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From: Russell Standish <R.Standish.domain.name.hidden>

Date: Wed, 23 Jan 2002 14:04:57 +1100 (EST)

H J Ruhl wrote:

*>
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*> At 1/23/02, you wrote:
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*> >H J Ruhl wrote:
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*> > >
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*> > > I have the following question regarding Juergen's paper:
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*> > >
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*> > > In the very first sentence of the abstract it is assumed that universes
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*> > > have histories. If by this it is meant that a particular universe has a
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*> > > particular unique identifiable history does this not mean that that
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*> > > universe is computable?
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*> >
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*> >
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*> >Why should it? It seems a universe's history is the only property a
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*> >universe can have, ie universes are histories.
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*>
*

*> I do not see that at all. Why does it need a history? All it needs is the
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*> capability of finding a next state.
*

It doesn't need the capacity to find the next state. If it has that

capacity, then the history is computable. It is a poor assumption to

assume that the universe is deterministic (history computable from

initial state).

Histories are any description unfolding with time, whatever that

happens to be. Time appears to be necessary for consiousness..

*>
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*>
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*> >There are plenty of
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*> >noncomputable descriptions that can serve as histories - for example
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*> >the binary expansion of Chaitin's Omega.
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*>
*

*>
*

*>
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*> That was not my point. The initial state of a universe is not computable -
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*> it just was. The point is the method of association of any history with a
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*> particular universe.
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*>
*

My point is that any history just is. However, those that are

computable from a simple initial state are dense in a large subset of

such histories (subset proportional to 2^{-C}, where C is the

complexity of the initial state), so we should expect a random sample

to select a history that is approximately a computable outcome from a

simple initial state.

*> As to your example how would you parse it into segments each describing a
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*> state of the universe? The universe may be doing so and thus computing
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*> Omega and not know it. This as I understand it is possible for non halting
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*> computers since no selection to compute Omega was made.
*

Good point - perhaps Omega is a bad example. It is possible that an

algorithm exists for computing the binary expansion of Omega, its just

that you can never prove that it does. However, there are uncountably

infinite number of binary strings for which no algorithm

exists. Choose any one of these.

*>
*

*> Hal
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*>
*

----------------------------------------------------------------------------

Dr. Russell Standish Director

High Performance Computing Support Unit, Phone 9385 6967, 8308 3119 (mobile)

UNSW SYDNEY 2052 Fax 9385 6965, 0425 253119 (")

Australia R.Standish.domain.name.hidden

Room 2075, Red Centre http://parallel.hpc.unsw.edu.au/rks

International prefix +612, Interstate prefix 02

----------------------------------------------------------------------------

Received on Tue Jan 22 2002 - 19:16:19 PST

Date: Wed, 23 Jan 2002 14:04:57 +1100 (EST)

H J Ruhl wrote:

It doesn't need the capacity to find the next state. If it has that

capacity, then the history is computable. It is a poor assumption to

assume that the universe is deterministic (history computable from

initial state).

Histories are any description unfolding with time, whatever that

happens to be. Time appears to be necessary for consiousness..

My point is that any history just is. However, those that are

computable from a simple initial state are dense in a large subset of

such histories (subset proportional to 2^{-C}, where C is the

complexity of the initial state), so we should expect a random sample

to select a history that is approximately a computable outcome from a

simple initial state.

Good point - perhaps Omega is a bad example. It is possible that an

algorithm exists for computing the binary expansion of Omega, its just

that you can never prove that it does. However, there are uncountably

infinite number of binary strings for which no algorithm

exists. Choose any one of these.

----------------------------------------------------------------------------

Dr. Russell Standish Director

High Performance Computing Support Unit, Phone 9385 6967, 8308 3119 (mobile)

UNSW SYDNEY 2052 Fax 9385 6965, 0425 253119 (")

Australia R.Standish.domain.name.hidden

Room 2075, Red Centre http://parallel.hpc.unsw.edu.au/rks

International prefix +612, Interstate prefix 02

----------------------------------------------------------------------------

Received on Tue Jan 22 2002 - 19:16:19 PST

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