date:20050620

Stathis Papaioannou writes:
 Here is another way of explaining this situation. When there are multiple 
 parallel copies of you, you have no way of knowing which copy you are, 
 although you definitely are one of the copies during any given moment, with 
 no telepathic links with the others or anything like that. If a proportion 
 of the copies are painlessly killed, you notice nothing, because your 
 successor OM will be provided by one of the copies still going (after all, 
 this is what happens in the case of teleportation). Similarly, if the number 
 of copies increases, you notice nothing, because during any given moment you 
 are definitely only one of the copies, even if you don't know which one. 

 However, if your quantum coin flip causes 90% of the copies to have bad 
 experiences, you *will* notice something: given that it is impossible to 
 know which particular copy you are at any moment, or which you will be the 
 next moment, then there is a 90% chance that you will be one of those who 
 has the bad experience. Similarly, if you multiply the number of copies 
 tenfold, and give all the new copies bad experiences, then even though the 
 old copies are left alone, you will still have a 90% chance of a bad 
 experience, because it is impossible to know which copy will provide your 
 next OM.

I'm not sure I fully understand what you are saying, but it sounds like
you agree at least to some extent that copies count.  The number of
copies, even running in perfect synchrony, will affect the measure of
what that observer experiences, or as you would say, his subjective
probability.

So let me go back to Bruno's thought experiment and see if I understand
you.  You will walk into a Star Trek transporter and be vaporized and
beamed to two places, Washington and Moscow, where you will have two
(independent) copies wake up.  Actually they are uploads and running on
computers, but that doesn't matter (we'll assume).  Bruno suggests that
you would have a 50-50 expectation of waking up in Washington or Moscow,
and I think you agree.

But suppose it turns out that the Moscow computer is a parallel
processor which, for safety, runs two copies of your program in perfect
synchrony, in case one crashes.  Two synchronized copies in Moscow,
one in Washington.

Would you say in this case that you have a 2/3 expectation of waking up
in Moscow?

And to put it more sharply, suppose instead that in Washington you will
have 10 copies waking up, all independent and going on and living their
lives (to the extent that uploads can do so), sharing only the memory
of the moment you walked into the transporter.  And in Moscow you will
have only one instance, but it will be run on a super-parallel computer
with 100 computing elements, all running that one copy in parallel and
synchronized.

So you have 10 independent copies in Washingon, and 100 copies that
are all kept in synchrony in Moscow.  What do you expect then?  A 90%
chance of waking up in Washington, because 9/10 of the versions of you
will be there?  Or a 90% chance of waking up in Moscow, because 9/10 of
the copies of you will be there?

I think, based on what you wrote above, you will expect Moscow, and that
copies count in this case.

If you agree that copies count when it comes to spatial location, I
wonder if you might reconsider whether they could count when it comes
to temporal location.  I still don't have a good understanding of this
situation either, it is counter-intuitive, but if you accept that the
number of copies, or as I would say, measure, does make a difference,
then it seems like it should apply to changes in time as well as space.

Hal Finney

Re: copy method important?


George Levy writes:

Psychological copying is much less stringent than Physical copying. It 
requires that the person being copied feels the same as the original, a la 
Turing test. This introduce the intriguing  possibility of psychological 
indeterminacy which allows me to regard myself as the same person this 
evening as I was this morning, even though I am actually physically 
strictly different. Psychological indeterminacy  support COMP and the 
associated experiments between Brussels, Washington and Moscow and is not 
restricted by the Quantum Non-Cloning Theorem. Psychological indeterminacy 
also raises the question of how different should I be until I become 
someone else. How big am I?


Yes, and the answer to the question how different should I be until I 
become someone else is ultimately arbitrary. One neo-Lockean theory in the 
philosophy of personal identity (I forget which philosopher this is due to, 
perhaps someone could enlighten me) goes like this: there are three 
individuals A, B, C at three sequential times t1, t2, t3 respectively. C has 
no recollection of ever being A or anything about A's experiences; however, 
B recalls something about being A, and C recalls something about being B. 
Therefore, with this partial transfer of memories, we can say that A and C 
were actually the same person. This allows us to maintain that a person with 
failing memory remains the same person. However, it also allows us to say 
that any arbitrary person X at time t1 was identical with any other 
arbitrary and apparently unrelated person Y at a later time t2, provided 
that suitable intermediates could be found between t1 and t2.


--Stathis Papaioannou

_
Sell your car for $9 on carpoint.com.au   
http://www.carpoint.com.au/sellyourcar

Re: death

Stathis Papaioannou writes:
 Returning to your example, if God creates a person, call him A, and a day 
 later kills him, A will be really dead (as opposed to provisionally dead) if 
 there will never be any successor OM's to his last conscious moment. Now, 
 suppose God kills A and then creates an exact copy of A along with his 
 environment, call him B, on the other side of the planet. B has all of A's 
 memories up to the moment before he was killed. This destruction/creation 
 procedure is, except for the duplication of the environment, exactly how 
 teleportation is supposed to work. I think most people on this list would 
 agree that teleportation (if it could be made to work, which not everyone 
 does agree is possible) would be a method of transportation, not execution: 
 even though the original dies, the copy has all his memories and provides 
 the requisite successor OM in exactly the same way as would have happened if 
 the original had continued living. So in the example above, if B is an exact 
 copy of A in an exact copy of A's environment, A would become B and not 
 even notice that there had been any change.

I'm not sure I would put it like this, although I agree that this would
probably become a common way of describing it.  But there are some aspects
of the process by which A becomes B which are different from our usual,
moment-to-moment continuity of identity.  One obvious difference is that
it is a divine miracle.  This can hardly be neglected.  Even if we imagine
this being done technologically rather than miraculously, with A's brain
being scanned and transmitted to where B will be created, the process of
making this scan will increase the measure of that OM for A by virtue
of storing it in extra places.  This may manifest as the potential for
future copies of A to be created starting with that exact mental moment.
People may come to view transporting as a dangerous activity which puts
them at risk of the creation of unauthorized copies.

These are all ways in which seemingly abstract and metaphysical questions
become manifest in the real world.  I think it is important to see that
these are not merely imperfections in the thought experiments which we
should ignore in the interests of getting at the real issues.  In my
model, the number of implementations is all important.  It is a major
determinant of measure.  Any technology which messes around with this
stuff is likely to affect the measure of the relevant observer moments.
Having your mental state recorded increases its measure, which manifests
physically as a greater chance that it can interact with the world.


