### Re: Interested in thoughts on this excerpt from Martin Rees

```

Le 13-août-06, à 12:57, Stathis Papaioannou a écrit :

Bruno Marchal writes:

I know it looks counterintuitive, but an AI can know which computer
is
running and how many they are. It is a consequence of comp, and the
UDA
the computer which is running are the relative universal number
which
exist in arithmetical platonia (arithmetical truth is already a
universal video game, if you want, and it is the simplest). How many
are they? 2^aleph_zero.
I have already explain it here:
http://www.mail-archive.com/everything-list@eskimo.com/msg05272.html

It is a key point and we can come back on it if you have some
difficulties.

Well now I'm confused! I thought the whole point of the earlier part
of the UDA
as discussed in the cited post (and many others of yours) is that you
*can't*
know the details of your implementation, such as what type of
computer
you are
being run on, how fast it is running, if there are arbitrary delays
in
the program,
and so on. Are you now saying that if I am being run on the 3rd of
100
PC's in
the basement of the local university computer science department, but
everyone
is keeping this a secret from me, there is a way I can figure out
what's going on
all by myself?!

Did you read my old post to Brett Hall:
http://www.mail-archive.com/everything-list@eskimo.com/msg05272.html
Perhaps you could comment it and tell me what does not convince you.
It
is indeed correct that the earlier parts of the UD Argument show that
a
nature
of a computer which would support the machine's computation until ...
you realize that for exactly those reasons the machine first person
expectations can only be computed (exactly and in principle) through a
measure on all possible computations (reducing physics to searching
such a measure). But then the first person can no more be associated
with *any* particular computations. Read the Brett Hall post where I
explain more, again in a steppy fashion (but the point is different
from the UDA).
To sum up that point:
1) comp shows we cannot know which computations supported us.
2) digging deeper in comp, this means eventually we are supported by
*all* (relative) computations (relative to some actual state; the
actuality itself is handled in the traditional indexical way, and
eventually indexicality is treated through the logic of
self-reference (G and G*).

I did read the cited post. I can see that given step 7 - from the
inside, we
cannot tell if we are in a physical world emulation or a Platonia
emulation -
we could say that we are emulated by all appropriate computations.

OK. Even in a sort of simultaneous way. In a *probabilistic* sense we
are in all those appropriate computations. Like I said to Peter, even
if we are in a material universe (if that means something), then one
instant later we are not (with probability 1 minus epsilon).

[I think
it is still logically possible that we are emulated at any instant by
one
computation in the ensemble, and that there might still be a separate
physical world, at this point at least.]

Yes. It is logically possible. But arithmetically or probabilistically
quasi-improbable.

I can see that step 8 is right:
if we are simulated in a massive real world computer, to make a
prediction
about the future we must take into account all the computations passing
through our present state and define a measure on them.

All right, but then you should see that physics (let us see it as a
science of concrete and exact prediction) is already given by a purely
mathematical measure on a mathematical set (the set of computations
going through my actual comp state).

I will accept step
9 on your authority, although this seems amazing: we can derive the
laws of
physics from a measure on first person computational histories.

I guess you mean that you don't see how to make the extraction. UDA
just shows that IF comp is true, then physics has to be derivable from
computer science/number theory.
To see how we can do the extraction is another matter. I do it by
asking UDA, no more to *you*, but to an universal machine.

Now, step 10
is my problem: if the laws of physics as per step 9 turn out to match
our
experimentally verifiable reality, then we are no more simulated by
the physical
computer than by any of the non-physical ones in Platonia.

Why does it mean that we are no more simulated by the physical computer
than one of the non-physical ones if the laws of physics match the
prediction
from the assumption that we are being simulated? Surely all that it
suggests is
that we are indeed being simulated - somewhere.

I was using the weak form of OCCAM.  With comp we must always take into
account all simulations.

You also state in step 10 that ...to say we belong to the massive
computer has
no real meaning: if it stops, ```

### RE: Interested in thoughts on this excerpt from Martin Rees

```
Russell Standish writes:

Precisely my point!

On Tue, Aug 08, 2006 at 08:42:04AM -0700, 1Z wrote:

Stathis Papaioannou wrote:

By increasing the measure locally in our universe, are you making no
difference, or only a
small amount of difference to the measure overall in Platonia?

You can't make a difference in Platonia. There is no time there,
no change, and no causality.

It's like making a difference in a material, deterministic world, which we
assume has time, change
and causality aplenty.

Stathis Papaioannou
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### RE: Interested in thoughts on this excerpt from Martin Rees

```
Russell Standish writes:

Precisely my point!

On Tue, Aug 08, 2006 at 08:42:04AM -0700, 1Z wrote:

Stathis Papaioannou wrote:

By increasing the measure locally in our universe, are you making no
difference, or only a
small amount of difference to the measure overall in Platonia?

You can't make a difference in Platonia. There is no time there,
no change, and no causality.

It's like making a difference in a material, deterministic world, which we
assume has time, change
and causality aplenty.

Stathis Papaioannou
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### RE: Interested in thoughts on this excerpt from Martin Rees

```

Bruno Marchal writes:

I know it looks counterintuitive, but an AI can know which computer is
running and how many they are. It is a consequence of comp, and the
UDA
the computer which is running are the relative universal number which
exist in arithmetical platonia (arithmetical truth is already a
universal video game, if you want, and it is the simplest). How many
are they? 2^aleph_zero.
I have already explain it here:
http://www.mail-archive.com/everything-list@eskimo.com/msg05272.html

It is a key point and we can come back on it if you have some
difficulties.

Well now I'm confused! I thought the whole point of the earlier part
of the UDA
as discussed in the cited post (and many others of yours) is that you
*can't*
know the details of your implementation, such as what type of computer
you are
being run on, how fast it is running, if there are arbitrary delays in
the program,
and so on. Are you now saying that if I am being run on the 3rd of 100
PC's in
the basement of the local university computer science department, but
everyone
is keeping this a secret from me, there is a way I can figure out
what's going on
all by myself?!

Did you read my old post to Brett Hall:
http://www.mail-archive.com/everything-list@eskimo.com/msg05272.html
Perhaps you could comment it and tell me what does not convince you. It
is indeed correct that the earlier parts of the UD Argument show that a
of a computer which would support the machine's computation until ...
you realize that for exactly those reasons the machine first person
expectations can only be computed (exactly and in principle) through a
measure on all possible computations (reducing physics to searching
such a measure). But then the first person can no more be associated
with *any* particular computations. Read the Brett Hall post where I
explain more, again in a steppy fashion (but the point is different
from the UDA).
To sum up that point:
1) comp shows we cannot know which computations supported us.
2) digging deeper in comp, this means eventually we are supported by
*all* (relative) computations (relative to some actual state; the
actuality itself is handled in the traditional indexical way, and
eventually indexicality is treated through the logic of
self-reference (G and G*).

I did read the cited post. I can see that given step 7 - from the inside, we
cannot tell if we are in a physical world emulation or a Platonia emulation -
we could say that we are emulated by all appropriate computations. [I think
it is still logically possible that we are emulated at any instant by one
computation in the ensemble, and that there might still be a separate
physical world, at this point at least.]  I can see that step 8 is right:
if we are simulated in a massive real world computer, to make a prediction
about the future we must take into account all the computations passing
through our present state and define a measure on them. I will accept step
9 on your authority, although this seems amazing: we can derive the laws of
physics from a measure on first person computational histories. Now, step 10
is my problem: if the laws of physics as per step 9 turn out to match our
experimentally verifiable reality, then we are no more simulated by the
physical
computer than by any of the non-physical ones in Platonia.

Why does it mean that we are no more simulated by the physical computer
than one of the non-physical ones if the laws of physics match the prediction
from the assumption that we are being simulated? Surely all that it suggests is
that we are indeed being simulated - somewhere.

You also state in step 10 that ...to say we belong to the massive computer has
no real meaning: if it stops, nothing can happen to us for example That
is
true, but it does not mean that we are not actually being simulated in a
particular computer, just that we cannot *know* which computer it is unless
we have external knowledge. But in any case, this is just what I was saying
before: you can't know which computer you are being simulated on. Are you
disagreeing with this statement because you believe you *can* narrow it down
to knowing that you are not being simulated on a physical computer?

Stathis Papaioannou
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### RE: Interested in thoughts on this excerpt from Martin Rees

```
Bruno Marchal writes (quoting SP):

...a controlled
experiment in which measure can be turned up and down leaving
everything else
the same, such as having an AI running on several computers in
perfect
lockstep.

I think that the idea that a lower measure OM will appear more complex
is a consequence of Komogorov like ASSA theories (a-la Hal Finney,
Mallah, etc.). OK?

I understand the basic principle, but I have trouble getting my mind
around
the idea of defining a measure when every possible computation exists.

I am not sure I understand. All real number exist, for example, and it
is the reason why we can put a measure on it. All computations exist
(this is equivalent with arithmetical realism) yet some are or at least
could be relatively more frequent than others.

Sure, but it's the details that are mind-boggling. Why do dog-computations
bark and cat-computations meow? If there is a definite mathematical answer
how do we even begin to fathom it? Or would you go the reductionist route
of starting with basic physical laws, on which chemistry, biology, psychology
etc. are built, the more basic sciences supporting the less basic?

I agree from some 1 pov. But 1 plural pov here would lead to some
Bell
inequalities violation. That is: sharable experiments which shows
indirectly the presence of some alternate computations.

I don't understand this statement. I am suggesting that the computers
are
running exactly the same program - same circuitry, same software, same
initial conditions, all on a classical scale. I don't see that there
is any way
for the AI to know which computer he was running on (if that question
is
even meaningful) or how many computers were running.

I know it looks counterintuitive, but an AI can know which computer is
running and how many they are. It is a consequence of comp, and the UDA
the computer which is running are the relative universal number which
exist in arithmetical platonia (arithmetical truth is already a
universal video game, if you want, and it is the simplest). How many
are they? 2^aleph_zero.
I have already explain it here:
http://www.mail-archive.com/everything-list@eskimo.com/msg05272.html

It is a key point and we can come back on it if you have some
difficulties.

Well now I'm confused! I thought the whole point of the earlier part of the UDA
as discussed in the cited post (and many others of yours) is that you *can't*
know the details of your implementation, such as what type of computer you are
being run on, how fast it is running, if there are arbitrary delays in the
program,
and so on. Are you now saying that if I am being run on the 3rd of 100 PC's in
the basement of the local university computer science department, but everyone
is keeping this a secret from me, there is a way I can figure out what's going
on
all by myself?!

If I
were the AI the only advantage I can think of in having multiple
computers running
is for backup in case some of them broke down; beyond that, I
wouldn't
care if there
were one copy or a million copies of me running in parallel.

Except, as I said above, for the relative probabilities. But this is
equivalent with accepting a well done back-up will not change your
normal measure.

Yes, I think what you mean by relative probabilities is that if
there were
several possible versions of me next moment, then I would be more
likely
to experience the one with higher measure. It is only relative to the
other
possibilities that measure makes a subjective difference.

Ah but you get the point now!

So, as long as this *relative* measure does not come into play, the absolute
measure makes no difference?

Stathis Papaioannou
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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Le 10-août-06, à 14:16, Stathis Papaioannou wrote :

Bruno: I am not sure I understand. All real number exist, for
example, and it
is the reason why we can put a measure on it. All computations exist
(this is equivalent with arithmetical realism) yet some are or at
least
could be relatively more frequent than others.

Stathis: Sure, but it's the details that are mind-boggling. Why do
dog-computations
bark and cat-computations meow? If there is a definite mathematical
how do we even begin to fathom it?

I think there is a definite (but necessarily partial)  mathematical
answer once we assume the comp hyp. It seems to me that the UD argument
explains informally what shape this mathematical answer could have: a
measure problem. Now I am not sure I understand why you don't see it.
This is because I can infer by most of your posts that you handle well
the relevant thought experiments. You certainly convince me I should
the lobian interview.

Or would you go the reductionist route
of starting with basic physical laws, on which chemistry, biology,
psychology
etc. are built, the more basic sciences supporting the less basic?

Except that the UDA is supposed to help to understand that the
basic-ness of science could be the other way round: psychology/theology
being more fundamental than physics. I hope I will be clear on that.
I have put a first version of the roadmap in the trash, because it
was too long and at the same time it was not even addressing some
difficulties which I am guessing many people have through your post. It
is hard because I try to write a short text, and simultaneously I try
to anticipate the sort of objections I find reasonable through my
reading of the current many posts on the notion of persons.

I know it looks counterintuitive, but an AI can know which computer is
running and how many they are. It is a consequence of comp, and the
UDA
the computer which is running are the relative universal number which
exist in arithmetical platonia (arithmetical truth is already a
universal video game, if you want, and it is the simplest). How many
are they? 2^aleph_zero.
I have already explain it here:
http://www.mail-archive.com/everything-list@eskimo.com/msg05272.html

It is a key point and we can come back on it if you have some
difficulties.

Well now I'm confused! I thought the whole point of the earlier part
of the UDA
as discussed in the cited post (and many others of yours) is that you
*can't*
know the details of your implementation, such as what type of computer
you are
being run on, how fast it is running, if there are arbitrary delays in
the program,
and so on. Are you now saying that if I am being run on the 3rd of 100
PC's in
the basement of the local university computer science department, but
everyone
is keeping this a secret from me, there is a way I can figure out
what's going on
all by myself?!

Did you read my old post to Brett Hall:
http://www.mail-archive.com/everything-list@eskimo.com/msg05272.html
Perhaps you could comment it and tell me what does not convince you. It
is indeed correct that the earlier parts of the UD Argument show that a
of a computer which would support the machine's computation until ...
you realize that for exactly those reasons the machine first person
expectations can only be computed (exactly and in principle) through a
measure on all possible computations (reducing physics to searching
such a measure). But then the first person can no more be associated
with *any* particular computations. Read the Brett Hall post where I
explain more, again in a steppy fashion (but the point is different
from the UDA).
To sum up that point:
1) comp shows we cannot know which computations supported us.
2) digging deeper in comp, this means eventually we are supported by
*all* (relative) computations (relative to some actual state; the
actuality itself is handled in the traditional indexical way, and
eventually indexicality is treated through the logic of
self-reference (G and G*).

Yes, I think what you mean by relative probabilities is that if
there were
several possible versions of me next moment, then I would be more
likely
to experience the one with higher measure. It is only relative to the
other
possibilities that measure makes a subjective difference.

Ah but you get the point now!

So, as long as this *relative* measure does not come into play, the
absolute
measure makes no difference?

But physics arise (or should arise, with the comp hyp.) from the
*relative* measure, and physics will be what makes possible for
consciousness to be able to manifest itself. George asked me to explain
this like if I was talking to some grandmother, but it is tricky to do
that. The reason is ```

### Re: Interested in thoughts on this excerpt from Martin Rees

```

Le 08-août-06, à 15:54, W. C. a écrit :

From: Bruno Marchal

...
find it
somehow ambiguous.
Let me comment anyway.
Human classical teleportation, although possible in principle, will
not be
possible in our life time (except  for those who will succeed in some
lucky
cryogenisation process). Artificial brain will first be developed with
graft of genetically engineered animals neurons, through progress in
harnessing the immune system and prion diseases (that will take
time). Only
latter will come purely artificial digital brain, and even this
will be a
matter of piece by piece progress (artificial hypocampus, artificial
limbic
system,  until artificial cortex (this one will take perhaps a
millenium), and pionner of immortality will have hard time for many
technical but also social and ethical reasons.

