Re: why can't we erase information?
Jesse Mazer wrote: As for the question of why we live in a universe that apparently has this property, I don't think there's an anthropic explanation for it, I'd see it as part of the larger question of why we live in a universe whose fundamental laws seem to be so elegant and posess so many symmetries, one of which is time-symmetry (or to be more accurate, CPT-symmetry, which means the laws of physics are unchanged if you switch particles with antiparticles and flip the 'parity' along with reversing which direction of time is labeled 'the future' and which is labeled 'the past'). Some TOEs that have been bandied about here say that we should expect to live in a universe whose laws are very compressible, so maybe this would be one possible way of answering the question. Let me be more explicit about the point I was trying to make. Most of the TOEs that try to explain why our laws are so elegant (for example Schmidhuber's) do so by assuming that all possible computations exist, with our universe being in some sense a random selection among all possible computations. Elegant universes with simple laws have high algorithmic probability (i.e., high probability of being produced by a random program), thus explaining why we live in one. The problem I was trying to point out with this approach is that the standard Turing machine we usually use to define computations is not reversible, meaning it includes instructions such as set the current tape location to 0 (regardless of what's currently on it) that erase information. Most programs that we (human beings) write use these kinds of instructions all the time, and thus are not reversible. A random program on such a machine could only avoid irreversibility by chance. But our universe apparently does avoid them, so this observation seems to require further explanation under this kind of approach. Of course we can use a reversible Turing machine, or a quantum computer (which is also inherently reversible), to define algorithmic probability, in which case we would expect a random program to be reversible. But that seems like cheating... --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
Ti Bo wrote: On reversibility, there is the observation (I think acredittable to Tom Toffoli) that most/all irreversible systems have a reversible subsystem and the dynamics arrive in that subsystem after some (finite) time. Thus any system that we observe a while after it has started will, with high likelihood, be reversible. In some sense the irreversibility dissipates and leaves a reversible core. That's an interesting observation, but are you suggesting that it can explain why our universe is reversible? If so, how? Do you have a reference to a fuller explication of the idea? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
Saibal Mitra wrote: How would an observer know he is living in a universe in which information is lost? Information loss means that time evolution can map two different initial states to the same final state. The observer in the final state thus cannot know that information really has been lost. If the universe allows two different states to evolve into the same final state, the second law of thermodynamics wouldn't hold, and we would be able to (in principle) contruct perpetual motion machines. I don't know why you say this can't be detected by an observer. In theory all we have to do is prepare two systems in two different states, and then observe that they have evolved into the same final state. Of course in practice the problem is which two different states? And as I suggest earlier, it may be that for anthropic reasons one or both of these states is very difficult to access. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
From: Wei Dai [EMAIL PROTECTED] Reply-To: everything-list@googlegroups.com To: everything-list@googlegroups.com Subject: Re: why can't we erase information? Date: Mon, 10 Apr 2006 16:11:28 -0700 Jesse Mazer wrote: As for the question of why we live in a universe that apparently has this property, I don't think there's an anthropic explanation for it, I'd see it as part of the larger question of why we live in a universe whose fundamental laws seem to be so elegant and posess so many symmetries, one of which is time-symmetry (or to be more accurate, CPT-symmetry, which means the laws of physics are unchanged if you switch particles with antiparticles and flip the 'parity' along with reversing which direction of time is labeled 'the future' and which is labeled 'the past'). Some TOEs that have been bandied about here say that we should expect to live in a universe whose laws are very compressible, so maybe this would be one possible way of answering the question. Let me be more explicit about the point I was trying to make. Most of the TOEs that try to explain why our laws are so elegant (for example Schmidhuber's) do so by assuming that all possible computations exist, with our universe being in some sense a random selection among all possible computations. Elegant universes with simple laws have high algorithmic probability (i.e., high probability of being produced by a random program), thus explaining why we live in one. The problem I was trying to point out with this approach is that the standard Turing machine we usually use to define computations is not reversible, meaning it includes instructions such as set the current tape location to 0 (regardless of what's currently on it) that erase