Talk:Interpretations of quantum mechanics

Localism: Copenhagen vs Ensemble

Guys, I'm not an expert at all, but I'm looking at that Comparison Box, where under "Localism," it lists Ensemble as No, and Copenhagen as Yes, and that seems backwards to me. Niels Bohr's Copenhagen interpretation is explicitly non-local. The Copenhagen interpretation is that when a laboratory device observes part of an entangled state, There's a wave function collapse where the other pieces of the entangled function now have new distributions. That's the essence of non-localism. By contrast, the Ensemble interpretation is local. That's the essence of the theory, why Einstein developed it, because he strongly clung to localism. The Ensemble Interpretation does away with this whole business of entangled wave functions that change instantly faster than the speed of light; it's heavily influenced by classical mechanics. There's only one particle in the Ensemble Interpretation. The wave fuctions are statistical averages, not properties of one particle. Am I wrong? 2601:645:8201:E3E0:134:23C6:EC8A:40C4 (talk) 20:14, 15 March 2020 (UTC) Jason Catlin

"Copenhagen" means many things to many people; some variants describe themselves as "local" and others don't. XOR'easter (talk) 20:24, 15 March 2020 (UTC)

So why don't we replace "Copenhagen" in the comparison with eg "von Neumann" or any other definite model. It seems really pointless to compare to something no one agrees is a thing. Johnjbarton (talk) 16:58, 13 December 2023 (UTC)

It might be interesting to try making table rows for "Bohr", "Heisenberg", "Omnès", "Zeilinger", etc. Well, having a table at all is kind of silly when so many of the entries have to be heavily qualified with footnotes, but it might be worth trying. XOR'easter (talk) 18:11, 13 December 2023 (UTC)

Removal of stochastic mechanics

Hi XOR'easter, I'm having trouble understanding your removal of the section on stochastic mechanics – It seems to me that everything in the comparison table should have a section written about it. I also don't see why it's listing at minority interpretations of quantum mechanics warrants its removal, effectively all (bar a couple) of the sections on interpretations have a corresponding listing over at that page, so I'm not sure what you mean here. Is there some other reason for the removal? Volteer1 (talk) 18:06, 28 February 2021 (UTC)

The Nelsonian stochastic interpretation is so obscure it's not even asked about in surveys of which interpretations physicists prefer. Per WP:UNDUE, it doesn't really fit in a big-picture overview of quantum interpretations. XOR'easter (talk) 18:11, 28 February 2021 (UTC)

Okay, that makes a little more sense. All good. Volteer1 (talk) 18:19, 28 February 2021 (UTC)

Well, the topic has returned and the description is opaque. Johnjbarton (talk) 17:03, 13 December 2023 (UTC)

Re-removed. XOR'easter (talk) 18:00, 13 December 2023 (UTC)

Non-interpretations?

Does Quantum Darwinism actually belong on this list? In other words, it's a research program and a methodology, but is it an interpretation of quantum mechanics? Or is it mathematics that can be applied in an interpretation-neutral way? My own inclination would be the latter, but are there actual secondary sources on this? (Sometimes Zurek writes as though he is advancing a new "existential" interpretation, and sometimes he praises the virtues of being interpretation-neutral.) Perhaps both Quantum Darwinism and objective-collapse theories should be moved to another section, called "Related concepts" or something like that. Quantum Darwinism arguably isn't an interpretation by itself, and objective-collapse theories are attempts to answer the kinds of questions that interpretations also try to answer but by replacing quantum mechanics with a different theory. XOR'easter (talk) 18:34, 13 December 2023 (UTC)

I agree that "objective-collapse" is not an interpretation but a alternative theory and should be distinguished from true interpretations; I also agree that quantum darwinism is not an interpretation but a mechanism; some say it's incorporated in Zurek's Existential Interpretation of quantum mechanics Sánchez-Cañizares: Classicality First: Why Zurek’s Existential Interpretation of Quantum Mechanics Implies Copenhagen, but don't know more about that. There was a discussion at Physics Stack Exchange a while ago on whether QD is an interpretation. --Qcomp (talk) 19:05, 13 December 2023 (UTC)

OK, I've moved those two subsections into a new section all their own. XOR'easter (talk) 19:14, 13 December 2023 (UTC)

