Re: why can't we erase information?
On Sat, May 06, 2006 at 10:24:05PM -0400, [EMAIL PROTECTED] wrote: Russell, my apologies for the approximate typing. I don't assign to your not following my comments to that awful new keyboard I tried to use (light grey letters on a slightly less light grey base - not visible and I am not a good 'blind'typist) with the YAHOO-mail spellchecker that garbles up the letters - I think your uncertainty stems from a different knowledge-base I use. No doubt. Classical thermodynamics I learned in 1942 when I identified it as the science which tells us how things would go wouldn't they go the way they do go meaning the game of isotherm and reversible equational craze in closed systems. Then later Prigogine et al improved upon it, but I still hold the field within the limited model of our epistemic - ever changing, enriching - interpretation of the (obsolete) historical bases from very primitive knowledge level times and accordingly primitive measurements by unsophisticated instrumentation, subject to an all ingenious explanation on THAT level. (Think about the dozen+ (and still counting) changing views about the 'entropy' conceptS). Indeed - you are thinking of the difference between equilibrium thermodynamics (which is classical in the sense of being a mature topic, but of extremely limited validity), and nonequilibrium thermodynamics which applies to much of the rest of reality, but which is very much an ongoing research topic. I have always eschewed equilibrium physics in favour of the more exciting nonequlibrium topics. Nevertheless, the concept of closed system applies in both equilibrium and nonequlibrium cases. * Singularity in my view is a no-system because there is no way we can extract any information about it - unless we give up the definition. This is how I view a 'closed' system, (not lawyerish: well, you can look at it as semi-closed, or even open, if you like,...) If it is closed, it is closed. Singularity is nice to speak about, I hold: there is no such thing only in sci-fi. We get usded to many sci-fi marvels and in the 15th step it looks like real. Singularities are one of the features of General Relativity, but are contradictory in the sense that GR is expected to break down (in the sense of failing to describe reality) near them. So perhaps singularities do or do not exist. In fact we really don't know much about how they should behave assuming they do exist. The business of event horizons (which would cloak singularities, as well as other high density regions of space - collectively known as black holes) and information flow is certainly a case in point. Unitarity is tied up with information conservation, and some studies indicate black holes violate unitarity. I'm personally sceptical that unitarity is ever violated, except as a process of observation (the creation of information). But I have no plans to work in this area. Russell, when I said good bye to my polymer science (1987) and started to think I tried to throw out things to be 'believed' (axioms, paradoxes, emergence, chaos). I retired with limited movablity and allowed myself to get away from conventional reductionism. You are in the profession, books projects, responsibility for what you said yesterday: I don't want to persuade you to think differently, especially since I am fully aware of the embryonic level of the 'new ways' I still try to find. I have questions, very few answers and I doubt them. John I'm well aware that you are following a deconstruction approach. A little of this is healthy of course, but too much leads to one getting lost. Is it not better to understand the language of science, to debate the topics using understood terms of science, and occasionally lob in the hand grenade that causes a radical change in understanding. -- 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?
Thanks, Russell, I really do not want to continue - seems side-line to you and side line to me. I just cannot keep my mouse shut. 1. The 'nonequilibrium' topics still identify a certain 'cut' within the boundaries of them, neglecting wider - maybe unobserved/able - effects from 'unrelated' sides. (see my '3' below) Pertinent to 'closed systems' as well. In (my) wholistic view nothing is shut of of anything in an intereffectiveness that may include unknown elements at the level of our present cognitive inventory. 2. Suppose singularity is not - where does the (alleged) GR break down? It is a 150th consequential idea from a questionable startup-figment and we just continue to build logically, quantitatively, formally - call it science. To be clear: I appreciate and USE the technological marvels based on such questionable theoretical background. I believe in human ingenuity even on wrong premises. 3.To your last par: one cannot have it both ways. Einstein (what a comparison to myself!!!) did not accept all Newton in his thinking and tackled only certain terms in a new view. Copernicus did not abide by the well proven Flat Earth and just 'included' at some points his new ideas. You cannot keep creationism when you think in evolution. I may get lost - as you say - but it won't last long. I won't either. In the meantime I have the luxury of tasting the new ideas. And I feel I am not alone in these ways John M - Original Message - From: Russell Standish [EMAIL PROTECTED] To: everything-list@googlegroups.com Sent: Wednesday, May 10, 2006 2:01 AM Subject: Re: why can't we erase information? On Sat, May 06, 2006 at 10:24:05PM -0400, [EMAIL PROTECTED] wrote: Russell, my apologies for the approximate typing. I don't assign to your not following my comments to that awful new keyboard I tried to use (light grey letters on a slightly less light grey base - not visible and I am not a good 'blind'typist) with the YAHOO-mail spellchecker that garbles up the letters - I think your uncertainty stems from a different knowledge-base I use. No doubt. Classical thermodynamics I learned in 1942 when I identified it as the science which tells us how things would go wouldn't they go the way they do go meaning the game of isotherm and reversible equational craze in closed systems. Then later Prigogine et al improved upon it, but I still hold the field within the limited model of our epistemic - ever changing, enriching - interpretation of the (obsolete) historical bases from very primitive knowledge level times and accordingly primitive measurements by unsophisticated instrumentation, subject to an all ingenious explanation on THAT level. (Think about the dozen+ (and still counting) changing views about the 