Re: Quantum Immortality and Information Flow
Saibal Mitra wrote: Correction, I seem to have misunderstood Statis' set up. If you really create a new world and then create and kill the person there then the probability of survival is 1. This is different from quantum mechanical branch splitting. To see this, consider first what would have happened had the person not been killed. Then his measure would have doubled. But because he is killed in one of the two copies of Earth, his measure stays the same. In a quantum suicide experiment his measure would be reduced by a factor two. To say that measure is doubled or halved it is not sufficient to take the measure at the final point. You really must compare measure at two points, in effect take a ratio. So depending where the initial point is you could come to different conclusions. If your initial point is before the new world is created (and the clone in that world is killed), then, you are right. There is no change in the measure of the original person. However, if the initial point is taken after the world is created but before the clone is killed, then the measure of the clone goes to zero "in that world." One could always argue that the world branches and the clone continues living in other worlds. George
Re: Quantum Immortality and Information Flow
Correction, I seem to have misunderstood Statis' set up. If you really create a new world and then create and kill the person there then the probability of survival is 1. This is different from quantum mechanical branch splitting. To see this, consider first what would have happened had the person not been killed. Then his measure would have doubled. But because he is killed in one of the two copies of Earth, his measure stays the same. In a quantum suicide experiment his measure would be reduced by a factor two. - Original Message - From: "Saibal Mitra" <[EMAIL PROTECTED]> To: "Stathis Papaioannou" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; "Jesse Mazer" <[EMAIL PROTECTED]> Cc: Sent: Sunday, November 27, 2005 02:25 AM Subject: Re: Quantum Immortality and Information Flow > The answer must be a) because (and here I disagree with Jesse), all that > exists is an ensemble of isolated observer moments. The future, the past, > alternative histories, etc. they all exist in a symmetrical way. It don't > see how some states can be more ''real'' than other states. Of course, the > universe we experience seems to be real to us while alternative universes, > or past or future states of this universe are not being experienced by us. > > > So, you must think of yourself at any time as being randomly sampled from > the set of all possible observer moments. To get to answer b) you have to > redefine your identity so that experiencing having done the experiment > becomes a necessary part of your identity. But this is cheating because you > wouldn't say that if ''death'' were replaced by a partial memory erasure > such that the experience of having done the experiment were wiped out form > your memory. > > > > > > - Original Message - > From: "Stathis Papaioannou" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Cc: > Sent: Saturday, November 26, 2005 11:51 AM > Subject: Re: Quantum Immortality and Information Flow > > > > > > Stathis Papaioannou writes: > > If on the basis of a coin toss the world splits, and in one branch I am > > instantaneously killed while in the other I continue living, there are > > several possible ways this might be interpreted from the 1st person > > viewpoint: > > > > (a) Pr(I live) = Pr(I die) = 0.5 > > > > (b) Pr(I live) = 1, Pr(I die) = 0 > > > > (c) Pr(I live) = 0, Pr(I die) = 1 > > > > Even on this list, there are people who might say (a) above is the case > > rather than (b) or (c). > > > > Bruno Marchal replies: > > Are you sure? > > > > I was thinking of people who accept some ensemble theory such as MWI, but > > don't believe in QTI. I must admit, I find it difficult to understand how > > even a dualist might justify (a) as being correct. Would anyone care to > > help? > > > > Stathis > > > > _ > > Start something musical - 15 free ninemsn Music downloads! > > > http://ninemsn.com.au/share/redir/adTrack.asp?mode=click&clientID=667&referral=HotmailTaglineNov&URL=http://www.ninemsn.com.au/startsomething > > >
Re: Quantum Immortality and Information Flow
