Re: KIM 2.3 (was Re: Time)
On 19/01/2009, at 9:58 PM, Bruno Marchal wrote: Le 18-janv.-09, à 11:32, Kim Jones a écrit : On 18/01/2009, at 4:38 PM, Brent Meeker wrote: I have no doubt that digital mechanism and materialism are incompatible, though. Is that because, under materialism, consciousness depends on causal links? Brent supernatural causal links All right, if you define supernatural causal links by the natural relation existing among natural numbers (or other finite things). Assuming comp, of course. But Brent was momentarily speaking of materialism - materialism doesn't acknowledge any form of comp immateriality except according to the (probably) false mind/body dualism, where the mind is allowed to be an ethereal emanation of the brain. But that's not even immateriality in your specific sense - that's popular superstition. You've cured me of that. Mind is computation; matter is computation - consciousness is not unique in the sense of some special pleading that allows it to avoid Turing emulability. That natural supernatural is really super in the sense that, as a machine or number, we cannot prove or known all the relations from which physics and nature emerge or supervene on. Once comp is assumed this follows, yes. Kim, (and others) are you OK with the first person indeterminacy issue? I am happy to move on from this now. I cannot see how there can be a way of distinguishing any of my copies. Are you ok that, from a first person point of view, throwing a coin and self-duplication are identical or isomorphic experience? The two appear fundamentally the same process apart from the numbers of atoms involved And, do you agree that introducing delays does not change the expectations (the probabilities, or the credibilities) used for the first person indeterminacy? Discussion over the last few days points has circled around this; personally, I now accept that I only exist when my conscious mind is up and running. During delays in teleportation my conscious mind cannot run on any hardware so I have no way of experiencing the delay. In fact the delay makes no difference to the outcome from my perspective. In step 6 every consistent extension is now virtual but this makes no difference to my belief that I am the same person I was before teleportation since I anticipate a consistent extension and that is what I experience. All that the experiment has to do is match my expectations with a consistently logical and convincing reality and I am prepared every time to say This is real and this is happening to me despite delays, annihilated originals, virtual renderings etc. As long as I am convinced by the environment I find myself in, I am prepared to bet that it is causally connected to the one (I experienced) before it - which I guess it would be even if it were an unconvincing low-res simulation. Take all you time, but if you can ask some question, it will help me to prepare the answer. If UDA1..6 is well understood, meaning that there is no more question, I will try to imagine a way to explain step 7, and this without getting in the mathematical details (if that is possible). This is the hard part! Still, I feel that I can intuit it. This is where you show how physics arises from number. Also how the Multiverse and MWI find their place in comp. I know that sometimes, things can seems so incomprehensible that people cannot even ask any question. Not incomprehensible - just counter-intuitive. It's a mind-boggling exercise and up to here I do not feel you are losing any explanatory power by cutting back on the maths. In that case, tell me know that it is too much incomprehensible, and it will be my duty to make things even more clearer until the ah ah (meaning I understand or I have find an error. Best, Bruno - I did get a brief case of the Ah Ah (meaning I understand) when I read this article recently: Our world may be a giant hologram - space - 15 January 2009 - New Scientist Surely the discovery of the graininess of spacetime adds weight to the physics/psychology reversal of comp? regards, Kim --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-l...@googlegroups.com To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/everything-list?hl=en -~--~~~~--~~--~--~---
Re: Newbie Questions
Hi, Naive question: do physicists reconcile a really flat universe and the big bang theory? I don't see how. you mean this problem? http://en.wikipedia.org/wiki/Big_bang#Flatness.2Foldness_problem Inflationary theories give a solution, but it is a bit ad hoc. I am not a big fan of Big Bang - I like Paul Steinhardt's (not Eric Steinhart) cyclic universe, but I have not read enough about that model to know if it fares better explaining cosmological observations (but it is _compatible_ with current observations). But those reflections are from before my MWI times ;-) MWI explains fine-tuning (but not flatness) due to the anthropic principle. Cheers, Günther --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-l...@googlegroups.com To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/everything-list?hl=en -~--~~~~--~~--~--~---