 Now, consider the same situation with one difference. Instead of creating B 
 at the instant he kills A, God creates A and B at the same time, on opposite 
 sides of the planet but in exactly the same environment which will provide 
 each of them with exactly the same inputs, and their minds at all time 
 remain perfectly synchronised. God allows his two creatures to live for a 
 day, and then instantly and painlessly kills A. In the previous example, we 
 agreed that the creation of B means that A doesn't really die. Now, we have 
 *exactly* the same situation when A is killed: B is there to provide the 
 successor OM, and A need not even know that anything unusual had happened. 
 How could the fact that B was present a day, a minute or a microsecond 
 before A's death make any difference to A? All that matters is that B is in 
 the correct state to provide continuity of consciousness when A is killed. 
 Conversely, A and A's death cannot possibly have any direct effect on B. It 
 is not as if A's soul flies around the world and takes over B; rather, it 
 just so happens (because of how A and B were created) that B's mental states 
 coincide with A's, or with what A's would have been if he hadn't died.

If we focus on observer-moments, there are no A and B as separate
individuals.  There are two instantiations of a set of OMs.  Each OM has
double measure during the time that A and B exist, then it has single
measure after A has been destroyed.  It is meaningless to ask, after A
dies, if B is now A or still B, or maybe both?  (I am curious to know
how you would try to answer this question, using your terminology!)
Rather, there is then a single instantiation of the set of OMs.


 Who's measure is decreased here, A's or B's? How would any of them know 
 their measure had been decreased? It seems to me that neither A nor B could 
 *possibly* be aware that anything had happened at all. The only benefit of 
 having multiple exact copies of yourself around would seem to be as backup 
 if one is destroyed. If your measure were surreptitiously increased or 
 decreased, what symptoms would you expect to experience?

Well, we've been discussing this all along, and I have tried to answer
it several times, but I can only do so by analogy.  Having your measure
decreased is like having a chance of dying.  Having it increased is

RE: Copies Count


Hal Finney writes:


Stathis Papaioannou writes:
 Here is another way of explaining this situation. When there are 
multiple

 parallel copies of you, you have no way of knowing which copy you are,
 although you definitely are one of the copies during any given moment, 
with
 no telepathic links with the others or anything like that. If a 
proportion

 of the copies are painlessly killed, you notice nothing, because your
 successor OM will be provided by one of the copies still going (after 
all,
 this is what happens in the case of teleportation). Similarly, if the 
number
 of copies increases, you notice nothing, because during any given moment 
you

 are definitely only one of the copies, even if you don't know which one.

 However, if your quantum coin flip causes 90% of the copies to have bad
 experiences, you *will* notice something: given that it is impossible to
 know which particular copy you are at any moment, or which you will be 
the
 next moment, then there is a 90% chance that you will be one of those 
who

 has the bad experience. Similarly, if you multiply the number of copies
 tenfold, and give all the new copies bad experiences, then even though 
the

 old copies are left alone, you will still have a 90% chance of a bad
 experience, because it is impossible to know which copy will provide 
your

 next OM.

I'm not sure I fully understand what you are saying, but it sounds like
you agree at least to some extent that copies count.  The number of
copies, even running in perfect synchrony, will affect the measure of
what that observer experiences, or as you would say, his subjective
probability.

So let me go back to Bruno's thought experiment and see if I understand
you.  You will walk into a Star Trek transporter and be vaporized and
beamed to two places, Washington and Moscow, where you will have two
(independent) copies wake up.  Actually they are uploads and running on
computers, but that doesn't matter (we'll assume).  Bruno suggests that
you would have a 50-50 expectation of waking up in Washington or Moscow,
and I think you agree.

But suppose it turns out that the Moscow computer is a parallel
processor which, for safety, runs two copies of your program in perfect
synchrony, in case one crashes.  Two synchronized copies in Moscow,
one in Washington.

Would you say in this case that you have a 2/3 expectation of waking up
in Moscow?

And to put it more sharply, suppose instead that in Washington you will
have 10 copies waking up, all independent and going on and living their
lives (to the extent that uploads can do so), sharing only the memory
of the moment you walked into the transporter.  And in Moscow you will
have only one instance, but it will be run on a super-parallel computer
with 100 computing elements, all running that one copy in parallel and
synchronized.

So you have 10 independent copies in Washingon, and 100 copies that
are all kept in synchrony in Moscow.  What do you expect then?  A 90%
chance of waking up in Washington, because 9/10 of the versions of you
will be there?  Or a 90% chance of waking up in Moscow, because 9/10 of
the copies of you will be there?

I think, based on what you wrote above, you will expect Moscow, and that
copies count in this case.

If you agree that copies count when it comes to spatial location, I
wonder if you might reconsider whether they could count when it comes
to temporal location.  I still don't have a good understanding of this
situation either, it is counter-intuitive, but if you accept that the
number of copies, or as I would say, measure, does make a difference,
then it seems like it should apply to changes in time as well as space.


I agree that you will have a 90% chance of waking up in Moscow, given that 
that is the *relative* measure of your successor OM when you walk into the 
teleporter. This is the only thing that really matters with the copies, from 
a selfish viewpoint: the relative measure of the next moment:


(a) If you are copied 100 times and 99% of the copies tortured, you will 
certainly know this, as there is a 99% subjective probability that you will 
be tortured.


(b) If you are copied 100 times and the copies allowed to diverge, then 99% 
of the copies painlessly killed, that means you have a 99% chance of being 
killed, because in two steps, (i) there is a 100% chance your next OM will 
be one of the 100 copies; and (ii) there will be a 99% chance that you will 
have become one of the copies that will be killed, and if you are, then 
there will be 0% chance that you will have any next moment.


(c) If you are copied 100 times and all the copies are kept running in 
parallel, then 99% of the copies painlessly killed, you can't possibly know 
that anything odd has happened at all, because there is a 100% chance that 
your next OM will come from the one remaining copy. Similarly if there were 
10^100 copies *kept running in perfect sync* and all but one terminated. 
1/1=100/100=10^100/10^100=1.


--Stathis

Re: Dualism and the DA

2005-06-20 Thread Russell Standish

On Mon, Jun 20, 2005 at 12:01:48AM -0700, Jonathan Colvin wrote:
 Russell Standish wrote:
 
  (JC) If you want to insist that What would it be like to be a bat is 
   equivalent to the question What would the universe be like 
  if I had 
   been a bat rather than me?, it is very hard to see what the answer 
   could be. Suppose you
   *had* been a bat rather than you (Russell Standish). How would the 
   universe be any different than it is now? If you can answer that 
   question, (which is the key question, to my mind), then I'll grant 
   that the question is meaningful.
 