- Original Message - From: "Bruno Marchal" <[EMAIL PROTECTED]> To: "Saibal Mitra" <[EMAIL PROTECTED]> Cc: "Jesse Mazer" <[EMAIL PROTECTED]>; "Stathis Papaioannou" <[EMAIL PROTECTED]>; Sent: Monday, November 28, 2005 04:47 PM Subject: Re: Quantum Immortality and Information Flow > > Le 27-nov.-05, à 02:25, Saibal Mitra a écrit : > > > The answer must be a) because (and here I disagree with Jesse), all > > that > > exists is an ensemble of isolated observer moments. The future, the > > past, > > alternative histories, etc. they all exist in a symmetrical way. It > > don't > > see how some states can be more ''real'' than other states. > > But then how could we ever explain why some states seem to be more > *near*, or more probable than others from our point of view? Well, even if you assume ''ordinary'' laws of physics, you can have this view. Einstein tried to console a friend whose son had died, by saying that although he isn't alive now, he is ''still'' alive in the past. Relativity theory threats space and time in more or less symmetrical ways.It doesn't make any difference if you assume that you are sampled from a probability distribution (to be calculated from physics) over your experiences. > > Is the choice between Papaioannou's "a", "b" reflecting(*) the ASSA > and RSSA difference? > > Recall: ASSA = absolute self-sampling assumption. RSSA = relative > self-sampling assumption. > > (*) Stathis Papaioannou writes: > > If on the basis of a coin toss the world splits, and in one branch I am > > instantaneously killed while in the other I continue living, there are > > several possible ways this might be interpreted from the 1st person > > viewpoint: > > > > (a) Pr(I live) = Pr(I die) = 0.5 > > > > (b) Pr(I live) = 1, Pr(I die) = 0 > > > > (c) Pr(I live) = 0, Pr(I die) = 1 > > > > Even on this list, there are people who might say (a) above is the case > > rather than (b) or (c). > > > Saibal: > > > So, you must think of yourself at any time as being randomly sampled > > from > > the set of all possible observer moments. > > > This could make sense in a pure third person perspective, but then it > is no more a perspective. And, indeed, to predict the result of > anything I decide to test, I need to take into account relations > between observer-moments. Let me throw a dice. Are you saying to us > that to predict the result I need to take into account all > observer-moments and sample on them in some "uniform" way. Why should > people buy lotto-tickets? They could make the big win by their OM being > sampled on all OMs. > I'm not saying you are false, but your absolute sample does not > correspond tour first person experience (including physics) which we > want to explain. It seems to me. Well, the probability distribution has to be consistent with physics. In case of throwing a dice, one should consider the set of OMs that are experiencing the outcome of the throw. > > > > > To get to answer b) you have to > > redefine your identity so that experiencing having done the experiment > > becomes a necessary part of your identity. > > Not some absolute identity, but memories are part of our relative, > mundane, identity. > > > > > But this is cheating because you > > wouldn't say that if ''death'' were replaced by a partial memory > > erasure > > such that the experience of having done the experiment were wiped out > > form > > your memory. > > OK, but that is why the experiment is proposed with (absolute) death > (if that exists) and not with memory erasure. This could change the > probabilities a lot, and this can admit many different protocol for > verifying the probability distributions. It is another experiment. > Perhaps I miss your point. Yes, that was my point. The probabilities become sensitive to the details of the set up in a way that I find unphysical. If we just do conventional quantum measurement of z-component of a spin polarized in the x-direction. Then, in the MWI, you would say that there exists a world in which an observer sees spin up and a world in which spin down is experienced. Strictly speaking the two observers are not identical. Let's now modify the experiment so that in case of spin down the observer is annihilated and replaced by some arbitrary person. Then if we choose this person to be ''close'' to the original person then the probabilities are 1/2, but if I move sufficiently ''far away'' from the person then it should somehow jump to 1 for the original person.