Thanks for your patience. I can see that you are really very patient
because
questions that you may have replied hundreds of times before.
Although I appreciate your patience, I still don't agree with you
teleportation.
When we say teleportation, we mean we send someone from location A to
location B *like a magic* (Start Trek stuff).
The person at A is *exactly* the same as the one at B. This really has
little to do with digital or artificial stuff.
Human body and brain are analog, same for A  B. It's useless to use
digital
or artificial conversion (since I assume no substitution level).

But then there is really no problem between us. We just have a
different starting hypothesis.
You assume the negation of comp. That's all.
But analog machine can in general be simulated by digital machine. Only
analog machine using explicitly infinite thrid person information in
finite time will be non turing emulable. It is up to you to explain us
why you think infinite third person information is needed for having
a genuine person.
(First person infinite information will not work given that comp
predicts that first person are associated directly to a continuum (high
infinite) of information flows.

If I have a scar on my left hand, you need to teleport this scar also.
Same
for any of my old memories.
We are not talking about the teleportation of some *standard PC parts*
(like
the CPU/HDD) from A to B.

But where I think you are wrong is that articial brain and body, even
if it
needs a millenium of work to succeed with some reasonable
probability, will
not really help us in understanding the brain and its functioning. It
just
happens that, even if it is *very* difficult, the copy of a brain is
almost
infinitely easier that the understanding of how a brain work (even
assuming
some high substitution level).

Assume no substitution level, if you can teleport me (a male) from A
to B
and let me agree completely that I am *exactly* (body, memory,
consciousness
etc.) the same me,
I think it will let us own the complete understanding of the so-called
consciousness, existence of soul? ... such big questions.

To be sure here comp says something rather negative: humans brains
will
never completely understand the human brain. It is true that the 3000
humans will perhaps eventually understand the basics of 2000 AD
human's
brain, but only true their own bigger brain (including
self-developing
machine) which will be beyond their comprehension. A little like
bacteria
and amoeba learns to reproduce themselves without any higher level
understanding of what is going on.

See my comment above. Sooner or later, I think human beings will have

No problem per se (withouit comp). With comp, I can explain why we can
have better and better answers, but there is no last answer. But then
comp explains why.

Of course if comp is correct we can understand very fundamental
principles
which are at the logical origin of the realities  (that's what
we are
discussing now).

Bruno

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

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### RE: Interested in thoughts on this excerpt from Martin Rees

```
WC writes:

Classical teleportation cannot copy something exact to the quantum level,
but rather involves making a close enough copy. It is obvious, I think,
that this is theoretically possible, but it is not immediately obvious how
good the copy of a person would have to be (what Bruno calls the
substitution level) in order to feel himself to be the same person. But
as mentioned above, I don't think we need to insist on perfect duplication
to the quantum level, because this doesn't even happen from moment to
moment in everyday life.

Thanks for the info. although I still don't think substitution level exists.
If teleportation of human beings is real (I hope I can see it in my life),
I think all biggest questions (such as consciousness, soul? Creator? the
origin of the universe, meaning of life ... etc.)
of this universe should have been solved.

Are you saying that you believe a copy of a person must be *exactly* the same
to be the same person? (Note that even this is more than some people would
concede, as there are some who hold that even an exact copy would not suffice.)
But what about the fact that people do change, physically and mentally, from
moment to moment? Surely this implies that we don't need the copy to be exact,
but we need to determine how close to exact it has to be. Also, I don't see how
practical teleportation would solve the other problems you mention. It is
useful as
a thought experiment in the philosophy of personal identity, in particular, but
all
that is required in these arguments is the *theoretical* possibility. I think
this is
where you err: the sorts of arguments we have been discussing would be neither
more nor less convincing if teleportation became a practical reality tomorrrow.

Stathis Papaioannou
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### RE: Interested in thoughts on this excerpt from Martin Rees

```
From: W. C.

From: Bruno Marchal
...
Not at all. I mean it in the operational physical sense. Like observing
your hand with a microscope, or looking closely to the path of an
electron.
...

Any microscope (optical or electron type)? What's the min. magnification
resolution to see it?
I need to find one to try what you said.

I tried to check my finger as you said with different resolutions of
microscopes.
But I still can't see that matter is the result of a sum on an infinity
of interfering computations.
Can you tell me why?

Thanks.

WC.

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### RE: Interested in thoughts on this excerpt from Martin Rees

```
Bruno Marchal writes:

Le 07-août-06, à 15:52, W. C. a écrit :

From: Bruno Marchal
...
Comp says that there is a level of description of yourself such that
you
survive through an emulation done at that level. But the UD will
simulate
not only that level but all level belows. So comp makes the following
prediction: if you look at yourself or at you neighborhood
sufficiently
close enough, you can in principle detect, indirectly, (by computing
the
relative comp histories) the presence of all the sublevel
computations.

Not at all. I mean it in the operational physical sense. Like observing
your hand with a microscope, or looking closely to the path of an
electron.

closely you see more and more detail, and I understand that you have other
arguments suggesting that this is all due to the ensemble of computations
underpinning the physical reality, but are you suggesting that the fact that
you can observe these levels is *by itself* evidence for these levels and
sublevels of computation?

Stathis Papaioannou
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### Re: Interested in thoughts on this excerpt from Martin Rees

```
Le Mardi 8 Août 2006 08:00, W. C. a écrit :
Can you tell me why?

Because you are bad faith and don't read correctly what others tell you.

If you have some more stupid questions like this, don't hesitate and go
continue polluting the mailing list.

Quentin

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Le 08-août-06, à 10:10, Quentin Anciaux a écrit :

Le Mardi 8 Août 2006 08:00, W. C. a écrit :
Can you tell me why?

Because you are bad faith and don't read correctly what others tell
you.

If you have some more stupid questions like this, don't hesitate and go
continue polluting the mailing list.

Hi Quentin,

Take it easy. Perhaps you are just quicker than me, but up to now I
would say W. C. has some *genuine* misunderstanding, perhaps shared by
other people too who are too shy to send a post (I know some).
Apparently W. C. does not believe in comp (he said he does not believe
in the existence of a substitution level), nor does he believe in the
QM-MWI (he said he read the FOR book a long time ago and that he has
not been convinced).
This makes him (or her?) quite coherent. W. C. seems to defend
Naturalism, but the fact that he/she follows the list shows that he/she
is at least open to some doubt and that he/she has some open-mindness.
I have met bad faith people in comparison with which W. C. is still
quite reasonable, imo. Conversation with him or her  can help to
understand difficulties.
Nevertheless, there is one important point in one of his/her recent
message where he/she is deadly wrong, and that is the subject of my
next message.

Best,

Bruno

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

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Le 08-août-06, à 05:49, W. C. a écrit :

From: Stathis Papaioannou

...
Classical teleportation cannot copy something exact to the quantum
level,
but rather involves making a close enough copy. It is obvious, I
think,
that this is theoretically possible, but it is not immediately
obvious how
good the copy of a person would have to be (what Bruno calls the
substitution level) in order to feel himself to be the same
person. But
as mentioned above, I don't think we need to insist on perfect
duplication
to the quantum level, because this doesn't even happen from moment to
moment in everyday life.

Thanks for the info. although I still don't think substitution level
exists.
If teleportation of human beings is real (I hope I can see it in my
life),
I think all biggest questions (such as consciousness, soul? Creator?
the
origin of the universe, meaning of life ... etc.)
of this universe should have been solved.

it somehow ambiguous.
Let me comment anyway.
Human classical teleportation, although possible in principle, will not
be possible in our life time (except  for those who will succeed in
some lucky cryogenisation process). Artificial brain will first be
developed with graft of genetically engineered animals neurons, through
progress in harnessing the immune system and prion diseases (that will
take time). Only latter will come purely artificial digital brain,
and even this will be a matter of piece by piece progress (artificial
hypocampus, artificial limbic system,  until artificial cortex
(this one will take perhaps a millenium), and pionner of immortality
will have hard time for many technical but also social and ethical
reasons.

But where I think you are wrong is that articial brain and body, even
if it needs a millenium of work to succeed with some reasonable
probability, will not really help us in understanding the brain and its
functioning. It just happens that, even if it is *very* difficult, the
copy of a brain is almost infinitely easier that the understanding of
how a brain work (even assuming some high substitution level). To be
sure here comp says something rather negative: humans brains will never
completely understand the human brain. It is true that the 3000 AD
humans will perhaps eventually understand the basics of 2000 AD human's
brain, but only true their own bigger brain (including
self-developing machine) which will be beyond their comprehension. A
little like bacteria and amoeba learns to reproduce themselves
without any higher level understanding of what is going on.

Of course if comp is correct we can understand very fundamental
principles which are at the logical origin of the realities
(that's what we are discussing now).

Bruno

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

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Le 08-août-06, à 08:00, W. C. a écrit :

But I still can't see that matter is the result of a sum on an
infinity
of interfering computations.
Can you tell me why?

My opinion here is that you should (re)read the FOR book. We do have
empirical reasons (quantum mechanics) that physical reality is the
result of interfering computable waves.
Now, why comp makes this necessary (not just empirically inferable) is
what I try to explain to the list since sometime (and that relies in
fine on some not so well known results in theoretical computer
science). I can only ask you to read carefully either old posts, or my
papers, or to follow carefully futures explanations.

Bruno

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

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Le 08-août-06, à 05:34, Stathis Papaioannou a écrit :

Bruno Marchal writes (quoting SP):

...a controlled
experiment in which measure can be turned up and down leaving
everything else
the same, such as having an AI running on several computers in
perfect
lockstep.

I think that the idea that a lower measure OM will appear more complex
is a consequence of Komogorov like ASSA theories (a-la Hal Finney,
Mallah, etc.). OK?

I understand the basic principle, but I have trouble getting my mind
around
the idea of defining a measure when every possible computation exists.

I am not sure I understand. All real number exist, for example, and it
is the reason why we can put a measure on it. All computations exist
(this is equivalent with arithmetical realism) yet some are or at least
could be relatively more frequent than others.

I agree from some 1 pov. But 1 plural pov here would lead to some
Bell
inequalities violation. That is: sharable experiments which shows
indirectly the presence of some alternate computations.

I don't understand this statement. I am suggesting that the computers
are
running exactly the same program - same circuitry, same software, same
initial conditions, all on a classical scale. I don't see that there
is any way
for the AI to know which computer he was running on (if that question
is
even meaningful) or how many computers were running.

I know it looks counterintuitive, but an AI can know which computer is
running and how many they are. It is a consequence of comp, and the UDA
the computer which is running are the relative universal number which
exist in arithmetical platonia (arithmetical truth is already a
universal video game, if you want, and it is the simplest). How many
are they? 2^aleph_zero.
I have already explain it here:
http://www.mail-archive.com/everything-list@eskimo.com/msg05272.html

It is a key point and we can come back on it if you have some
difficulties.

If I
were the AI the only advantage I can think of in having multiple
computers running
is for backup in case some of them broke down; beyond that, I
wouldn't
care if there
were one copy or a million copies of me running in parallel.

Except, as I said above, for the relative probabilities. But this is
equivalent with accepting a well done back-up will not change your
normal measure.

Yes, I think what you mean by relative probabilities is that if
there were
several possible versions of me next moment, then I would be more
likely
to experience the one with higher measure. It is only relative to the
other
possibilities that measure makes a subjective difference.

Ah but you get the point now!

Bruno

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

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### Re: Interested in thoughts on this excerpt from Martin Rees

```
On Tue, Aug 08, 2006 at 01:11:19PM +1000, Stathis Papaioannou wrote:

Is it still correct to say that a computation running on two physical
computers (that is, what
we think of as physical computers, whatever the underlying reality may be)
has almost twice
the measure as it would have if it were running on one computer? Otherwise,
there would
be no point backing up anything, relying instead on Platonia's infinite hard
disk.

Stathis Papaioannou

It does not change the measure of the computation in Platonia. I think
that is the clear message from COMP. But it does change the measure
within the physical universe that we inhabit.

Backing up things is to improve robustness in the face of noise (or
equivalently the second law). I don't know of anybody doing it to
increase measure per se.

On the other hand printing 100 copies of my book is all about
increasing the measure of my book within our physical universe, and
not backing it up (5 copies distributed to the main libraries of the
world would suffice for that!)

Cheers

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### RE: Interested in thoughts on this excerpt from Martin Rees

```
Russell Standish writes:

Is it still correct to say that a computation running on two physical
computers (that is, what
we think of as physical computers, whatever the underlying reality may be)
has almost twice
the measure as it would have if it were running on one computer? Otherwise,
there would
be no point backing up anything, relying instead on Platonia's infinite
hard disk.