  
  No different in the 3rd person, very obviously different in 
  the 1st person
 
 I don't really know what that means. The only way I can make sense of the
 question is something like, If I was a bat instead of me (Jonathan Colvin),
 then the universe would consist of a bat asking the question I'm asking
 now. That's a counterfactual, a way in which the universe would be
 objectively different.

It wouldn't be counterfactual, because by assumption bats ask this
question of themselves anyway. Hence there is no difference in the 3rd
person. The 1st person experience is very different though. There are
only 1st person counterfactuals.

I definitely acknowledge the distinction between 1st and 3rd
person. This is not the same as duality, which posits a 3rd person
entity (the immaterial soul).

 
 This is, I think, the crux of the reference class issue with the DA. My (and
 your) reference class can not be merely conscious observers or all
 humans, but must be something much closer to someone (or thing) discussing
 or aware of the DA). 

I don't think this is a meaningful reference class. I can still ask
the question why am I me, and not someone else without being aware
of the DA. All it takes is self-awareness IMHO.

 I note that this reference class is certainly
 appropriate for you and me, and likely for anyone else reading this. This
 reference class certainly also invalidates the DA (although immaterial souls
 would rescue it).
 
 But at this point, I am, like Nick Bostrom, tempted to throw my hands up and
 declare the reference class issue pretty much intractable.
 
 Jonathan Colvin

Incidently, I think I may have an answer to my Why am I not Chinese
criticism, and the corresponding correction to Why am I not an ant
seems to give the same answer as I originally proposed.

I might put this in a separate posting, once I've polished my current
manuscript...

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.


A/Prof Russell Standish  Phone 8308 3119 (mobile)
Mathematics0425 253119 ()
UNSW SYDNEY 2052 [EMAIL PROTECTED] 
Australiahttp://parallel.hpc.unsw.edu.au/rks
International prefix  +612, Interstate prefix 02



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Re: death



Le 19-juin-05, à 15:52, Hal Finney a écrit :


I guess I would say, I would survive death via anything that does not
reduce my measure.


But if the measure is absolute and is bearing on the OMs, and if that 
is only determined by their (absolute) Kolmogorov complexity (modulo a 
constant) associated to the OM (how is still a mystery for me(*)), 
how could anything change the measure of an OM?


Bruno

(*) a mystery because your observer moments (OMs) are piece of 
*subjective* (1-person) moment, isn't it?


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

Re: Conscious descriptions



Le 17-juin-05, à 07:19, Russell Standish a écrit :


Hmm - this is really a definition of a universal machine. That such a
machine exists is a theorem. Neither depend on the Church-Turing
thesis, which says that any effective computation can be done using
a Turing machine (or recursive function, or equivalent). Of course the
latter statement can be considered a definition, or a formalisation,
of the term effective computation.


Hmm - I disagree. Once you give a definition of what a turing machine 
is, or of what a program fortran is, then it is a theorem that 
universal turing machine exists and that universal fortran program 
exists. To say that a universal machine exists, computing by definition 
*all* computable function, without any turing or fortran 
qualification, you need Church thesis.


Bruno


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

Re: Dualism and the DA (and torture once more)

Le 19-juin-05, à 02:39, Jonathan Colvin a écrit :

I'm sure the one in Moscow will also answer that he feels really to be the
one in Moscow.

OK.

But what you haven't answered is in what way the universe is
any different under circumstance (A) than (B). This is because there is
surely *no* difference at all.

There is no 3-difference at all, but only a God can know that. There is a first person difference: it is the difference between writing in my personal diary oh I'm in Moscow and oh I'm in Washington.
Note that here we can understand why the question why I am the one in W or why I am the one in M are 100% meaningless. This does not entail that the question where will I be in the next duplication is meaningless.

This is the reason why it makes no sense (to me) to take the position that
if I copy myself, there is a 50% chance of (A) me being observer A, and a
50% chance of (B) me being observer B. There is no difference between (A)
and (B).

This is because you look at the experiment only from the third person point of view. Suppose we iterate the self-duplication 64 times. Among the 2^64 copies most will acknowledge that they are living a random experiment (it can be shown that most of the 2^64 sequence of W and M (or 1 and 0) are kolmogorov-chaitin-solovay incompressible.
For them, that is from their first person point of view, they are in a state of maximal indeterminacy and their best theories will be that they are confronted to a Bernouilli random experience. Of course, taking your God-like point of view you can tell them that they are under an illusion, giving that there is no 3-person difference (as God knows). Let us call that illusion the first person experience and let us try to explain it. The illusion exists, unless comp is false and the reconstituted people are zombies.

This is also the reason why I choose (A) a 50% chance of torture over (B)
being copied ten times, and one copy getting tortured (where it is suggested
there is only a 10% chance of me getting tortured).

Remember that for me this sort of reasoning always suppose no future merging or duplication and also that the copies have sufficiently diverge (and then the exact computation is most probably intractable, like in real physics).

There are clearly two
different possible universes under (A) (one where I get tortured, one where
I don't). Under (B), there is no way I can make sense of what the 10%
probability applies to. The universe is identical under situation (a) I'm
person 1 who gets tortured and (b) I'm person 2-10 who doesn't.

I am with you here. and if you agree with the 50% I made my point. The 10% was introduced only for treating a case where the copies did not diverge (or the comp histories going through the states of those copies.

To insist that there *is* a difference surely requires some new kind of
dualism. Perhaps it is a valid dualism;

Not this one. Only the duality between 1 and 3 person is valid.

but I think it should be accepted
that theories reifying the 1st person are fundamentally dualistic.

The word dualism is a little too vague. Once you agree with the 50% for a WM duplication, you accept the only sort of dualism I defend, but it is more an epistemological dualism than an ontological one. It is about *knowledge* not *being* (still less substance).
This means you accept the step 3 of the Universal Dovetailing Argument (UDA):
http://iridia.ulb.ac.be/~marchal/publications/SANE2004Slide.pdf
Explanations in english:
http://iridia.ulb.ac.be/~marchal/publications/SANE2004MARCHAL.htm

But I
know what your response will be..the dualism comes from reifying the 3rd
person independent universe, and if we accept only the 1st person as real,
there is no dualism. It is quite a metaphysical leap, though, to discard the
3rd person universe. I'd like to know how to justify such a shift.

Careful, you are the one making a big leap, here. You go from the 3th step to the 8th step in the Universal Dovetailing Argument. I don't pretend it is easy or obvious. But it is not a metaphysical leap, it is a logical conclusion, once we take the comp hyp seriously enough, and this without hiding the 1-3 distinction under the rug.

It does not seem simpler by Occam, because instead of 1 universe containing
many observers, we have a multiplicity of universes, each with 1 observer.

