Douglas_Knight comments on Bloggingheads: Yudkowsky and Aaronson talk about AI and Many-worlds - Less Wrong

18 Post author: Vladimir_Nesov 16 August 2009 04:06PM

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Comment author: shirisaya 17 August 2009 08:16:25PM 1 point [-]

On the issue of many-world, I must just be slow because I can't see how it is "obviously" correct. It certainly seems both self consistent and consistent with observation, but I don't see how this in particular puts it so far ahead of other ways of understanding QM as to be the default view. If anyone knows of a really good summary for somebody who's actually studied physics on why MWI is so great (and sadly, Eliezer's posts here and on overcomingbias don't do it for me) I would greatly appreciate the pointer.

In particular, two things that I have a hard time wrapping my head around are: -If multiple worlds really are "splitting" from our own how is this accomplished without serious violations of mass and energy conservation. (I'm sure somebody has treated this somewhere since it's so basic, but I've never seen it.) -Even assuming everything else is fine, the actual mechanism for which world diverge has to be spelled out. (Maybe it is somewhere, if so please help me end my ignorance.)

I'll admit that I haven't actually spent a great deal of time considering the issue, but I've never come across answers to basic questions of this sort.

Comment author: Douglas_Knight 18 August 2009 04:18:54AM 3 points [-]

if multiple worlds really are "splitting"

What if instead of talking about "many worlds" we just said "no collapse"? If there's just this state and it evolves according to Schroedinger's equation. Then then of course there's conservation of energy.

Comment author: shirisaya 18 August 2009 02:34:05PM 0 points [-]

Sure, I'm certainly not saying that the Copenhagen interpretation is correct, and my understanding is that a decoherence view is both more useful and simpler. MWI (at least as I understand it) is a significantly stronger claim. When we take the probabilities that come from wave state amplitudes as observed frequencies among actually existing "worlds" then we are claiming that there are many different versions of me that actually exist. It's this last part that I find a bit of a stretch.

Comment author: Douglas_Knight 18 August 2009 06:13:40PM 3 points [-]

If many different versions of you existing bothers you, does Schroedinger's cat bother you?

The extent to which MWI is a stronger claim than "no collapse," it's purely interpretative. It certainly doesn't posit any "splitting" beyond vanilla QM. Questions about conservation of energy suggest that you don't get this.