Stathis Papaioannou

It does not change the measure of the computation in Platonia. I think
that is the clear message from COMP. But it does change the measure
within the physical universe that we inhabit.

Backing up things is to improve robustness in the face of noise (or
equivalently the second law). I don't know of anybody doing it to
increase measure per se.

On the other hand printing 100 copies of my book is all about
increasing the measure of my book within our physical universe, and
not backing it up (5 copies distributed to the main libraries of the
world would suffice for that!)

By increasing the measure locally in our universe, are you making no
difference, or only a
small amount of difference to the measure overall in Platonia? For example, if
all the matter
in the universe were converted to computers repeatedly calculating 2+2=4
would that give
2+2=4 a bit of an edge over 3+3=6 in Platonia? What about the far more
complex
computations underlying human consciousness: my understanding was that the
appearance
of an orderly physical world that goes along with these is not an optional
extra, but a necessary
consequence of the type of computation under consideration. That would mean
that all of the
measure attributed to a conscious moment is in fact tied up in the (apparent)
physical world,
because there are no computations of the required type possible that don't give
the appearance
of a physical world. (If there are, we have to explain why we don't experience
them.) So if you
increase the measure locally by duplicating and running a sentient program, you
are increasing the
measure in Platonia as a whole, since there isn't anywhere else where sentient
programs of the
sort with which we are familiar might be hiding.

Stathis Papaioannou
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### RE: Interested in thoughts on this excerpt from Martin Rees

```
From: Bruno Marchal

...
somehow ambiguous.
Let me comment anyway.
Human classical teleportation, although possible in principle, will not be
possible in our life time (except  for those who will succeed in some lucky
cryogenisation process). Artificial brain will first be developed with
graft of genetically engineered animals neurons, through progress in
harnessing the immune system and prion diseases (that will take time). Only
latter will come purely artificial digital brain, and even this will be a
matter of piece by piece progress (artificial hypocampus, artificial limbic
system,  until artificial cortex (this one will take perhaps a
millenium), and pionner of immortality will have hard time for many
technical but also social and ethical reasons.

Thanks for your patience. I can see that you are really very patient because
questions that you may have replied hundreds of times before.
Although I appreciate your patience, I still don't agree with you about the
teleportation.
When we say teleportation, we mean we send someone from location A to
location B *like a magic* (Start Trek stuff).
The person at A is *exactly* the same as the one at B. This really has
little to do with digital or artificial stuff.
Human body and brain are analog, same for A  B. It's useless to use digital
or artificial conversion (since I assume no substitution level).
If I have a scar on my left hand, you need to teleport this scar also. Same
for any of my old memories.
We are not talking about the teleportation of some *standard PC parts* (like
the CPU/HDD) from A to B.

But where I think you are wrong is that articial brain and body, even if it
needs a millenium of work to succeed with some reasonable probability, will
not really help us in understanding the brain and its functioning. It just
happens that, even if it is *very* difficult, the copy of a brain is almost
infinitely easier that the understanding of how a brain work (even assuming
some high substitution level).

Assume no substitution level, if you can teleport me (a male) from A to B
and let me agree completely that I am *exactly* (body, memory, consciousness
etc.) the same me,
I think it will let us own the complete understanding of the so-called
consciousness, existence of soul? ... such big questions.

To be sure here comp says something rather negative: humans brains will
never completely understand the human brain. It is true that the 3000 AD
humans will perhaps eventually understand the basics of 2000 AD human's
brain, but only true their own bigger brain (including self-developing
machine) which will be beyond their comprehension. A little like bacteria
and amoeba learns to reproduce themselves without any higher level
understanding of what is going on.

See my comment above. Sooner or later, I think human beings will have

Of course if comp is correct we can understand very fundamental principles
which are at the logical origin of the realities  (that's what we are
discussing now).

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Le 08-août-06, à 08:58, Stathis Papaioannou a écrit :

Not at all. I mean it in the operational physical sense. Like
observing
your hand with a microscope, or looking closely to the path of an
electron.

closely you see more and more detail, and I understand that you have
other
arguments suggesting that this is all due to the ensemble of
computations
underpinning the physical reality, but are you suggesting that the
fact that
you can observe these levels is *by itself* evidence for these levels
and
sublevels of computation?

Comp predicts that if you look closely enough you will see reality
blurring. The evidence from empirical science (quantum physics) is that
indeed reality blurs, but of course informal comp does not give the
details of the blurring process. (That is why I get technical at some
point). When we look at an electron in some well defined state of
energy around the nucleus, we see literally a map of accessible
worlds. The electron behaves as if it blurs around the nucleus, and
what chemists call an orbital is really a map of where you can find the
position of the electron would you decide to measure it.
The microscope image is somehow misleading, because both with comp and
already with the quantum, the many histories can manifest themselves
through *isolation* only, like the Schroedinger cat in its box.
Practically a hot macroscopic box does interact too heavily with the
environment so that we cannot really isolate it, so we cannot make our
comp history completely independent of what happen in the box, and
thats why confirmation or refutation of comp or of the quantum needs
the microscopic world. But macro-effects are not excluded and are
arguably already present for the quantum (superfluid,
superconductivity, violation of Bell's inequality on large distance,
etc.)

Bruno

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

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

W. C. wrote:

Thanks for the info. although I still don't think substitution level exists.
If teleportation of human beings is real (I hope I can see it in my life),
I think all biggest questions (such as consciousness, soul? Creator? the
origin of the universe, meaning of life ... etc.)
of this universe should have been solved.

If you can first solve the How To Detect A Zombie problem...

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Bruno Marchal wrote:
Le 08-août-06, à 08:58, Stathis Papaioannou a écrit :

Not at all. I mean it in the operational physical sense. Like
observing
your hand with a microscope, or looking closely to the path of an
electron.

closely you see more and more detail, and I understand that you have
other
arguments suggesting that this is all due to the ensemble of
computations
underpinning the physical reality, but are you suggesting that the
fact that
you can observe these levels is *by itself* evidence for these levels
and
sublevels of computation?

Comp predicts that if you look closely enough you will see reality
blurring. The evidence from empirical science (quantum physics) is that
indeed reality blurs, but of course informal comp does not give the
details of the blurring process.

One thing we *do* know for sure is that Harry Potter universes --
*literal* HP universes -- are computable, since the special effects
in the Harry Potter movies were computer generated!

Therefore the problem with everythingism is that it predicts *too much*
weirdness. (And, as I am forever pointing out,
materialism-contingency-empiricism [*] doesn't exclude quantum
fuzziness or many
worlds, providing there are contingent facts about how much fuzziness
and how many worlds).

[*] my term for the non-everythingist philosophy.

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Bruno Marchal wrote:

My opinion here is that you should (re)read the FOR book. We do have
empirical reasons (quantum mechanics) that physical reality is the
result of interfering computable waves.

Quantum weirdness is entirely compatible with
materialism-contingency-empiricism.

Schrodinger's equation is a contingent fact about the world, derived
from observation, which describs what matter can and can't do.

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Bruno Marchal wrote:
Le 08-août-06, à 05:34, Stathis Papaioannou a écrit :

Bruno Marchal writes (quoting SP):

...a controlled
experiment in which measure can be turned up and down leaving
everything else
the same, such as having an AI running on several computers in
perfect
lockstep.

I think that the idea that a lower measure OM will appear more complex
is a consequence of Komogorov like ASSA theories (a-la Hal Finney,
Mallah, etc.). OK?

I understand the basic principle, but I have trouble getting my mind
around
the idea of defining a measure when every possible computation exists.

I am not sure I understand. All real number exist, for example, and it
is the reason why we can put a measure on it.

I'm confused. In previous conversations you have claimed not to
known what exists means.

All computations exist
(this is equivalent with arithmetical realism) yet some are or at least
could be relatively more frequent than others.

If computation are simply integers, they all have the same measure.

If there is some more complex relation, the existence of computations
is not guaranteed by the existence of integers. Any computer
progamme can be represented as a sting of 1's and 0's, but only
int the context of some particular computer.

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Stathis Papaioannou wrote:

By increasing the measure locally in our universe, are you making no
difference, or only a
small amount of difference to the measure overall in Platonia?

You can't make a difference in Platonia. There is no time there,
no change, and no causality.

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### Re: Interested in thoughts on this excerpt from Martin Rees

```
Precisely my point!

On Tue, Aug 08, 2006 at 08:42:04AM -0700, 1Z wrote:

Stathis Papaioannou wrote:

By increasing the measure locally in our universe, are you making no
difference, or only a
small amount of difference to the measure overall in Platonia?

You can't make a difference in Platonia. There is no time there,
no change, and no causality.

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Le 06-août-06, à 15:59, Stathis Papaioannou a écrit :

Russell Standish writes:

This is one of those truly cracked ideas that is not wise to air in
polite company. Nevertheless, it can be fun to play around with in
this forum. I had a similarly cracked idea a few years ago about 1st
person experienced magic, which we batted around a bit at the tiome
without getting anywhere.

The trouble I have with this idea is that I can't see the connection
between OM measure and the sensation of passage of time. In contrast
to your statement of nothing however, a lower measure OM will appear
more complex - so we experience growth in knowledge as our measure
decreases. Increasing measure OM's will correspond to memory
erasure, in the sense of quantum erasure.

My thought was that if there are twice as many copies of you running
in parallel,
you are in a sense cramming twice as much experience into a given
objective time
period, so maybe this stretches out the time period to seem twice as
long.

I certainly doubt that!

There
is admittedly no good reason to accept that this is so (that's why
it's a cracked
idea, as you say!), and I would bet that it *isn't* so, but it's the
only half-plausible
subjective effect I can think of due to change in measure alone.

The (relative) number or proportion of emulation will never change a
content of an experience, but could change the relative probabilities,
both in comp and in QM.

I believe that what you mean when you say that a lower measure OM will
appear
more complex is somewhat different to the scenario I had in mind: a
controlled
experiment in which measure can be turned up and down leaving
everything else
the same, such as having an AI running on several computers in perfect
lockstep.

I think that the idea that a lower measure OM will appear more complex
is a consequence of Komogorov like ASSA theories (a-la Hal Finney,
Mallah, etc.). OK?

(I realise this is not the same as changing measure in the multiverse,
which would
not lend itself so easily to experiment.) Would the AI notice anything
if half the
computers were turned off then on again? I think it would be
impossible for the AI
to notice that anything had changed without receiving external
information.

I agree from some 1 pov. But 1 plural pov here would lead to some Bell
inequalities violation. That is: sharable experiments which shows
indirectly the presence of some alternate computations.

If I
were the AI the only advantage I can think of in having multiple
computers running
is for backup in case some of them broke down; beyond that, I wouldn't
care if there
were one copy or a million copies of me running in parallel.

Except, as I said above, for the relative probabilities. But this is
equivalent with accepting a well done back-up will not change your
normal measure.

Bruno

Stathis Papaioannou

On Sat, Aug 05, 2006 at 10:44:49PM +1000, Stathis Papaioannou wrote:

I have asked the question before, what do I experience if my measure
in the multiverse increases or decreases? My preferred answer, contra
the ASSA/ QTI skeptics, is nothing. However, the interesting
observation
that our perception of time changes with age, so that an hour seems
subjectively much longer for a young child than for an older person,
would
seem to correlate with decreasing measure as a person grows older.
One
explanation for this could be that if there are more copies of us
around
in the multiverse, we have more subjective experience per unit time.
This
would mean that if we lived forever, the years then the centuries
and millenia
would fly past at a subjectively faster and faster rate as we age
and our
measure continuously drops.

I actually believe that a psychological explanation for this
phenomenon is more
likely correct (an hour is a greater proportion of your life if you
are a young child)
but it's an interesting idea.

Stathis Papaioannou

Date: Fri, 4 Aug 2006 02:10:53 +1000
From: [EMAIL PROTECTED]
Subject: Re: Interested in thoughts on this excerpt from Martin Rees

Someone called me to task for this posting (I forget who, and I've
lost the posting now). I tried to formulate the notion I expressed
here more precisely, and failed! So I never responded.

What I had in mind was that future observer moment of my current one
will at some point have a total measure diminishing at least as fast
as an exponental function of OM age. This is simply a statement that
it becomes increasingly improbable for humans to live longer than a
certain age.