'entropy' conceptS). Indeed - you are thinking of the difference between equilibrium thermodynamics (which is classical in the sense of being a mature topic, but of extremely limited validity), and nonequilibrium thermodynamics which applies to much of the rest of reality, but which is very much an ongoing research topic. I have always eschewed equilibrium physics in favour of the more exciting nonequlibrium topics. Nevertheless, the concept of closed system applies in both equilibrium and nonequlibrium cases. * Singularity in my view is a no-system because there is no way we can extract any information about it - unless we give up the definition. This is how I view a 'closed' system, (not lawyerish: well, you can look at it as semi-closed, or even open, if you like,...) If it is closed, it is closed. Singularity is nice to speak about, I hold: there is no such thing only in sci-fi. We get usded to many sci-fi marvels and in the 15th step it looks like real. Singularities are one of the features of General Relativity, but are contradictory in the sense that GR is expected to break down (in the sense of failing to describe reality) near them. So perhaps singularities do or do not exist. In fact we really don't know much about how they should behave assuming they do exist. The business of event horizons (which would cloak singularities, as well as other high density regions of space - collectively known as black holes) and information flow is certainly a case in point. Unitarity is tied up with information conservation, and some studies indicate black holes violate unitarity. I'm personally sceptical that unitarity is ever violated, except as a process of observation (the creation of information). But I have no plans to work in this area. Russell, when I said good bye to my polymer science (1987) and started to think I tried to throw out things to be 'believed' (axioms, paradoxes, emergence, chaos). I retired with limited movablity and allowed myself to get away from conventional reductionism. You are in the profession, books projects, responsibility for what you said yesterday: I don't want to persuade you
Re: why can't we erase information?
On Wed, May 10, 2006 at 09:28:44AM -0400, [EMAIL PROTECTED] wrote: Thanks, Russell, I really do not want to continue - seems side-line to you and side line to me. I just cannot keep my mouse shut. Seems I'm the same :) 1. The 'nonequilibrium' topics still identify a certain 'cut' within the boundaries of them, neglecting wider - maybe unobserved/able - effects from 'unrelated' sides. The cuts appear in models to make them tractable. Experiments testing the models are set up to approximate the conditions of the model as well as is able. This is science. The models are applicable to describing reality only as far as how these conditions are approximated by the real system. This is easier in some systems than others - it fairly easy with respect to bridges and buildings, but much more difficult when it comes to figuring out what happens when we double atmospheric CO_2 concentration. In the latter system there are many interconnections, and figuring out what can be cut without invalidating the model is no easy task. 3.To your last par: one cannot have it both ways. Einstein (what a comparison to myself!!!) did not accept all Newton in his thinking and tackled only certain terms in a new view. Copernicus did not abide by the well proven Flat Earth and just 'included' at some points his new ideas. You cannot keep creationism when you think in evolution. Hence my comment about the hand grenade. Einstein was careful to only change one or two things at a time - he still stayed within scientific discourse. I may get lost - as you say - but it won't last long. I won't either. Well great, but your writings do give that impression... In the meantime I have the luxury of tasting the new ideas. And I feel I am not alone in these ways So do I, and I really think most scientists do as well. It's probably the teachers of science who miss out - and maybe that's what's missing from science education, the buzz of the new. I largely self-taught myself maths and science at school - I studied quantum mechanics in year 11, and general relativity in year 12. Mind you, I didn't have particularly good text books, so I had to unlearn some stuff later on :( -- 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 Thu, May 04, 2006 at 08:04:40AM -0700, John M wrote: Russell, thanks for your fime and effort to reply. 3 things: 1. You picked my Hawkng typo, I have many more. I do recall that post and it gives me while writing, the subconscious vacillation: which version is the right and which the left? Very rarely do I wright his name. Well I was having a little dig at you - not being at all serious about it... 2. You use usable (used) physics views in a topic way away from classical physics views, puting a systems talk into space-time measuring with a morphology I cannot (don't want to) follow in this thread. This is the usual definition and context of the term closed system. Of course the term closed means many other things: a closed set for instance, or closure in formal systems (which means the formal system is complete). But I always thought we were talking about the thermodynamic meaning. 3. In your last par you said it: isolated from the rest of the unkiverse exactly the singularity I DO identify with Tom's description of a closed system. But I'm not sure a singularity is a closed system (the thermodynamics meaning anyway). And 2Qs: Yours: What is an unknowable closed system? If nothing (including information) comes out it must be pretty unknowable. In that ballgame ou suppose: it turns open from c;osed and then again closed, I assume it disappears from our observation. I see no indication that it keeps the same coordinates when dissappeared as we found kit at when it was open. The coordunates you want to find it at dissipate as well. I don't see why this should happen - perhaps it happens sometimes, but not to classical thermodynamics systems. Not to mention the changes or world ujndergoes to... Mine: RSt: Usually because it doesn't move :) Consider something inside a shielded container in a vacuum... How is move identified in connection with (my version of) closed system (singularity) with no interconnection in space lor time of OUR habiturl system? Assigning coordinates to no-info sounds funny. And the shielded vacuum container is Physics 101. I am on a different track... Regards John M I suspect I don't follow you at all... -- 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?
