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From: Bruno Marchal <marchal.domain.name.hidden>

Date: Thu, 22 Apr 2004 16:15:42 +0200

At 05:27 21/04/04 -0400, Kory Heath wrote:

*>Bruno Marchal wrote a 10-point argument about determining whether or not
*

*>we are simulated by some massive computer. Here is point 9 from that post:
*

*>
*

*>>9) Now, from computer science and logic, startlingly enough perhaps,
*

*>>we can isolate a measure on the 1-person comp histories, and this
*

*>>give us the laws of physics (this is too technical to be put here, and
*

*>>actually I have derived only the logical structure of the probability
*

*>>one, but I got something non trivial and very close to a quantum logic
*

*>>(which can be seen as the logic of the quantum probability one, as
*

*>>von Neumann has shown).
*

*>
*

*>Bruno, I agree with everything in points 1-7 of the post I'm referring to.
*

Cool.

(Kory is referring to my post

http://www.escribe.com/science/theory/m5384.html )

*>I think I understand the main thrust of points 8 and 10, but they both
*

*>depend on the truth of the quoted point 9.
*

Not at all. The point 8 follows only from the points 1-7. Actually the points

1 to 8 sum up the main result of my thesis, that is the reversal

physics/machine's psychology (once we assume comp).

This made the point 9 just a mathematical confirmation.

I will try to explain, but actually it is me who does not understand why

you don't see that the point 8 follows from the point 1-7.

The proof really stop at 8.

9 is a mathematical confirmation with

observer modelized (or even identify) with "equivalence class" of

states of sound universal Turing machines.

*>I find this point [9] highly dubious, and I'm interested to hear more
*

*>about why you believe it (or whether I'm actually interpreting it correctly).
*

OK. I promise I will try to make it clear, but that will be possible

only if you realize that 8 follows from 1-7. Keeping we assume comp all

through.

I will first continue to comment your post, as a sort of preparation.

*>Is it your contention that if we start only with the idea of Platonia
*

*>(which contains all possible computational structures and "events"), and
*

*>we analyze the structure of all possible 1st-person histories weaving
*

*>their way through this Platonia, we would see that a majority of them find
*

*>themselves in universes like the one we currently inhabit, with stars,
*

*>galaxies, relativity, quantum physics, etc.?
*

No. Such a contention is not mine. What you say here

does not follow from neither 1-8, nor 9.

Only the laws of physics follows, but the existence of the moon

or of galaxies are not necessarily "laws of physics", but are

quite possibly "geographical laws" (like being in Moscow

instead of Washington). Now the stability of

the appearance of matter is related to the laws of physics,

and so, if (to talk like you) we analyze the structure of all

possible 1st-person histories going trough your actual

Kory-Heath state (including your memory of stars and

galaxies) then the measure of your computational

continuations in Platonia without stars and galaxies

will (or should) be negligible. The disappearance of galaxies

could be seen as a "talking white rabbit" event.

So, only worlds with entities very similar to Kory Heath

should contains galaxies. If this was false (in Platonia)

then comp would be false (and refutable).

*>I find that extremely hard to believe; there are an infinite number of
*

*>multi-dimensional cellular-automata worlds that contain nothing like
*

*>stars, galaxies, or the familiar physics we know,
*

But then they don't contain entities sufficiently

close to Kory Heath, (they don't go through Kory-Heath comp

states) and those world/stories don't belong to your

actual first person indeterminacy domain.

*>and I don't see any reason to believe that all the 1st-person histories
*

*>weaving their way through these computational structures (which surely
*

*>exist in Platonia) have less measure than those that weave through the
*

*>structures more resembling our own universe.
*

You are right. No doubt there are worlds without stars

and galaxies, but having srats and gilixas instead, and

some Burno arguing to some Kyro about the geographical

nature of those objects. Nothing in 1-8 prevents this.

*>I find it much easier to believe - in fact, it seems almost necessarily
*

*>true - that, when we analyze the structure of all the 1st-person histories
*

*>weaving their way through Platonia, we see that virtually all observers
*

*>observe indeterminacy. This in itself seems like a non-trivial finding. It
*

*>would be even more non-trivial if one could analyze the structure of the
*

*>indeterminacy that virtually all 1st-person observers must observe, and
*

*>find that it is very much like "quantum logic". This seems to be one of
*

*>your claims, and it certainly seems possible (though I don't know enough
*

*>yet to judge the issue for myself). However, it's a much further leap to
*

*>conclude that we can go on to derive "the laws of physics" from the
*

*>analysis of 1st-person histories weaving their way through Platonia. In
*

*>the quote above, you acknowledge that you haven't actually done this -
*

*>"actually I have derived only the logical structure of the probability
*

*>one, but I got something non trivial and very close to a quantum logic" -
*

*>but you seem to believe that it can be done. Why?
*

All right, you miss something. As I said, I feel *I* miss

something because it seems to me that the point 8 follows

directly from 1-7. (I suggest people print the post

http://www.escribe.com/science/theory/m5384.html

for having the 1-9 points in front of the eyes). Point 10

is not necessary because it concerns the particular

question by Brett Hall. First let me copy the point 8,

and let me rewrite it more carefully (if not less

diplomatically!).