Whilst individual OMs will have exponentially decreasing measure due
to the linear increase in complexity as a function of universe age,
total OM measure requires summing over all OMs of a given age (which
can compensate). This total OM measure```

### Re: Interested in thoughts on this excerpt from Martin Rees

```

Le 07-août-06, à 01:44, W. C. a écrit :

From: Bruno Marchal
...
But it is easy to explain that this is already a simple consequence
of
comp. Any piece of matter is the result of a sum on an infinity of
interfering computations: there is no reason to expect this to be
clonable without cloning the whole UD, but this would not change any
internal measures (by Church thesis and machine independence).
...

I remember you said comp can be tested experimentally due to others
consequences (like the observable interference among many computations,
etc.).
Can you provide more details on how to do the experiment to see
matter is
the result of a sum on an infinity of  interfering computations???

Comp says that there is a level of description of yourself such that
you survive through an emulation done at that level. But the UD will
simulate not only that level but all level belows. So comp makes the
following prediction: if you look at yourself or at you neighborhood
sufficiently close enough, you can in principle detect, indirectly, (by
computing the relative comp histories) the presence of all the sublevel
computations.
So it is enough to observe closely your neighborhood. But of course
experimental physicists does exactly that, and the fact that they infer
Many-Worlds (many Histories/many computations) from their observations
can be seen retrospectively as a confirmation of comp.
(This explains that up to now, only people with a good grasp of the
conceptual difficulties of the quantum theory can swallow the
consequences of comp, more or less).
To be sure negative interferences remains quite astonishing (after
such an informal reasoning), but then if you take into account the
results in computer science and mathematical logic, there are evidence
that negative interference appears as related to some variant of the
incompleteness phenomena. This is somehow counter-intuitive and hard to
justify in french. More in a summary which should come asap. I hope

Bruno

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

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### RE: Interested in thoughts on this excerpt from Martin Rees

```
From: Bruno Marchal
...
Comp says that there is a level of description of yourself such that you
survive through an emulation done at that level. But the UD will simulate
not only that level but all level belows. So comp makes the following
prediction: if you look at yourself or at you neighborhood sufficiently
close enough, you can in principle detect, indirectly, (by computing the
relative comp histories) the presence of all the sublevel computations.

I still can't see how matter is the result of a sum on an infinity of
interfering computations.
Common people can touch and feel the matter (this physical universe). They
don't need this strange process to see it.
As said before, I don't think substitution level exists. So Comp. and UDA
won't work here.

So it is enough to observe closely your neighborhood. But of course
experimental physicists does exactly that, and the fact that they infer
Many-Worlds (many Histories/many computations) from their observations can
be seen retrospectively as a confirmation of comp.
(This explains that up to now, only people with a good grasp of the
conceptual difficulties of the quantum theory can swallow the consequences
of comp, more or less).

I think many good physicist won't agree with you.

To be sure negative interferences remains quite astonishing (after such
an informal reasoning), but then if you take into account the results in
computer science and mathematical logic, there are evidence that negative
interference appears as related to some variant of the incompleteness
phenomena. This is somehow counter-intuitive and hard to justify in
french. More in a summary which should come asap. I hope this already
helps.

Thanks.

WC.

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Le 07-août-06, à 15:52, W. C. a écrit :

From: Bruno Marchal
...
Comp says that there is a level of description of yourself such that
you
survive through an emulation done at that level. But the UD will
simulate
not only that level but all level belows. So comp makes the following
prediction: if you look at yourself or at you neighborhood
sufficiently
close enough, you can in principle detect, indirectly, (by computing
the
relative comp histories) the presence of all the sublevel
computations.

Not at all. I mean it in the operational physical sense. Like observing
your hand with a microscope, or looking closely to the path of an
electron.

I still can't see how matter is the result of a sum on an infinity of
interfering computations.
Common people can touch and feel the matter (this physical universe).
They
don't need this strange process to see it.

I would say that here we are trying to explain those touch and feel
the matter without begging the question. My working hypothesis is
comp.

As said before, I don't think substitution level exists. So Comp. and
UDA
won't work here.

Are you saying that your hypothesis is some negation of comp. Then
there is no problem with my work of course. (Except that many
consequences that I extract from comp remains derivable by much weaker
version of comp).

So it is enough to observe closely your neighborhood. But of course
experimental physicists does exactly that, and the fact that they
infer
Many-Worlds (many Histories/many computations) from their
observations can
be seen retrospectively as a confirmation of comp.
(This explains that up to now, only people with a good grasp of the
conceptual difficulties of the quantum theory can swallow the
consequences
of comp, more or less).

I think many good physicist won't agree with you.

Of course those physicist would believe in the wave collapse will have
more reason than Everett followers to swallow what I say.
To be sure I don't take a many or even all physicists think this or
that as an argument for this or that. Of course it is nice to justify
why such wrong belief can rise.

To be sure negative interferences remains quite astonishing (after
such
an informal reasoning), but then if you take into account the results
in
computer science and mathematical logic, there are evidence that
negative
interference appears as related to some variant of the incompleteness
phenomena. This is somehow counter-intuitive and hard to justify in
french. More in a summary which should come asap. I hope this
helps.

Thanks.

Asap.

Bruno

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

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Bruno Marchal wrote:

Of course those physicist would believe in the wave collapse will have
more reason than Everett followers to swallow what I say.

Not much more. Physical MWI is a materialist-contingent-empiricst
theory
and therefore just as much opposed to your
idealist-necessitarian-rationalist
approach as single-universe physics.

To be sure I don't take a many or even all physicists think this or
that as an argument for this or that.

Because you don't believe in empriricism, but that is all rather
circular.

Of course it is nice to justify
why such wrong belief can rise.

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### RE: Interested in thoughts on this excerpt from Martin Rees

```
From: Bruno Marchal
...
Not at all. I mean it in the operational physical sense. Like observing
your hand with a microscope, or looking closely to the path of an
electron.
...

Any microscope (optical or electron type)? What's the min. magnification
resolution to see it?
I need to find one to try what you said.

Thanks.

WC.

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### RE: Interested in thoughts on this excerpt from Martin Rees

```
Russell Standish:

On Sun, Aug 06, 2006 at 11:59:42PM +1000, Stathis Papaioannou wrote:
My thought was that if there are twice as many copies of you running in
parallel,
you are in a sense cramming twice as much experience into a given objective
time
period, so maybe this stretches out the time period to seem twice as
long. There
is admittedly no good reason to accept that this is so (that's why it's a
cracked
idea, as you say!), and I would bet that it *isn't* so, but it's the only
half-plausible
subjective effect I can think of due to change in measure alone.

I believe that what you mean when you say that a lower measure OM will
appear
more complex is somewhat different to the scenario I had in mind: a
controlled
experiment in which measure can be turned up and down leaving everything
else
the same, such as having an AI running on several computers in perfect
lockstep.
(I realise this is not the same as changing measure in the multiverse,
which would
not lend itself so easily to experiment.) Would the AI notice anything if
half the
computers were turned off then on again? I think it would be impossible for
the AI
to notice that anything had changed without receiving external information.
If I
were the AI the only advantage I can think of in having multiple computers
running
is for backup in case some of them broke down; beyond that, I wouldn't care
if there
were one copy or a million copies of me running in parallel.

Stathis Papaioannou

This thought experiment has been discussed a few times in this
list. I agree with you that one wouldn't expect there to be any
difference in subjective experience, but more than that wrt Bruno's
work, assuming COMP  (which you have to anyway to consider the thought
experiment), there is actually no way to change the measure of a
particular computation - computations exist in Platonia wuth
presumably some measure (measure is fixed in my approach by the
actions of the observer, but others do not necessarily have an answer
to what the measure is). That is why Bruno can eliminate the concrete
universe hypothesis altogether.

Is it still correct to say that a computation running on two physical computers
(that is, what
we think of as physical computers, whatever the underlying reality may be) has
almost twice
the measure as it would have if it were running on one computer? Otherwise,
there would
be no point backing up anything, relying instead on Platonia's infinite hard
disk.

Stathis Papaioannou
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### RE: Interested in thoughts on this excerpt from Martin Rees

```
Bruno Marchal writes (quoting SP):

...a controlled
experiment in which measure can be turned up and down leaving
everything else
the same, such as having an AI running on several computers in perfect
lockstep.

I think that the idea that a lower measure OM will appear more complex
is a consequence of Komogorov like ASSA theories (a-la Hal Finney,
Mallah, etc.). OK?

I understand the basic principle, but I have trouble getting my mind around
the idea of defining a measure when every possible computation exists.

(I realise this is not the same as changing measure in the multiverse,
which would
not lend itself so easily to experiment.) Would the AI notice anything
if half the
computers were turned off then on again? I think it would be
impossible for the AI
to notice that anything had changed without receiving external
information.

I agree from some 1 pov. But 1 plural pov here would lead to some Bell
inequalities violation. That is: sharable experiments which shows
indirectly the presence of some alternate computations.

I don't understand this statement. I am suggesting that the computers are
running exactly the same program - same circuitry, same software, same
initial conditions, all on a classical scale. I don't see that there is any way
for the AI to know which computer he was running on (if that question is
even meaningful) or how many computers were running.

If I
were the AI the only advantage I can think of in having multiple
computers running
is for backup in case some of them broke down; beyond that, I wouldn't
care if there
were one copy or a million copies of me running in parallel.

Except, as I said above, for the relative probabilities. But this is
equivalent with accepting a well done back-up will not change your
normal measure.

Yes, I think what you mean by relative probabilities is that if there were
several possible versions of me next moment, then I would be more likely
to experience the one with higher measure. It is only relative to the other
possibilities that measure makes a subjective difference.

Stathis Papaioannou
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### RE: Interested in thoughts on this excerpt from Martin Rees

```
From: Stathis Papaioannou

...
Classical teleportation cannot copy something exact to the quantum level,
but rather involves making a close enough copy. It is obvious, I think,
that this is theoretically possible, but it is not immediately obvious how
good the copy of a person would have to be (what Bruno calls the
substitution level) in order to feel himself to be the same person. But
as mentioned above, I don't think we need to insist on perfect duplication
to the quantum level, because this doesn't even happen from moment to
moment in everyday life.

Thanks for the info. although I still don't think substitution level exists.
If teleportation of human beings is real (I hope I can see it in my life),
I think all biggest questions (such as consciousness, soul? Creator? the
origin of the universe, meaning of life ... etc.)
of this universe should have been solved.

Thanks.

WC..

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### RE: Interested in thoughts on this excerpt from Martin Rees

```

Date: Fri, 4 Aug 2006 19:17:21 +1000
From: [EMAIL PROTECTED]
Subject: Re: Interested in thoughts on this excerpt from Martin Rees

This is one of those truly cracked ideas that is not wise to air in
polite company. Nevertheless, it can be fun to play around with in
this forum. I had a similarly cracked idea a few years ago about 1st
person experienced magic, which we batted around a bit at the tiome
without getting anywhere.

The trouble I have with this idea is that I can't see the connection
between OM measure and the sensation of passage of time. In contrast
to your statement of nothing however, a lower measure OM will appear
more complex - so we experience growth in knowledge as our measure
decreases. Increasing measure OM's will correspond to memory
erasure, in the sense of quantum erasure.

Cheers

On Sat, Aug 05, 2006 at 10:44:49PM +1000, Stathis Papaioannou wrote:

I have asked the question before, what do I experience if my measure
in the multiverse increases or decreases? My preferred answer, contra
the ASSA/ QTI skeptics, is nothing. However, the interesting observation
that our perception of time changes with age, so that an hour seems
subjectively much longer for a young child than for an older person, would
seem to correlate with decreasing measure as a person grows older. One
explanation for this could be that if there are more copies of us around
in the multiverse, we have more subjective experience per unit time. This
would mean that if we lived forever, the years then the centuries and
millenia
would fly past at a subjectively faster and faster rate as we age and our
measure continuously drops.

I actually believe that a psychological explanation for this phenomenon is
more
likely correct (an hour is a greater proportion of your life if you are a
young child)
but it's an interesting idea.

Stathis Papaioannou

Date: Fri, 4 Aug 2006 02:10:53 +1000
From: [EMAIL PROTECTED]
Subject: Re: Interested in thoughts on this excerpt from Martin Rees

Someone called me to task for this posting (I forget who, and I've
lost the posting now). I tried to formulate the notion I expressed
here more precisely, and failed! So I never responded.

What I had in mind was that future observer moment of my current one
will at some point have a total measure diminishing at least as fast
as an exponental function of OM age. This is simply a statement that
it becomes increasingly improbable for humans to live longer than a
certain age.

Whilst individual OMs will have exponentially decreasing measure due
to the linear increase in complexity as a function of universe age,
total OM measure requires summing over all OMs of a given age (which
can compensate). This total OM measure is a 3rd person type of
quantity - equivalent to asking what is the probability of a conscious
organism existing at universe age t. It seems plausible that this
might diminish in some exponential or faster fashion after a few
standard deviation beyond the mean time it takes to evolve
consciousness, but I do not have any basis for making this claim. If
we assume a normal distribution of times required for evolving
consciousness, then the statement is true for example, but I'm wise
enough to know that this assumption needs further justification. The
distribution may be a meanless thing like a power law for example.

So sorry if I piqued someones interest too much - but then we can leave
this notion as a conjecture :)

Cheers

On Fri, Jul 28, 2006 at 12:07:37AM +1000, Russell Standish wrote:
Thanks for giving a digested explanation of the argument. This paper
was discussed briefly on A-Void a few weeks ago, but I must admit to
not following the argument too well, nor RTFA.

My comment on the observer moment issue, is that in a Multiverse, the
measure of older observer moments is less that younger ones. After a
certain point in time, the measure probably decreases exponentially or
faster, so there will be a mean observer moment age.

So contra all these old OMs dominating the calculation, and giving
rise to an expected value of Lambda close to zero, we should expect
only a finite contribution, leading to an expected finite value of
Lambda.

We don't know what the mean age for an observer moment should be, but
presumably one could argue anthropically that is around 10^{10}
years. What does this give for an expected value of Lambda?

Of course their argument does sound plausible for a single universe -
is this observational evidence in favour of a Multiverse?

Cheers

--
*PS: A number of people ask me```

### RE: Interested in thoughts on this excerpt from Martin Rees

```
Russell Standish writes:

This is one of those truly cracked ideas that is not wise to air in
polite company. Nevertheless, it can be fun to play around with in
this forum. I had a similarly cracked idea a few years ago about 1st
person experienced magic, which we batted around a bit at the tiome
without getting anywhere.

The trouble I have with this idea is that I can't see the connection
between OM measure and the sensation of passage of time. In contrast
to your statement of nothing however, a lower measure OM will appear
more complex - so we experience growth in knowledge as our measure
decreases. Increasing measure OM's will correspond to memory
erasure, in the sense of quantum erasure.