This thread is still alive! It seems that information can't be erased in this thread either :) I think that information can't be erased because of the way time is (or should be) defined. If you take the observer moment approach to the multiverse, then you have to define a notion of time. That definition will then imply conservation of information. --~--~-~--~~~---~--~~ 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, my apologies for the approximate typing. I don't assign to your not following my comments to that awful new keyboard I tried to use (light grey letters on a slightly less light grey base - not visible and I am not a good 'blind'typist) with the YAHOO-mail spellchecker that garbles up the letters - I think your uncertainty stems from a different knowledge-base I use. Classical thermodynamics I learned in 1942 when I identified it as the science which tells us how things would go wouldn't they go the way they do go meaning the game of isotherm and reversible equational craze in closed systems. Then later Prigogine et al improved upon it, but I still hold the field within the limited model of our epistemic - ever changing, enriching - interpretation of the (obsolete) historical bases from very primitive knowledge level times and accordingly primitive measurements by unsophisticated instrumentation, subject to an all ingenious explanation on THAT level. (Think about the dozen+ (and still counting) changing views about the 'entropy' conceptS). The 'scientific view' does not fit into the interconnected and interactive wholeness - it is topically boundaried (reduced?) into a model view. It is representative to our ongoing sciences, we cannot think including the 'totality' using our matter-limited brainfunction, - only in a 'reduced-to-models' way, which is pretty efficient as long as we do not want to explain them all by the results drawn from within a limited model. Our present view (totality, or wholeness) is far from know-it-all, but I think it covers more information than had Ptolemy, Newton, Adam Smith or Rousseau. Brilliance of mind does not substitute for factual knowledge. * Singularity in my view is a no-system because there is no way we can extract any information about it - unless we give up the definition. This is how I view a 'closed' system, (not lawyerish: well, you can look at it as semi-closed, or even open, if you like,...) If it is closed, it is closed. Singularity is nice to speak about, I hold: there is no such thing only in sci-fi. We get usded to many sci-fi marvels and in the 15th step it looks like real. Russell, when I said good bye to my polymer science (1987) and started to think I tried to throw out things to be 'believed' (axioms, paradoxes, emergence, chaos). I retired with limited movablity and allowed myself to get away from conventional reductionism. You are in the profession, books projects, responsibility for what you said yesterday: I don't want to persuade you to think differently, especially since I am fully aware of the embryonic level of the 'new ways' I still try to find. I have questions, very few answers and I doubt them. John - Original Message - From: Russell Standish [EMAIL PROTECTED] To: everything-list@googlegroups.com Sent: Saturday, May 06, 2006 12:17 AM Subject: Re: why can't we erase information? On Thu, May 04, 2006 at 08:04:40AM -0700, John M wrote: Russell, thanks for your fime and effort to reply. 3 things: 1. You picked my Hawkng typo, I have many more. I do recall that post and it gives me while writing, the subconscious vacillation: which version is the right and which the left? Very rarely do I wright his name. Well I was having a little dig at you - not being at all serious about it... 2. You use usable (used) physics views in a topic way away from classical physics views, puting a systems talk into space-time measuring with a morphology I cannot (don't want to) follow in this thread. This is the usual definition and context of the term closed system. Of course the term closed means many other things: a closed set for instance, or closure in formal systems (which means the formal system is complete). But I always thought we were talking about the thermodynamic meaning. 3. In your last par you said it: isolated from the rest of the unkiverse exactly the singularity I DO identify with Tom's description of a closed system. But I'm not sure a singularity is a closed system (the thermodynamics meaning anyway). And 2Qs: Yours: What is an unknowable closed system? If nothing (including information) comes out it must be pretty unknowable. In that ballgame ou suppose: it turns open from c;osed and then again closed, I assume it disappears from our observation. I see no indication that it keeps the same coordinates when dissappeared as we found kit at when it was open. The coordunates you want to find it at dissipate as well. I don't see why this should happen - perhaps it happens sometimes, but not to classical thermodynamics systems. Not to mention the changes or world ujndergoes to... Mine: RSt: Usually because it doesn't move :) Consider something inside a shielded container in a vacuum... How is move identified in connection with (my version of) closed system (singularity) with no interconnection in space lor time of OUR habiturl
Re: why can't we erase information?
