems to have picked up on it either. Does it warrant a short mention on a page like this one, or should it go up for deletion? EverGreg 19:09, 24 August 2007 (UTC)

Thanks. My gut instinct is that if it's non-pseudo it should stay, but I'll have a look before I vote KEEP.  :-) --Michael C. Price talk 19:13, 24 August 2007 (UTC)

[edit] Decoherence approach

It seems to me that in the paragraph "decoherence approach" we don't actually present a philosophical interpretation of anything, we just explain a mathematical result (and a corresponding actual physical phenomenon) in common english language. Don't we? This looks very strange because the paragraph is a subparagraph of "Summary of common QM interpretations".--Pokipsy76 08:50, 16 September 2007 (UTC)

[edit] Again on decoherence

In the introduction we read:

Quantum decoherence is the prominent physical approach to the subject.

but if we follow the link we discover that quantum the coerence is not a philosophical or interpretational issue: it is just a physical phenomenon. So that phrase looks very strange to me.--Pokipsy76 09:01, 16 September 2007 (UTC)

It should be explained more clearly that decoherence is a uncontroversial tool used in various controversial interpretations (such as consistent histories, existential inter', MWI, Bohm's pilot wave).--Michael C. Price talk 13:09, 19 November 2007 (UTC)

[edit] Comparison

The comparison table might be misleading and needs an overhaul or could be removed. E.g., waveform is never defined in the article; is it equivalent to wave function? Waveform is used in telecommunication and electronic engineering to denote the shape of a signal. Any opinion?

Yes, waveform=wavefunction. And I vote for ovehaul.1Z (talk) 11:27, 19 November 2007 (UTC)

[edit] Minority QM interpretations new article

I created a new article to catalog the obscure QM theories. any QM school of thought not well known enough to be listed in the main interprations article, should be listed here vroman (talk) 05:31, 1 April 2008 (UTC)

[edit] "Consciousness causes collapse" vs. "Quantum mysticism"

This ("Interpretation of quantum mechanics") article seems "good" (at least to someone struggling to understand quantum mechanics amid the popular pseudoscience...) and seems to be maintained by some "serious" people.

"Consciousness causes collapse" is here, but, the link to the "Main article:" leads to "Quantum mysticism". However, there's lots of [unique/different] good info (I think) in the old "Consciousness causes collapse" article at

http://en.wikipedia.org/w/index.php?title=Consciousness_causes_collapse&oldid=193438546

PLEASE HELP: how do we recover/reinstate/etc. such useful info? I tried unsuccessfully to BOLDly "undo" the redirection...

My guess is that the editors *here* can't be aware of actions taken in the "Main articles" linked from here.

If someone can fix/improve the "Main article: Consciousness causes collapse", and perhaps (briefly?) explain how/why it became "Quantum mysticism" (even after I tried to "undo" the redirection) I'd really appreciate it.

Thanks! —Preceding unsigned comment added by Curious1i (talk • contribs) 03:12, 13 March 2008 (UTC)

I think "Consciousness causes collapse" is a red rag to a bull for some people. I have redone this section as the Participatory Anthropic Principle, which is a theory of Johnny Wheeler - who has just died and was the last of the titans of 20th-century physics. I hope this will mean people won't dismiss it as mysticism. To me it seems a "better" theory than many-worlds (in the sense of William of Ockham). Aarghdvaark (talk) 17:56, 3 May 2008 (UTC)

The PAP seems more a matter of cosmology. Wigner seems to be the primary source of the role of consciousness in collapse and Penrose, for example, credits him for this. I will make a rewrite of this after I have assembled the sources. Colonel Warden (talk) 18:14, 3 May 2008 (UTC)
OK. True about cosmology, but the interpretation of quantum mechanics and cosmology are intertwined, e.g. many-worlds is as much about cosmology (why this universe) as quantum mechanics.Aarghdvaark (talk) 06:49, 4 May 2008 (UTC)