What is the least inflationary or most everyday common sense interpretation of QM? Given that it's philosophy and not physics, the questions seems a good one.

Cited here, there are three alternative propositions that can be denied

1.A The wave-function of a system is complete , i.e. the wave-function specifies (directly or indirectly) all of the physical properties of a system. 1. B The wave-function always evolves in accord with a linear dynamical equation (e.g. the Schrödinger equation). 1. C Measurements of, e.g., the spin of an electron always (or at least usually) have determinate outcomes, i.e., at the end of the measurement the measuring device is either in a state which indicates spin up (and not down) or spin down (and not up).

Madulin, The Essence of Space-Time, p7

Many world interpretations give up 1C. Here, Schrödinger’s cat is not both dead and alive because these two events are kept separate by doceherence.

In other words, when the box is opened, the observer and the possibly-dead cat split into an observer looking at a box with a dead cat, and an observer looking at a box with a live cat. But since the dead and alive states are decoherent...

In the Copenhagen interpretation of 1B

According to Schrödinger, the Copenhagen interpretation implies that the cat remains both alive and dead until the state is observed. Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics

Rejecting 1A occurs in hidden variable interpretations, but seems to give philosophy too strong a hand.

Which interpretation of QM which allows most for common sense? In particular, has it been demonstrated that it's only in the (extra-ordinary) many world interpretations that

the equations of physics that model the time evolution of systems without embedded observers are sufficient for modelling systems which do contain observers; in particular there is no observation-triggered wave function collapse which the Copenhagen interpretation proposes.

If so, can we limit the branching that, in the MW interpretation, occurs upon observation, into something unreal?

  • Is there any chance you could spell out a little further what exactly you'd like a (brief) explanation about?
    – Joseph Weissman
    Commented Sep 12, 2016 at 22:31
  • are you joking? did you read what i wrote, i repeat the same explicit and sensible question like three times. i even say why i think it's sensible !
    – user6917
    Commented Sep 12, 2016 at 23:21
  • "Shut up and calculate." Commented Sep 12, 2016 at 23:30
  • 2
    Although "shut up and calculate" was originally directed at Copenhagen it fits the statistical interpretation much better. No wave function, no collapse, no dead and alive cats, no worlds. In fact, no ontology at all. Events occur with certain probabilities, they exhibit correlations, quantum mechanics describes how to calculate both. Shut up and calculate! en.wikipedia.org/wiki/Ensemble_interpretation
    – Conifold
    Commented Sep 13, 2016 at 0:08
  • Try reading people.virginia.edu/~ecd3m/1110/Fall2014/…
    – user19423
    Commented Sep 13, 2016 at 4:10

2 Answers 2


This question presumes not only the existence of common sense, but that two individual's common sense about a very peculiar topic might somehow coincide.

As Einstein categorized it, there were four major aspects of a QM interpretation:

  • Realism - Can we predict the future state of a particle without measuring it?
  • Completeness - Does it account for every particle?
  • Local realism - Is the behavior of a particle fully defined by its neighborhood, or is there "spooky action at a distance."
  • Determinism - Is the exact time evolution of a universe fully specified by its current state, or is there randomness involved.

As it turns out, you can't have all of these. Bell's Inequalities prevent it. Each interpretation sacrifices one of these.

The Copenhagen interpretation sacrifices determinism, introducing the concept of a wave-function collapse. It's currently the most popular.

Many Worlds sacrifices realism. After an "event" where the different histories split, you have no predictive power over the other side.

deBroglie-Bohem sacrifices local realism, by permitting non-local variables

The list goes on and on. However, not one of them is 'common sense.' This should be obvious, if you think about it. The behaviors measured in quantum mechanics are anything but intuitive; it's no surprise there is no common sense solution.

Personally, I find the Ensemble theory to be most intuitive. In the ensemble theories, there is no transition from "classical physics" to "quantum mechanics." Instead, classical physics is treated as a limiting case when you have lots and lots of unknowns which are interacting with your system. This is quite intuitive, but comes with a dark price: it implies that everything you learned in classical physics is wrong. There is no transition from QM to classical physics; there are merely regions where we got away with assuming classical physics because it was "close enough." However, for many this is highly unintuitive because their entire worldview is based on the assumptions that are not valid in ensemble theory.

  • thanks for the reply, tho i was talking about less specifialist common sense than "sacrificing realism" in that sense
    – user6917
    Commented Sep 13, 2016 at 1:34
  • 2
    Each of those approaches has its own non-common-sense sides, because QM does not fit well with what we traditionally call "common sense." In fact, it has a horrible tendency of defying common sense every chance it gets. The "Delayed Choice Quantum Eraser" is my favorite, for its apparent violation of causality itself.
    – Cort Ammon
    Commented Sep 13, 2016 at 3:54

Common sense is just what a particular person happen to think is obvious or sensible or something like that. Some common sense may be right, some may be wrong. Different people think different ideas are common sense. So we can't use common sense as an authority to sort out what we should think. There is also no other source of knowledge or criterion that can be used as an authority. A theory should be judged by taking it seriously as an explanation and working out whether it is consistent, whether it solves problems and that sort of thing. You should adapt your common sense to the explanation you judge is correct rather than expecting the world to conform to your preferences for a laws of physics.

By the explanation based standard the competition is not even close. the only interpretation that is any good as an explanation is the MWI. See 'The Fabric of Reality' by David Deutsch, chapter 2.

If so, can we limit the branching that, in the MW interpretation, occurs upon observation, into something unreal?

No. The only existing explanation of the EPR experiment requires that systems carrying information about the results of the experiments, such as the measuring instrument, wires transmitting the results and so on are described by Heisenberg picture observables. Those observables describe objects existing in multiple versions, see



The same is true for other experiments such as single particle interference experiments, as illustrated by the so-called delayed choice experiment.

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