Wednesday, October 10, 2012

Copenhagen more coherent than many-worlds

Cosmologist Sean M. Carroll writes:
For a long time, quantum mechanics could be treated as a black box. You had an atomic nucleus sitting their quietly, not really deviating from your classical intuition, and then some quantum magic would occur, and now you have several decay products flying away. The remoteness of the quantum effects themselves is what has enabled physicists to get away for so long using quantum mechanics without really understanding it. (Thereby enabling such monstrosities as the “Copenhagen interpretation” of quantum mechanics, and its unholy offspring “shut up and calculate.”) ...

The objection to Copenhagen is just that it’s completely incoherent. It imagines a distinct “classical” realm, doesn’t tell you what’s in that realm and what’s truly quantum, doesn’t explain when wave functions collapse, etc. The Born Rule isn’t “explained” at all — it’s just postulated. And the Uncertainty Principle is exactly the same in MWI as it is in Copenhagen, so I’m not sure what the distinction is there.

MWI has its own issues, certainly, as do all other known versions of QM. But at least it’s well-defined, whereas Copenhagen is kind of a joke.
No, the Copenhagen interpretation is not a joke. It is a lot more coherent than the Many-worlds interpretation (MWI).

Copenhagen does not postulate the Born rule, but at least it explains the probabilities. The MWI does not explain probabilities at all, and has no experimental evidence for it.

The core of the problem is that Niels Bohr was a positivist while Carroll subscribes to this view:
The basic scientific assumption is that there is exists a complete and coherent description of how the world works. ... Given what we know about the universe, there seems to be no reason to invoke God as part of this description.
This view lead Carroll to believe in zillions of unobesrvable alternate universes and all sorts of other bizarre hypotheses, but he refuses to accept a scientific explanation that he regards as incomplete.

There is no reason to accept MWI.

A recent essay asks, Has Science Established that the Cosmos is Physically Comprehensible? The answer is no.

Science is all about testing hypotheses, and not leaping to unverifiable conclusions just because you pursue a more complete and coherent description of how the world works. I say Carroll has a very wrong idea of science. That is why he subscribes to string theory and other nonsense.


  1. I like the "shut up and calculate" approach.

  2. I believe Richard P. Feynman is the source of the quote... problem is, calculating something is completely different than comprehending or understanding what you are calculating. As with computers, garbage in- garbage out no matter how accurate your calculations. Feynman didn't really want to understand the mechanical underpinnings of physics, and openly discouraged people from trying to do so, just as Heisenberg and Bohr did. I am reminded of the Great and Powerful Oz telling Dorothy, "Pay no attention to the man behind the curtain..." it's just the same old logical fallacy, 'the appeal to authority' dressed up in complicated maths to scare away the curious or skeptical. Sad truth is, science and physics has been losing logical coherence for quite some time, Bertrand Russell in 1930 said " The desire to make an intelligible system out of it [the world] is an outcome of fear, in fact a kind of agoraphobia or fear of open places.", which is in effect an admission of defeat and an abandonment of reason and understanding. To do any actual science of any kind, you must first assume the universe is intelligible, otherwise, if the universe is unintelligible science and reason are not possible or meaningful, and you shouldn't call yourself any kind of scientist.
    If Sean Caroll truly subscribes to MWI, then he is a hypocrite, as he seems to enjoy bashing the existence of a God or any kind of faith, yet subscribes to a theory that admits that everything exists in some other infinite number of alternate universes... just not this one.
    It's Funny how people who seem to want to believe in an infinite number of universes they can't observe, look down their noses at people in THIS universe who believe in things they can't observe.

  3. The quote "Shut up and calculate" is due to David Mermin, even tho it is often attributed to Faynman or Dirac.

    I agree that Carroll's theological skeptidism is hard to reconcile with his belief in MWI.

  4. I used to be opposed to the "shut up and calculate" approach. Then I saw the light when I realized that it is easy to invent stuff to make anything make sense if one is imaginative enough, even if it's wrong. So it's better to concentrate only on what we know is right and just "shut up and calculate".

  5. That's right. Stick to what we know is right, and label everything else speculation. MWI is wild speculation.