Talk:Relational quantum mechanics

message: The sentence here and solution hereafter does not seem to make sense to me : 
"But, let us imagine that {\displaystyle O'}O' measures the spin of {\displaystyle S}S, and finds it to have spin down (and note that nothing in the analysis above precludes this from happening). What happens if he talks to {\displaystyle O}O, and they compare the results of their experiments? {\displaystyle O}O, it will be remembered, measured a spin up on the particle. This would appear to be paradoxical: the two observers, surely, will realise that they have disparate results."
In effect, the operator M forbids that any projection of O' own measurement of S can be in a different state than O(up), since O measured up. This would make the interpretation coherent. The tower of observers looks necessary only to reconcile unitarity.
Please, authors of this section, can you either comment or modify?  — Preceding unsigned comment added by 2A01:E0A:168:1C30:D580:FDEE:1A6B:773E (talk) 12:45, 1 September 2020 (UTC)
thread_title:  "Coherence"

message: The section on ontology and epistemology contains numerous statements which are unsourced and seem to be original research.  What's more, some of the claims flatly contradict explicit statements made by Rovelli in his papers.  The most blatant example is:
Epistemologically, RQM differs fundamentally from Bohr's understanding of the role of quantum mechanics as a theory: Bohr felt that quantum mechanics is not a theory about the world as it is, but a theory about what we (humans) can say about the world. On the other hand, while RQM is very much a theory about what can be said about the world (where "said" refers to any correlation of state between any two relata), it claims to be exhaustive in its description. There is nothing more to the world than the net of relational descriptions.
On the second page of "Relational EPR", this statement is flatly contradicted by an explicit reference to Bohr's account of knowledge in physics as a motivation for the relational programme.  The statement also seems to contradict itself ("Bohr felt that quantum mechanics is a theory about what we can say about the world" is followed by "while RQM is very much a theory about what can be said about the world").
The remainder of the section is gratuitious name dropping and unsourced claims of correlation to the writings of other philosophers.
I suggest that the entire section should be removed.
--Auspex1729 (talk) 22:04, 22 August 2008 (UTC)
replies: text: I'm adding a request for a citation on the claims of nominalism.  This has not been advocated by Rovelli (I may see if he is interested in weighing in on this).  I have removed the incorrect paragraph on the contrast between Bohr's philosophy and RQM. --Auspex1729 (talk) 22:17, 22 August 2008 (UTC)
replies: text: I axed the whole thing as there haven't been any citations added. -Jordgette (talk) 23:33, 17 November 2009 (UTC)
thread_title:  Ontology and Epistemology 

message: The citations, references and footnotes of this article are a disaster.  I'm going to flag them for cleanup and attempt to do so when I have more time.--Auspex1729 (talk) 22:39, 23 August 2008 (UTC)
thread_title:  Citations, References and Footnotes 

message: Forgive me if I'm wrong, but I'm missing something major from this article.  The article seems to suggest a relational + quantum description of reality.  As far as I'm aware, for such a theory to be considered complete, it would need to embed a description of gravity.  Clearly, this would have to be embedded in the relational model, however, it's not clear what the resultant model of quantum gravity is.  Could the article at least hint at what the resulting gravitational theory might look like?  70.247.168.170 (talk) 04:28, 5 March 2012 (UTC)
thread_title:  Gravity? 

message: I see some discussion here in the talk section on the value of this interpretation. I don't think this is the right place for such discussion. On the other hand, I think it would be a good idea to add a section to the main article mentioning criticism that may have been expressed by other phycisists. This may be hard to find  and I haven't searched for it. Anyway I am suggesting to those collaborating with this article to look for such criticism, which would make the article a little more balanced and contribute to a neutral point of view. Alex Pascual (talk) 18:56, 26 March 2014 (UTC)
thread_title:  Criticism  