information. Most programs that we (human beings) write use these kinds of instructions all the time, and thus are not reversible. A random program on such a machine could only avoid irreversibility by chance. But our universe apparently does avoid them, so this observation seems to require further explanation under this kind of approach. Of course we can use a reversible Turing machine, or a quantum computer (which is also inherently reversible), to define algorithmic probability, in which case we would expect a random program to be reversible. But that seems like cheating... I have a vague memory that there was some result showing the algorithmic complexity of a string shouldn't depend too strongly on the details of the Turing machine--that it would only differ by some constant amount for any two different machines, maybe? Does this ring a bell with anyone? Jesse --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
Hi All, I feel like a Toffoli disciple. I cannot recreate the argument right now, but he argues that an increase in entropy is compatible with reversible and irreversible processes, but a decrease in entropy is only compatible with reversible dynamics. The argument is interesting and the book where it appears (he was talking at the Data Ecologies 05 event last year) is due out some time soon... cheers, tim On Apr 11, 2006, at 4:26 AM, Jesse Mazer wrote: Likewise, I think the second law is interpreted as the destruction of information needs a bit of clarification--as entropy increases, there are more and more microstates compatible with a given macrostate so the observer is losing information about the microstate, but information is not really being lost at a fundamental level, since *in principle* it would always be possible to measure a system's exact microstate. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
I think that this observation could explain why we see a reversible universe: all the irreversibility has already happened. If we think of a dynamics with discrete time then we have a collection of points with directed arcs between them. As a graph, this has the structure of several cycles with trees connected to some of the points. The trees correspond to the irreversible part of the dynamics, the cycles to the reversible part. If the largest tree is of height h, then after h time steps, the system must be in a state on one of the cycles. Thus the dynamics is reversible. Of course this argument requires a finite state system, which is usually assumed in such discussions. An uncountably infinite counterexample to this idea is an infinite tree, with every node branching to two predecessors. At every state and every time step there is an irreversible transition. A countable counterexample can be assembled by grafting a copy of the natural numbers onto the integers with the system state transition taking n to n-1. Then 0 has two predecessors. Because there is no bound on the time taken for a pair of distinct states (the same positive integer on the two branches) to be mapped together, the reversibility does not dissipate. I thought I had a copy of the paper here, but I cannot locate it. If memory serves me right, it was one of a series of papers that Toffoli wrote in the last half of the 90s dealing with computation and physics. Most of them are good reading anyway, so have a dive into: http://pm1.bu.edu/~tt/publ.html Tim On Apr 11, 2006, at 1:19 AM, Wei Dai wrote: Ti Bo wrote: On reversibility, there is the observation (I think acredittable to Tom Toffoli) that most/all irreversible systems have a reversible subsystem and the dynamics arrive in that subsystem after some (finite) time. Thus any system that we observe a while after it has started will, with high likelihood, be reversible. In some sense the irreversibility dissipates and leaves a reversible core. That's an interesting observation, but are you suggesting that it can explain why our universe is reversible? If so, how? Do you have a reference to a fuller explication of the idea? -Tim Boykett TIME'S UP::Research Department \ / Industriezeile 33b A-4020 Linz Austria X+43-732-787804(ph) +43-732-7878043(fx) / \ [EMAIL PROTECTED]http://www.timesup.org - http://www.timesup.org/fieldresearch/setups/index.html --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
Jesse Mazer: I have a vague memory that there was some result showing the algorithmic complexity of a string shouldn't depend too strongly on the details of the Turing machine--that it would only differ by some constant amount for any two different machines, maybe? Does this ring a bell with anyone? That is correct, but the constant is a multiplicative one, and could be made arbitrarily large. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