My thought was that if there are twice as many copies of you running in
parallel,
you are in a sense cramming twice as much experience into a given objective
time
period, so maybe this stretches out the time period to seem twice as long.
There
is admittedly no good reason to accept that this is so (that's why it's a
cracked
idea, as you say!), and I would bet that it *isn't* so, but it's the only
half-plausible
subjective effect I can think of due to change in measure alone.

I believe that what you mean when you say that a lower measure OM will appear
more complex is somewhat different to the scenario I had in mind: a controlled
experiment in which measure can be turned up and down leaving everything else
the same, such as having an AI running on several computers in perfect
lockstep.
(I realise this is not the same as changing measure in the multiverse, which
would
not lend itself so easily to experiment.) Would the AI notice anything if half
the
computers were turned off then on again? I think it would be impossible for the
AI
to notice that anything had changed without receiving external information. If
I
were the AI the only advantage I can think of in having multiple computers
running
is for backup in case some of them broke down; beyond that, I wouldn't care if
there
were one copy or a million copies of me running in parallel.

Stathis Papaioannou

On Sat, Aug 05, 2006 at 10:44:49PM +1000, Stathis Papaioannou wrote:

I have asked the question before, what do I experience if my measure
in the multiverse increases or decreases? My preferred answer, contra
the ASSA/ QTI skeptics, is nothing. However, the interesting observation
that our perception of time changes with age, so that an hour seems
subjectively much longer for a young child than for an older person, would
seem to correlate with decreasing measure as a person grows older. One
explanation for this could be that if there are more copies of us around
in the multiverse, we have more subjective experience per unit time. This
would mean that if we lived forever, the years then the centuries and
millenia
would fly past at a subjectively faster and faster rate as we age and our
measure continuously drops.

I actually believe that a psychological explanation for this phenomenon is
more
likely correct (an hour is a greater proportion of your life if you are a
young child)
but it's an interesting idea.

Stathis Papaioannou

Date: Fri, 4 Aug 2006 02:10:53 +1000
From: [EMAIL PROTECTED]
Subject: Re: Interested in thoughts on this excerpt from Martin Rees

Someone called me to task for this posting (I forget who, and I've
lost the posting now). I tried to formulate the notion I expressed
here more precisely, and failed! So I never responded.

What I had in mind was that future observer moment of my current one
will at some point have a total measure diminishing at least as fast
as an exponental function of OM age. This is simply a statement that
it becomes increasingly improbable for humans to live longer than a
certain age.

Whilst individual OMs will have exponentially decreasing measure due
to the linear increase in complexity as a function of universe age,
total OM measure requires summing over all OMs of a given age (which
can compensate). This total OM measure is a 3rd person type of
quantity - equivalent to asking what is the probability of a conscious
organism existing at universe age t. It seems plausible that this
might diminish in some exponential or faster fashion after a few
standard deviation beyond the mean time it takes to evolve
consciousness, but I do not have any basis for making this claim. If
we assume a normal distribution of times required for evolving
consciousness, then the statement is true for example, but I'm wise
enough to know that this assumption needs further justification. The
distribution may be a meanless thing like a power law for example.

So sorry if I piqued someones interest too much - but then we can leave
this notion as a conjecture```

### Re: Interested in thoughts on this excerpt from Martin Rees

```
On Sun, Aug 06, 2006 at 11:59:42PM +1000, Stathis Papaioannou wrote:
My thought was that if there are twice as many copies of you running in
parallel,
you are in a sense cramming twice as much experience into a given objective
time
period, so maybe this stretches out the time period to seem twice as long.
There
is admittedly no good reason to accept that this is so (that's why it's a
cracked
idea, as you say!), and I would bet that it *isn't* so, but it's the only
half-plausible
subjective effect I can think of due to change in measure alone.

I believe that what you mean when you say that a lower measure OM will appear
more complex is somewhat different to the scenario I had in mind: a
controlled
experiment in which measure can be turned up and down leaving everything else
the same, such as having an AI running on several computers in perfect
lockstep.
(I realise this is not the same as changing measure in the multiverse, which
would
not lend itself so easily to experiment.) Would the AI notice anything if
half the
computers were turned off then on again? I think it would be impossible for
the AI
to notice that anything had changed without receiving external information.
If I
were the AI the only advantage I can think of in having multiple computers
running
is for backup in case some of them broke down; beyond that, I wouldn't care
if there
were one copy or a million copies of me running in parallel.

Stathis Papaioannou

This thought experiment has been discussed a few times in this
list. I agree with you that one wouldn't expect there to be any
difference in subjective experience, but more than that wrt Bruno's
work, assuming COMP  (which you have to anyway to consider the thought
experiment), there is actually no way to change the measure of a
particular computation - computations exist in Platonia wuth
presumably some measure (measure is fixed in my approach by the
actions of the observer, but others do not necessarily have an answer
to what the measure is). That is why Bruno can eliminate the concrete
universe hypothesis altogether.

Cheers

--
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is of type application/pgp-signature. Don't worry, it is not a
virus. It is an electronic signature, that may be used to verify this
email came from me if you have PGP or GPG installed. Otherwise, you
may safely ignore this attachment.

A/Prof Russell Standish  Phone 8308 3119 (mobile)
Mathematics0425 253119 ()
UNSW SYDNEY 2052 [EMAIL PROTECTED]
Australiahttp://parallel.hpc.unsw.edu.au/rks
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### RE: Interested in thoughts on this excerpt from Martin Rees

```
From: Bruno Marchal
...
But it is easy to explain that this is already a simple consequence  of
comp. Any piece of matter is the result of a sum on an infinity of
interfering computations: there is no reason to expect this to be
clonable without cloning the whole UD, but this would not change any
internal measures (by Church thesis and machine independence).
...

I remember you said comp can be tested experimentally due to others
consequences (like the observable interference among many computations,
etc.).
Can you provide more details on how to do the experiment to see matter is
the result of a sum on an infinity of  interfering computations???

Thanks.

WC.

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### Re: Interested in thoughts on this excerpt from Martin Rees

```
Someone called me to task for this posting (I forget who, and I've
lost the posting now). I tried to formulate the notion I expressed
here more precisely, and failed! So I never responded.

What I had in mind was that future observer moment of my current one
will at some point have a total measure diminishing at least as fast
as an exponental function of OM age. This is simply a statement that
it becomes increasingly improbable for humans to live longer than a
certain age.

Whilst individual OMs will have exponentially decreasing measure due
to the linear increase in complexity as a function of universe age,
total OM measure requires summing over all OMs of a given age (which
can compensate). This total OM measure is a 3rd person type of
quantity - equivalent to asking what is the probability of a conscious
organism existing at universe age t. It seems plausible that this
might diminish in some exponential or faster fashion after a few
standard deviation beyond the mean time it takes to evolve
consciousness, but I do not have any basis for making this claim. If
we assume a normal distribution of times required for evolving
consciousness, then the statement is true for example, but I'm wise
enough to know that this assumption needs further justification. The
distribution may be a meanless thing like a power law for example.

So sorry if I piqued someones interest too much - but then we can leave
this notion as a conjecture :)

Cheers

On Fri, Jul 28, 2006 at 12:07:37AM +1000, Russell Standish wrote:
Thanks for giving a digested explanation of the argument. This paper
was discussed briefly on A-Void a few weeks ago, but I must admit to
not following the argument too well, nor RTFA.

My comment on the observer moment issue, is that in a Multiverse, the
measure of older observer moments is less that younger ones. After a
certain point in time, the measure probably decreases exponentially or
faster, so there will be a mean observer moment age.

So contra all these old OMs dominating the calculation, and giving
rise to an expected value of Lambda close to zero, we should expect
only a finite contribution, leading to an expected finite value of
Lambda.

We don't know what the mean age for an observer moment should be, but
presumably one could argue anthropically that is around 10^{10}
years. What does this give for an expected value of Lambda?

Of course their argument does sound plausible for a single universe -
is this observational evidence in favour of a Multiverse?

Cheers

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### RE: Interested in thoughts on this excerpt from Martin Rees

```
CW writes:

c) Accepting a) and b) you assume physical laws making time travel
possible (which is of course controversial;  this could be in principle
possible with very special assumption, which could also be false in
principle with other assumption).

Time travel is as possible as teleportation of human beings.

If you do theoretical reasonings you have to make clear the assumptions
which are making things possible in principle. Up to here, I can follow
you (I can imagine such fundamental assumptions).

Of course, there are many details and assumptions to say PUA is possible.
My point is that PUA is possible just like teleportation of human beings.
I think they have similar possibility.

Not at all. There is a *huge* difference between what is possible in theory and
what is possible practically. A person wearing down a mountain with his fingers
is a practical impossibility, but there is nothing in the laws of physics
making it a
theoretical impossibility. A person flying to Alpha Centauri in 5 minutes is
logically
possible, but the laws of physics make it theoretically impossible. A person
being
simultaneously taller than 180cm and shorter than 170cm is a logical
impossibility.
These three examples for everyday purposes are equally unlikely to happen, but
they are fundamentally different from a philosophical standpoint. In the case
of
classical teleportation, there is nothing in the laws of physics making it
theoretically
impossible, and it is certainly not logically impossible. Time travel is much
more
dubious: it may be a physical impossibility, and it may even be a logical
impossibility.

Stathis Papaioannou
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### RE: Interested in thoughts on this excerpt from Martin Rees

```
From: Stathis Papaioannou

Not at all. There is a *huge* difference between what is possible in theory
and what is possible practically. A person wearing down a mountain with his
fingers is a practical impossibility, but there is nothing in the laws of
physics making it a theoretical impossibility. A person flying to Alpha
Centauri in 5 minutes is logically possible, but the laws of physics make
it theoretically impossible. A person being simultaneously taller than
180cm and shorter than 170cm is a logical impossibility. These three
examples for everyday purposes are equally unlikely to happen, but they are
fundamentally different from a philosophical standpoint. In the case of
classical teleportation, there is nothing in the laws of physics making it
theoretically impossible, and it is certainly not logically impossible.
Time travel is much more dubious: it may be a physical impossibility, and
it may even be a logical impossibility.

Thank you for a very clear explanation of these 3
theoretical/practical/logical possibility differences.
I remember I saw some papers before saying that time travel is theoretically
possible, although it remains an open question.
It's like teleportation. Maybe you can demonstrate with 1 or 2 particles in
QM.
But it's another very different thing when we are talking about human beings
(or simple animals).
Maybe other very knowledgeable prof. (like scerir???) in this list can
provide useful ref.

Thanks.

WC.

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Le 04-août-06, à 15:18, W. C. a écrit :

I remember other people mentioned before. *Normal* people can't accept
that
there is no physical universe.
Even Buddhists won't say that.

Sorry. I was short. All what I say is that IF we take the comp hyp
seriously enough THEN we can see that physical is not a primitive
things (this follows from the UD reasoning, you can ask question). I
was meaning there is no primitive or substantial or primary
physicalness. Naïve primitive Matter is a form of ether (assuming
comp). On the contrary physics, as the science of observable patterns
reemerge as a study of relative measure on computations (more exactly
quotient of set of computations by a relation of undistinguishability
related to person's point of view). Those are well defined through the
Church thesis in computer science. Now the objective idealist (not
solipsist) type of reality we are lead to from the comp assumption has
been defended by many buddhist schools (mainly from the Mahayana), and
has been more or less the orthodox way to consider reality during a
millennium of greek philosophy/theology. You are right it hurts common
sense.

The rest of your post has been well answered by Stathis and Quentin,
imo. I have nothing to add.
Recall that nobody asks you to believe that comp is correct, just to
assume it for the sake of the argument.

Bruno

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

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### RE: Interested in thoughts on this excerpt from Martin Rees

```

I have asked the question before, what do I experience if my measure
in the multiverse increases or decreases? My preferred answer, contra
the ASSA/ QTI skeptics, is nothing. However, the interesting observation
that our perception of time changes with age, so that an hour seems
subjectively much longer for a young child than for an older person, would
seem to correlate with decreasing measure as a person grows older. One
explanation for this could be that if there are more copies of us around
in the multiverse, we have more subjective experience per unit time. This
would mean that if we lived forever, the years then the centuries and millenia
would fly past at a subjectively faster and faster rate as we age and our
measure continuously drops.

I actually believe that a psychological explanation for this phenomenon is more
likely correct (an hour is a greater proportion of your life if you are a young
child)
but it's an interesting idea.

Stathis Papaioannou

Date: Fri, 4 Aug 2006 02:10:53 +1000
From: [EMAIL PROTECTED]
Subject: Re: Interested in thoughts on this excerpt from Martin Rees

Someone called me to task for this posting (I forget who, and I've
lost the posting now). I tried to formulate the notion I expressed
here more precisely, and failed! So I never responded.

What I had in mind was that future observer moment of my current one
will at some point have a total measure diminishing at least as fast
as an exponental function of OM age. This is simply a statement that
it becomes increasingly improbable for humans to live longer than a
certain age.

Whilst individual OMs will have exponentially decreasing measure due
to the linear increase in complexity as a function of universe age,
total OM measure requires summing over all OMs of a given age (which
can compensate). This total OM measure is a 3rd person type of
quantity - equivalent to asking what is the probability of a conscious
organism existing at universe age t. It seems plausible that this
might diminish in some exponential or faster fashion after a few
standard deviation beyond the mean time it takes to evolve
consciousness, but I do not have any basis for making this claim. If
we assume a normal distribution of times required for evolving
consciousness, then the statement is true for example, but I'm wise
enough to know that this assumption needs further justification. The
distribution may be a meanless thing like a power law for example.

So sorry if I piqued someones interest too much - but then we can leave
this notion as a conjecture :)

Cheers

On Fri, Jul 28, 2006 at 12:07:37AM +1000, Russell Standish wrote:
Thanks for giving a digested explanation of the argument. This paper
was discussed briefly on A-Void a few weeks ago, but I must admit to
not following the argument too well, nor RTFA.

