On 20 Jan 2010, at 11:25, Stathis Papaioannou wrote:

2010/1/20 Nick Prince <m...@dtech.fsnet.co.uk>:If the no clone theorem were a problem then you could not survivemorethan a moment, since your brain is constantly undergoing classical level changes.How interesting!! I had forgotten that most people believe that consciousness is a classical rather than quantum process (Penrose excepted). Thank you for bringing this to my attention. So the no clone theorem should not pose a problem for copy builders after all.Even if perfection to the quantum level is needed for a copy (it can't be, since our brains do change over time, whether quantum level events are important or not) the no clone theorem says that it is not possible to make a perfect clone at will. It is still possible to make a perfect clone by preparing multiple variations of a copy.

`I agree. Quantum computer does not violate Church thesis, and are`

`emulable by classical Turing machine (combinators, elementary`

`arithmetics, etc.).`

`In particular the Universal Dovetailer does execute the emulation of`

`all rational approximation of the relativistic Schroedinger equation`

`applied to the quantum state of the Milky Way.`

`In the UD-time, defined by the (arithmetical) execution step some`

`(fixed) universal dovetailing, you will have to wait gigantic time`

`before the UD generate such a state, and again comparable time before`

`it proceeds to the next step, but this is irrelevant because the first`

`person cannot be aware of the "delays" of the reconstitution or`

`(quatum-like) preparation.`

What do you think could happen if there were 100 copies of yourunningin parallel and 90 were terminated? If you think you woulddefinitelycontinue living as one of the 10 remaining copies then to beconsistent you have to accept QTI. If you think there is a chancethatyou might die I find it difficult to understand how this could be reconciled with any consistent theory of personal identity.I know. To be consistent with my other assumptions I would have to believe in QTI but it is just so difficult to swallow. I think the hardest bit comes when we think of what we would experience. SupposeI lived in 200BC or before. It's hard to think of ways you couldkeepon surviving apart from alien visitations with copying machines etc. This is one reason I have looked in some detail into Tiplers omega point theory. I don't think this should be written off as being too whacky just because others have got onto the Tipler bashing bandwagon. It has not been refuted yet in terms of the accelerated expansion of the universe or for other reasons which I can eloborate on - but that is besides the point. If Tiplers final simulation is a Universal Dovetailer then anyone who has ever lived in the past could in principle find themselves as a consistent extension in that simulation. This is one explanation how people could avoid ending up in a cul de sac branch.Well, it is possible that the MWI is false. And as I understand it the MWI does not actually say that anything that can happen, will happen, although it is often assumed that it does; so it may be that sometimes probabilities go down to zero, which would make the QTI false.

`I would say, to Nick Prince, that Tipler is a bit naïve on his`

`theology, which is based on Aristotelian implicit assumptions. His`

`book on immortality is very courageous, and contains interesting`

`points. Yet, he completely abandon rigor when it comes to theology. It`

`is more a reflexion on Christian theology by a physicist, than a`

`rigorous attempt in general or theoretical theology. Of course, the`

`lack of rigor in theology is almost institutionalized on this planet`

`since a long time.`

`Then Tipler seems not to be aware that the comp hyp he is using is not`

`compatible with its explicit physicalism ...`

`He is not aware also of the quantum immortality which follows from the`

`quantum MW, and he missed like many the comp immortality.`

`I don't think it makes sense that the QTI or the comp-TI can be false`

`in any way (except by making the QT or comp false). To die with`

`probability one you have to really find a finite proof in Robinson`

`arithmetic that 0 = 1. If you find a proof that 0 = 1, you will just`

`backtrack, perhaps up to Peano or Robinson arithmetic.`

According to RSSA and the RSSA your absolute measure in themultiversedecreases with each branching as versions of you die. According totheRSSA this doesn't matter as at least one of you is left standing; according to the ASSA, this does matter and you eventually die. Theonly way I can make sense of the latter is if you have anessentialistview of personal identity. Under this view if a copy is made of you and the original dies, you die. Under what Parfit calls the reductionist view of personal identity, you live.Hmm.. I think that what I am calling absolute measure you think ofasrelative measure or something like it. I thought absolute measurewasthe total measure of my existence across the whole multiverse. If I cannot die then RSSA implies this would be conserved. As you traverse down a particular branch though, your measure would indeed decrease for both RSSA and ASSA but it would eventually decrease to zero for ASSA when you died! With RSSA it could only decrease asymptotically to zero, but never completly disappear.There is the absolute measure of a particular OM, and there is the absolute measure of all the OM's associated with a particular person, and both of these are fixed. As you age, the absolute measure of the OM you are experincing decreases because versions of you die. I think everyone agrees with this.

