Graduate Many Worlds versus Thermal interpretation

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The discussion centers on the contrasting interpretations of quantum mechanics, specifically the Many Worlds Interpretation (MWI) and the Thermal Interpretation. Bryce DeWitt's work is noted for promoting MWI within the theoretical physics community, although some find its treatment superficial. Both MWI and the Thermal Interpretation are argued to provide a coherent understanding of the universe's state, essential for quantum gravity theories. The differences between MWI and Decoherent Histories (DH) are highlighted, particularly that MWI posits all histories occur while DH asserts only one history is realized. The conversation emphasizes the need for clarity in defining how a 'real' history is determined in these interpretations.
A. Neumaier
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TL;DR
Points out an interesting book by Bryce DeWitt on quantum gravity and its interpretation issues
The two volume treatise
which discusses the canonical approach to dynamical quantum gravity, is probably responsible for the fact that the many worlds interpretation (MWI) of quantum mechanics has a sizable support in the theoretical physics community. His emphasis on the MWI is not to my taste and seems to me far too superficial, sweeping all the difficulties under the carpet.

But one can replace his interpretation discussion without any loss of substance by a reference to my thermal interpretation, since the latter shares the main reason why DeWitt championed MWI:

In both interpretations, the state of the universe makes sense (a necessary prerequisite of any theory of quantum gravity) , and no other covariant interpretation has this virtue.
 
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In both interpretations, the state of the universe makes sense (a necessary prerequisite of any theory of quantum gravity) , and no other covariant interpretation has this virtue.

I believe Decoherent Histories also shares this virtue, and is as readily generaliseable to quantum gravity.

https://arxiv.org/abs/1803.04605
 
Morbert said:
I believe Decoherent Histories also shares this virtue, and is as readily generaliseable to quantum gravity.

https://arxiv.org/abs/1803.04605

Isn't DH the same as Everett? Reading James B. Hartle it's hard not to conclude that
 
Quanundrum said:
Isn't DH the same as Everett? Reading James B. Hartle it's hard not to conclude that

There are important differences. E.g. Given a set of decoherent histories of a closed system, both Both MW and DH would resolve a pure initial state into orthogonal branches corresponding to the histories. But MW says all histories occur, while DH says only one history occurs.
 
Morbert said:
There are important differences. E.g. Given a set of decoherent histories of a closed system, both Both MW and DH would resolve a pure initial state into orthogonal branches corresponding to the histories. But MW says all histories occur, while DH says only one history occurs.

If it doesn't define how one 'real' history occur, then it's just semantics?
 
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These papers by Pegg et al. (doi: 10.1016/j.shpsb.2008.02.003 [section 4]; https://www.researchgate.net/publication/230928426_Retrodiction_in_quantum_optics [section 3.2]) seem to show that photon Bell correlations can be inferred using quantum theory in a manner that is compatible with locality by performing quantum retrodiction (i.e. inferring information about the past: e.g. https://doi.org/10.3390/sym13040586; more papers at end) where they evolve backward from Alice's measured outcome...

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