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It's always a shame when the Copenhagen interpretation of quantum mechanics is presented as how reality works. Most of the perceived weirdness of QM comes from

It's always a shame when the Copenhagen interpretation of quantum mechanics is presented as how reality works. Most of the perceived weirdness of QM comes from the leaps of faith required to make the Copenhagen interpretation work.

n4r9 11y ago
There's a lot of truth in that, and the orthodox interpretation is indeed riddled with incoherence. But what fascinates me is that after so much effort, the quantum community seems to be further away than ever from coming to a consensus on interpreting the theory. Every proposed interpretation does away with some foundational issue, yet introduces another in the process.
- ikeboy 11y ago
  They may not have a consensus, but why do you think they're further away from consensus than they were in the past?
  - n4r9 11y ago
    If you mean "what has led you to think they're further away from consensus": mostly just gut feeling, as a (younger) member of that community. I've not seen any rigorous and comprehensive studies of which interpretations garner the most support, but it does seem like popularity is currently divided between the orthodox and several other interpretations that have evolved from "niche" to "significant minority" in recent years. If instead you mean "by what process are they further away from consensus": I would suggest that the recent surge of research in quantum information theory has stimulated a greater interest in foundational issues, which in turn has led to an invigoration of the interpretations debate.
    - gfodor 11y ago
      http://www.preposterousuniverse.com/blog/2013/01/17/the-most-embarrassing-graph-in-modern-physics/ http://www.preposterousuniverse.com/blog/2013/01/17/the-most... In short Copenhagen still (sadly) rules the day, followed by many worlds and QIT.
      - n4r9 11y ago
        I meant "rigorous and comprehensive" to include "representative of the entire quantum community". That poll was conducted at a single conference and had 33 participants. The bias inherent in this approach can be seen when the same poll was conducted at two other conferences: http://arxiv.org/abs/1303.2719 http://arxiv.org/abs/1303.2719 http://arxiv.org/abs/1306.4646 http://arxiv.org/abs/1306.4646 In both cases, de-Broglie Bohm interpretations ruled the day. As the abstract of the latter paper states: > ...the results do strongly suggest several interesting cultural facts -- for example, that there exist, within the broad field of "quantum foundations", sub-communities with quite different views, and that (relatedly) there is probably even significantly more controversy about several fundamental issues than the already-significant amount revealed in the earlier poll.
        gfodor 11y ago
        My bad, on a phone and recalled the link from a while back to share it.
        williamjennings 11y ago
        My opinion is that the Copenhagen interpretation does not contradict DeBroglie in terms of nuclear chemistry, but solely thermodynamics. The Copenhagen interpretation makes a leap of faith with the Born Rule as it is based on Maxwell-Boltzmann statistics. The work of t'Hooft is a more modern alternative for ensembles where the outcome is stochastic, rather than probabilistic. Photosynthesis has that property, as do many other enzymatic systems.
        n4r9 11y ago
        Not sure what you mean by "contradict". Certainly you won't easily find experiments for which the two offer different predictions. They are very different in terms of their ontology though: DeBroglie states that particles have definite positions and momenta at all times whereas Copenhagen does not.
        williamjennings 11y ago
- omalleyt 11y ago
  Pilot wave theory: the "weird effects" that QM displays are really just the result of space time being a thing that vibrates in a wave-like pattern influenced by mass. And the reason this is cool is because when you put everyday objects in situations like that stated above, they exhibit quantum interference and everything else.
  - n4r9 11y ago
    So this is essentially what is meant by the "deBroglie-Bohm" interpretation. There is an underlying definite configuration of all matter, but it is "guided" deterministically by the wavefunction psi. This avoids issues associated with wave function collapse, but by no means does it rid us of all the "weird effects". In particular, the pilot wave is explicitly non-local, in that for a Bell-type experiment the choice of measurement in one location will (instantaneously) affect the physical state of affairs in the other location.
TTPrograms 11y ago
Quantum mechanics is simply a set of equations that describe the universe. Whether or not those equations make sense or are interpretable is irrelevant, as our capability to understand intuitively is only based on the types of interactions we observe every day. To ask somebody what interpretation they prefer is akin to asking a mathematician how they interpret the reality of ZFC they prefer. It's interesting, but ultimately pointless, because it has more to do with our ability to interpret than with the real meaning of the statements. To that end, Copenhagen makes the important point - "Shut up and calculate".
- Florin_Andrei 11y ago
  > To that end, Copenhagen makes the important point - "Shut up and calculate". No, it doesn't. It adds a few assumptions on top of that. That's the point of the whole debate. To be fair, the many-worlds interpretation also does that.
  - TTPrograms 11y ago
    What testable assumptions does Copenhagen add to quantum mechanics? Are there other interpretations that don't add testable assumptions?
- omalleyt 11y ago
  That's how people used to view "imaginary" numbers...and the field of complex analysis laid dormant for 200 years. When a valid geometric interpretation was found that backed up the algebraic existence of these numbers, the field blossomed. We're humans, we can't understand equations without knowing what they "mean."
nmyk 11y ago
It's a shame when physics is presented as how reality works! Rather than what it is: our best model.
- AnimalMuppet 11y ago
  Physics is our best model? OK, I buy that. The Copenhagen interpretation? Not so much. It's an interpretation. The actual physics is in the equations. I can believe the equations without believing the Copenhagen interpretation, or any interpretation.
  - nmyk 11y ago
    Right. The various interpretations are not so much science as philosophy. At best, they're scientific hypotheses, and that's only if they turn out to be falsifiable.
- effie 11y ago
  Exactly. Many people seem to fall into trap of regarding established theories of theoretical physics as some ultimate truths about the world, instead of as currently used useful models which are necessarily imperfect simplifications of things. It is depressing to see science, which has contributed to exposition of fallacy of church teachings during the past centuries and help enlighten people, to be on its best way to becoming a church full of dogma and blind followers itself.

