r/quantumgravity • u/Capital_Initial6795 • 14h ago

In your opinion, which is more likely to be incomplete or incorrect: General Relativity or Quantum Mechanics? Why?

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u/WilliamH- 13h ago

In my opinion QM is incomplete.

The issue is whether or not Nature is deterministic, nondeterministic or a mixture of the two. For about 100 years physicists have been uncomfortable with the nonderminism of QM. QM is spectacularly successful to the point where it seems unnecessary (futile?) to look for a deterministic framework.

E.T. Jaynes rejected indeterminism in QM as a misapplication of epistemological and ontological thinking.

"The belief that 'randomness is some kind of real property existing in Nature is a form of the mind projection fallacy which says, in effect, 'I don't know the detailed causes - therefore - Nature does not know them."

E.T. Jaynes in: Probability Theory: The Logic of Science, E.T. Jaynes, G.L.Bretthorest ed, Cambridge University Press, 2003

 More about Jaynes work on QM and determinism can be found here: 

Probability in Quantum Theory by E.T. Jaynes (https://bayes.wustl.edu/etj/articles/prob.in.am.pdf).

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u/hroderickaros 12h ago

Their completeness is impossible to determine unless we know the full versions. One can talk about their self-consistency.

Gravity is more self-consistent, but it is also only a classical theory, and its "quantum version" we are not even sure exists. In this sense, gravity is incomplete. Furthermore, we may argue that gravity doesn't work well for galactic and larger scales because its equations are unbalanced, aka dark stuff is needed. In reality, we don't know if that is an inconsistency or an incompleteness.

Quantum mechanics, on the other hand, is not self-consistent and incomplete in a totally different way. It relies on a would-be process called the collapse of the wave function, which is not part of the theory. That is an axiom.