My comment on the observer moment issue, is that in a Multiverse, the
measure of older observer moments is less that younger ones. After a
certain point in time, the measure probably decreases exponentially or
faster, so there will be a mean observer moment age.

So contra all these old OMs dominating the calculation, and giving
rise to an expected value of Lambda close to zero, we should expect
only a finite contribution, leading to an expected finite value of
Lambda.

We don't know what the mean age for an observer moment should be, but
presumably one could argue anthropically that is around 10^{10}
years. What does this give for an expected value of Lambda?

Of course their argument does sound plausible for a single universe -
is this observational evidence in favour of a Multiverse?

Cheers

--
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is of type application/pgp-signature. Don't worry, it is not a
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may safely ignore this attachment.

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### RE: Interested in thoughts on this excerpt from Martin Rees

```
CW writes:

It's like teleportation. Maybe you can demonstrate with 1 or 2 particles in
QM.
But it's another very different thing when we are talking about human beings
(or simple animals).
Maybe other very knowledgeable prof. (like scerir???) in this list can
provide useful ref.

There is a distinction between quantum teleportation and classical
teleportation.
Quantum teleportation involves transmitting the exact quantum state of an entity
and has actually been demonstrated experimentally with handfuls of particles in
the past decade. Here is reasonably simple summary:

http://www.research.ibm.com/quantuminfo/teleportation/

The cited article states that for reasons of *engineering* difficulty we won't
be
teleporting people around in the near future, but there is no theoretical
reason
why it couldn't eventually be done. A person who quantum teleports from A to
B would arrive at B in an *identical* physical state, which is actually more
than
can be said if he had walked, since our quantum state changes every moment.
So, if we remain the same person when walking, we should remain the same
person when quantum teleporting. It is theoretically possible that there is
some
non-physical factor necessary for consciousness which does not survive perfect
physical duplication but there is no reason whatsoever to believe this. It
would be
like saying that there is some non-physical factor in my computer, and a
perfect
physical copy of it would not be functionally equivalent because it would lack
this
factor.

Classical teleportation cannot copy something exact to the quantum level, but
rather involves making a close enough copy. It is obvious, I think, that this
is
theoretically possible, but it is not immediately obvious how good the copy of
a
person would have to be (what Bruno calls the substitution level) in order to
feel himself to be the same person. But as mentioned above, I don't think we
need to insist on perfect duplication to the quantum level, because this
doesn't
even happen from moment to moment in everyday life.

Stathis Papaioannou
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### Re: Interested in thoughts on this excerpt from Martin Rees

```
Hi Stathis,

I agree with what you say. Note that quantum information is very
different from classical information. Quantum information in general
cannot be copied or cloned, so that there is no relative local back-up
possible. That is why in quantum teleportation, the annihilation of the
original is unavoidable.

But it is easy to explain that this is already a simple consequence
of comp. Any piece of matter is the result of a sum on an infinity of
interfering computations: there is no reason to expect this to be
clonable without cloning the whole UD, but this would not change any
internal measures (by Church thesis and machine independence).

Of course we can prepare quantum identical states, as the UD cannot not
emulates them all, or their rational approximations, which by linearity
of the quantum laws, are enough (from the 1-person point of view).

QM explains well how bits emerge from qubits, but comp promises a
reversed transformation: how qubits are necessarily dreamed by bits.

Bruno

Le 05-août-06, à 15:34, Stathis Papaioannou a écrit :

CW writes:

It's like teleportation. Maybe you can demonstrate with 1 or 2
particles in
QM.
But it's another very different thing when we are talking about human
beings
(or simple animals).
Maybe other very knowledgeable prof. (like scerir???) in this list
can
provide useful ref.

There is a distinction between quantum teleportation and classical
teleportation.
Quantum teleportation involves transmitting the exact quantum state of
an entity
and has actually been demonstrated experimentally with handfuls of
particles in
the past decade. Here is reasonably simple summary:

http://www.research.ibm.com/quantuminfo/teleportation/

The cited article states that for reasons of *engineering* difficulty
we won't be
teleporting people around in the near future, but there is no
theoretical reason
why it couldn't eventually be done. A person who quantum teleports
from A to
B would arrive at B in an *identical* physical state, which is
actually more than
can be said if he had walked, since our quantum state changes every
moment.
So, if we remain the same person when walking, we should remain the
same
person when quantum teleporting. It is theoretically possible that
there is some
non-physical factor necessary for consciousness which does not survive
perfect
physical duplication but there is no reason whatsoever to believe
this. It would be
like saying that there is some non-physical factor in my computer, and
a perfect
physical copy of it would not be functionally equivalent because it
would lack this
factor.

Classical teleportation cannot copy something exact to the quantum
level, but
rather involves making a close enough copy. It is obvious, I think,
that this is
theoretically possible, but it is not immediately obvious how good the
copy of a
person would have to be (what Bruno calls the substitution level) in
order to
feel himself to be the same person. But as mentioned above, I don't
think we
need to insist on perfect duplication to the quantum level, because
this doesn't
even happen from moment to moment in everyday life.

Stathis Papaioannou
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### Re: Interested in thoughts on this excerpt from Martin Rees

```
This is one of those truly cracked ideas that is not wise to air in
polite company. Nevertheless, it can be fun to play around with in
this forum. I had a similarly cracked idea a few years ago about 1st
person experienced magic, which we batted around a bit at the tiome
without getting anywhere.

The trouble I have with this idea is that I can't see the connection
between OM measure and the sensation of passage of time. In contrast
to your statement of nothing however, a lower measure OM will appear
more complex - so we experience growth in knowledge as our measure
decreases. Increasing measure OM's will correspond to memory
erasure, in the sense of quantum erasure.

Cheers

On Sat, Aug 05, 2006 at 10:44:49PM +1000, Stathis Papaioannou wrote:

I have asked the question before, what do I experience if my measure
in the multiverse increases or decreases? My preferred answer, contra
the ASSA/ QTI skeptics, is nothing. However, the interesting observation
that our perception of time changes with age, so that an hour seems
subjectively much longer for a young child than for an older person, would
seem to correlate with decreasing measure as a person grows older. One
explanation for this could be that if there are more copies of us around
in the multiverse, we have more subjective experience per unit time. This
would mean that if we lived forever, the years then the centuries and
millenia
would fly past at a subjectively faster and faster rate as we age and our
measure continuously drops.

I actually believe that a psychological explanation for this phenomenon is
more
likely correct (an hour is a greater proportion of your life if you are a
young child)
but it's an interesting idea.

Stathis Papaioannou

Date: Fri, 4 Aug 2006 02:10:53 +1000
From: [EMAIL PROTECTED]
Subject: Re: Interested in thoughts on this excerpt from Martin Rees

Someone called me to task for this posting (I forget who, and I've
lost the posting now). I tried to formulate the notion I expressed
here more precisely, and failed! So I never responded.

What I had in mind was that future observer moment of my current one
will at some point have a total measure diminishing at least as fast
as an exponental function of OM age. This is simply a statement that
it becomes increasingly improbable for humans to live longer than a
certain age.

Whilst individual OMs will have exponentially decreasing measure due
to the linear increase in complexity as a function of universe age,
total OM measure requires summing over all OMs of a given age (which
can compensate). This total OM measure is a 3rd person type of
quantity - equivalent to asking what is the probability of a conscious
organism existing at universe age t. It seems plausible that this
might diminish in some exponential or faster fashion after a few
standard deviation beyond the mean time it takes to evolve
consciousness, but I do not have any basis for making this claim. If
we assume a normal distribution of times required for evolving
consciousness, then the statement is true for example, but I'm wise
enough to know that this assumption needs further justification. The
distribution may be a meanless thing like a power law for example.

So sorry if I piqued someones interest too much - but then we can leave
this notion as a conjecture :)

Cheers

On Fri, Jul 28, 2006 at 12:07:37AM +1000, Russell Standish wrote:
Thanks for giving a digested explanation of the argument. This paper
was discussed briefly on A-Void a few weeks ago, but I must admit to
not following the argument too well, nor RTFA.

My comment on the observer moment issue, is that in a Multiverse, the
measure of older observer moments is less that younger ones. After a
certain point in time, the measure probably decreases exponentially or
faster, so there will be a mean observer moment age.

So contra all these old OMs dominating the calculation, and giving
rise to an expected value of Lambda close to zero, we should expect
only a finite contribution, leading to an expected finite value of
Lambda.

We don't know what the mean age for an observer moment should be, but
presumably one could argue anthropically that is around 10^{10}
years. What does this give for an expected value of Lambda?

Of course their argument does sound plausible for a single universe -
is this observational evidence in favour of a Multiverse?

Cheers

--
*PS: A number of people ask me about the attachment to my email, which
is of type application/pgp-signature. Don't worry, it is not a
virus. It is an electronic signature, that may be used to verify this
email came from me if you have PGP or GPG installed. Otherwise, you
may safely ignore this attachment```

### RE: Interested in thoughts on this excerpt from Martin Rees

```
From: Bruno Marchal
All we need to *reason* for getting consequence of comp is that such
substitution is *in principle* possible. Theoreticians does that, in many
fields. I insist that the UDA (Universal Dovetailer Argument) is based on
the notion of generalized brain: you could say that your brain in the
entire galaxy. By comp this entails the entire galaxy is turing emulable,
then, this is enough to say the platonic UD will go through your
generalized brain soon or later (in term of number of steps), and that is
enough to understand that comp makes obligatory that the laws of physics
emerge from the relation existing among numbers (that + other steps of the
reasoning of course). The impracticality of substitution is just not
relevant to throw out the theoretical consequences. Then comp can be tested
experimentally due to others consequences (like the observable interference
among many computations, etc.). OK?

I have an idea (or dream) for some time. Let's call it the perfect universe
argument (PUA).
The purpose of PUA is to produce a perfect universe (a perfect world without
any crimes, any bad things, any natural disasters ... etc.).
It's as follows:
(1) I teleport myself to the origin of the universe.
(2) I adjust some parameters of the universe. (This is like adjusting some
parameters in a modern PC program
so that you can get the perfect result when running the program.)
(3) The adjustment changes the whole universe immediately and the universe
becomes perfect.
PUA is possible in principle, right? Does it agree to Comp. and UDA?

From: Stathis Papaioannou
Do you believe that IF you vanished at point A and a copy of you created at
point B who was physically and mentally similar to the original to the same
extent as if you had walked from A to B you would have survived? If you
answer no then you are opening yourself up to the possibility that would
not survive the walk either. If you argue that the copy might be
physiacally the same but mentally different then you are saying there is
some non-physical basis to identity which survives walking but not
teleportation, which I suppose is possible, but there is no reason to
believe that such a strange thing would or could have evolved.

I can't compare teleportation of human beings with walking since
teleportation is still a fiction now.
It's also unknown if there is something non-physical in human (or living)
beings.

Thanks.

WC.

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### RE: Interested in thoughts on this excerpt from Martin Rees

```
CW writes:

From: Stathis Papaioannou
Do you believe that IF you vanished at point A and a copy of you created at
point B who was physically and mentally similar to the original to the same
extent as if you had walked from A to B you would have survived? If you
answer no then you are opening yourself up to the possibility that would
not survive the walk either. If you argue that the copy might be
physiacally the same but mentally different then you are saying there is
some non-physical basis to identity which survives walking but not
teleportation, which I suppose is possible, but there is no reason to
believe that such a strange thing would or could have evolved.

I can't compare teleportation of human beings with walking since
teleportation is still a fiction now.
It's also unknown if there is something non-physical in human (or living)
beings.

Yes, but it's still possible to imagine what would happen *if* something were
done that at the moment seems impossible. If sodium chloride were produced
by a machine which causes the transmutation of hydrogen into other elements,
would it still taste salty? I would say that the answer is of course, whether
or
not such a machine could ever be built. I don't even see how it is *logically*
possible that pure NaCl could taste different depending on where it came from.

Stathis Papaioannou
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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Le 04-août-06, à 08:03, W. C. a écrit :

From: Bruno Marchal
All we need to *reason* for getting consequence of comp is that such
substitution is *in principle* possible. Theoreticians does that, in
many
fields. I insist that the UDA (Universal Dovetailer Argument) is
based on
the notion of generalized brain: you could say that your brain in the
entire galaxy. By comp this entails the entire galaxy is turing
emulable,
then, this is enough to say the platonic UD will go through your
generalized brain soon or later (in term of number of steps), and
that is
enough to understand that comp makes obligatory that the laws of
physics
emerge from the relation existing among numbers (that + other steps
of the
reasoning of course). The impracticality of substitution is just not
relevant to throw out the theoretical consequences. Then comp can be
tested
experimentally due to others consequences (like the observable
interference
among many computations, etc.). OK?

I have an idea (or dream) for some time. Let's call it the perfect
universe
argument (PUA).
The purpose of PUA is to produce a perfect universe (a perfect world
without
any crimes, any bad things, any natural disasters ... etc.).
It's as follows:
(1) I teleport myself to the origin of the universe.

Are you sure that this is possible, even just in principle? Actually,
just to show me that it could be possible in principle you have to give
me your fundamental assumptions. Actually it looks like you are
assuming the following:
a) there is a physical universe (well, with comp this is already
impossible)
b) accepting a) you assume that that universe has an origin (this
would be impossible even in principle in case there is no origin)
c) Accepting a) and b) you assume physical laws making time
travel possible (which is of course controversial;  this could be in
principle possible with very special assumption, which could also be
false in principle with other assumption).
If you do theoretical reasonings you have to make clear the assumptions
which are making things possible in principle. Up to here, I can
follow you (I can imagine such fundamental assumptions).

(2) I adjust some parameters of the universe. (This is like adjusting
some
parameters in a modern PC program
so that you can get the perfect result when running the program.)
(3) The adjustment changes the whole universe immediately and the
universe
becomes perfect.

Your 2 and 3 are unfortunately definitely impossible with comp
not obvious (but follows from diagonalization similar to those I have
already illustrated). Let me just say that it can be shown that if you
want your PU enough rich for Universal machine to appear, then you
cannot, even in principle, filter those bad machines will easily

PUA is possible in principle, right? Does it agree to Comp. and UDA?

So the PUA *is* incompatible with comp. The most basic contradiction is
given by the consequence of the UDA: there is no physical universe:
only computations/dreams some of which coheres so as to provides
local first person plural notion supervening on them. But even in the
case those coherence would define for all practical purposes a
physical universe, and even if it has some sort of physical origin
and you can teleport yourself to its origin, the laws of computer
science will eventually prevent you of reprogramming the universe to
satisfy your goal of making it perfect.

Now, honestly this is a good news. Perfection is a virtue, and comp
makes it impossible to define any virtue from inside the universe,
and this saves our freeness, and explains why even Gods cannot conceive
sufficiently rich universe with build-in perfection.

From: Stathis Papaioannou
Do you believe that IF you vanished at point A and a copy of you
created at
point B who was physically and mentally similar to the original to
the same
extent as if you had walked from A to B you would have survived? If
you
answer no then you are opening yourself up to the possibility that
would
not survive the walk either. If you argue that the copy might be
physiacally the same but mentally different then you are saying there
is
some non-physical basis to identity which survives walking but not
teleportation, which I suppose is possible, but there is no reason to
believe that such a strange thing would or could have evolved.

I can't compare teleportation of human beings with walking since
teleportation is still a fiction now.

But classical teleportation is possible in principle once we assume
comp. Now I don't want to argue for comp, but there is no contradiction
between comp and any known facts. To be sure I did believe in non-comp
at the time I thought that classical mechanics was valid, but the
quantum kills all the non-comp aspect of physics, until now.

It's also unknown ```

### RE: Interested in thoughts on this excerpt from Martin Rees

