Re: How does this probability thing work in MWI?

From: Juergen Schmidhuber <>
Date: Mon, 22 Nov 1999 10:03:44 +0100

>So what about the continuations corresponding to the longer algorithms?
>Those worlds still exist, don't they? If so, then for every shorter
>algorithm, there are continuations of longer algorithms, which were
>identical up to that point, but which now represent worlds which don't
>follow the laws of QM, but in which people neverthless still live in. You
>can say that the universal prior determines that I will probably follow a
>short algorithm, but what can you possibly say about all those people in all
>those worlds who didn't follow the shortest algorithm? Unless there are
>less worlds like theirs than like ours, I just can't see how you can dismiss
>their worlds as less probable.

Continuations corresponding to longer algorithms also get computed, of
course. But they are less probable indeed. According to the universal
prior the probability of an algorithm is the probability of successively
guessing each of its bits. The longer the algorithm, the smaller its

I believe this simple and in hindsight obvious line of reasoning
was absent in previous MWI discussions. The UTM theory of everything
provides a novel explanation that seems more convincing than the
traditional hand-waving.

Received on Mon Nov 22 1999 - 01:13:30 PST

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