We have a multiplicity of well defined computations, all statically existing in the arithmetical Platonia. It is simpler by occam (QM also presupposed those computations). Some computations can be seen as histories by internal self-referential inference inductive machine.

How does this differ from solipsism?

Please believe me, if comp leads to solipism, I will take it as a powerful argument against comp. But that would be currently highly premature. The logical possibility that comp makes solipsim false is due to the nuance between first person point of view (as I describe it through the duplication experiment) and

Re: death


Hal Finney writes:


Stathis Papaioannou writes:
 Returning to your example, if God creates a person, call him A, and a 
day
 later kills him, A will be really dead (as opposed to provisionally 
dead) if
 there will never be any successor OM's to his last conscious moment. 
Now,

 suppose God kills A and then creates an exact copy of A along with his
 environment, call him B, on the other side of the planet. B has all of 
A's
 memories up to the moment before he was killed. This 
destruction/creation

 procedure is, except for the duplication of the environment, exactly how
 teleportation is supposed to work. I think most people on this list 
would
 agree that teleportation (if it could be made to work, which not 
everyone
 does agree is possible) would be a method of transportation, not 
execution:
 even though the original dies, the copy has all his memories and 
provides
 the requisite successor OM in exactly the same way as would have 
happened if
 the original had continued living. So in the example above, if B is an 
exact
 copy of A in an exact copy of A's environment, A would become B and 
not

 even notice that there had been any change.

I'm not sure I would put it like this, although I agree that this would
probably become a common way of describing it.  But there are some aspects
of the process by which A becomes B which are different from our usual,
moment-to-moment continuity of identity.  One obvious difference is that
it is a divine miracle.  This can hardly be neglected.  Even if we imagine
this being done technologically rather than miraculously, with A's brain
being scanned and transmitted to where B will be created, the process of
making this scan will increase the measure of that OM for A by virtue
of storing it in extra places.  This may manifest as the potential for
future copies of A to be created starting with that exact mental moment.
People may come to view transporting as a dangerous activity which puts
them at risk of the creation of unauthorized copies.


Wouldn't it be relatively simple to do this sort of experiment if, in the 
far future, most people live as sentient software on a computer network?



These are all ways in which seemingly abstract and metaphysical questions
become manifest in the real world.  I think it is important to see that
these are not merely imperfections in the thought experiments which we
should ignore in the interests of getting at the real issues.  In my
model, the number of implementations is all important.  It is a major
determinant of measure.  Any technology which messes around with this
stuff is likely to affect the measure of the relevant observer moments.
Having your mental state recorded increases its measure, which manifests
physically as a greater chance that it can interact with the world.


I agree that there may be good reasons why running multiple copies of an 
individual may come to be seen as desirable, the most obvious one being 
backup in case of disaster.


 Now, consider the same situation with one difference. Instead of 
creating B
 at the instant he kills A, God creates A and B at the same time, on 
opposite
 sides of the planet but in exactly the same environment which will 
provide

 each of them with exactly the same inputs, and their minds at all time
 remain perfectly synchronised. God allows his two creatures to live for 
a
 day, and then instantly and painlessly kills A. In the previous example, 
we
 agreed that the creation of B means that A doesn't really die. Now, we 
have

 *exactly* the same situation when A is killed: B is there to provide the
 successor OM, and A need not even know that anything unusual had 
happened.

 How could the fact that B was present a day, a minute or a microsecond
 before A's death make any difference to A? All that matters is that B is 
in
 the correct state to provide continuity of consciousness when A is 
killed.
 Conversely, A and A's death cannot possibly have any direct effect on B. 
It
 is not as if A's soul flies around the world and takes over B; rather, 
it
 just so happens (because of how A and B were created) that B's mental 
states

 coincide with A's, or with what A's would have been if he hadn't died.

If we focus on observer-moments, there are no A and B as separate
individuals.  There are two instantiations of a set of OMs.  Each OM has
double measure during the time that A and B exist, then it has single
measure after A has been destroyed.  It is meaningless to ask, after A
dies, if B is now A or still B, or maybe both?  (I am curious to know
how you would try to answer this question, using your terminology!)
Rather, there is then a single instantiation of the set of OMs.


I agree with this; there is no way from a first person perspective that A 
and B can identify themselves as separate individuals, or perceive that 
anything has changed when one of them is terminated. I called them A and B 
for the sake of argument because I thought that is what you were implying,

Re: copy method important?

Le 18-juin-05, à 20:36, Norman Samish a écrit :

I'm no physicist, but doesn't Heisenberg's Uncertainty Principle forbid
making exact quantum-level measurements, hence exact copies? If so, then
all this talk of making exact copies is fantasy.

Many good answers has been given. And my comment will overlap some of them.

The most physicalist one is to referindeed to Tegmark's paper where he justifies by Everett/decoherence that the evidence is that our brain, when seen as an information handling computing machine, acts as a classical machine. But comp makes physicalism wrong, and Tegmark's answer cannot be fundamentally genuine.

The importance of quantum decoherence in brain processes
M Tegmark 2000, quant-ph/9907009, Phys. Rev. E 61, 4194-4206
161 Why the brain is probably not a quantum computer
M Tegmark 2000, Information Sciences 128, 155-179

Then, concerning the comp 1-person indeterminacy, even if my computational state is a quantum states, the Universal Dovetailer Argument (UDA) is still going through. This is a consequence of the fact that quantum computation does not violate Church's thesis. That entails that you can simulate a quantum computer with a classical computer. Sure, there is a relative exponential slow-down of the computation, but this is not relevant because the universal dovetailer is naturally slow down by its heavy dovetailing behavior, and then the first person cannot be aware of that slow down.

And then I recall I gave an exercise: show that with comp the no-cloning theorem can easily be justified a priori from comp. As I said this follows easily from the Universal dovetailer Argument. The argument shows that physical observable reality (relatively to what you decide to measure here and now) emerges as an average on all computations (generated by the UD) going through your actual state. Suppose now that you decide to observe yourself with at a finer and finer level of description. At some moment you will begin to observe yourself at a level below you substitution level (which I recall is the level where you survive through copy). Below that level comp predict you will be confronted with the 1-comp indeterminacy, that is you will see the many computation/histories. Now that is strictly speaking an infinite set , and there is no reason at all, a priori, that this set is a computational object, so there is no reason at all you could duplicate exactly.