Point 8: (original version from post 5384)

8) So, if we are being simulated by a massive computer somewhere

in a real universe, then to make any first person verifiable prediction

we must take into account all the possible computations going through

our actual state. So "the laws of physics", which we can temporarily

define as the laws of whatever we can predict consistently, should

be given by a measure on those 1-person computational histories.

Point 8bis: (Attempt toward a clearer ameliorated version. I have

also make some emphases):

8bis) So, if we are being simulated by a massive computer

somewhere in a real universe, then to make ANY first person

verifiable prediction, we must take as domain of 1-person

indeterminacy all the possible maximal consistent computational

computations GOING THROUGH, AND FROM, OUR ACTUAL STATE,

and existing in Platonia (more precisely in UD*, which is the complete

infinite execution of the Universal Dovetailer).

Let us (re)defined the laws of physics as the laws we can

always predict and verify consistently (if any!).

Now, having accepted the 1-7 points, the occurrence of such

laws must have a measure 1, so the laws of physics must be

derivable from what has measure 1 relatively to the measure

on the computational histories. OK?

Let me illustrate a simple experiment in physics. Let us

decide to let a chalk fallen. And let us compare some theories.

A) The naive common sense theory: As far as I remember

chalk always falls on the ground, so I infer that this will

happen again.

B) The first physicist: giving the laws F=ma, and Newton's

gravitation law, I can predict with reasonable accuracy

that the chalk will fall on the ground about here and about

that time.

C) The second physicist: the chalk is a many body

quantum object in interaction with many bodies, so let us

apply some gravitationnal form of Feynman summation on

all quantum computational histories. After some phase

randomization I can predict the chalk will fall here and at

some time with more than 60 correct decimals.

(He has been quick! I guess he used a quantum pocket

calculator!)

D) The computationalist: first let me bet on a comp level

of substitution (which exists *hopefully*), and let me bet

on my actual comp states, that is the one which describes

my brain/body state in front of the chalk which I will let

fallen. Now giving 1-7 (through comp) I "know" that

my future first person experience is giving by a sum (average)

on all computations (existing in Platonia) going from and

through that state, and RELATIVE to that state.

Obviously to compute that you need to run the complete

UD in finite time and that's impossible, also you would be

unable to recognize your own comp histories when described

at other levels, so the computationalist will probably just

answer "uncomputable".

But "platonistically" it remains that if comp is true

the actual physical invariant must emerge as an average

on ALL the maximal consistent extensions relative to our

actual states (worlds, observer-moments, whatever ...).

Although that can be proved useless for actually predicting the

behavior of the chalk, it is enough for deriving physics.

And that derivation goes in the reverse sense, that is, the

more easy part will be the abstract logical structures, but

that is enough for giving the geometry of the multiple histories.

Well I must go now, and if I hurry myself to much I will

begin to be unclear ;-) Tell me if you have understand that

keeping faith in comp through 1-7 leads necessarily to 8.

Don't hesitate to give me an objection.

The only difficulty in "8", I think, is to remember that

we *assume* comp.

Then all what is needed for 9 (the mathematical confirmation)

is to accept to "modelize" or

better "identify" a platonistic observer by a sound modest

(lobian) universal church-turing-post-markov-fortran-lisp-

java-whatever machine (including quantum one).

And to interview it about those relative consistent

extensions and its inferable platonistic geometries

and what is stable in their discourses. That has been

made possible by the discovery of incompleteness

(Godel 31) and its "axiomatizability" (Solovay 76).

Bruno

http://iridia.ulb.ac.be/~marchal/

Received on Thu Apr 22 2004 - 10:24:44 PDT

Date: Thu, 22 Apr 2004 16:15:42 +0200

At 05:27 21/04/04 -0400, Kory Heath wrote:

Cool.

(Kory is referring to my post

http://www.escribe.com/science/theory/m5384.html )

Not at all. The point 8 follows only from the points 1-7. Actually the points

1 to 8 sum up the main result of my thesis, that is the reversal

physics/machine's psychology (once we assume comp).

This made the point 9 just a mathematical confirmation.

I will try to explain, but actually it is me who does not understand why

you don't see that the point 8 follows from the point 1-7.

The proof really stop at 8.

9 is a mathematical confirmation with

observer modelized (or even identify) with "equivalence class" of

states of sound universal Turing machines.

OK. I promise I will try to make it clear, but that will be possible

only if you realize that 8 follows from 1-7. Keeping we assume comp all

through.

I will first continue to comment your post, as a sort of preparation.

No. Such a contention is not mine. What you say here

does not follow from neither 1-8, nor 9.