Materialism was:Re: KIM 2.3
Brent, I wonder, what do you mean with materialism (I ask this having been a materialist myself)? Physics only describes relations. (see for instance here http://plato.stanford.edu/entries/structural-realism/) I gather you accept MWI, so quite a lot of relations hold. The question is, why the quantum (as Wheeler, I think, put it)? Bruno's COMP gives a very elegant _explanation_. Also, with COMP, the mind-body problem indeed disappears. We have computations within computations within computations. (And I think that Bruno is correct when assuming that there is no _lowest_ level). It needn't even be a pure idealism, but rather Russelian neutral monism - some states more or less conscious - the degree of consciousness depending on the degree of self-reflexivity (see for instance here for a theory of consciousness which works well with COMP: http://plato.stanford.edu/entries/consciousness-higher/) Back to the ontological problem of the grounding: materialism is in essence the thesis that there is, at bottom, a substance, which has no independent properties, but serves as instantiator for other properties. But why should such a strange thing exist? Why not let the relations stand for themselves? Especially for an MWI-theorist; if you only accept a single world, matter does seem much more plausible - going through diverse transformations, that being all there is, and located somewhere in an otherwise empty spacetime or whatever - but those are all very naive intuitions which modern physics has moved beyond (and all the more so critical reflection on the results of modern physics). A big question: why should there be such a thing as a lowest level, a grounding? While for a materialist, the imagination of turtles all the way down http://en.wikipedia.org/wiki/Turtles_all_the_way_down is quite strange, computations all the way down is very intuitive. Well, awe-inspiring intuitive ;-)) Think of the fractal video Bruno sent out a little while ago. What explanatory power does matter hold? None, I conjecture. Please give at least one so we can discuss. Cheers, Günther --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-l...@googlegroups.com To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/everything-list?hl=en -~--~~~~--~~--~--~---
Re: QM Turing Universality
Hi Bruno,
I have finished the reading of the paper I mentioned (Deutsch's
Universal Quantum Turing Machine revisited) and I see they have very
similar problems, probably better described.
I finished a rather careful reading of that paper (QTM revisited) too,
http://arxiv.org/pdf/quant-ph/0701108v1
and if I got it right the main authors' point is:
Claims:
1) An Universal Probabilistic Turing Machine (PTM) can simulate the set
of PTMs with computable transition probabilities EXACTLY.
2) An Universal QTM can simulate the set of QTMs with computable
amplitudes only approximately.
Conclusion:
The notion of universality for Quantum TM is not of the same kind that
we have for Determinictic TM and Probabilistic TM.
Well, the first claim is correct and the corresponding algorithm for an
EXACT simulation is very simple. I think you know this well, but for the
sake of having a good reference, see for example Lemma 7.14 in
http://www.cs.princeton.edu/theory/complexity/bppchap.pdf
A tricky point, of course, is that in order to achive an EXACT
simulation your algorithm will potentionally never stop. For example,
trying to achieve ouput probability P=1/3 using UPTM with transitional
probabilities {0,1/2,1} is exact only in the limit.
In practice, such an EXACT simulation is not needed, and people prefer
to say that one machine CAN simulate other machine if properties in
question can be approximated with ARBITRARY accuracy. Yes, and it should
be reasonably fast. Typically the penalty for a better accuracy is
upper-bounded by a polylog factor.
Regarding the second claim, it is not true to my knowledge.
Approximation of amplitudes is a convergent process - set your accuracy,
suffer polylog slowdown factor, done. Wanna go to the limit, you get an
exact simulation.
The paper mentions (but
does not tackle) an old problem already described by Shi 2002, which
made me think at the time that the notion of Universality is a bit
dubious in the quantum realm.
I don't know which problem do you mean. In the QTM Revisited paper, the
authors do not suply a valid reference, the paper they refer to does not
exist and they don't get right even the first name of Dr. Shi.
