Why does the Copenhagen interpretation of QM assert that random events occur if such a claim cannot ever be proven or disproven?

A related question:

How to tell if QM is really random?

Edit On second thought it could certainly be disproven. It couldn't, to my understanding, be shown that randomness as Copenhagen asserts is provable in any sense of statistical significance. Is this true? If it is, why does Copenhagen assert randomness instead of asserting that no non-disprovable deterministic rules are known?

Edit 2: I've created a proper place for arguing about what an interpretation is:

What is an interpretation of quantum mechanics?

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    $\begingroup$ As the wording says, it is an interpretation, not a proof, it what those guys thought the most likely to be the "ultimate truth" behind the equations. $\endgroup$ – Wolphram jonny Nov 9 '14 at 3:21
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    $\begingroup$ I think most physicists do not actually give too much thought to this and do not adhere to a particular interpretation, but rather to the "shut up and calculate" doctrine (see mtnmath.com/faq/meas-qm-6.html) $\endgroup$ – Wolphram jonny Nov 9 '14 at 4:03
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    $\begingroup$ No, the question is why assert anything? $\endgroup$ – Praxeolitic Nov 9 '14 at 4:28
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    $\begingroup$ You might as well have asked why MWI asserts (untestable) multiple worlds, or why Bohmian mechanics asserts (untestable) pilot waves, or why ... Every interpretation of QM has some aspect of metaphysics (i.e., untestable assumptions) to it, at least so far. $\endgroup$ – David Hammen Nov 9 '14 at 5:00
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    $\begingroup$ I do also find those strange but I don't think they are mainstream. Even if all interpretations of QM are untestable the question still stands. Why make untestable claims? $\endgroup$ – Praxeolitic Nov 9 '14 at 5:52

We do experiments and come up with distributions of the variables that can be measured.

There exists a very deterministic theory, Quantum Mechanics, that predicts accurately probability distributions for our measurements and the theory is continuously validated.

Probabilities exist in the classical physics regime and mean exactly the same thing as the probabilities measured and fitted with quantum mechanical solutions.

Assuming randomness is on the lines of KISS (keep it simple stupid). If there were not all these people trying to find a classical framework underneath the quantum mechanical probabilities there would be no need for the assertion of randomness, it would be self evident, as it is for the throws of dice.

So it is the theories that assert the existence of deterministic underlayers for quantum mechanics that, by contrast, force an "assertion" of randomness. If quantum mechanical probabilities could be shown to be biased (the way a dice can be biased by cleverly weighting it) then new standard models and theories would be developed. At the moment as far as I know deterministic underlayer theories have problems with Lorenz invariance, which is another well validated theory of particle physics.

  • $\begingroup$ It makes a ton of sense that this is the real motivation but could you cite a source? $\endgroup$ – Praxeolitic Nov 9 '14 at 5:54
  • $\begingroup$ It is my opinion of course, formed by experience and reading. Have a look at this blog entry on the copenhagen interpretation motls.blogspot.gr/2011/05/… , which is much broader than your question. $\endgroup$ – anna v Nov 9 '14 at 6:24
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    $\begingroup$ " If there were not all these people ...". Yes, people can be a nuisance. That's why one has to conduct all these costly and time-consumming experiments to prove things everybody should just accept. $\endgroup$ – bright magus Nov 9 '14 at 8:57
  • $\begingroup$ "... as far as I know deterministic underlayer theories have problems with Lorenz invariance, which is another well validated theory of particle physics". How about Lorentz "variations" (violations) and the following spontaneous symmetry breaking concept? $\endgroup$ – bright magus Nov 9 '14 at 11:25
  • $\begingroup$ as have commented elsewhere, an interpretation is part of (physical) theory, for the very simple reason that the interpretation is that thing that tells when and where the theory applies. $\endgroup$ – Nikos M. Nov 11 '14 at 18:17

I must contradict anna v and acouriousmind.

Firstly, I agree: The physical everyday work is determined by experiments and calculation and not by interpretation.

But we sent out physicists to come back with results. Certainly they shall calculate, apply rigor, but do not forget the reason why you are working! The KISS-(keep-it-simple-stupid)-argumentation confesses incapacity and seems to be an attempt to dispense physics from its initial task.