Only the laws of physics follows, but the existence of the moon

or of galaxies are not necessarily "laws of physics", but are

quite possibly "geographical laws" (like being in Moscow

instead of Washington). Now the stability of

the appearance of matter is related to the laws of physics,

and so, if (to talk like you) we analyze the structure of all

possible 1st-person histories going trough your actual

Kory-Heath state (including your memory of stars and

galaxies) then the measure of your computational

continuations in Platonia without stars and galaxies

will (or should) be negligible. The disappearance of galaxies

could be seen as a "talking white rabbit" event.

So, only worlds with entities very similar to Kory Heath

should contains galaxies. If this was false (in Platonia)

then comp would be false (and refutable).

But then they don't contain entities sufficiently

close to Kory Heath, (they don't go through Kory-Heath comp

states) and those world/stories don't belong to your

actual first person indeterminacy domain.

You are right. No doubt there are worlds without stars

and galaxies, but having srats and gilixas instead, and

some Burno arguing to some Kyro about the geographical

nature of those objects. Nothing in 1-8 prevents this.

All right, you miss something. As I said, I feel *I* miss

something because it seems to me that the point 8 follows

directly from 1-7. (I suggest people print the post

http://www.escribe.com/science/theory/m5384.html

for having the 1-9 points in front of the eyes). Point 10

is not necessary because it concerns the particular

question by Brett Hall. First let me copy the point 8,

and let me rewrite it more carefully (if not less

diplomatically!).

Point 8: (original version from post 5384)

8) So, if we are being simulated by a massive computer somewhere

in a real universe, then to make any first person verifiable prediction

we must take into account all the possible computations going through

our actual state. So "the laws of physics", which we can temporarily

define as the laws of whatever we can predict consistently, should

be given by a measure on those 1-person computational histories.

Point 8bis: (Attempt toward a clearer ameliorated version. I have

also make some emphases):

8bis) So, if we are being simulated by a massive computer

somewhere in a real universe, then to make ANY first person

verifiable prediction, we must take as domain of 1-person

indeterminacy all the possible maximal consistent computational

computations GOING THROUGH, AND FROM, OUR ACTUAL STATE,

and existing in Platonia (more precisely in UD*, which is the complete

infinite execution of the Universal Dovetailer).

Let us (re)defined the laws of physics as the laws we can

always predict and verify consistently (if any!).

Now, having accepted the 1-7 points, the occurrence of such

laws must have a measure 1, so the laws of physics must be

derivable from what has measure 1 relatively to the measure

on the computational histories. OK?

Let me illustrate a simple experiment in physics. Let us

decide to let a chalk fallen. And let us compare some theories.

A) The naive common sense theory: As far as I remember

chalk always falls on the ground, so I infer that this will

happen again.

B) The first physicist: giving the laws F=ma, and Newton's

gravitation law, I can predict with reasonable accuracy

that the chalk will fall on the ground about here and about

that time.

C) The second physicist: the chalk is a many body

quantum object in interaction with many bodies, so let us

apply some gravitationnal form of Feynman summation on

all quantum computational histories. After some phase

randomization I can predict the chalk will fall here and at

some time with more than 60 correct decimals.

(He has been quick! I guess he used a quantum pocket

calculator!)

D) The computationalist: first let me bet on a comp level

of substitution (which exists *hopefully*), and let me bet

on my actual comp states, that is the one which describes

my brain/body state in front of the chalk which I will let

fallen. Now giving 1-7 (through comp) I "know" that

my future first person experience is giving by a sum (average)

on all computations (existing in Platonia) going from and

through that state, and RELATIVE to that state.

Obviously to compute that you need to run the complete

UD in finite time and that's impossible, also you would be

unable to recognize your own comp histories when described

at other levels, so the computationalist will probably just

answer "uncomputable".

But "platonistically" it remains that if comp is true

the actual physical invariant must emerge as an average

on ALL the maximal consistent extensions relative to our

actual states (worlds, observer-moments, whatever ...).

Although that can be proved useless for actually predicting the

behavior of the chalk, it is enough for deriving physics.

And that derivation goes in the reverse sense, that is, the

more easy part will be the abstract logical structures, but

that is enough for giving the geometry of the multiple histories.

Well I must go now, and if I hurry myself to much I will

begin to be unclear ;-) Tell me if you have understand that

keeping faith in comp through 1-7 leads necessarily to 8.

Don't hesitate to give me an objection.

The only difficulty in "8", I think, is to remember that

we *assume* comp.

Then all what is needed for 9 (the mathematical confirmation)

is to accept to "modelize" or

better "identify" a platonistic observer by a sound modest

(lobian) universal church-turing-post-markov-fortran-lisp-

java-whatever machine (including quantum one).

And to interview it about those relative consistent

extensions and its inferable platonistic geometries

and what is stable in their discourses. That has been

made possible by the discovery of incompleteness

(Godel 31) and its "axiomatizability" (Solovay 76).

Bruno

http://iridia.ulb.ac.be/~marchal/

Received on Thu Apr 22 2004 - 10:24:44 PDT

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