Yes, I agree. But it could be that information loss is a bit ambiguous. E.g. 't Hooft has shown that you can start with a deterministic model exhibiting information loss and end up with quantum mechanics. Saibal - Original Message - From: Jesse Mazer [EMAIL PROTECTED] To: everything-list@googlegroups.com Sent: Monday, April 10, 2006 03:22 AM Subject: Re: why can't we erase information? Saibal Mitra wrote: How would an observer know he is living in a universe in which information is lost? Information loss means that time evolution can map two different initial states to the same final state. The observer in the final state thus cannot know that information really has been lost. If he is able to figure out the fundamental laws of physics of his universe, then he could see whether or not they have this property of it being possible to deduce past states from present ones (I think the name for this property might be 'reversible', although I can't remember the difference between 'reversible' and 'invertible' laws). For example, the rules of Conway's Game of Life cellular automaton are not reversible, but if it were possible for such a world to support intelligent beings I don't see why it wouldn't be in principle possible for them to deduce the underlying rules. As for the question of why we live in a universe that apparently has this property, I don't think there's an anthropic explanation for it, I'd see it as part of the larger question of why we live in a universe whose fundamental laws seem to be so elegant and posess so many symmetries, one of which is time-symmetry (or to be more accurate, CPT-symmetry, which means the laws of physics are unchanged if you switch particles with antiparticles and flip the 'parity' along with reversing which direction of time is labeled 'the future' and which is labeled 'the past'). Some TOEs that have been bandied about here say that we should expect to live in a universe whose laws are very compressible, so maybe this would be one possible way of answering the question. Jesse - Defeat Spammers by launching DDoS attacks on Spam-Websites: http://www.hillscapital.com/antispam/ --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
Le 11-avr.-06, à 01:11, Wei Dai a écrit : Jesse Mazer wrote: As for the question of why we live in a universe that apparently has this property, I don't think there's an anthropic explanation for it, I'd see it as part of the larger question of why we live in a universe whose fundamental laws seem to be so elegant and posess so many symmetries, one of which is time-symmetry (or to be more accurate, CPT-symmetry, which means the laws of physics are unchanged if you switch particles with antiparticles and flip the 'parity' along with reversing which direction of time is labeled 'the future' and which is labeled 'the past'). Some TOEs that have been bandied about here say that we should expect to live in a universe whose laws are very compressible, so maybe this would be one possible way of answering the question. Let me be more explicit about the point I was trying to make. Most of the TOEs that try to explain why our laws are so elegant (for example Schmidhuber's) do so by assuming that all possible computations exist, with our universe being in some sense a random selection among all possible computations. Elegant universes with simple laws have high algorithmic probability (i.e., high probability of being produced by a random program), thus explaining why we live in one. Except that I done understand what you mean by our universe, due to the 1/3 person pov distinction. Adding that ourselves are the result of a long (deep) computations could help here (cf Bennett's work on computational depth), but will be enough only if you allow the result of the deep computation to remains stable on some dovetailing on the reals, to explain away the first person rabbits! The problem I was trying to point out with this approach is that the standard Turing machine we usually use to define computations is not reversible, meaning it includes instructions such as set the current tape location to 0 (regardless of what's currently on it) that erase information. To my knowledge, Hao Wang (a expert on Godel) has been the first to program a universal turing machine which never erase its tape. Much work has been done (cf Toffoli). Abramski has written a compiler transforming irreversible programs into reversible one. In term of combinators, a quantum world lacks Kestrels (capable of eliminating information) and Warbler or Starling or any combinators capable of duplicating information. I explain this in my last paper (the one which is not yet on my web page). Most programs that we (human beings) write use these kinds of instructions all the time, and thus are not reversible. A random program on such a machine could only avoid irreversibility by chance. But our universe apparently does avoid them, so this observation seems to require further explanation under this kind of approach. Of course we can use a reversible Turing machine, or a quantum computer (which is also inherently reversible), to define algorithmic probability, in which case we would expect a random program to be reversible. But that seems like cheating... Certainly. Note that a kripke multiverse with a symmetric accessibility relation (good for reversibility), needs to obey to the modal law LASE: p - BDp. I got it with the interview of the lobian machine but only for the atomic p. This means that true irreversibility is still an open problem with comp, but there is some evidence at the bottom. Apparently information, at the bottom, cannot be created, cannot be erased, and cannot in general be duplicated. Quite unlike classical bits. But with comp this is just due to our ignorance about the infinite set of computations which emulate us. I think it is the same with Everett, information is never lost at the bottom, but when we measure bottom states, we entangle ourselves with all possible alternative results and the information dissipates through parallel histories. The increase of entropy could be a local and a first person (plural) phenomenon. Bruno http://iridia.ulb.ac.be/~marchal/ --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: The Riemann Zeta Pythagorean TOE
