Re: How does this probability thing work in MWI?

From: Christopher Maloney <>
Date: Sat, 13 Nov 1999 21:52:49 -0500

In this and your previous post, I think you are confusing the MWI with
a *theory*. The MWI is not a theory, it is an *Interpretation* of the
theory of Quantum Mechanics. QM defines the math and therefore the
measure which is manifested by the MWI.

On the other hand, your questions about measure certainly do apply to
the theory discussed on this list, the All-Universes Hypothesis (AUH).
With the AUH, we need to justify the measure of the alternative worlds,
in order to make predictions for observations. The AUH is not
equivalent to the MWI. It is a sort of super-many-worlds idea, but it
doesn't presuppose quantum mechanics, as MWI does. In fact, ideally
we would be able to derive QM from the AUH. In fact, Russell Standish
purports to have done that in his just pre-released paper, at

Fritz Griffith wrote:
> I have read the Everett FAQ
> (, and I think it's
> one of the most comprehensive descriptions of MWI I have found on the
> internet. I have one question though - in question 24: "Does many-worlds
> allow free-will?", it says, "If both sides of a choice are selected in
> different worlds why bother to spend time weighing the evidence before
> selecting? The answer is that whilst all decisions are realised, some are
> realised more often than others - or to put to more precisely each branch of
> a decision has its own weighting or measure which enforces the usual laws of
> quantum statistics.". My question is, where does this weighting come from?
> Do some branches occur more often than others? Or is there just some sort
> of assumed probability as to which world will be yours?
> Fritz Griffith
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Chris Maloney
"Donuts are so sweet and tasty."
-- Homer Simpson
Received on Sat Nov 13 1999 - 19:10:09 PST

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