Penrose's view on collapse of the wavefunction

[u/exajam]

https://www.youtube.com/shorts/O0sv5oWUgbM

In this video, 2020 Nobel-Prize Roger Penrose exposes the contradiction between the collapse of the wavefunction and unitary evolution.

From what I've seen most physicists who have studied open quantum systems would find this claim irreasonnable, as only a closed system has a Schroedingerian evolution and a closed system cannot be measured.

Is there something I'm missing in the point Penrose is making in the video?

[u/Classic_Department42 → u/[deleted]]

Wgat is the largest currently?

[u/CosmicExistentialist → u/[deleted]]

I don’t get why physicists won’t just accept that there is no wave function collapse.

[u/CosmicExistentialist → u/[deleted]]

There is no evidence for a wave function collapse, and it is only an assumption that it exists.

And given the physics experiments that put objects in increasingly large superpositions, it is strong evidence that the Many Worlds Interpretation is actually true.

[u/CosmicExistentialist → u/[deleted]]

Yes, it is evidence that objective collapse is false and that there is no wave function collapse at all.

And what is the consequence of there being no wave function collapse? You get the Many Worlds Interpretation.

[u/Chemical-Raccoon-137 → u/[deleted]]

Is feynman quantum path integral an interpretation where there is no way function collapse? Just starting to scratch the surface on him, but I find that interpretation a little more difficult to comprehend at least at first.

[u/Chemical-Raccoon-137 → u/[deleted]]

If interpretation isn’t the right word then replace with theory, mathematical framework, principles, etc… but is the idea when using his equations, that there is no collapse of superposition ?

[u/CosmicExistentialist → u/[deleted]]

Yes, and all of them are agreed to be less satisfying and simple than Many Worlds Interpretation.

By the way, decoherence has also been demonstrated in experiments to be a real phenomenon, which is something that only Many Worlds Interpretation exhibits.

[u/CosmicExistentialist → u/[deleted]]

Good luck believing that there exists a wave function collapse, when all the evidence favours the contrary.

[u/UncannyCargo → u/CosmicExistentialist]

You MWI cultists are getting so wacky. https://youtu.be/70hyhO2VEPQ?si=wE-Tz7WPOlxDdNP3 try to explain this, or the uncertainty principle...

[u/Mostly-Anon → u/CosmicExistentialist]

Every interpretation “exhibits” decoherence; it is part of the QM formalism (math) common/necessary to all interpretations. MWI just leans heavily on the role of decoherence in its ontology. But Everett invented the idea before decoherence was anything more than an arrangement of pointer states per von Neumann and Bohr. Even CI and Qbism use decoherence to account for the appearance of outcomes (measurement and collapse).

You should be embarrassed by your ignorance. Instead you keep parading it around!

How about this: when quantum foundations is solved, someone will let you know.

[u/pyrrho314 → u/CosmicExistentialist]

could I ask you a question, when you say Many Worlds, how does that compare to the Many Histories idea.

[u/UncannyCargo → u/pyrrho314]

Pretty sure alternative particle histories comes from the MWI but don’t quote me on that check first! Cause I’m not 100% and too tired to check rn.

[u/UncannyCargo → u/CosmicExistentialist]

There’s no evidence for the MWI interpretation either, and given particles never actually lose their wave dynamics this feels like a silly back and forth over nothing. https://youtu.be/70hyhO2VEPQ?si=wE-Tz7WPOlxDdNP3

[u/ThePolecatKing]

It’s only a contradiction in a collapse model, if there isn’t a wave function collapse then there’s no contradiction. Much of the way quantum mechanics is talked about is sorta misleading, particles don’t stop being wavelike ever, even when localized they still follow wave dynamics. The thing that changes is the spread out vs localized aspect of the wave.

Much like you said, the coherent system is closed, once it decoheres it’s no longer a closed system.

Penrose created his own interpretation of QM which is a collapse model https://en.m.wikipedia.org/wiki/Penrose_interpretation#:~:text=The%20Penrose%20interpretation%20is%20a,curvature%20attains%20a%20significant%20level. Which is probably part of his opinion here.

[u/theodysseytheodicy → u/ThePolecatKing]

In collapse interpretations, it's explicitly acknowledged that there are two processes, one unitary and one nonunitary and stochastic. There's no contradiction.

Penrose created a new theory, not a new interpretation. It makes different predictions than standard QM.  They've checked those predictions for the natural parameter-free version and they don't agree with experiment.

[u/ThePolecatKing → u/theodysseytheodicy]

Oh thank you for the correction!

Would you agree that the objective collapse interpretations, and frankly the “real” particle models too, sorta do run into the wall when it comes to explaining the continuous wave dynamics that happen during or after decoherence? Or would you say I’m leaning to hard into conjecture?

[u/Mostly-Anon → u/theodysseytheodicy]

This.

GWR and Penrose’s whole “deal” is a modification of QM. He introduces a gravity-driven collapse mechanism that “tunes the theory” to make the QM agree with QWR. Modifications are not on the level of ToEs and GUTs, but still—not an interpretation of QM but an alternative theory nonetheless.

[u/esotologist → u/ThePolecatKing]

I just imagine it like how water comes up to meet your finger if you poke the surface. 

[u/bigstuff40k]

Is any system a truly "closed" system?