Here you can appreciate the difference between Schmidhuber's comp and my comp. In Schmidhuber's comp the physical universe is a computational object and there is no 1-indeterminacy, and non-cloning is rather mysterious. My comp is the more humble bet that I am a computational object. With my comp, I (first person) bet on the existence of a level of substitution for some 3 description of my body (that is a first person says yes to its doctor when the doctor proposes a substitution of his body by *some* digital machine). Then, what the UDA shows is that the universe, whatever it is, cannot be a computational object, and no piece of real (observable) matter can be cloned, a priori.

Logically, it is still logically possible that the theoretical computer science constraints makes this reasoning invalid, but this would be a consequence of a sort of an arithmetical conspiracy. (Given that the logic of observable proposition *is* already proved to be highly NOT boolean and even quantum-like, but ok here I am in the arithmetical translation of the UDA: note that I am introducing the combinators to just been able to interview the Lobian machine on the non-cloning question, and also on the complete reversibility of the laws of physics).

The easy (not quite rigorous) proof of the non-cloning theorem from comp shows that the QM non cloning can be seen (retrospectively, sure) as a confirmation of comp. Here is another exercise (a little bit less easy): show that the fact we can test experimentally and share with each other such non-cloning behavior would confirm, not only comp, but would vindicate the differentiation between the 1-person point of view, and the 1-person plural point of view (I just mention it in my post to Jonathan): for a computationalist the observability of non cloning is an evidence against solipsism! (well the observability of QM indeterminacy also, and is perhaps more easy to use). It is also an evidence that we share the level of substitution.

Bruno

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

Re: copy method important?

2005-06-20 Thread daddycaylor


Stathis wrote:
Scouring the universe to find an exact copy of RM's favourite marble may seem a very inefficient method of duplication, but when it comes to conscious observers in search of a successor OM, the obvious but nonetheless amazing fact is that nobody needs to search or somehow bring the the observer and the OM together: if the successor OM exists anywhere in the plenitude, then the mere fact of its existence means that the observer's consciousness will continue.

What feature of the universe(s) causes you to be able to say that the dead OM continues to be conscious rather than continues to be dead? Aren't there just as many universes (or more?) or future moments in this universe, where there is no conscious OM? It seems like it's a wash (unknown) when it comes to being able to claim the existence of immortality or not, based on that type of argument.

Tom Caylor

RE: Dualism and the DA

Jonathan Colvin writes:
 This is, I think, the crux of the reference class issue with the DA. My (and
 your) reference class can not be merely conscious observers or all
 humans, but must be something much closer to someone (or thing) discussing
 or aware of the DA). I note that this reference class is certainly
 appropriate for you and me, and likely for anyone else reading this. This
 reference class certainly also invalidates the DA (although immaterial souls
 would rescue it).

But we don't use such a specific reference class in other areas of
reasoning.  We don't say, why do things fall to the ground, and answer it,
because we are in a reference class of people who have observed things
fall to the ground.

If we explain an observed phenomenon merely by saying that we are
in the reference class of people who have observed it, we haven't
explained anything.  We need to be a little more ambitious.

Hal Finney

RE: Copies Count

Stathis Papaioannou writes:
 I agree that you will have a 90% chance of waking up in Moscow, given that 
 that is the *relative* measure of your successor OM when you walk into the 
 teleporter. This is the only thing that really matters with the copies, from 
 a selfish viewpoint: the relative measure of the next moment:

So let me try an interesting variant on the experiment.  I think someone
else proposed this recently, the idea of retroactive causation.
I won't put that exact spin on it though.

Suppose you will again be simultaneously teleported to Washington
and Moscow.  This time you will have just one copy waking up in each.
Then you will expect 50-50 odds.  But suppose that after one hour,
the copy in Moscow gets switched to the parallel computer so it is
running with 10 times the measure; 10 copies.  And suppose that you know
beforehand that during that high-measure time period (after one hour)
in Moscow you will experience some event E.

What is your subjective probability beforehand for experiencing E?
I think you agreed that if you had been woken up in Moscow on
the super-parallel computer that you would expect a 90% chance of
experiencing E.  But now we have interposed a time delay, in which your
measure starts off at 1 in Moscow and then increases to 10.  Does that
make a difference in how likely you are to experience E?

I am wondering if you think it makes sense that you would expect a 50%
probability of experiencing events which take place in Moscow while
your measure is 1, but a 90% probability of experiencing events like
E, which take place while your measure is 10?  I'm not sure about this
myself, because I am skeptical about this continuity-of-identity idea.
But perhaps, in your framework, this would offer a solution to the
problem you keep asking, of some way to notice or detect when your
measure increases.

In that case we would say that you could notice when your measure
increases because it would increase your subjective probability of
experiencing events.

Perhaps we could even go back to the thought experiment where you have
alternating days of high measure and low measure.  Think of multiple
lockstep copies being created on high measure days and destroyed on low
measure days.  Suppose before beginning this procedure you flip a quantum
coin (in the MWI) and will only undergo it if the coin comes up heads.
Now, could you have a subjective anticipation of 50% of experiencing the
events you know will happen on low-measure days, but an anticipation of
90% of experiencing the events you know will happen on high-measure days?
Then that would be a tangible difference, and you would be justified in
pre-arranging your affairs so that pleasant events happen on the high
measure days and unpleasant ones happen on the low measure days.

It's an interesting concept in any case.  I need to think about it more,
but I'd be interested to hear your views.

Hal Finney

Re: death

Bruno Marchal writes:
 Le 19-juin-05, =E0 15:52, Hal Finney a =E9crit :

  I guess I would say, I would survive death via anything that does not
  reduce my measure.

 But if the measure is absolute and is bearing on the OMs, and if that=20
 is only determined by their (absolute) Kolmogorov complexity (modulo a=20=
 constant) associated to the OM (how is still a mystery for me(*)),=20
 how could anything change the measure of an OM?

That's true, from the pure OM perspective death doesn't make sense
because OMs are timeless.  I was trying to phrase things in terms of
the observer model in my reply to Stathis.  An OM wants to preserve
the measure of the observer that it is part of, due to the effects of
evolution.  Decreases in that measure would be the meaning of death,
in the context of the multiverse.