Knowledge is not only the physical experiment and the physical calculation but also their corresponding interpretation. If you would remove interpretation (and in particular: Copenhagen interpretation) there would be left a gap. Interpretation is not only needed for the public but also for other physicists which are working on other topics. A gravitation specialist needs an idea about quantum nonlocality, even if he is not following the same physical concept.

Copenhagen, many worlds, hidden variables and guide wave are more than simple speculation. Each of them is one view of one aspect of quantum nonlocality, and they are probably complementary, each of them including one part of the truth, which we are not able to find by experiments. They have been developed by the most competent physicists, and they have been maintained for many decenniums. To say with a handwave that they are not part of physics seems to be rather shortsighted. Without these interpretations no substantial knowledge about nonlocality would be left.

In short: Sometimes we can say "B follows from A". But sometimes our knowledge is only: "B seems to follow from A" or even, in the worst case "One possible explanation of A might be B". These are no empty phrases. They are part of physical knowledge.

  • $\begingroup$ This doesn't answer the question. $\endgroup$ – Praxeolitic Nov 9 '14 at 19:22
  • $\begingroup$ I do like the content of this though. Check my "Edit 2" for a better home for these sorts of answers. $\endgroup$ – Praxeolitic Nov 9 '14 at 19:42

[Disclaimer: this is a personal view. It is not necessarily reflective of what physicists at large think, nor is it accepted canon]

Interpretations are what happens when people forget what science is all about. With all that we know, with all that we have found out to predict the world, we tend to assign reality to concepts like operators or wavefunctions. But at the end of the day, all that matters is predicting what is observed. And none of the interpretations of QM differ about that. They muse endlessly about what is real and what may be derived, but there is no empirical way to distinguish between a world with non-local hidden variables and a world that is random, but local. And Bell's theorem tells us that there is no deterministic theory that could ever reproduce quantum behaviour from locality and determinism.

In that spirit

"Shut up and calculate"

is really what it is all about. Science is empty if it doesn't produce testable results. And if two approaches generate the same results, they are equivalent. Quibbling over which may be right or wrong misses the whole point. There is no need to interpret anything. All these interpretations, be they Copenhagen, or Many Worlds, or Bohmian, commit the same, basic mistake: They ascribe reality to things which are not measurable, they want to explain where there is really nothing left to explain. There is nothing more than predicting all the outcomes of all measurements. And that is where all these interpretations falter, and give in.

All "interpretations" of QM must necessarily predict the same outcomes for experiments. Otherwise, they would have been shown to be false. But as they do not make different predictions, it is moot to discuss them. They are the same.

Intuition is a not a good master once you begin to seriously deal with phyiscs. Rigor is.

  • $\begingroup$ i upvoted byt i disagree with almost every other word on your post. Still it is acceptable as answer. A small comment, shust up and calculate does not need quantum mechanics nor classical mechanics nor relativity nor higgs nor anything, just setup a statistical model, get the data, fit them and get any other parameters with an error range. This is literaly shut up and calculate. Surely you will disagree with this. $\endgroup$ – Nikos M. Nov 11 '14 at 18:14
  • $\begingroup$ Plus let me state Newtonian mechanics is rigorous, yet they dont account for special relativity nor quantum mechanics. Plus they are also beatiful (as a mathematical theory, hamiltinians, symplectic manifodls, symmetries), still they dont account for special relativity nor quantum mechanics. How did Einstein develop special relativity (and general relativity)? Did he use a symmetry of newtonian mechanics or just strong physical intuition (which then became formal)? $\endgroup$ – Nikos M. Nov 11 '14 at 18:27
  • $\begingroup$ @NikosM.: One could also think in classical mechanics of Hamiltonian, Lagrangian and Newtonian mechanics as three "interpretations" of the same thing. And, oddly enough, people there just shut up and apply whatever they like best to any problem without asking themselves which of these is more "real". People do not elevate them to untestable statements about reality. $\endgroup$ – ACuriousMind Nov 11 '14 at 19:59
  • $\begingroup$ i will not turn this into a chat, but i'll add another comment. Surely you must disagre with what you stated in previous comment. Exactly because 2 (mathematical) theories can both be rigorous and beautiful, yet one agrees with experiment (and can predict also), while the other not, is certainly not a definiton of untestable. As i siad in other comment and answer, an interpretation of a theory is that simple thing which says wehn and where the theory is to be applied (or in other words, what qualifies as a concrete model of the theory) $\endgroup$ – Nikos M. Nov 11 '14 at 22:12

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