Le 11-avr.-06, à 00:19, John M a écrit : Comp? I always considered it the - so far - best ways the human mind could invent for reductionist thinking. I am too busy this week to comment this delicate point. I will explain later some basic think in computer science which are needed, not only to get some light on comp in general and the UD (and G), but also to clarify question about Kolmogorov algorithmic complexity (or Solovay, Chaitin one(*)). I hope that I will succeed to open your mind with the idea that comp is not only not reductionist but that comp gives a sort of vaccine against a very vast set of possible reductionism. The price is the realization that we don't know what numbers really are, or what machines are capable of. But I cannot explain this without saying more on the diagonalization procedure. Understanding comp needs some amount of understanding (theoretical) comp...uter science. A+ B. (*) cf Jesse: I have a vague memory that there was some result showing the algorithmic complexity of a string shouldn't depend too strongly on the details of the Turing machine--that it would only differ by some constant amount for any two different machines, maybe? Does this ring a bell with anyone? http://iridia.ulb.ac.be/~marchal/ --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
- Original Message - From: Wei Dai [EMAIL PROTECTED] To: everything-list@googlegroups.com Sent: Tuesday, April 11, 2006 01:46 AM Subject: Re: why can't we erase information? Saibal Mitra wrote: How would an observer know he is living in a universe in which information is lost? Information loss means that time evolution can map two different initial states to the same final state. The observer in the final state thus cannot know that information really has been lost. If the universe allows two different states to evolve into the same final state, the second law of thermodynamics wouldn't hold, and we would be able to (in principle) contruct perpetual motion machines. I don't know why you say this can't be detected by an observer. In theory all we have to do is prepare two systems in two different states, and then observe that they have evolved into the same final state. Of course in practice the problem is which two different states? And as I suggest earlier, it may be that for anthropic reasons one or both of these states is very difficult to access. Yes, in principle you could observe such a thing. But it may be that generic models exhibiting information loss look like model that don't have information loss to internal observers. 't Hooft's deterministic models are an example of this. I'm also skeptical about observers being able to make more efficient machines. The problem with that, as I see it (I haven't read Lloyd's book yet) is as follows. Consider first a model without information loss, like our own universe. What is preventing us from converting heat into work with 100% efficiency is lack of information. If we had access to all the information that is present then you could make an effective Maxwell's Daemon. Lacking such information, Maxwell's Deamon has to make measurements, which it has to act on. But eventually it has to clear it's memory, and that makes it ineffective. To get rid of this problem Maxwell's Daemon would have to be able to reset its memory without changing the state of the rest of the universe. This could possibly be done in an universe with information loss, but that could only work if the Daemon has control over the information loss process. If information loss interferes with the actions of the Daemon, then it isn't much use. You could also think of the possiblity of some ''physical process'' which would be sort of a ''passive Maxwell's Deamon'' that could reduce the entropy in such universe. Using that you could create a temperature difference between two objects. To extract work you now need to let heat flow between the two objects. So, at that stage you need an entropy to increase again. So, to me this doesn't seem to be a generic world in which you have information loss, rather a world in which it is preserved but where it can be overruled at will. The benefits come from that magical power. Saibal - Defeat Spammers by launching DDoS attacks on Spam-Websites: http://www.hillscapital.com/antispam/ --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
I'm not a physicist, so I'm asking a question. How much of this we have no information loss in this universe prinicple are we simply assuming at the outset? I know that a lot of it is unverified theory, like in the case of Stephen Hawking's black hole vs. no black hole from infinity argument, etc. For instance, are we simply assuming, by the sacred laws of thermodynamics, that in the quantum background there is always an antiparticle for each particle in order to annihilate each other? Or could it be that particles and antiparticles appear and disappear asymmetrically on their own, under our observational radar, even though that wouldn't be elegant? Perhaps all these undetectable asymmetries add up to cancel out any observable asymmetries. Weirder things have happened in quantum physics. Are we assuming by elegance that there is no information loss? You can just tell me to go back to my math if you want. Tom Saibal Mitra wrote: How would an observer know he is living in a universe in which information is lost? Information loss means that time evolution can map two different initial states to the same