Thus I may only assume that you/the authors refer to this paper
http://arxiv.org/pdf/quant-ph/0205115v2
I have read this paper few years ago and after a quick today's scan I'm
not aware of some explicitly described problem. On the contrary, the
message of the paper is that it is 'easy' to find universal set of
quantum gates (given that you start, for better or worse, from classical
universal set of gates).
To sum up: is there a (never stopping) quantum counting algorithm? I
think I can build a Quantum UD from it, well in case the Shi problem
is not too much devastating.
But here, and now, I got a feeling there is just no quantum counting
algorithm ...
Please be more specific about what do you mean by a quantum counting
algorithm. Sometimes I'm not too bright guy :-)
Is this what you mean?
step 1\ |0
step 2\ |0 + |1
step 3\ |0 + |1 + |2
or (a classical machine operated by quantum means)
step 1\ |0
step 2\ |1
step 3\ |2
or something different :-)
Best,
mirek
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Re: Materialism was:Re: KIM 2.3
Günther Greindl wrote: Brent, I wonder, what do you mean with materialism (I ask this having been a materialist myself)? I didn't use the term - it is one being attributed to me simply because I question the adequacy of logic and mathematics to instantiate physics. Physics only describes relations. (see for instance here http://plato.stanford.edu/entries/structural-realism/) I gather you accept MWI, so quite a lot of relations hold. I don't accept any such esoteric theories - I merely entertain them. The question is, why the quantum (as Wheeler, I think, put it)? Bruno's COMP gives a very elegant _explanation_. I agree it is elegant, but whether it can really explain the world remains to be seen. Also, with COMP, the mind-body problem indeed disappears. We have computations within computations within computations. (And I think that Bruno is correct when assuming that there is no _lowest_ level). But the problem reappears as the body-problem. Why is materialism so successful as a model of the world? It needn't even be a pure idealism, but rather Russelian neutral monism - some states more or less conscious - the degree of consciousness depending on the degree of self-reflexivity (see for instance here for a theory of consciousness which works well with COMP: http://plato.stanford.edu/entries/consciousness-higher/) Back to the ontological problem of the grounding: materialism is in essence the thesis that there is, at bottom, a substance, which has no independent properties, but serves as instantiator for other properties. It seems somewhat gratuitous to call this a substance. I'd say materialism holds (on simple empirical grounds) that some things exist and some don't. But why should such a strange thing exist? Why should some things exist and others not - because if everything existed there would be no distinction between exist and not-exist (I know that's a stilly argument, but it is similar to the kind of logic chopping I sometimes see from the proponents of everything exists). Why not let the relations stand for themselves? Especially for an MWI-theorist; if you only accept a single world, matter does seem much more plausible - going through diverse transformations, that being all there is, and located somewhere in an otherwise empty spacetime or whatever - but those are all very naive intuitions which modern physics has moved beyond (and all the more so critical reflection on the results of modern physics). I think I'm as qualified to speak for modern physics as you and I don't think it has moved beyond. MWI is attractive for several reasons, but it is well short of Tegmarkia. A big question: why should there be such a thing as a lowest level, a grounding? While for a materialist, the imagination of turtles all the way down http://en.wikipedia.org/wiki/Turtles_all_the_way_down is quite strange, computations all the way down is very intuitive. Well, awe-inspiring intuitive ;-)) Think of the fractal video Bruno sent out a little while ago. I think Tegmark grounded his everything by supposing that the lowest level was uncomputable. What explanatory power does matter hold? None, I conjecture. Please give at least one so we can discuss. Materialism has been very effective in not only explaining, but in predicting things. That doesn't prove it's right, but I could ask what explanatory power does everything exists hold. Remember that a theory that could explain anything, fails to explain at all. For myself, I find Bruno's theory very intriguing. It is more specific than Tegmark's and so I believe has more hope of making contact with empiricism. But for me that is the proof of the pudding - not logical arguments about how nature must be. Brent --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-l...@googlegroups.com To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/everything-list?hl=en -~--~~~~--~~--~--~---