`I am not sure "absolute measure of an OM" makes any sense. Even for 3-`

`OM.`

`Relative measure for 3-OM makes sense, but the comp supervenience`

`thesis does not relate 1-OM with such relative measure in any easy`

`way. That's why we have to find a good (mathematical) definition of 1-`

`OM, and before that, of "first person" (like the one by Theaetetus),`

`and then do some math.`

Relative measure concerns the ratio of the measure of one OM to that of another OM or set of OM's. The ASSA/RSSA distinction came up in relation to QS/QTI, which concerns the probability of your next moment of experience. The RSSA says you should consider only the OM's which are candidates for your next moment and assume that your next moment is sampled randomly from these. In this case, their absolute measure is irrelevant, and only their measure relative to each other is important. The ASSA assumes that the sampling should be over all your OM's, so if the absolute measure of your all potential next moments is greatly decreased because the guillotine blade is falling and is 1mm from your neck, then your probability of surviving to the next moment is very low. This is a corollary of the claim that you are more likely to find yourself in a high measure OM than a low measure OM. Hopefully someone can comment if I have misrepresented the ASSA view, because I just don't see how it could make sense.

`I think the term "observer moment" (OM) comes from Nick Bostrom.`

`Usually I don't use it, except in short conversation when the context`

`helps to give it some meaning.`

`The problem with this expression, or more precisely with many uses of`

`that expression, is that, somehow, it is still based on some identity`

`thesis like 3-OM ==== 1-OM. But with the comp supervenience thesis,`

`things are far more complex. Roughly speaking, although from the 1-OM`

`view, it makes sense to put a measure on all 3-OM reasonably extending`

`the 3-OM chosen by the doctor for your 1-OM, the measure itself will`

`be related to the mathematical structure of the complete computational`

`histories of those 3-OM.`

`And things are even more complex when you take into account that we`

`can backtrack per amnesia, if we follow Saibal Mitra, so that the "1-`

`you" is not a well defined notion.`

`Here the math can help, but almost negatively, by showing indeed that`

`no machine can ever really know who she is. Your 1-you just cannot be`

`defined by you (be it the 1-you, or the 3-you).`

`For the 3-OM, the (very big, though) set of "next" 3-OM can make`

`sense. But for the 1-OM, it does not. It happens that with the`

`Theaetetical definition of knowing (Bp & p) and observing (Bp & ~B~p)`

`we can associate topological and quantum space of coherent sets of`

`computational consistent extensions (when p is Sigma_1) so that the`

`logic of the "measure one" can be derived from the math (that is done`

`in AUDA), and it gives something resembling quantum logic, and`

`confirming the universal-dovetailer-related kind of MW.`

For those who missed the definition of "p" and "B":

`p is for Sigma_1 arithmetical sentences. They are provably equivalent`

`with sentence having the shape ExP(x) where P is a decidable`

`predicate. They have the property that, when true, they are provable`

`(by sigma_1 complete (= universal) machine. So "p -> Bp" are TRUE for`

`them. And B here and above is for Gödel's 1931 provability predicate.`

`Löbian machine "knows" that they are Sigma_1 complete: they can PROVE,`

`for them, that "p -> Bp".`

`It is really the computer science constraints which put a mathematical`

`structure on the machine's mindscape, and it is hard for me to imagine`

`we can progress if we don't dig a bit more on the math of computer`

`science. I am sorry for that.`

`Even before using computer science, a bit of modal logic (which is far`

`more easy) can help. People can perhaps search on "modal" in the`

`archive for many (old) posts illustrating this. Modal logic, with`

`unary connector like B and D (D = ~B~), are *the* tool for doing`

`rigorous metaphysics (not just the computationalist one).`

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

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