New Interpretation

Fröhlich, Klaus (2023). "Quantum Mechanical Measurement in Monistic Systems Theory". Science and Philosophy. 11 (2): 76–83. doi:10.23756/sp.v11i2.1350. ISSN 2282-7757. Wikiwau (talk) 13:37, 7 January 2024 (UTC)

Not notable: too new, no reviews, insecure web site. Johnjbarton (talk) 16:21, 7 January 2024 (UTC)

To be a little blunt about it: Wikipedia is not the place for everything that claims to be an interpretation of quantum mechanics. See WP:UNDUE and WP:SECONDARY. XOR'easter (talk) 15:50, 8 January 2024 (UTC)

Agree --Chetvorno^TALK 18:56, 8 January 2024 (UTC)

Sources for "Nature" section?

The meta-analysis in the "Nature" section seems like an essay and essentially has no references. Any ideas what the source might be? Seems like the ideas are probably in the Sources refs. Johnjbarton (talk) 01:27, 24 March 2024 (UTC)

It seems to have originally been added back in 2011. XOR'easter (talk) 14:47, 24 March 2024 (UTC)

Thanks, confirms my guess. The section which follows it "challenges" is likely WP:SYNTH. To me it reads like a "List of Things I Do Not Understand". I think the Nature section is savable; I see no value in the "Challenges" list. Johnjbarton (talk) 16:50, 24 March 2024 (UTC)

Many Worlds and local dynamics

I might be missing the point here, but given that Many Worlds posits that astronomically-remote events can fragment my local reality, how is it classed as a "yes" for local dynamics in the table? Are there some flavours of Many Worlds that do and some that don't? If so, then a more subtle entry in the table is needed. PLUMBAGO 14:24, 28 March 2024 (UTC)

The entire column (or table) is nonsense. "Local dynamics" links to principle of locality which attempts to describe "locality" as applied in physics. But "local dynamics" presumably means (based on table entries) whether the interpretation can be bounded sensibly. So the famous Heisenberg cut is exactly a bound on the dynamics: under normal QM interpretations analysis stops at the cut. Many Worlds says "yes, stops at every interaction" and then "no, the entire universe for all times is always involved". A similar quibble-based "analysis" applies to every entry. That's because there is no definition of "local dynamics" given or can be given.

The entire table has this problem. Every single row is exactly indistinguishable from every other row on any objective criteria. So the table has to be based on subjective criteria which, by nature, are subject to endless and fruitless debate. Johnjbarton (talk) 16:41, 28 March 2024 (UTC)

Many Worlds does not posit that astronomically-remote events can fragment your local reality. Splitting is strictly local, as any physical process. There is no controversy about Many-Worlds having local dynamics, see the discussion in Talk:Bell_test#Many-Worlds and the many sources cited there. Tercer (talk) 17:40, 28 March 2024 (UTC)

My understanding is that at least some physicists view MWI in this way. But I'm no physicist, so am likely completely wrong. So I'll leave as is, although I note the comment from Johnjbarton about wider issues with this table. (As an off-piste question merely to satisfy my own curiosity, what form does a locally-branching universe take given that multiple outcomes from (say) an event on Earth eventually reach the Andromeda Galaxy. Do systems in Andromeda branch when they come into contact with arriving "signals" from these multiple branches (locally that is; i.e. at light speed)? If there's a good source you could point me at, that'd be great - thanks!) PLUMBAGO 10:43, 30 March 2024 (UTC)

Well you could look at the discussion I linked and the sources cited there to convince you that this is not a controversial point.

Off the top of my had I can recommend you the book "The Emergent Multiverse" by David Wallace, he talks about the locality of branching there. But the answer to your question is yes, systems in Andromeda branch when they come into contact with the signals.

Just note that this doesn't happen necessarily at light speed, this is just an upper bound. The precise speed will depend on which interaction is transmitting the decoherence, which may be photons, or sound, or collisions of air molecules, or gravitational waves, etc. It may also be nothing at all, in a Wigner's friend type of experiment. By assumption decoherence doesn't reach Wigner, so he never branches. Tercer (talk) 13:03, 30 March 2024 (UTC)

Brilliant - thanks Tercer. PLUMBAGO 09:26, 31 March 2024 (UTC)

My pleasure. Tercer (talk) 10:18, 31 March 2024 (UTC)