message: What's the deal with Relational quantum mechanics vs. Relational approach to quantum physics?
*As early as in 1985, S. Kochen suggested that the paradoxes of quantum physics could be overcome by developing a relational approach,  which was needed at one time to solve the paradoxes of  relativistic physics of space and time (S. Kochen, Symposium of the Foundations of Modern Physics: 50 Years of the Einstein-Podolsky-Rosen Gedankenexperiment, (World Scientific Publishing Co., Singapore, 1985), pp. 151-69.)
*Relational quantum mechanics:  treats the state of a quantum system as being observer-dependent, that is, the state is the relation between the observer and the system. This interpretation was first delineated by Carlo Rovelli in  1994. 
*Relational approach to quantum physics:  asserts that the physical world can only be studied accurately in terms of relationships between systems, as all experimentally verifiable facts about the world result explicitly from interactions (such as the interaction between a light field and a detector). [...] The approach was adopted, in a time span of 1992-1996, by Q. Zheng, S. Hughes, and T. Kobayashi in the University of Tokyo.( Zheng et al. (1992, 1996)) [...] It is also hoped that this entry will serve as a complement to Rovelli's relational quantum mechanics (RQM).
So:
*Rovelli "the state is the relation between the observer and the system"
*Zheng et al. "all experimentally verifiable facts about the world result explicitly from interactions"
This appears to me to be one and the same basic idea. Then why are both articles basically disjunct in terms of the literature they cite? And why does the Zheng page say "It is also hoped that this entry will serve as a complement to Rovelli's RQM"? I can imagine that two groups came up with the same idea independently in the 1990s, but since then clearly there must have been some degree of collaboration or confluence, or at least third-party literature comparing the two approaches? Why does Wikipedia keep this in two separate articles?
Is the Relational approach to quantum physics page in essence about a single paper that happened to end up under-appreciated because the Rovelli paper was on the same topic and became the attractor for later work on the topic? 
--dab (𒁳) 13:24, 18 April 2015 (UTC)
replies: text: You might be right. The articles should probably be combined at some point; since RQM has gotten much more traction, I’d vote for Relational approach to quantum physics to be rolled into this one. -Jordgette [talk] 01:02, 19 April 2015 (UTC)
replies: text: I am not a physicist; however the two summaries (Rovelli vs Zheng et al.) do not appear to me to be one and the same idea at all.  But then I maybe I am missing something: Rovelli states that the observation is meaningful only within the context of the observer's frame of reference, whereas Zheng et al. assert that physics can only be expressed in terms of interactions (aka observations), but they might not claim that observation is meaningful only within the context of the observer's frame of reference. It also seems to me that Rovelli equates causality with the role of the quantum observer, and even implies that the speed of light may correlate with the scope of interactions - which appears to be substantially distinct from Zheng et al. (20040302 (talk) 10:17, 10 October 2016 (UTC)
replies: text: Closing merge proposal for lack of consensus over 2.5 years. Klbrain (talk) 04:21, 5 September 2017 (UTC)
thread_title: duplication? independent development?

message: I'm unable to make sense of Postulate 3, which says that Ubc satisfies an equation that doesn't mention Ubc.  How to read/fix this? Vaughan Pratt (talk) 00:11, 2 December 2018 (UTC)
thread_title:  Something wrong with Postulate 3 

message: I may be stepping away from the serious intent here a little but, back in 1997, I was independently reaching what seems to be the same conclusion as Rovelli: that the problems of superposition reduce to statements that different observers have different information.  For some pre-Wikipedia meanderings, please see the sci.physics thread, Schrodinger's Bus p.r.newman (talk)  — Preceding undated comment added 12:18, 6 March 2021 (UTC)
replies: text: I think that's broadly similar to what Rovelli is saying. Of course, there are experiments in which superpositions can be physically prepared, and subsequently destroyed through decoherence...so to me, it seems that if superposition is just about observers' information, then some very radical things about measurement and the Heisenberg cut are implied. But we aren't really improving the encyclopedia here are we :-)  -Jordgette [talk] 19:36, 7 March 2021 (UTC)
thread_title:  Information and Correlation ... and Buses?