Without getting into a long hurrang, I think that Tegmark is correct, at least 
in part. Briefly, there has to be a reason why these alternate worlds exist. 
I'm referring to the Everett-Wheeler hypothesis and not just wishful thinking. 
Granted, if I remember correctly, Tegmark does deal with the whole issue in 
terms of mathematical models, which I don't really care for, however, I can 
tolerate it. 

As for the issue of measurement, all possible worlds can be viewed as still 
existing, without measurement, in a superpositional state, until they are 
observed (or "measured"). So you still get a "plurality of worlds". 
My question is how does anyone know whether "law-like" worlds  vastly outnumber 
"lawful" ones?

If I have to, I can go look up Tegmark's Scientific American article on it all, 
to get a refresher on it. I'm just hoping I don't have to.

I met Tegmark about a year ago or so. Nice guy. I stumbled into his office, 
since the door was open, and introduced myself, mentioning that I was also an 
"Everett man". "Everett-man?" he replied puzzled. "Yeah, you know - Hugh 
Everett, Everett/Wheeler hypothesis?" at which point he excitedly jumped out of 
his seat and shook my hand, laughing.

----- Original Message ----- 
From: "Patrick Leahy" 
To: EverythingList 
Subject: White Rabbit vs. Tegmark 
Date: Mon, 23 May 2005 00:03:55 +0100 (BST) 

> I looked into this mailing list because I thought I'd come up with 
> a fairly cogent objection to Max Tegmark's version of the 
> "everything" thesis, i.e. that there is no distinction between 
> physical and mathematical reality... our multiverse is one 
> particular solution to a set of differential equations, not 
> privileged in any way over other solutions to the same equations, 
> solutions to other equations, and indeed any other mathemetical 
> construct whatsoever (e.g. outputs of UTMs). 
> Sure enough, you came up with my objection years ago, in the form 
> of the "White Rabbit" paradox. Since usage is a bit vague, I'll 
> briefly re-state it here. The problem is that worlds which are 
> "law-like", that is which behave roughly as if there are physical 
> laws but not exactly, seem to vastly outnumber worlds which are 
> strictly "lawful". Hence we would expect to see numerous departures 
> from laws of nature of a non-life-threating kind. 
> This is a different objection to the prediction of a complete 
> failure of induction... it's true that stochastic universes with no 
> laws at all (or where laws abruptly cease to function) should be 
> vastly more common still, but they are not observed due to 
> anthropic selection. 
> A very similar argument ("rubbish universes") was put forward long 
> ago against David Lewis's modal realism, and is discussed in his 
> "On the plurality of worlds". As I understand it, Lewis's defence 
> was that there is no "measure" in his concept of "possible worlds", 
> so it is not meaningful to make statements about which kinds of 
> universe are "more likely" (given that there is an infinity of both 
> lawful and law-like worlds). This is not a defense which Tegmark 
> can make, since he does require a measure (to give his thesis some 
> anthropic content). 
> It seems to me that discussion on this list back in 1999 more or 
> less concluded that this was a fatal objection to Tegmark's version 
> of the thesis, although not to some alternatives based exclusively 
> on UTM programs (e.g. Russell Standish's Occam's Razor paper). 
> Is this a fair summary, or is anyone here prepared to defend Tegmark's 
> thesis? 
> Paddy Leahy 
> ====================================================== 
> Dr J. P. Leahy, University of Manchester, 
> Jodrell Bank Observatory, School of Physics & Astronomy, 
> Macclesfield, Cheshire SK11 9DL, UK 
> Tel - +44 1477 572636, Fax - +44 1477 571618 

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