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From: Gilles HENRI <Gilles.Henri.domain.name.hidden>

Date: Mon, 22 Mar 1999 12:01:11 +0100

In MWI you could perhaps view one grid as one

*>universe, and imagine that each locus is mapped to another in a grid above
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*>it, which is what we would (from our subjective viewpoint) call one
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*>Planck-time later. In fact, in MWI, each locus is mapped to an arbitrary
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*>number of locuses one Planck-time away from it, so one grid maps on to
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*>infinitely many grids just one step (Planck time) away.
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*>
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*>If you choose to see a certain set of relationships as representing a time
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*>axis, and others as being space, you can view the whole from the outside in
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*>such a way that you can see ass sorts of weird and wonderful things, like
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*>you or I. This is similar, as Tegmark has pointed out, to zooming in on a
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*>fractal picture and saying 'wow! look what's in there!'
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James, that's exactly the point I try to make precise.

You say "you choose...", "you can...". It implies some gauge freedom in

your representations, just like you can choose different electromagnetic

potentials for the same physical fields. But they must correspond to the

the same reality, i.e. producing the same observable consequences

(electromagnetic fields), independantly of the chosen gauge. All what is

physically measurable and observer independant must correspond to invariant

quantities. This requirement is so strong that in fact the physical content

of a theory lies in these invariance groups.

However a numerical representation of a complex reality (like describing

the universe with a string (or grid...) of 0 and 1) possess no invariant

upon the choice of the representation (or at least I cannot figure one!),

except may be the property of computability. It doesn't content any

information about topology, space-time splitting, curvature, and so on....

all things you could hope to reproduce in a theory of the Universe!! Nor is

there any invariant relationship properties between two "maps".

So I can't see how one can hope to describe the world with such a

representation.

Gilles

Received on Mon Mar 22 1999 - 03:14:15 PST

Date: Mon, 22 Mar 1999 12:01:11 +0100

In MWI you could perhaps view one grid as one

James, that's exactly the point I try to make precise.

You say "you choose...", "you can...". It implies some gauge freedom in

your representations, just like you can choose different electromagnetic

potentials for the same physical fields. But they must correspond to the

the same reality, i.e. producing the same observable consequences

(electromagnetic fields), independantly of the chosen gauge. All what is

physically measurable and observer independant must correspond to invariant

quantities. This requirement is so strong that in fact the physical content

of a theory lies in these invariance groups.

However a numerical representation of a complex reality (like describing

the universe with a string (or grid...) of 0 and 1) possess no invariant

upon the choice of the representation (or at least I cannot figure one!),

except may be the property of computability. It doesn't content any

information about topology, space-time splitting, curvature, and so on....

all things you could hope to reproduce in a theory of the Universe!! Nor is

there any invariant relationship properties between two "maps".

So I can't see how one can hope to describe the world with such a

representation.

Gilles

Received on Mon Mar 22 1999 - 03:14:15 PST

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