Thursday, 27 September 2007

Many worlds for sure!

This from NS about new successes of the Many Worlds Interpretation of QM (my emphasis) :

“The trick is to examine a quantum experiment while excluding probability theory and accepting the many-worlds interpretation.

The multiverse has a branching structure, created as the universe splits into parallel versions of itself. The thickness of the branches can be calculated solely using deterministic equations, getting around the uncertainties usually associated with quantum physics. What the Oxford gang found is that the branching structure exactly reproduces the peculiar probabilities predicted by the Born rule. The branching also gives the illusion of probabilistic outcomes to measurements.”

…which ties in nicely with what Stephen Wolfram (founder of Mathematica and general physics/maths/computing guru!) has been saying for some time and talks about in a recent article:

“The alien feeling doesn't stop there. Another thing that seems alien is the idea that our whole universe and its complete history could be generated just by starting with some particular small network, then applying definite rules.

For the past 75+ years, quantum mechanics has been the pride of physics, and it seems to suggest that this kind of deterministic thinking just can't be correct.

It's a slightly long story (often still misunderstood by physicists), but between the arbitrariness of updating orders that produce a given causal network, and the fact that in a network one doesn't just have something like local 3D space, it looks as if one automatically starts to get a lot of the core phenomena of quantum mechanics--even from what's in effect a deterministic underlying model.”

Basically Wolfram’s ‘hobby’ is hunting for the right axiom + inference rules pair (to use words from “I am a strange loop” where Hofstadter’s talking about symbolic logic and other foundations of mathmatics. More about that book at a later date!) to generate our exact universe (or set of parallel universes) for scratch!

Wolfram’s “A New Kind of Science” (that’s been sitting very heavily on my bookshelf for a couple of years now) is devoted to the study of the behaviour of very simple rules applied to simple starting conditions. This field Is basically the generation and analysis of computational chaos.

Look into John Conway’s “Game of Life” if you’re unfamiliar with it: a beautiful example of emergence from simple rules. It’s analogous to our universe in that it’s a microcosm the kind of starting point and rules Wolfram’s searching for.

This stuff might all seem obtuse, but I think it’s amazingly, fundamentally important (to everything literally). And just as Chaos was (arguably) the 3rd major revolution in Physics of the 20th century (and by that I mean the 3rd most important sea change at all; as we all know Physics underpins all the physical sciences, which in turn found society) so the integration of the computational universe with our understanding of our everyday surroundings will be a massive modification to fundamental thinking in the coming era...

[A New Kind of Science appears to be fully available online in a less likely to break your desk than the 1200 page hardback version! Honestly, it’s worth just dipping into it randomly! Here: ]

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