Re: Quantum Immortality and Information Flow
- Original Message - From: "Jonathan Colvin" <[EMAIL PROTECTED]> To: Sent: Sunday, November 27, 2005 10:02 PM Subject: RE: Quantum Immortality and Information Flow > > Saibal wrote: > > > > The answer must be a) because (and here I disagree with > > > > Jesse), all that exists is an ensemble of isolated observer > > > > moments. The future, the past, alternative histories, etc. > > > > they all exist in a symmetrical way. It don't see how some > > > > states can be more ''real'' than other states. Of course, the > > > > universe we experience seems to be real to us while > > > > alternative universes, or past or future states of this > > > > universe are not being experienced by us. > > > > > > > > > > > > So, you must think of yourself at any time as being randomly > > > > sampled from the set of all possible observer moments. > > > > > > > > > > > > I'm not sure how this works. Suppose I consider my state > > now at time > > as > > > a random sample of all observer moments. Now, after having > > typed this > > > sentence, I consider my state at time . Is > > this also a > > random > > > sample on all observer moments? I can do the same at now > > , and > > so-on. > > > It seems very unlikely that 3 random samples would coincide > > so closely. So > > > in what sense are these states randomly sampled? > > > > It's a bit like symmetry breaking. You have an ensemble of > > all possible > > observer moment, but each observer moment can only experience > > its own state. > > So, the OM samples itself. > > > > There exists an observer moment representing you at N > > seconds, at N + 4 > > seconds and at all possible other states. They all ''just > > exist'' in the > > plenitude, as Stathis wrote. The OM representing you at N + 4 has the > > memory of being the OM at N. Subjectively the OMs experience > > time evolution, > > even though the plenitude itself doesn't have a time evolution at the > > fundamental level. > > I understand all that, but I still don't see in what sense these OM's are > randomly sampled. > > Here's a related question. The DDA insists that we must all consider > ourselves random observers on our reference class, whatever it is (class of > all observers is standard). Now, if I am a random observer, and you (Saibal) > are a random observer, what are the odds that two observers selected > randomly from the class of all observers would be discoursing on the same > mailing list? We can only conclude that one of us can not be random, but > must have been selected by the other. But did I select you, or did you > select me? If we select each other, the randomness issue is not resolved. > > Another possibility is, I suppose, to simply *define* randomness as observer > self-selection. Perhaps observer self-selection is the only truly random > phenomenon in the universe (everything else appearing random is merely > unpredictable). But it is then a purely a first-person phenomenon, and I can > not consider anything else in the universe (including *your* observer > moments) as random. > Yes, I meant ''random'' in the sense of observer self selection. But note that the laws of physics define, in principle, a probability distribution over the set over all possible states you can be in. One element of that set corresponds to you reading this sentence. The probability of this is given by an integral of the probability of states of the universe that are consistent with you experiencing this OM. So, you ''integrate out'' everything that is not part of the OM and you are left with the probability of the OM.
Re: Quantum Immortality and Information Flow
- Original Message - From: "Brent Meeker" <[EMAIL PROTECTED]> To: Cc: Sent: Sunday, November 27, 2005 07:41 PM Subject: Re: Quantum Immortality and Information Flow > Saibal Mitra wrote: > > - Original Message - > > From: "Jonathan Colvin" <[EMAIL PROTECTED]> > > To: > > Sent: Sunday, November 27, 2005 05:49 AM > > Subject: RE: Quantum Immortality and Information Flow > > > > > > > >>Saibal wrote: > >> > >>>The answer must be a) because (and here I disagree with > >>>Jesse), all that exists is an ensemble of isolated observer > >>>moments. The future, the past, alternative histories, etc. > >>>they all exist in a symmetrical way. It don't see how some > >>>states can be more ''real'' than other states. Of course, the > >>>universe we experience seems to be real to us while > >>>alternative universes, or past or future states of this > >>>universe are not being experienced by us. > >>> > >>> > >>>So, you must think of yourself at any time as being randomly > >>>sampled from the set of all possible observer moments. > >> > >> > >> > >>I'm not sure how this works. Suppose I consider my state now at time > > > > as > > > >>a random sample of all observer moments. Now, after having typed this > >>sentence, I consider my state at time . Is this also a > > > > random > > > >>sample on all observer moments? I can do the same at now , and > > > > so-on. > > > >>It seems very unlikely that 3 random samples would coincide so closely. So > >>in what sense are these states randomly sampled? > > > > > > It's a bit like symmetry breaking. You have an ensemble of all possible > > observer moment, but each observer moment can only experience its own state. > > So, the OM samples itself. > > > > There exists an observer moment representing you at N seconds, at N + 4 > > seconds and at all possible other states. They all ''just exist'' in the > > plenitude, as Stathis wrote. The OM representing you at N + 4 has the > > memory of being the OM at N. > > This I find confusing. How is there memory associated with an obserever moment? > Is it equivocation on "memory"? As an experience, remembering something takes > much longer than what I would call "a moment". It may involve a sequence > images, words, and emotions. Of course in a materialist model of the world the > memories are coded in the physical configuration of your brain, even when not > being experienced; but an analysis that takes OM's as fundamental can't refer to > that kind of memories. Well, what really matters is that the laws of physics define a probability distribution over OMs. So, there is no problem thinking of yourself as being sampled randomly from that probability distribution. The length of an OM can be taken to be zero. Even if recalling something takes time, at any time you are at a certain point in that process. There exists an OM that recalls going through that sequence, but that is also at a specific moment in time.