final state. The observer in the final state thus cannot know that information really has been lost. If the universe allows two different states to evolve into the same final state, the second law of thermodynamics wouldn't hold, and we would be able to (in principle) contruct perpetual motion machines. I don't know why you say this can't be detected by an observer. In theory all we have to do is prepare two systems in two different states, and then observe that they have evolved into the same final state. Of course in practice the problem is which two different states? And as I suggest earlier, it may be that for anthropic reasons one or both of these states is very difficult to access. Yes, in principle you could observe such a thing. But it may be that generic models exhibiting information loss look like model that don't have information loss to internal observers. 't Hooft's deterministic models are an example of this. I'm also skeptical about observers being able to make more efficient machines. The problem with that, as I see it (I haven't read Lloyd's book yet) is as follows. Consider first a model without information loss, like our own universe. What is preventing us from converting heat into work with 100% efficiency is lack of information. If we had access to all the information that is present then you could make an effective Maxwell's Daemon. Lacking such information, Maxwell's Deamon has to make measurements, which it has to act on. But eventually it has to clear it's memory, and that makes it ineffective. To get rid of this problem Maxwell's Daemon would have to be able to reset its memory without changing the state of the rest of the universe. This could possibly be done in an universe with information loss, but that could only work if the Daemon has control over the information loss process. If information loss interferes with the actions of the Daemon, then it isn't much use. You could also think of the possiblity of some ''physical process'' which would be sort of a ''passive Maxwell's Deamon'' that could reduce the entropy in such universe. Using that you could create a temperature difference between two objects. To extract work you now need to let heat flow between the two objects. So, at that stage you need an entropy to increase again. So, to me this doesn't seem to be a generic world in which you have information loss, rather a world in which it is preserved but where it can be overruled at will. The benefits come from that magical power. Saibal - Defeat Spammers by launching DDoS attacks on Spam-Websites: http://www.hillscapital.com/antispam/ --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
A few years ago I posted a speculation about Harry Potter universes, from the Schmidhuber perspective. Schmidhuber argues that the reason we don't see such a universe is that its program would be more complex, hence its algorithmic-complexity measure would be less. Such a universe would basically have natural laws identical to what we see, but in addition it would have exceptions to the laws. You wave a wand and say Lumino! and light appears. (Here I am taking the Harry Potter name rather literally, but the same thing applies to the more general concept of universes with magical exceptions to the rules.) You could also argue, as Wei does, on anthropic grounds that in such a universe the ease of exploiting magic would reduce selection pressure towards intelligence. Indeed in the Harry Potter stories there are magical animals but it is never explained why their amazing powers did not allow them to dominate the world and kill off mundane creatures long before human civilization arose. I suggested that the Schmidhuber argument has a loophole. It's true that the measure of a simple universe is much greater than a universe with the same laws plus one or more exceptions. But if you consider the set of all universes built on those laws plus exceptions, considering all possible variants on exceptions, the collective measure of all these universes is roughly the same as the simple universe. So Schmidhuber gives us no good reason to reject the possibility that our universe may have exceptions to the natural laws. If we do live in an exceptional universe, we are more likely to live in one which is only slightly exceptional, i.e. one whose laws are among the simplest possible modifications from the base laws. Unfortunately, without a better picture of the true laws of physics and an understanding of the language that expresses them most simply, we can't say much about what form exceptions might take. We know that they would be likely to be simple, in the same language that makes our base laws simple, but since we don't know that language it is hard to draw conclusions. Here is where the anthropic argument advanced by Wei Dai sheds some light; one thing we could say is that these simple exceptions should not be exploitable by life and make things so easy as to remove selection pressure. So this would constrain the kinds of exceptions that could exist. Ironically, waving a wand and speaking in Latin would indeed be the kind of exception that would not likely be exploited by unintelligent life forms. So purely on anthropic principles we could not fully rule out Harry Potter magic. But the complexity of embedding Latin phrases in the natural laws would argue strongly against us living in such a universe. Hal Finney --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: Do prime numbers have free will?
