Monday, May 22, 2023

Many-worlds is not an Interpretation

Scott Aaronson, a quantum mechanics (QM) and quantum computer (QC) expert, writes:
There’s no such thing as a “many worlds theorem.” Many worlds is an interpretation. There’s a genuine case for it but the case is philosophical, and remains argued about by people who understand everything there is to know about the subject. ...

No, many-worlders and non-many-worlders make exactly the same predictions for what QCs will and won’t be able to do. That’s why many worlds is an “interpretation,” rather than a competing empirical theory!

I challenged him on this, and he replied:
I’m aware of all of this. The hardcore many-worlders think that non-many-worlders have a nonsense theory from which one shouldn’t be able to make predictions at all, and the hardcore Copenhagenists, QBists, etc. think exactly the same of many-worlders. Nevertheless, they do make the same predictions, regardless of whether they should! 🙂

At least, they do to whatever extent they accept the empirical recipe of QM. People who deny the empirical recipe are (I’d say) neither many-worlders nor Copenhagenists nor QBists nor etc., but believers in a rival physical theory (whether or not they have clear ideas about what the rival theory is).

And as for the QC skeptics who accept QM, but believe some yet-to-be-discovered principle “censors” or “screens off” scalable QC? I’d hope that even they could still make the same conditional predictions: “yes, if it weren’t for our yet-to-be-discovered principle, then this is how a QC would operate, and this is the class of problems it could solve in polynomial time.”

: The I no longer agree with calling many-worlds an "interpretation". It would be if they accepted the empirical recipe of QM, but they don't.

The empirical recipe gives unique outcomes to experiments, but the many-worlders deny that. David Deutsch is a many-worlder, and he says a QC would prove the parallel universes.

I guess I am the skeptic who accepts QM, but believes some yet-to-be-discovered principle “censors” or “screens off” scalable QC. Scott has become a many-worlder, so he would probably also say I must believe in some yet-to-be-discovered principle that collapses the wave function.

This is not exactly my view. I am a positivist, and do not believe in yet-to-be-discovered principles. I accept what Scott calls "the empirical recipe of QM". How could I not? It works amazingly well.

I am skeptical about scalable QC.

I am also skeptical about intelligent life on other planets. Not because I believe in a yet-to-be-discovered principle. It just seems unlikely to me.

Scott's main point is to attack Kaku's new book on quantum supremacy, which I also attacked on May 6.

1 comment:

  1. You know, Roger,

    There must be a certain time limit (within error bars, of course, I mean, with a PDF) for which, if you let a black cat with a white nose rest his/her/its/their paws on your head, then, things still *are* oaakaay.

    But once that time limit is exceeded (either by the strong-ness of the cat's ``deterministic free will'' or by the weak-ness of the head-possessor's ``deterministic free will''), then, ...

    ...then, all the bets are off.... Then, it's all becomes the Many Paws on the Many Heads...

    [BTW, this may come as shocking to many, but *I* never had much respect for that Deutsch guy. ... Despite his being at Oxford/Cambridge or so.

    ... But then, the Brits are a different people. They even elect Mrs. Sudha Murthy's Daughter's Husband as their Prime Minister. And, Indians (say the Indian Army Brats) in California (say, the SF Bay Area) not only *become* delighted at finally having had success in leaving India behind and making money in the aforementioned Areas, they also derive much *delights* out of the aforementioned fact.

    If you ask me, I would offer a suggestion:

    These Indians in the California, esp. the SF Bay Area (and their American whatevers) should start considering the water as fully equivalent to soil. Then one could repeat, you know:

    Go *West*, *Young* (Indian) (Wo)men!...