Hal Finney

Re: Dualism and the DA

2005-06-20 Thread Pete Carlton

On Jun 17, 2005, at 10:17 PM, Russell Standish wrote:snipI still find it hard to understand this argument. The question "Whatis it like to be a bat?" still has meaning, but is probablyunanswerable (although Dennett, I notice considers it answerable,contra Nagel!)Dennett considers it answerable, but he thinks the answer is probably "Nothing at all".That is, it isn't "like" anything at all to be a bat, because bats can do all the tasks they need to do to get by without it being "like" anything at all for them.I still think the confusion over personal identity is due to the misplaced importance we're putting on the concept of "I".  Here's what Bruno said later:"Note that here we can understand why the question "why I am the one in W" or "why I am the one in M" are 100% meaningless. This does not entail that the question where will I be in the next duplication is meaningless."I think the second question, "where will I be in the next duplication", is also meaningless.  I think that if you know all the 3rd-person facts before you step into the duplicator - that there will be two doubles made of you in two different places, and both doubles wil be psychologically identical at the time of their creation such that each will say they are you - then you know everything there is to know.  There is no further question of "which one will I be"?  This is simply a situation which pushes the folk concept of "I" past its breaking point; we don't need to posit any kind of dualism to paper over it, we just have to revise our concept of "I".

Re: Dualism and the DA

Pete Carlton writes:
 I think the second question, where will I be in the next  
 duplication, is also meaningless.  I think that if you know all the  
 3rd-person facts before you step into the duplicator - that there  
 will be two doubles made of you in two different places, and both  
 doubles wil be psychologically identical at the time of their  
 creation such that each will say they are you - then you know  
 everything there is to know.  There is no further question of which  
 one will I be?  This is simply a situation which pushes the folk  
 concept of I past its breaking point; we don't need to posit any  
 kind of dualism to paper over it, we just have to revise our concept  
 of I.

I agree that this view makes sense.  We come up with all these mind
bending and paradoxical thought experiments, and even though everyone
agrees about every fact of the third-person experience, no one can agree
on what it means from the first person perspective.  Maybe, then, there
is no fact of the matter to agree on, with regard to the first person.

On the other hand, in a world where Star Trek transporters were common,
it seems likely that most people would carry over their conventional views
about continuity of identity to the use of this technology.  Once they
have gone through it a few times, and have memories of having done so,
it won't seem much different from other forms of transportation.

Copies seem a little more problematic.  We're pretty cavalier about
creating and destroying them in our thought experiments, but the social
implications of copies are enormous and I suspect that people's views
about the nature of copying would not be as simple as we sometimes assume.

I doubt that many people would be indifferent between the choice of
having a 50-50 chance of being teleported to Moscow or Washington, vs
having copies made which wake up in both cities.  The practical effects
would be enormously different.  And as I wrote before, I suspect that
these practical differences are not to be swept under the rug, but point
to fundamental metaphysical differences between the two situations.

Hal Finney

Reference class (was dualism and the DA)

2005-06-20 Thread Jonathan Colvin

Russell Standish wrote: 
   (JC) If you want to insist that What would it be like 
 to be a bat 
   is  equivalent to the question What would the universe be like
   if I had
been a bat rather than me?, it is very hard to see what the 
answer could be. Suppose you
*had* been a bat rather than you (Russell Standish). 
 How would the 
universe be any different than it is now? If you can 
 answer that 
question, (which is the key question, to my mind), then 
 I'll grant 
that the question is meaningful.
  
   
   No different in the 3rd person, very obviously different 
 in the 1st 
   person
  
  I don't really know what that means. The only way I can 
 make sense of 
  the question is something like, If I was a bat instead of me 
  (Jonathan Colvin), then the universe would consist of a bat 
 asking the 
  question I'm asking now. That's a counterfactual, a way in 
 which the 
  universe would be objectively different.
 
 It wouldn't be counterfactual, because by assumption bats ask 
 this question of themselves anyway. Hence there is no 
 difference in the 3rd person. The 1st person experience is 
 very different though. There are only 1st person counterfactuals.

That's quite an assumption. *Do* all conscious things ask this question of
themselves? Babies don't. Senile old people don't. I'm not sure that
medieval peasants ever thought to ask this question, or pre-literate
cavemen. 


 
 I definitely acknowledge the distinction between 1st and 3rd 
 person. This is not the same as duality, which posits a 3rd 
 person entity (the immaterial soul).
 
  
  This is, I think, the crux of the reference class issue 
 with the DA. 
  My (and
  your) reference class can not be merely conscious 
 observers or all 
  humans, but must be something much closer to someone (or thing) 
  discussing or aware of the DA).
 
 I don't think this is a meaningful reference class. I can 
 still ask the question why am I me, and not someone else 
 without being aware of the DA. All it takes is self-awareness IMHO.

You *could* certainly. Perhaps it is important as to whether you actually
*do* ask that question (and perhaps it should be in the context of the DA). 


  I note that this reference class is certainly appropriate 
 for you and 
  me, and likely for anyone else reading this. This reference class 
  certainly also invalidates the DA (although immaterial souls would 
  rescue it).
  
  But at this point, I am, like Nick Bostrom, tempted to 
 throw my hands 
  up and declare the reference class issue pretty much intractable.
  
  Jonathan Colvin
 
 Incidently, I think I may have an answer to my Why am I not Chinese
 criticism, and the corresponding correction to Why am I not an ant
 seems to give the same answer as I originally proposed.

I'd be interested to hear it. Here's something else you could look
at...calculate the median annual income for all humans alive today (I
believe it is around $4,000 /year), compare it to your own, and see if you
are anyway near the median. I predict that the answer for you (and for
anyone else reading this), is far from the median. This result is obviously
related to the why you are not Chinese criticism, and is, I believe, the
reason the DA goes astray.

Jonathan Colvin

Re: Reference class (was dualism and the DA)

2005-06-20 Thread Saibal Mitra

- Original Message - 
From: Jonathan Colvin [EMAIL PROTECTED]
To: 'Russell Standish' [EMAIL PROTECTED]
Cc: 'EverythingList' everything-list@eskimo.com
Sent: Monday, June 20, 2005 09:52 PM
Subject: Reference class (was dualism and the DA)

 Russell Standish wrote:
(JC) If you want to insist that What would it be like
  to be a bat
is  equivalent to the question What would the universe be like
if I had
 been a bat rather than me?, it is very hard to see what the
 answer could be. Suppose you
 *had* been a bat rather than you (Russell Standish).
  How would the
 universe be any different than it is now? If you can
  answer that
 question, (which is the key question, to my mind), then
  I'll grant
 that the question is meaningful.

No different in the 3rd person, very obviously different
  in the 1st
person

   I don't really know what that means. The only way I can
  make sense of
   the question is something like, If I was a bat instead of me
   (Jonathan Colvin), then the universe would consist of a bat
  asking the
   question I'm asking now. That's a counterfactual, a way in
  which the
   universe would be objectively different.

  It wouldn't be counterfactual, because by assumption bats ask
  this question of themselves anyway. Hence there is no
  difference in the 3rd person. The 1st person experience is
  very different though. There are only 1st person counterfactuals.