```
From: Bruno Marchal
Are you sure that this is possible, even just in principle? Actually, just
to show me that it could be possible in principle you have to give me your
fundamental assumptions. Actually it looks like you are assuming the
following:
a) there is a physical universe (well, with comp this is already
impossible)

I remember other people mentioned before. *Normal* people can't accept that
there is no physical universe.
Even Buddhists won't say that.

b) accepting a) you assume that that universe has an origin (this would
be impossible even in principle in case there is no origin)

Just like everything, it's more reasonable that there was an origin than no
origin, even for the universe.

c) Accepting a) and b) you assume physical laws making time travel
possible (which is of course controversial;  this could be in principle
possible with very special assumption, which could also be false in
principle with other assumption).

Time travel is as possible as teleportation of human beings.

If you do theoretical reasonings you have to make clear the assumptions
which are making things possible in principle. Up to here, I can follow
you (I can imagine such fundamental assumptions).

Of course, there are many details and assumptions to say PUA is possible.
My point is that PUA is possible just like teleportation of human beings.
I think they have similar possibility.

Your 2 and 3 are unfortunately definitely impossible with comp without
deciding your PU (your Perfect Universe) being trivial. This is not obvious
(but follows from diagonalization similar to those I have already
illustrated). Let me just say that it can be shown that if you want your PU
enough rich for Universal machine to appear, then you cannot, even in

Just like I can make a PC program running perfectly. I don't see why *this*
universe can't be perfect.

So the PUA *is* incompatible with comp. The most basic contradiction is
given by the consequence of the UDA: there is no physical universe: only
computations/dreams some of which coheres so as to provides local first
person plural notion supervening on them. But even in the case those
coherence would define for all practical purposes a physical universe,
and even if it has some sort of physical origin and you can teleport
yourself to its origin, the laws of computer science will eventually
prevent you of reprogramming the universe to satisfy your goal of making
it perfect.

Which laws of computer science? My computer science says I can make a
perfect program.

From: Stathis Papaioannou
Yes, but it's still possible to imagine what would happen *if* something
were done that at the moment seems impossible. If sodium chloride were
produced by a machine which causes the transmutation of hydrogen into other
elements, would it still taste salty? I would say that the answer is of
course, whether or not such a machine could ever be built. I don't even
see how it is *logically* possible that pure NaCl could taste different
depending on where it came from.

I still can't compare teleportation of human beings with NaCl. Too far away!

Thanks.

WC.

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### Re: Interested in thoughts on this excerpt from Martin Rees

```
Le 02-août-06, à 10:20, C. W. a écrit :

Hi, Bruno,

Sorry for my na鴳e question.
Common people would think that UDA is just imagination since you use the
teleportation
example and teleportation of human beings is still a science fiction.
Nobody can show that the substitution level really exists and teleportation
of human beings is really workable.
I really wonder if it's OK to use teleportation as thought experiment.

All we need to *reason* for getting consequence of comp is that such substitution is *in principle* possible. Theoreticians does that, in many fields.
I insist that the UDA (Universal Dovetailer Argument) is based on the notion of generalized brain: you could say that your brain in the entire galaxy. By comp this entails the entire galaxy is turing emulable, then, this is enough to say the platonic UD will go through your generalized brain soon or later (in term of number of steps), and that is enough to understand that comp makes obligatory that the laws of physics emerge from the relation existing among numbers (that + other steps of the reasoning of course).
The impracticality of substitution is just not relevant to throw out the theoretical consequences.
Then comp can be tested experimentally due to others consequences (like the observable interference among many computations, etc.). OK?

Bruno

PS (I am alas again busy. Please be patient for the replies).

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

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### RE: Interested in thoughts on this excerpt from Martin Rees

```

CW writes:

Hi, Bruno,

Sorry for my na鴳e question.
Common people would think that UDA is just imagination since you use the
teleportation
example and teleportation of human beings is still a science fiction.
Nobody can show that the substitution level really exists and teleportation
of human beings is really workable.
I really wonder if it's OK to use teleportation as thought experiment.

Do you believe that IF you vanished at point A and a copy of you created
at point B who was physically and mentally similar to the original to the same
extent as if you had walked from A to B you would have survived? If you
answer no then you are opening yourself up to the possibility that would
not survive the walk either. If you argue that the copy might be physiacally
the same but mentally different then you are saying there is some
non-physical basis to identity which survives walking but not teleportation,
which I suppose is possible, but there is no reason to believe that such a
strange thing would or could have evolved.

Stathis Papaioannou
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### Re: Interested in thoughts on this excerpt from Martin Rees

```
Hi, Bruno,

Sorry for my na鴳e question.
Common people would think that UDA is just imagination since you use the
teleportation
example and teleportation of human beings is still a science fiction.
Nobody can show that the substitution level really exists and teleportation
of human beings is really workable.
I really wonder if it's OK to use teleportation as thought experiment.

Thanks.

WC.

-Original Message-
[mailto:[EMAIL PROTECTED] On Behalf Of Bruno Marchal
Sent: Friday, July 28, 2006 5:38 PM
Subject: Re: Interested in thoughts on this excerpt from Martin Rees

Le 26-juil.-06, ?13:34, Russell Standish wrote :

Yes, although you do have a different perception of theology to Rees,
and indeed practically all other scientists I know of. I won't comment
on theologians of course, I don't really know any all that well.

Not to say your perception is wrong, but it will take a Herculean
effort to get other to think along your lines.

All what I say is that IF we assume the Comp Hypothesis then there is
no choice in the matter.
I have already done the Herculean effort under the UDA. I don't think
there is problem with that. Even in this list, if you look carefully,
critics always converge toward a critics of COMP, not of the reasoning.
I would say in the average 50% of those who really doesn't like the
idea of the reversal Physics/psycho-bio-theo-logy-number-theory will
criticize the yes doctor or the Arithmetical realism (until they see
what I mean by it). I have never met a critics of Church thesis, except
the physicalist reinterpretation done by David Deutsch (which does not
work).
...
...
...

_
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### Re: Interested in thoughts on this excerpt from Martin Rees

```

Le 26-juil.-06, à 13:34, Russell Standish wrote :

Yes, although you do have a different perception of theology to Rees,
and indeed practically all other scientists I know of. I won't comment
on theologians of course, I don't really know any all that well.

Not to say your perception is wrong, but it will take a Herculean
effort to get other to think along your lines.

All what I say is that IF we assume the Comp Hypothesis then there is
no choice in the matter.
I have already done the Herculean effort under the UDA. I don't think
there is problem with that. Even in this list, if you look carefully,
critics always converge toward a critics of COMP, not of the reasoning.
I would say in the average 50% of those who really doesn't like the
idea of the reversal Physics/psycho-bio-theo-logy-number-theory will
criticize the yes doctor or the Arithmetical realism (until they see
what I mean by it). I have never met a critics of Church thesis, except
the physicalist reinterpretation done by David Deutsch (which does not
work).

Let me quote Danny who send this message sometime ago, + an answer I
wrote at that time but never send, and which can give clue why the
reversal will ndeed take time to be swallowed. In one word: it is just
that theology is a taboo field since the Roman made theology reserved
for political purposes. Dogmatic Materialist and Atheist has always
benefit of this by an apparent reaction which really goes in the same
Aristotelian direction.

Danny wrote (some times ago):

I doubt Marchal's ideas will be made widely known or popularized in
the foreseeable future.  The problem isn't with the name of his
theory, or with any problem with Bruno per se beyond this:  There
doesn't seem to be an easily reducible way to summarize the theory in
a manner that is digestible to anyone beyond the highly specialized in
similar fields.  I certainly understand the basics of some of his
ideas, but when it gets into all his logical analysis I just have
never found myself willing to devote myself to the time required to
really get into the detail of where he is coming from.  And I would
consider myself highly interested in these topics and at least
reasonably intelligent.

Even something as mundane as the MWI (to this group at least) runs
into a brickwall when presented to the layperson.  You should see the
conversations I have with my wife.  Tell people everything is made of
strings.  Or space and time can be warped and curved.  They may not
understand the science and math behind it at all, but at least you are
speaking their language.

The world is not ready for his ideas.  Even for the most part the
world of scientists in my opinion.

An old attempt toward an answer:

Let us go back at the eve of humanity ...

Since humans are humans, mainly two very opposite ways to handle
fundamental questions has been developed. Note that ten thousand
intermediate positions between those two ways exists.

Those two ways are:

1) Close your eyes, and think.
2) Open your eyes, and think.

We could call the first way the mystical way, and the second the
empirical way. Unfortunately today we are living with some prejudices,
and many scientist would say that the mystical way are unscientific
and that only the empirical way would be scientific.
Personally I doubt very much that such a separation should be done
there. Empirist can be as irrational as some mystics can be. And
history tells us that mysticism can lead to rationalism. Indeed,  in
of *rational* mysticism or rational theology from Pythagoras to
Proclus: it can be called platonism. The main gift of that rational
mysticism (platonism) has been the *science* of mathematics (as opposed
as its art and technic which Pythagoras knew by its many travels in the
east and south).
Today 1) is close to the theoretical minded mind, and 2) is close
to the experimentalist minded mind, and I don't think it would be an
exaggeration to say everybody believes science has developed through a
perpetuating back and forth between both theories and experimentations.
And a darwinist could add that we have now empirical reasons to believe
that such a back and forth between theory/representation and
experiment/practice has begun well before humanity. Our evolved genome
and brain is already reflecting the presence of build-in theories
(innate ideas) an trials.

Nevertheless, although locally 1) and 2) are both necessary for
surviving, it seems to me that at a deeper level, with respect to the
fundamental inquiries, the difference between 1) and 2) cannot been
neglected. The difference culminated through the work of Plato and
Aristotle with their very different conceptions of reality.

For Plato (and many eastern researchers) , grosso modo, reality should
explain what we see without taking it for granted. In particular matter
and nature are ```

### Re: Interested in thoughts on this excerpt from Martin Rees

```
Russell Standish writes, regarding http://arxiv.org/abs/astro-ph/0607227 :

Thanks for giving a digested explanation of the argument. This paper
was discussed briefly on A-Void a few weeks ago, but I must admit to
not following the argument too well, nor RTFA.

My comment on the observer moment issue, is that in a Multiverse, the
measure of older observer moments is less that younger ones. After a
certain point in time, the measure probably decreases exponentially or
faster, so there will be a mean observer moment age.

I had a similar thought. I am curious to know your reasoning or
justification for why this should be true.

I have not read the papers referenced by this one, but the authors allude
to previous work: Given some a priori distribution of the values of
the fundamental constants across the ensemble, the probability for a
'typical' obserer to measure a certain value of one or more of these
constants is usually taken to be proportional to the number of observers
(or the number of observers per baryon).

It is this last parenthetical comment I found interesting.  Apparently
there has been a difference in previous work about whether the measure
should be proportional to observers vs observers per baryon.  Consider
two cases: one observer in a universe of a given size, or one observer
in a universe twice that big.  These would be considered the same by a
number-of-observers measure, but the first would have twice the measure
if it was observers per baryon.

I argued some time past, based on some hand-wavey arguments, that the
latter measure is better - we attribute a portion of a universe's measure
to an observer, proportional to the fraction of the universe that the
observer takes up.  This came from the UDASSA concept I was describing
in detail last year.  It amounts to the observers-per-baryon measure.
It's interesting that physicists have considered a similar idea.

In terms of time, like Russell I would say that ancient observer-moments
should get less measure than early ones, for the same basic reason -
system that instantiates the OM within the universe.  My reasoning
though would imply that measure should be inversely proportional to
age, rather than Russell's suggestion of an exponential decay.  So I am
curious where he got that.  I could describe my reasoning in more detail
if there is interest.

So contra all these old OMs dominating the calculation, and giving
rise to an expected value of Lambda close to zero, we should expect
only a finite contribution, leading to an expected finite value of
Lambda.

We don't know what the mean age for an observer moment should be, but
presumably one could argue anthropically that is around 10^{10}
years. What does this give for an expected value of Lambda?

I don't know if I know enough physics to figure that out.  I'll take
another look at the paper.

I see that I misstated the reason why the CC limits observation.
It's not that the universe becomes uninhabitable.  Rather, computation
and observation is assumed to be proportional to internal energy divided
by external universe temperature.  It turns out that the optimal strategy
is to accumulate and store up as much energy as you can, as the universe
expands and cools.  Then, when the universe is all cooled down, you go

In a universe with a high CC, you can't accumulate as much energy,
because it expands more quickly and hence mass-energy thins out faster.
It cools down sooner and you don't have as much stored up at that time,
so you can't do as much.

So what we would have to say is that that strategy is no longer optimal
because such distant observer-moments will have low measure, and we care
more about OMs which have high measure.  (I admit that few people take
the idea seriously that seemingly undetectable OM measure changes should
matter, but I can assume that this is a super-advanced civilization and
everyone is smart, so of course they will agree with me!)

Instead, the optimal strategy maximizes the total measure of OM-
computations, and that requires doing more computations early.  OTOH,
it is more efficient to wait until the universe is cooler, we can do more
computing with the same amount of energy.  Maximizing the product of these
two effects would require a detailed model for how quickly measure decays
with time.  (We'd also have to consider whether measure should change with
temperature, which it might in my model, I have to think about it more.)

Of course their argument does sound plausible for a single universe -
is this observational evidence in favour of a Multiverse?

I think what you're saying is that if this is the only universe, and if
OMs will be far in the future, hence by the ASSA we are unlikely to be
experiencing present-day OMs.  This was the basic concept of a paper ```

### Re: Interested in thoughts on this excerpt from Martin Rees

```
Saibal Mitra writes:
From: Hal Finney [EMAIL PROTECTED]
The real problem is not just that it is a philosophical speculation,
it is that it does not lead to any testable physical predictions.
The string theory landscape, even if finite, is far too large for
systematic exploration.  Our ideas, with an infinite number of possible
universes, are even worse.