--- Stathis Papaioannou [EMAIL PROTECTED] wrote: among others: * I understood Tom's phrase atomic parts as meaning component parts rather than literally what scientists call atoms fine, I used Tom's word. It went to a nice extreme. * Then about 'rules': It was deliberately left vague: the rules are not necessarily the rules of present day science, but the rules of any possible future science, or, as you suggest, the rules known by an omniscient being. Are you still talking about 'rules' reduced (!) to the limited model view they pertain to (=reductionistic) or do you imply the untellable 'rules' of the tota;ity? In that case I don't know how to valuate any 'rules'. The 'omniscient being' would 'know' that detailed rules are off. In everything interefficient to everything incl. those 'trends' we consider parts within the model, (a definitely reductionist view) forming continually in the ceaseless change of the wholeness. It's above me! * And warm thanks for your consent: Yes, this is just what I meant: the truly random is beyond *any* rules, including ones not yet discovered. Otherwise, it would not be truly random. (I find 'untruly random' similar to 'just a bit pregnant'). * from the truncated message: John M writes: Tom Caylor writes: 1) The reductionist definition that something is determined by the sum of atomic parts and rules. So how about this: EITHER something is determined by the sum of atomic parts and rules OR it is truly random. Sum of atomic parts? I am not sure about the figment based on primitive observations and on then applicable explanatory calculative conclusions within the narrow model of the ancient scientist's views, called atom. skip Same with chaos: we just did not (yet?) learn that kind of processes in the wide world existence that would result in our chaos- called process. (Like random.) I'm not sure what you mean here. In principle, a chaotic process could follow very simple and well-understood rules. The difficulty is that a future state of a chaotic system may be so sensitively dependent on initial conditions that it is impossible to measure these conditions to the requisite level of accuracy. The limitation is practical, not theoretical. And how do you think to evaluate ALL initial conditions in a wide world where everything is interconnected and intereffective? Practically (not theoretically G you cannot, so chaotic comes in in practice. Please, do not mix up the 'concept' with the limited science of the physical chaologists who restricted their conclusions to handpicked cases where (their) explanations may apply. Gleick's excellent journalism impressed even the most 'scientific' minds. He made the untellable clearly statable. His stupid butterfly still haunts the minds. Make yourself a god that could figure it all out. But the point is that it is *impossible* even in theory - even for an omniscient being - to figure it out. If I undergo destructive teleportation and two exact copies emerge in two separate locations, A and B, can I expect to find myself at A or at B? Let me refrain from remarking on that stupid teleportation hoax in honor for the esteemed listmembers. Your question rewords into: Is the cat dead or alive? Physics is a nice limited model formulated over the past ~10 millennia, to explain in its own rite whatever was thought to be observed. Then QM made it into a linear way of thinking accepting some of the paradoxes arising within the model 'physics'. I for one do not find QM more wholistic than St. Physix herself, in the contrary. It extends into limited models even the 'concepts' left uncut in physics (eg. particles galore). The Cavalcanti problem is part of the 'game'. Part of the term 'thought experiment' as I wrote yesterday to Bruno. Star Trek or Harry Potter. I am an old man, do not have time for such fantasy - games. I hope to find something more reasonable. Thanks, Stathis, John M Stathis Papaioannou === message truncated === --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
On Mon, Apr 10, 2006 at 09:45:50PM -0700, Brent Meeker wrote: Russell Standish wrote: On Mon, Apr 10, 2006 at 12:03:47AM -0700, Brent Meeker wrote: Russell Standish wrote: Unitary evolution preserves information. It is only through measurement by an observer that information can be created or destroyed. Usually, the second law is interpreted as the destruction of information (anyone observing a closed system will over time know less information about the system), so it puzzles me that you have the sign the other way. What? You're saying that if I observe a system, then I know less about it. You must be using some non-standard meaning of know. Brent Meeker Yes - in the case of milk being stirred into coffee. Strange as it may seem, you know more information when the system is initially structured than after that initial structure has dispersed. What's that have to do with observing it? Stirring milk into coffee isn't observing it - and as you point out below, entropy depends on observation, i.e. on some coarse grained constraint. Your answer seems to consist of non-sequiturs. ISTM that my knowledge is increased when I observe something. Physically this corresponds to some small Your total knowledge increases, assuming perfect memory (which is itself debatable, but beside the point). But your knowledge of the current state of the system decreases. The information content of the system decreases (exactly offset by the rise in entropy). My point is that this is precisely because it is observed. If it weren't observed, one simply has a quantum superposition undergoing unitary evolution. Cheers -- 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 --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
