Re: How does this probability thing work in MWI?

From: Christopher Maloney <>
Date: Mon, 15 Nov 1999 21:45:06 -0500

Fritz Griffith wrote:
> So if MWI is just a mathematical interpretation of QM, then why, in every
> article I read about MWI, does it say that every world is equally real?
> Could they all be wrong? Also, if every world is not equally real, then
> wouldn't you basically have the Copenhagen view of QM?

This is a good point, I think. Perhaps "equally real" is misleading.
If the measure of two histories is unequal, perhaps one should say
that they are unequally real -- one is more real than another.
Actually, this is reminiscent of a discussion I had with Jacques
Mallah a while back about zombies. I don't believe that such a
thing as a zombie exists (something that looks and behaves like a
conscious human, but is not conscious) but I do believe that it is
probably valid to talk about some people as having a greater measure
than others -- that is, that some people are more real than others.

There's a significant difference, I think, between saying that
something is "less real" and saying that something is "not real".
Certainly, to those people of low measure, they themselves *feel*
themselves to be just as real as anyone else. But the measure
question comes up from a third person perspective (or "bird"
perspective, or "Archimedes" perspective): how likely is it that
a self-aware observer will find him/herself to be that person?

So, to make a long story short, I think confusion can arise from
the use of the word "real", whether one means it to be a boolean
on/off state, or something that can be measured by a continuum. If
one is using it as a boolean, then one would say that alternative
histories of MWI are all equally real, meaning that they all are
real, just as ours are. But they are not all equally probable.

> >From: Christopher Maloney <>
> >
> >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
> >
> >
> >

Chris Maloney
"Donuts are so sweet and tasty."
-- Homer Simpson
Received on Mon Nov 15 1999 - 18:58:36 PST

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