 That's quite an assumption. *Do* all conscious things ask this question of
 themselves? Babies don't. Senile old people don't. I'm not sure that
 medieval peasants ever thought to ask this question, or pre-literate
 cavemen.

  I definitely acknowledge the distinction between 1st and 3rd
  person. This is not the same as duality, which posits a 3rd
  person entity (the immaterial soul).

   This is, I think, the crux of the reference class issue
  with the DA.
   My (and
   your) reference class can not be merely conscious
  observers or all
   humans, but must be something much closer to someone (or thing)
   discussing or aware of the DA).

  I don't think this is a meaningful reference class. I can
  still ask the question why am I me, and not someone else
  without being aware of the DA. All it takes is self-awareness IMHO.

 You *could* certainly. Perhaps it is important as to whether you actually
 *do* ask that question (and perhaps it should be in the context of the
DA).

   I note that this reference class is certainly appropriate
  for you and
   me, and likely for anyone else reading this. This reference class
   certainly also invalidates the DA (although immaterial souls would
   rescue it).

   But at this point, I am, like Nick Bostrom, tempted to
  throw my hands
   up and declare the reference class issue pretty much intractable.

   Jonathan Colvin

  Incidently, I think I may have an answer to my Why am I not Chinese
  criticism, and the corresponding correction to Why am I not an ant
  seems to give the same answer as I originally proposed.

 I'd be interested to hear it. Here's something else you could look
 at...calculate the median annual income for all humans alive today (I
 believe it is around $4,000 /year), compare it to your own, and see if you
 are anyway near the median. I predict that the answer for you (and for
 anyone else reading this), is far from the median. This result is
obviously
 related to the why you are not Chinese criticism, and is, I believe, the
 reason the DA goes astray.

 Jonathan Colvin

I don't think so, because most people on Earth are not Chinese. The correct
refutation of the Doomsday Paradox was given by D. Dieks and involves the
Self Indicating Axiom. The definition of the reference class defines the set
of observers that you consider to be you. The DA involves applying Bayes's
theorem and to do that correctly you have then to use the correct a priori
probability which is also fixed by the choice of the reference class. The
two effects cancel and there is no Doomsday Problem. This is all explained
here:

http://arxiv.org/abs/gr-qc/0009081

Saibal

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Measure, Doomsday argument

2005-06-20 Thread Quentin Anciaux

Hi everyone,

I have some questions about measure...

As I understand the DA, it is based on conditionnal probabilities. To somehow 
calculate the chance on doom soon or doom late. An observer should reason 
as if he is a random observer from the class of observer.

The conditionnal probabilities come from the fact, that the observer find that 
he is the sixty billions and something observer to be born. Discover this 
fact, this increase the probability of doom soon. The probability is 
increased because if doom late is the case, the probability to find myself in 
a universe where billions of billions of observer are present is greater but 
I know that I'm the sixty billions and something observer.

Now I come to the measure of observer moment :
It has been said on this list, to justify we are living in this reality and 
not in an Harry Potter like world that somehow our reality is simpler, has 
higher measure than Whitte rabbit universe. But if I correlate this 
assumption with the DA, I also should assume that it is more probable to be 
in a universe with billions of billions of observer instead of this one.

How are these two cases different ?

Quentin

Re: copy method important?

2005-06-20 Thread Quentin Anciaux

Hi,

Le Lundi 20 Juin 2005 18:21, [EMAIL PROTECTED] a écrit :
 What feature of the universe(s) causes you to be able to say that the dead
 OM continues to be conscious rather than continues to be dead? 

An OM (Observer Moment) by definition must contains a conscious observer... If 
it's not the case... I don't understand the concept at all.

Quentin

Re: Measure, Doomsday argument

Quentin Anciaux writes:
 It has been said on this list, to justify we are living in this reality and 
 not in an Harry Potter like world that somehow our reality is simpler, has 
 higher measure than Whitte rabbit universe. But if I correlate this 
 assumption with the DA, I also should assume that it is more probable to be 
 in a universe with billions of billions of observer instead of this one.
 How are these two cases different ?

I would answer this by predicting that any universe which allows for a
substantial chance of billions of billions of observers would have to
be much more complex.  It would have a larger description, either in
terms of its natural laws or of the initial conditions.

Aside from the DA, we have another argument against the fact that
our universe is well suited for advanced civilizations, namely the
Fermi paradox: that we have not been visited by aliens.  These two are
somewhat similar arguments, the DA limiting civilization in time, and
Fermi limiting it in space.  In both cases it appears that our universe
is not particularly friendly to advanced forms of life.

The empirical question presents itself like this.  Very simple universes
(such as empty universes, or ones made up of simple repeating patterns)
would have no life at all.  Perhaps sufficiently complex ones would be
full of life.  So as we move up the scale from simple to complex, at
some point we reach universes that just barely allow for advanced life
to evolve, and even then it doesn't last very long.  The question is,
as we move through this transition region from nonliving universes,
to just-barely-living ones, to highly-living ones, how long is the
transition region?

That is, how much more complex is a universe that will be full of life,
compared to one which just barely allows for life?  We don't know the
answer to that, but in principle it can be learned, through study and
perhaps experimental simulations.  If it takes only a bit more complexity
to go from a just-barely-living universe to a highly-living one, then
we have a puzzle.  Why aren't we in one of the super-living universes,
when their complexity penalty is so low?

OTOH if it turns out that the transition region is wide, and that
you need a much more complex universe to be super-living than to be
just-barely-living, then that is consistent with what we see.  We are in
one of the universes in the transition region, and in fact so are most
advanced life forms.  The relative complexity of super-living universes
means that their measures are low, so even though they are full of life,
it is more likely for a random advanced life form to be in one of the
marginal universes like our own.

In this way the DA is consistent with the fact that we don't live in
a magical universe, but it implies some mathematical properties of the
nature of computation which we are not yet in a position to verify.

Hal Finney

FW: Required reading

2005-06-20 Thread Brent Meeker

Required reading indeed.  Thanks, Norm.

Brent

-Original Message-
From: Atoms and the Void [mailto:[EMAIL PROTECTED] Behalf Of Norman
Levitt
Sent: Monday, June 20, 2005 1:35 PM
To: [EMAIL PROTECTED]
Subject: Required reading

Rebecca Goldstein talking about Godel, Einstein, Wittgenstein, the
Wienerkreiss, positivism, realism, metaphysics and metamathematics in an
Edge interview.  She's a philosopher by training and a novelist by
profession.  Note that her knowledge of the mathematical issues is pretty
solid.  Not surprising in view of the fact that her husband is my Rutgers
colleague Sheldon Goldstein, the expert on Bohmian mechanics.

http://www.edge.org/3rd_culture/goldstein05/goldstein05_index.html

NL

Re: Measure, Doomsday argument

2005-06-20 Thread Saibal Mitra

- Original Message - 
From: Quentin Anciaux [EMAIL PROTECTED]
To: everything-list@eskimo.com
Sent: Monday, June 20, 2005 11:37 PM
Subject: Measure, Doomsday argument

 Hi everyone,

 I have some questions about measure...

