6 ms·

How certain are we at this point, that there are no hidden variables in quantum mechanics? I'm asking because I read an article a while ago about some advances

by m12k 4y ago

How certain are we at this point, that there are no hidden variables in quantum mechanics? I'm asking because I read an article a while ago about some advances in higher-dimensional math that turned out to simplify certain quantum mechanical computations [1]. And it got my hopes up that we might eventually see quantum mechanics explained this way - e.g. as a projection/cross-section of higher dimensional phenomena into our 3D/4D reality. That the "weirdness" of QM could be explained by the effects happening in higher dimensional space. But from our perspective those would be hidden variables, so I'm curious whether we've been able to rule those out completely, or only partially? [1] https://www.quantamagazine.org/physicists-discover-geometry-underlying-particle-physics-20130917/ https://www.quantamagazine.org/physicists-discover-geometry-...

alexfromapex 4y ago
When you look at entanglement it seems like interaction in a higher dimension is one of the only plausible explanations
- DebtDeflation 4y ago
  I think, ultimately, there are only 3 possible explanations for the paradoxes of the quantum world. 1) superdeterminism (everything including our choices in quantum experiments today were fully determined at the instant of the Big Bang), 2) something "outside" our observable reality acting as a global hidden variable (whether something like the bulk in brane cosmology or whatever is running the simulation in simulation theory) or 3) emergent spacetime (if space and time are emergent phenomena then locality and causation are not fundamental).
  - quantum_state 4y ago
    Option 3) seems to be more fun and natural. Would go for that.
sterlind 4y ago
iirc local hidden variables have been ruled out experimentally. global hidden variables have not, and form the basis of Pilot Wave Theory, but pilot waves have a lot of unresolved issues, and there's no full theory that explains what MWI and Copenhagen do.
ajuc 4y ago
We are certain that there are no local hidden variables because of https://en.wikipedia.org/wiki/Hidden-variable_theory#Bell's_theorem https://en.wikipedia.org/wiki/Hidden-variable_theory#Bell's_...
- ynniv 4y ago
  Until it's "Bell's Law", I think we should consider quantum mechanics a statistical approximation. Every time QM is questioned people point to Bell's Theorem and challenge anyone to disprove it, when it seems to me that it is QM which is making extraordinary claims that require extraordinary evidence. Every theory of physics has at one point been "the ultimate", and they have all been replaced by better theories as our ability to investigate has expanded.
  - ko27 4y ago
    Are you serious? Theorems are laws. It's like me doubting the Pythagorean theorem because I can't understand the proof. Local hidden variables can not explain experimental results of QM. That's a fact. Ask any QM Physicist and you'll get the same answer.
    - ynniv 4y ago
      That's the same argument every model has made for the history of science, but :shrug:. The value of a model is its predictive capability. Thinking any one to be absolute truth blinds us from progress.
      - dandanua 4y ago
        If we see that a model doesn't work - it becomes an absolute truth.
    - ncmncm 4y ago
      No. Local hidden variables can not explain experimental results of QM without implying something many people find distasteful. But no one has demonstrated any objective reason why that distaste has anything to do with the universe or its laws. So, another way to say it is local hidden variables do explain experimental results of QM if you are willing to accept the implications, none of which contradict observation.
miltondts 4y ago
I just want to correct some comments that say we are certain there are no local variables and that they have been ruled out experimentally. This is false information and even Bell himself knew it: "There is a way to escape the inference of superluminal speeds and spooky action at a distance. But it involves absolute determinism in the universe, the complete absence of free will." https://en.wikipedia.org/wiki/Superdeterminism#Overview https://en.wikipedia.org/wiki/Superdeterminism#Overview
- doliveira 4y ago
  I'd say superdeterminism is an even stronger version of global hidden variables
- kryptiskt 4y ago
  That's not local variables, that's a global conspiracy. And it's an unfalsifiable cop-out to the problem.
  - ddddfdohvsyknn 4y ago
    Physicists have a term for conspiracies, they call them symmetries.
  - miltondts 4y ago
    Regarding global conspiracy: "Explicit construction of Local Hidden Variables for any quantum theory up to any desired accuracy" https://arxiv.org/abs/2103.04335 https://arxiv.org/abs/2103.04335 Regarding unfalsifiable, from [0] "If engineers ever succeed in making such quantum computers, it seems to me that the CAT is falsified; no classical theory can explain quantum mechanics." By "such quantum computers" he means computers that can run Shor's algorithm. "...but factoring a number with millions of digits into its prime factors will not be possible – unless fundamentally improved classical algorithms turn out to exist." [0] - https://arxiv.org/abs/1405.1548 https://arxiv.org/abs/1405.1548 Now, this does not mean these theories are ready, but they are being worked on.
- ko27 4y ago
  Okay, I just want to correct you that superdeterminism is not a local hidden variable theory.
im3w1l 4y ago
So I was going to write a response to this but then I realized something. 1. The wavefunction is non-local, it contains non-local entanglements. Many-worlds even says it describes the whole world. 2. The wavefunction cannot be directly observed. 3. Many worlds interpretation doesn't have a notion of collapse - there is no randomness. So if you think about it, MWI is a deterministic global hidden variable theory. I have no idea how I didn't see it until now.