Re: Quantum Immortality and Information Flow
Le 01-déc.-05, à 07:17, Stathis Papaioannou a écrit :
Why does an OM need to contain so much information to link it to other
OMs making up a person? [the complete message is below].
I am not sure I understand. Are you saying, like Saibal Mitra, that OMs
(Observer-Moments) are not related? How, in this case, would you
interpret your own talk about "next observer moment" (those which could
be dead end)?
Is there not a confusion between the idea of physicalist (causal) view
of the relation between OMs (which, as Brent meeker said should be
explained from a more primitive (mathematical, immaterial, not causal,
...) notion of OM, with those very (more primitive) OMs.
Are you assuming some notion of multiverse richer than (or just
different from) a notion of multi-OMs?
At least, when you "interview" a sound lobian machine on such questions
(through the modal logic G), or better when you interview its "guardian
angel" (through its modal logic G*), you can understand that the
"ultimate" multiverse can reasonably be said not having structure, and
that multiverse-structures *appear* for each notion of self-referential
points of view (not necessarily first person pov). The first person pov
makes the "multiverse" a temporal structure, the first person plural
pov makes the multiverse a quantum probability structure.
***
Mhh I know this could look like jargon. Let me give "easy"
exercises for anybody following this list.
Let me define a Multiverse (called also "frame" by Kripke) as any
non-empty set W together with an accessibility relation R defined on
the set. Elements of that set are called "world", by definition, and I
follow the convention to denote worlds by greek letters (or their
english transcription: alpha, beta, gamma, delta, eta, epsilon, iota,
kappa, omega, nu, theta, etc.). R is called the accessibility relation.
So the simplest example of multiverse is given by the set {alpha} +
the empty relation (so just one dead end!). Another example is the set
of natural numbers with the divisibility relation ( n R m iff n divide
m iff there is a k such that n * k = m).
Let me define a notion of illuminated multiverse (called "model" by the
modal logicians). It is just a Kripke multiverse where we associate to
each world a value 1 or 0 to each sentence letter. The Kripke
multiverse is "illuminated" when a truth value (1 or 0) is assigned to
each proposition, in each world.
Remember that in (propositional) logic we have sentence letter p, q, r,
etc.
We also say that p is true in alpha for p has value 1 in alpha (in some
illuminated multiverse).
Now Kripke semantics can be given in a very simple way, by just asking
that,
1) each world obeys to classical logic (that is: if 1 is assigned to p
in the world alpha, and if 1 is assigned to q in alpha, then 1 is
assigned to (p & q) in alpha, etc. The "etc" is just a pointer to the
usual truth table of classical propositional logic. I have already
explain this on this list but I can do it again if asked). In
particular each classical tautologies are true in all worlds, whatver
the illumination chosen (whatever the truth value of the sentence
letter are in each world: like (p -> p) or (p v ~p), etc.
2) Kripke says that Bp (also written box p, []p, etc.) is true in the
world alpha if p is true in all worlds beta accessible from alpha. From
this it follows that Dp (defined as an abbreviation of ~B~p) will be
true in some world alpha if there is some world beta, accessible from
alpha, and with p true in the world beta.
Now I will say that a formula A of modal logic is valid in a
illuminated multiverse (W, R, V) if A is true in all the worlds of
that illuminated multiverse.
And I will say that a formula A of modal logic is respected by a
multiverse (W,R) if A is valid
in all illuminated multiverse (W, R, V). Or equivalently: A is
respected in (W,R) if A is true in all worlds in W and this for all
"illuminations" V, i.e. for all assignment of truth value of the
sentence letters in all worlds.
Last definition: a multiverse (W,R) is said to be reflexive if the
relation R is reflexive (that is: if for all world in W we have xRx,
i.e. if each world is accessible to itself by the relation R.
The easy exercise is the following: show that if the multiverse is
reflexive then the multiverse respects the formula Bp -> p.
Slightly less easy: show that the reverse is true: show that if a
multiverse respects Bp -> p, then the multiverse is reflexive.
I would like to know if that exercise *seems* difficult. For those who
cannot do it, it just means there is a need to refresh some "naive set
theory" knowledge, and I will think about a book who can help.
Don't hesitate to answer out of line if you prefer.
Sorry to annoy you with that modal stuff, but we are at a point I could
no more comment the posts without m