 As I understand the DA, it is based on conditionnal probabilities. To
somehow
 calculate the chance on doom soon or doom late. An observer should
reason
 as if he is a random observer from the class of observer.

 The conditionnal probabilities come from the fact, that the observer find
that
 he is the sixty billions and something observer to be born. Discover
this
 fact, this increase the probability of doom soon. The probability is
 increased because if doom late is the case, the probability to find myself
in
 a universe where billions of billions of observer are present is greater
but
 I know that I'm the sixty billions and something observer.

This is a false argument see here:

http://arxiv.org/abs/gr-qc/0009081

To calculate the conditional probability given the birthrank you have you
must use Bayes' theorem. You then have to take into account the a priori
probability for a given birthrank. If you could have been anyone of all the
people that will ever live, then you must include this informaton in the
a-priori probability, and as a result of that the Doomsday Paradox is
canceled.

 Now I come to the measure of observer moment :
 It has been said on this list, to justify we are living in this reality
and
 not in an Harry Potter like world that somehow our reality is simpler,
has
 higher measure than Whitte rabbit universe. But if I correlate this
 assumption with the DA, I also should assume that it is more probable to
be
 in a universe with billions of billions of observer instead of this one.

 How are these two cases different ?

Olum also stumbles on this point in his article. I also agree with Hall's
earlier reply that (artificially) increasing the number of universes will
lead to a decrease in intrinsic measure. One way to see this is as follows
(this argument was also given by Hall a few years ago, if I remember
correctly):

According to the Self Sampling Asumption you have to include an
''anthropic'' factor in the measure. The more observers there are the more
likely the universe is, but you do have to multiply the number of observers
by the intrinsic measure. For any given universe U you can consider an
universe U(n) that runs U n times, So, the anthropic factor of U(n) is n
times that of U. This means that the intrinsic measure of U(n)  should go to
zero faster than 1/n, or else you wouldn't be able to normalize
probabilities for observers. U(n) contains
 Log(n)/Log(2) bits more than U (you need to specify the number n). So,
assuming that the intrinsic measure only depends on program size, it should
decay faster than 2^(-program length).

Saibal

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Defeat Spammers by launching DDoS attacks on Spam-Websites:
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RE: Measure, Doomsday argument

2005-06-20 Thread Jesse Mazer

From: Quentin Anciaux [EMAIL PROTECTED]
To: everything-list@eskimo.com
Subject: Measure, Doomsday argument
Date: Mon, 20 Jun 2005 23:37:45 +0200

Hi everyone,

I have some questions about measure...

As I understand the DA, it is based on conditionnal probabilities. To 
somehow

calculate the chance on doom soon or doom late. An observer should reason
as if he is a random observer from the class of observer.

The conditionnal probabilities come from the fact, that the observer find 
that

he is the sixty billions and something observer to be born. Discover this
fact, this increase the probability of doom soon. The probability is
increased because if doom late is the case, the probability to find myself 
in
a universe where billions of billions of observer are present is greater 
but

I know that I'm the sixty billions and something observer.

I always thought the DA was understood in terms of absolute probability, not 
conditional probability. Conditional probability is supposed to tell you, 
given your current observer-moment, what the probability of various possible 
next experiences is for you; absolute probability is supposed to give the 
probability of experiencing one observer-moment vs. another *now*. The DA is 
based on assuming my current observer-moment is randomly sampled from the 
set of all observer-moments (possibly weighted by their absolute 
probability, although some people reason as if each observer-moment is 
equally likely for the purposes of the random-sampling assumption), and 
noting that if civilization were to be very long-lasting, it'd be unlikely 
to randomly choose an observer-moment of a person so close to the beginning 
of civilization.

Jesse

Re: Measure, Doomsday argument

2005-06-20 Thread Jesse Mazer

Saibal Mitra wrote:

- Original Message -
From: Quentin Anciaux [EMAIL PROTECTED]
To: everything-list@eskimo.com
Sent: Monday, June 20, 2005 11:37 PM
Subject: Measure, Doomsday argument

 Hi everyone,

 I have some questions about measure...

 As I understand the DA, it is based on conditionnal probabilities. To
somehow
 calculate the chance on doom soon or doom late. An observer should
reason
 as if he is a random observer from the class of observer.

 The conditionnal probabilities come from the fact, that the observer 
find

that
 he is the sixty billions and something observer to be born. Discover
this
 fact, this increase the probability of doom soon. The probability is
 increased because if doom late is the case, the probability to find 
myself

in
 a universe where billions of billions of observer are present is greater
but
 I know that I'm the sixty billions and something observer.

This is a false argument see here:

http://arxiv.org/abs/gr-qc/0009081

To calculate the conditional probability given the birthrank you have you
must use Bayes' theorem. You then have to take into account the a priori
probability for a given birthrank. If you could have been anyone of all the
people that will ever live, then you must include this informaton in the
a-priori probability, and as a result of that the Doomsday Paradox is
canceled.

I don't think the cancellation argument in that paper works, unless you 
already *know* the final measure of one type of civilization vs. another 
from the perspective of the multiverse as a whole. For example, if I know 
for sure that 50% of civilizations end after 200 billion people have been 
born while 50% end after 200 trillion have been born, then it's true that 
observing my current birthrank to be the 100 billionth person born, I should 
not expect my civilization is any more likely to end soon, since 50% of all 
observers who find themselves to have the same birthrank are part of 
200-billion-person civilizations and 50% of all observers who find 
themselves to have the same birthrank are part of 200-trillion person 
civilizations. But if I don't know for sure what the measure of different 
civilizations is, suppose I am considering two alternate hypotheses: one 
which says 50% of all civilizations end after 200 billion people and 50% end 
after 200 trillion, vs. a second hypothesis which says 99% of all 
civilizations end after 200 billion people and 1% end after 200 trillion. In 
that case, observing myself to have a birthrank of 100 million should lead 
me, by Bayesian reasoning, to increase my subjective estimate that the 99/1 
hypothesis is correct, and decrease my subjective estimate that the 50/50 
hypothesis is correct.

Jesse

Re: copy method important?