On Mon, Apr 10, 2006 at 10:26:17PM -0400, Jesse Mazer wrote: As I understand it, you don't need exactly need an observer, you just need to identify various macro-variables (like pressure and temperature) which can be used to coarse-grain the phase space of the system, with entropy being proportional to the logarithm of the number of possible detailed microstates (detailed descriptions of the positions and momenta of all the particles, within the limits of the uncertainty principle) compatible with a given macrostate (descriptions of the system which only tell you the value of the macro-variables). Once you have chosen your set of macro-variables, they should have well-defined values for any system, regardless of whether it's being observed by anyone or not. Of course, the choice of variables is based on what properties we human observers are actually capable of measuring in practice, so I don't necessarily disagree with your statement, but I think it needs a little clarification. That is precisely my point. However, observers are needed to specify the thermodynamic variables (as otherwise these things are meaningless). I try to make this somewhat provocatively, sure, but denying the role of the observer is bit like sweeping it under the carpet. Likewise, I think the second law is interpreted as the destruction of information needs a bit of clarification--as entropy increases, there are more and more microstates compatible with a given macrostate so the observer is losing information about the microstate, but information is not really being lost at a fundamental level, since *in principle* it would always be possible to measure a system's exact microstate. Jesse Information also needs an observer. Information is lost from the observer. I would argue it is not hidden, unless you believe in the possibility of Laplace's daemon actually existing. (Which I suspect you are saying with your *in principle* clause). Also note that exact measurements of microstates is *in principle* incompatible with the Heisenberg Uncertainty Principle. -- 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 --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
There would have to be some pretty major conditions and caveats on this. A system undergoing thermodynamic stress (ie is nonequilibrium) will exhibit a lowering of entropy compared with its state at equilibrium. However, the process is decidedly nonreversible... Cheers. On Tue, Apr 11, 2006 at 09:18:01AM +0200, Ti Bo wrote: Hi All, I feel like a Toffoli disciple. I cannot recreate the argument right now, but he argues that an increase in entropy is compatible with reversible and irreversible processes, but a decrease in entropy is only compatible with reversible dynamics. The argument is interesting and the book where it appears (he was talking at the Data Ecologies 05 event last year) is due out some time soon... cheers, tim On Apr 11, 2006, at 4:26 AM, Jesse Mazer wrote: Likewise, I think the second law is interpreted as the destruction of information needs a bit of clarification--as entropy increases, there are more and more microstates compatible with a given macrostate so the observer is losing information about the microstate, but information is not really being lost at a fundamental level, since *in principle* it would always be possible to measure a system's exact microstate. -- 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 --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
Re: why can't we erase information?
Russell Standish wrote: Also note that exact measurements of microstates is *in principle* incompatible with the Heisenberg Uncertainty Principle. Well, that's why I defined microstates as detailed descriptions of the positions and momenta of all the particles, within the limits of the uncertainty principle. My memory is that in the quantum version of statistical mechanics, the phase space is partititioned into finite regions so that the uncertainty principle does not prevent you from measuring which region the system is in (and the regions are made as small as possible while still having that be true). I wonder if there'd be a natural way to look at statistical mechanics in the MWI interpretation though--I would think the maximal information about a system, analogous to the microstate, would be the system's exact quantum state (which only assigns amplitudes to different values of noncommuting variables like position and momentum), and the evolution of the system's quantum state over time should be completely deterministic, and also information-preserving in the sense that knowing the quantum state at a later time would tell you the quantum state at an earlier time. But I can't think what macrostates you'd use, since a particular quantum state can involve a superposition of different possible temperatures, pressures and so forth. Jesse --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Everything List group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~--~~~~--~~--~--~---