n4r9 11y ago

There's a lot of truth in that, and the orthodox interpretation is indeed riddled with incoherence. But what fascinates me is that after so much effort, the quantum community seems to be further away than ever from coming to a consensus on interpreting the theory. Every proposed interpretation does away with some foundational issue, yet introduces another in the process.

ikeboy 11y ago
They may not have a consensus, but why do you think they're further away from consensus than they were in the past?
- n4r9 11y ago
  If you mean "what has led you to think they're further away from consensus": mostly just gut feeling, as a (younger) member of that community. I've not seen any rigorous and comprehensive studies of which interpretations garner the most support, but it does seem like popularity is currently divided between the orthodox and several other interpretations that have evolved from "niche" to "significant minority" in recent years. If instead you mean "by what process are they further away from consensus": I would suggest that the recent surge of research in quantum information theory has stimulated a greater interest in foundational issues, which in turn has led to an invigoration of the interpretations debate.
  - gfodor 11y ago
    http://www.preposterousuniverse.com/blog/2013/01/17/the-most-embarrassing-graph-in-modern-physics/ http://www.preposterousuniverse.com/blog/2013/01/17/the-most... In short Copenhagen still (sadly) rules the day, followed by many worlds and QIT.
    - n4r9 11y ago
      I meant "rigorous and comprehensive" to include "representative of the entire quantum community". That poll was conducted at a single conference and had 33 participants. The bias inherent in this approach can be seen when the same poll was conducted at two other conferences: http://arxiv.org/abs/1303.2719 http://arxiv.org/abs/1303.2719 http://arxiv.org/abs/1306.4646 http://arxiv.org/abs/1306.4646 In both cases, de-Broglie Bohm interpretations ruled the day. As the abstract of the latter paper states: > ...the results do strongly suggest several interesting cultural facts -- for example, that there exist, within the broad field of "quantum foundations", sub-communities with quite different views, and that (relatedly) there is probably even significantly more controversy about several fundamental issues than the already-significant amount revealed in the earlier poll.
      - gfodor 11y ago
        My bad, on a phone and recalled the link from a while back to share it.
      - williamjennings 11y ago
        My opinion is that the Copenhagen interpretation does not contradict DeBroglie in terms of nuclear chemistry, but solely thermodynamics. The Copenhagen interpretation makes a leap of faith with the Born Rule as it is based on Maxwell-Boltzmann statistics. The work of t'Hooft is a more modern alternative for ensembles where the outcome is stochastic, rather than probabilistic. Photosynthesis has that property, as do many other enzymatic systems.
        n4r9 11y ago
        Not sure what you mean by "contradict". Certainly you won't easily find experiments for which the two offer different predictions. They are very different in terms of their ontology though: DeBroglie states that particles have definite positions and momenta at all times whereas Copenhagen does not.
        williamjennings 11y ago
omalleyt 11y ago
Pilot wave theory: the "weird effects" that QM displays are really just the result of space time being a thing that vibrates in a wave-like pattern influenced by mass. And the reason this is cool is because when you put everyday objects in situations like that stated above, they exhibit quantum interference and everything else.
- n4r9 11y ago
  So this is essentially what is meant by the "deBroglie-Bohm" interpretation. There is an underlying definite configuration of all matter, but it is "guided" deterministically by the wavefunction psi. This avoids issues associated with wave function collapse, but by no means does it rid us of all the "weird effects". In particular, the pilot wave is explicitly non-local, in that for a Bell-type experiment the choice of measurement in one location will (instantaneously) affect the physical state of affairs in the other location.

TTPrograms 11y ago

Quantum mechanics is simply a set of equations that describe the universe. Whether or not those equations make sense or are interpretable is irrelevant, as our capability to understand intuitively is only based on the types of interactions we observe every day. To ask somebody what interpretation they prefer is akin to asking a mathematician how they interpret the reality of ZFC they prefer. It's interesting, but ultimately pointless, because it has more to do with our ability to interpret than with the real meaning of the statements. To that end, Copenhagen makes the important point - "Shut up and calculate".

Florin_Andrei 11y ago
> To that end, Copenhagen makes the important point - "Shut up and calculate". No, it doesn't. It adds a few assumptions on top of that. That's the point of the whole debate. To be fair, the many-worlds interpretation also does that.
- TTPrograms 11y ago
  What testable assumptions does Copenhagen add to quantum mechanics? Are there other interpretations that don't add testable assumptions?
omalleyt 11y ago
That's how people used to view "imaginary" numbers...and the field of complex analysis laid dormant for 200 years. When a valid geometric interpretation was found that backed up the algebraic existence of these numbers, the field blossomed. We're humans, we can't understand equations without knowing what they "mean."

nmyk 11y ago

It's a shame when physics is presented as how reality works! Rather than what it is: our best model.

AnimalMuppet 11y ago
Physics is our best model? OK, I buy that. The Copenhagen interpretation? Not so much. It's an interpretation. The actual physics is in the equations. I can believe the equations without believing the Copenhagen interpretation, or any interpretation.
- nmyk 11y ago
  Right. The various interpretations are not so much science as philosophy. At best, they're scientific hypotheses, and that's only if they turn out to be falsifiable.
effie 11y ago
Exactly. Many people seem to fall into trap of regarding established theories of theoretical physics as some ultimate truths about the world, instead of as currently used useful models which are necessarily imperfect simplifications of things. It is depressing to see science, which has contributed to exposition of fallacy of church teachings during the past centuries and help enlighten people, to be on its best way to becoming a church full of dogma and blind followers itself.