I'm not so sure that our ideas are worse.

I should clarify, I meant that our ideas are even worse in terms of
systematic exploration of all the possibilities, because we generally
consider an infinity of possible universes, while the string theory
landscape predicts (some people say) about 10^500 possible universes.

If you read some recent articles,
e.g.:

http://arxiv.org/abs/astro-ph/0607227

you see that they haven't really formulated rigorous theories about measure,
probabilities etc. of the multiverse. It's still very much in the
handwaving stage.

This is actually a very interesting paper, by Starkman and Trotta.  I had
seen some mention of it but hadn't tracked it down.  Here is the abstract:

We revisit anthropic arguments purporting to explain the measured value
of the cosmological constant. We argue that different ways of assigning
probabilities to candidate universes lead to totally different anthropic
predictions. As an explicit example, we show that weighting different
universes by the total number of possible observations leads to an
extremely small probability for observing a value of Lambda equal to or
greater than what we now measure. We conclude that anthropic reasoning
within the framework of probability as frequency is ill-defined and
that it cannot be used to explain the value of Lambda, nor, likely,
any other physical parameters.

The paper is pretty technical but I thought I could understand the gist
of it.  The cosmological constant (Lambda) is a repulsive force which
drives galaxies apart in the Big Bang model.  Until a few years ago it was
thought to be entirely theoretical, but since then observations indicate
that it is real, and that the universal expansion is accelerating.
The question then becomes what would happen in universes with different
values of the CC.

The paper basically shows that observers (or civilizations) can last
longer in universes with smaller CC's.  The CC eventually puts an end
to the observations that can be made, because the expansion gets too
fast and there is no longer enough energy density.  The higher the CC,
the sooner this happens.  With CC's as high as what we observe, the
theoretical lifetime of civilization is much shorter than in universes
with smaller CC's.

The authors choose to use as their measure, the number of times the
CC can be measured in a given universe.  This makes low-CC universes
have a much higher measure, because the window for CC observations is
longer in those.  Hence they conclude that the highest probability is
for a CC much smaller than we observe, and so our own CC value cannot
be explained anthropically.

This is in contrast to earlier results which used different measures, such
as the number of galaxies, and found that our CC results were consistent
with anthropic considerations.  The authors argue that their measure is
at least as philosphically justifiable as those earlier papers, and their
real point is that no measure can be justified as better than another,
hence all anthropic reasoning is just hand-waving.

In our terms we might put it like this.  The new paper essentially uses a
measure which is the number of possible observer-moments in the universe.
Universes with a high CC go through a big rip process eventually,
accelerating to a super-expansion mode and presumably putting an end
to observers.  Universes with a low or zero CC go through this much
later or not at all, allowing for more observer-moments.  Hence this
measure gives a bonus to universes that last a long time.

Earlier papers apparently looked at a snapshot of time similar to the
present day, and in effect based the measure on the number of observers
(assumed to be proportional to the number of galaxies).  So we have a
distinction between an observer-moment measure and an observer measure.
The two apparently give very different results, the OM measure preferring
long-lasting universes while the observer measure is more interested in
the size of the universe.

I guess I'll stop here and see if there is more interest.  To leave with
a few questions: Is there any fundamental way to decide which measure
is best?  Do the OM measure and the observer measure really give
different results, and is that significant?  Are there other measures
that might be used, and what results would they get?  And finally, will
this apparent failure of anthropic reasoning discredit the concept among
working physicists?  As I mentioned, I've already seen it used in a blog
common on Woit's blog that I pointed to the other day, in just that way.

Hal Finney

```

### Re: Interested in thoughts on this excerpt from Martin Rees

```
Thanks for giving a digested explanation of the argument. This paper
was discussed briefly on A-Void a few weeks ago, but I must admit to
not following the argument too well, nor RTFA.

My comment on the observer moment issue, is that in a Multiverse, the
measure of older observer moments is less that younger ones. After a
certain point in time, the measure probably decreases exponentially or
faster, so there will be a mean observer moment age.

So contra all these old OMs dominating the calculation, and giving
rise to an expected value of Lambda close to zero, we should expect
only a finite contribution, leading to an expected finite value of
Lambda.

We don't know what the mean age for an observer moment should be, but
presumably one could argue anthropically that is around 10^{10}
years. What does this give for an expected value of Lambda?

Of course their argument does sound plausible for a single universe -
is this observational evidence in favour of a Multiverse?

Cheers

On Thu, Jul 27, 2006 at 11:08:04AM -0700, Hal Finney wrote:
This is actually a very interesting paper, by Starkman and Trotta.  I had
seen some mention of it but hadn't tracked it down.  Here is the abstract:

The paper basically shows that observers (or civilizations) can last
longer in universes with smaller CC's.  The CC eventually puts an end
to the observations that can be made, because the expansion gets too
fast and there is no longer enough energy density.  The higher the CC,
the sooner this happens.  With CC's as high as what we observe, the
theoretical lifetime of civilization is much shorter than in universes
with smaller CC's.

The authors choose to use as their measure, the number of times the
CC can be measured in a given universe.  This makes low-CC universes
have a much higher measure, because the window for CC observations is
longer in those.  Hence they conclude that the highest probability is
for a CC much smaller than we observe, and so our own CC value cannot
be explained anthropically.

--
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is of type application/pgp-signature. Don't worry, it is not a
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may safely ignore this attachment.

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### Re: Interested in thoughts on this excerpt from Martin Rees

```
Danny Mayes writes:
Interested in thoughts on this excerpt from Martin Rees
Which approximates my ideas on the nature of reality and the possible role
of intelligence.

Well, no offense to Martin or you, but that's pretty ordinary stuff which
we have been discussing on this list since 1998.  There is an entire
website devoted to the speculation that Rees describes, the possibility
that we live in a simulation: simulation-argument.com, by former list
member Nick Bostrom.

It's always kind of disconcerting to read popularizations of the kinds
of ideas we discuss here.  Writers have to approach them so delicately,
taking such pains to marvel at the amazing and perhaps outlandish
imagination it takes to consider them seriously.  I always read these
articles with a sinking feeling, knowing that they aren't going to
say anything new to me and frustrated that the concepts can't just be
delivered straight, the way we take them here.

I've been wanting to write something about the collision between physics
and the anthropic principle, and maybe this is a good time.  As Rees
describes, recent developments in string theory, have introduced the idea
of a landscape of possible stable models.  Each point on the landscape
would correspond to a possible set of particles and physical laws.
I haven't gotten a clear picture of whether this landscape is actually
infinite or merely very large; most writers seem to think the distinction
is unimportant, because the large is so very.  Rees is typical in
how he inconsistently says first one and then the other.  (I imagine
that most of us would see the distinction as rather more important.)

Anyway, as Rees describes, this is forcing physicists to consider the
possibility that the fundamental physics of our universe is no more
meaningful than the distance from the earth to the sun: a mere accident
of nature, with the anthropic principle explaining why we are here to
see it and ask about it.  I've seen this same earth-sun analogy used in
talks by other physicists.

But what Rees does not say is that many or most physicists are being
dragged down this path kicking and screaming.  Physics is not going gently
into the anthropic night.  Most physicists, I think, see this as the
death of physics.  Rees himself admits that it in effect blurs the line
between physics and philosophy.  It calls into question the entire program
of fundamental physics, to explain why the universe is the way it is.

The real problem is not just that it is a philosophical speculation,
it is that it does not lead to any testable physical predictions.
The string theory landscape, even if finite, is far too large for
systematic exploration.  Our ideas, with an infinite number of possible
universes, are even worse.  Physicists see acceptance of anthropic
explanations as the end of physics because there is no way to make
quantitative predictions when there are so many degrees of freedom.

Now, granted, predictions may still be possible in principle - given
that the string theory landscape is finite, you could in theory explore
every part of it and create probabilistic predictions contingent on what
has been observed so far.  The problem is that there is no prospect of
actually being able to do this.  Clearly it can't be done by brute force.
Maybe someone will come up with some kind of clever sampling approach,
or perhaps some structure can eventually be found in the landscape.
But at this point there is no reason to believe that such efforts will
amount to anything.

The result is that string theory in particular has reached a dead end.
This is what physicists have been banking on for twenty years to achieve
a grand unification, a theory of everything.  And instead, they have
found within the past couple of years that it is more like a theory of
anything, in the sense that seemingly any hypothetical universe might
be consistent with string theory.  Such a theory is no theory at all,
to physicists.

The situation has gotten so bad that there is a growing backlash
against string theory.  Proponents of rival theories, who have labored
in obscurity for decades, are coming out of the woodwork and demanding
their share of attention (and the substantial research funding of which
string theory has long received the lion's share).  Two major books
are coming out this fall which proclaim the death of string theory.
One is Not Even Wrong: The Failure of String Theory And the Search for
Unity in Physical Law by Peter Woit (his blog of the same name is here,
http://www.math.columbia.edu/~woit/wordpress/ ).  The other is by Lee
Smolin: The Trouble With Physics: The Rise of String Theory, The Fall
of a Science, and What Comes Next.  Amazon even pairs the books for
you so you can get a double dose of anti-string theory.  These books
have been well reviewed and there seems to be a sense that indeed,
the general approach of physics needs to be substantially rethought.

So the bottom line is that Rees leaves us with a highly ```

### Re: Interested in thoughts on this excerpt from Martin Rees

```
Le 26-juil.-06, à 06:29, Danny Mayes quoted Rees:

x-tad-biggerSo I favor peaceful coexistence rather than constructive dialogue between science and theology

With comp (or just with deep enough introspection) you can understand that science is just modesty, and that it is not domain dependent. I favor collaboration of scientists from many disciplines on the fundamental questions which by their very nature ask for interdisciplinary open mindness. You can do theology with a 100% scientific attitude.  Not doing that is the same as abandoning theology to authoritative argument. In that case, it is not astosnihing that theology looks irrational and unscientific.

Bruno

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

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### Re: Interested in thoughts on this excerpt from Martin Rees

```
Yes, although you do have a different perception of theology to Rees,
and indeed practically all other scientists I know of. I won't comment
on theologians of course, I don't really know any all that well.

Not to say your perception is wrong, but it will take a Herculean
effort to get other to think along your lines.

Cheers

On Wed, Jul 26, 2006 at 04:21:28PM +0200, Bruno Marchal wrote:

Le 26-juil.-06, à 06:29, Danny Mayes quoted Rees:

So I favor peaceful coexistence rather than constructive dialogue
between science and theology

With comp (or just with deep enough introspection) you can understand
that science is just modesty, and that it is not domain dependent. I
favor collaboration of scientists from many disciplines on the
fundamental questions which by their very nature ask for
interdisciplinary open mindness. You can do theology with a 100%
scientific attitude.  Not doing that is the same as abandoning theology
to authoritative argument. In that case, it is not astosnihing that
theology looks irrational and unscientific.

Bruno

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

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may safely ignore this attachment.

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### Re: Interested in thoughts on this excerpt from Martin Rees

```

- Original Message -
From: Hal Finney [EMAIL PROTECTED]
Sent: Wednesday, July 26, 2006 08:28 AM
Subject: Re: Interested in thoughts on this excerpt from Martin Rees

The real problem is not just that it is a philosophical speculation,
it is that it does not lead to any testable physical predictions.
The string theory landscape, even if finite, is far too large for
systematic exploration.  Our ideas, with an infinite number of possible
universes, are even worse.  Physicists see acceptance of anthropic
explanations as the end of physics because there is no way to make
quantitative predictions when there are so many degrees of freedom.

I'm not so sure that our ideas are worse. If you read some recent articles,
e.g.:

http://arxiv.org/abs/astro-ph/0607227

you see that they haven't really formulated rigorous theories about measure,
probabilities etc. of the multiverse. It's still very much in the
handwaving stage.

Saibal

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