by m12k 4y ago

alexfromapex 4y ago

When you look at entanglement it seems like interaction in a higher dimension is one of the only plausible explanations

DebtDeflation 4y ago
I think, ultimately, there are only 3 possible explanations for the paradoxes of the quantum world. 1) superdeterminism (everything including our choices in quantum experiments today were fully determined at the instant of the Big Bang), 2) something "outside" our observable reality acting as a global hidden variable (whether something like the bulk in brane cosmology or whatever is running the simulation in simulation theory) or 3) emergent spacetime (if space and time are emergent phenomena then locality and causation are not fundamental).
- quantum_state 4y ago
  Option 3) seems to be more fun and natural. Would go for that.

sterlind 4y ago

iirc local hidden variables have been ruled out experimentally. global hidden variables have not, and form the basis of Pilot Wave Theory, but pilot waves have a lot of unresolved issues, and there's no full theory that explains what MWI and Copenhagen do.

ajuc 4y ago

We are certain that there are no local hidden variables because of https://en.wikipedia.org/wiki/Hidden-variable_theory#Bell's_theorem https://en.wikipedia.org/wiki/Hidden-variable_theory#Bell's_...

ynniv 4y ago
Until it's "Bell's Law", I think we should consider quantum mechanics a statistical approximation. Every time QM is questioned people point to Bell's Theorem and challenge anyone to disprove it, when it seems to me that it is QM which is making extraordinary claims that require extraordinary evidence. Every theory of physics has at one point been "the ultimate", and they have all been replaced by better theories as our ability to investigate has expanded.
- ko27 4y ago
  Are you serious? Theorems are laws. It's like me doubting the Pythagorean theorem because I can't understand the proof. Local hidden variables can not explain experimental results of QM. That's a fact. Ask any QM Physicist and you'll get the same answer.
  - ynniv 4y ago
    That's the same argument every model has made for the history of science, but :shrug:. The value of a model is its predictive capability. Thinking any one to be absolute truth blinds us from progress.
    - dandanua 4y ago
      If we see that a model doesn't work - it becomes an absolute truth.
  - ncmncm 4y ago
    No. Local hidden variables can not explain experimental results of QM without implying something many people find distasteful. But no one has demonstrated any objective reason why that distaste has anything to do with the universe or its laws. So, another way to say it is local hidden variables do explain experimental results of QM if you are willing to accept the implications, none of which contradict observation.

miltondts 4y ago

I just want to correct some comments that say we are certain there are no local variables and that they have been ruled out experimentally. This is false information and even Bell himself knew it: "There is a way to escape the inference of superluminal speeds and spooky action at a distance. But it involves absolute determinism in the universe, the complete absence of free will." https://en.wikipedia.org/wiki/Superdeterminism#Overview https://en.wikipedia.org/wiki/Superdeterminism#Overview

doliveira 4y ago
I'd say superdeterminism is an even stronger version of global hidden variables
kryptiskt 4y ago
That's not local variables, that's a global conspiracy. And it's an unfalsifiable cop-out to the problem.
- ddddfdohvsyknn 4y ago
  Physicists have a term for conspiracies, they call them symmetries.
- miltondts 4y ago
  Regarding global conspiracy: "Explicit construction of Local Hidden Variables for any quantum theory up to any desired accuracy" https://arxiv.org/abs/2103.04335 https://arxiv.org/abs/2103.04335 Regarding unfalsifiable, from [0] "If engineers ever succeed in making such quantum computers, it seems to me that the CAT is falsified; no classical theory can explain quantum mechanics." By "such quantum computers" he means computers that can run Shor's algorithm. "...but factoring a number with millions of digits into its prime factors will not be possible – unless fundamentally improved classical algorithms turn out to exist." [0] - https://arxiv.org/abs/1405.1548 https://arxiv.org/abs/1405.1548 Now, this does not mean these theories are ready, but they are being worked on.
ko27 4y ago
Okay, I just want to correct you that superdeterminism is not a local hidden variable theory.

im3w1l 4y ago

So I was going to write a response to this but then I realized something. 1. The wavefunction is non-local, it contains non-local entanglements. Many-worlds even says it describes the whole world. 2. The wavefunction cannot be directly observed. 3. Many worlds interpretation doesn't have a notion of collapse - there is no randomness. So if you think about it, MWI is a deterministic global hidden variable theory. I have no idea how I didn't see it until now.