Does God play dice with the universe?

[jack]

It only recently occurred to me that people who objected to the non-deterministic nature of quantum mechanics were *right* if you think many-worlds interpretation is correct.

It's like, since Newton, physicists had a tacit assumption:

#1. The laws of physics are deterministic.

But then we discovered lots of evidence for QM that we couldn't ignore, and many people adopted a different assumption:

#2. The evidence for QM

And these seemed contradictory, so people who had #1 were (rightly) suspicious of #2, but people who accepted #2 felt they had no choice but to reject #1.

But was also assuming without even realising:

#3: there is only one universe, not a giant number of parallel universes

And it turns out that if you drop #3, you can keep #1 and #2.

Now, I don't think that's sufficient reason by itself to assume MWI. There are lots of other paradoxes that disappear (if QM works the way we think it does, though many physicists still think that is premature). But it's interesting that we might have to drop #1 one day, but not yet.

And I knew all that _in theory_, but I'd not actually stopped to think about Einstein's "god plays dice" quip since I learned slightly more about MWI.

Comments

[gerald_duck]

Are you aware of the concept of quantum immortality? I find it intriguing. Probably even more so than Schrodinger's Cat.

Whereas Schrodinger attempted to provide an obviously absurd interpretation of quantum physics and was (as I understand it) surprised people accepted it at face value, it's much harder to accept any theory that implies quantum immortality.

Personally, on an unreasoned, emotive level, my instinct is that sooner or later people will start modelling QM as chaotic rather than fundamentally unknowable. That would square #1 with #2 in a more satisfactory way than MWI.

[jack]

my instinct is that sooner or later people will start modelling QM as chaotic rather than fundamentally unknowable. That would square #1 with #2 in a more satisfactory way than MWI.

Hm. I agree that whenever anything looks random, "it's actually a chaotic system based on deterministic rules" is almost always the right guess.

But from a point of view of QM, that sounds exactly like the reasoning which led people to http://en.wikipedia.org/wiki/Hidden_variable_theory. That is, "if it LOOKS random, it may be determined by something we can't see". And this is one possible source for those "things we can't see".

But I understood that http://en.wikipedia.org/wiki/Bell's_theorem#Importance_of_the_theorem said that you couldn't have hidden variables of any sort set up in advance that explain the apparent "action at a distance" of QM. That's either:

* explained by both possibilities happening in different "worlds" (ie. waveform evolves into multiple non-interacting parts which all evolve normally)
* or the hidden information travels faster than light (which is an assumption we really think we're wrong to drop),
* or we ignore the physical reality and resort to the copenhagen interpretation
* or there's some resolution to the apparent contradiction we haven't thought of, by dropping some further assumption we've not considered...?

If that dichotomy is true, MWI seems by far the best get-out, since the problem is "surely that can't possibly be true, it's too ridiculous" which has previously shown to be a bad guide to physical reality, and everything else has worse problems. But have I misinterpreted the problems of hidden variable theory? Or do they not apply to a chaotic system for some reason I don't understand?

[jack]

Are you aware of the concept of quantum immortality? I find it intriguing.

I've read about it, but don't have any good answers. My instinct is that the problem comes in our understanding of "how to translate physical reality to the subjective experience of being a conscious brain in that reality" not in our understanding of the underlying physical reality, but I'm not sure.

Eg. I think I've seen similar thought experiments that could happen in a purely classical world, which if true says this is a philosophical problem we need to understand, but QM just makes more common, isn't conceptually related to. But I'm not sure.