Tom Caylor wrote: Actually, in reviewing the definition of Turing machine (it's been over 2 decades since I studied it) I agree with you. The Turing machine leaves behind a memory of its past through its writes to the tape. Maybe I don't understand what Wei Dai was saying with his setting of the head back to the start of the tape. In order to get back to the exact beginning *state* the Turing Machine would have to be instructed to do an inverse of all of the writes it has done and then go back to the start of the tape. But there is not always a unique inverse. There may be two distinct previous states A and B which would lead to the same state C on the next step--in this case the dynamics are not reversible. 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?
Le 03-mai-06, à 16:34, Tom Caylor a écrit : I am beside myself ;) Perhaps the interactive step-by-step approach that you've used in the past would be easier for you and more profitable for us. Thanks for the suggestion. I will give it a try asap. Speaking of impasse with myself and diagonalization, a thought occurred to me that an instruction that erases information, like a Turing machine goto statement (e.g. Wei Dai's go to the beginning of the tape instruction) ? Why a goto should erase anything ? Actually, in reviewing the definition of Turing machine (it's been over 2 decades since I studied it) I agree with you. The Turing machine leaves behind a memory of its past through its writes to the tape. Maybe I don't understand what Wei Dai was saying with his setting of the head back to the start of the tape. In order to get back to the exact beginning *state* the Turing Machine would have to be instructed to do an inverse of all of the writes it has done and then go back to the start of the tape. OK. Then it is not just a goto, it is a complete application of a reversible process. This will work only if you are using a reversible turing machine in the first place (like the one discover first by Hao Wang, Interesting work are those of Fredkin and Toffoli, and then the entire field of quantum computing). I believe that in the meta system, being open requires a paradigm shift in the meaning of understanding. This is not entirely clear for me. If we just stick to our reductionist meaning of understanding, then we are still closed and we haven't really gone out of the system. This new sense of understanding is what allows us to not go into an infinite or circular regress. It is what allows us to assign *true* meaning in the first place. I propose we come back on this after I (try to) explain a little bit more on diagonalization. I have a problem with the word reductionism. For some people number or machine are reductionist concepts, but I think that this opinion stems from a reductionist conception of number or machine. Surely some new understanding of machine or number is needed. But now, I must confess (!) that I am discovering that if the Riemann critical zeros really describe a spectrum related to a quasi (?) classical chaotic regime---as it can be suspected from experimental (but still purely mathematical!) evidences---then I could imagine that the prime numbers could eventually describe not only a Universal Wave Function (even if only by pieces but the first person doesn't care as far as those pieces have a positive density) but would also describe a sort of universal wave reduction like if an absolutely external observer was included freely in the number's gift ! So, recursion theory (computer science) allows internal metas, but primes, by their so much irregular behavior could still provide an apparent reduction justifying some external metas. Weird. I tend not to believe in it, though. Who did invite the primes to the banquet? Just thinking aloud. Perhaps my Spring Riemann fever ... Wishful, but good, thinking in my view. I take your I tend not to believe in it, though as saying that you don't think it's worth investing a lot of your resources in pursuing it. I didn't say that. But we still don't know if Riemann hyp. is true and the field is technical. Clearly something happens there. I tend to think that pursuing anything is worth it if it allows us to see in a new way why it is closer or further away from reality. The theory is that we can use these experiences to formulate a viewpoint of reality that is closer and closer to reality. Maybe. Believing in this theory is actually an act of faith in the goodness of reality that goes beyond what evolution can explain. I use the word goodness over and above understandability. If reality is understandable *by us* in any way close to the aspirations of the Everything List, then I feel pulled to express this as, Someone out there is truly being good to us. Plotinus says so but (from a 3 person point of view) I am not yet convinced. There are some evidences but we must try to be cold on this and to beware wishful thinking, and then we should also not to exaggerate in the opposite direction. We can have doubt when seeing kind people suffering a lot, and remember that the Platonists link evil with matter, and this question is not entirely clear from the comp or lobian discussion. We will not answer all this today, for sure. 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
Re: why can't we erase information?
Russell, thanks for your fime and effort to reply. 3 things: 1. You picked my Hawkng typo, I have many more. I do recall that post and it gives me while writing, the subconscious vacillation: which version is the right and which the left? Very rarely do I wright his name. 2. You use usable (used) physics views in a topic way away from classical physics views, puting a systems talk into space-time measuring with a morphology I cannot (don't want to) follow in this thread. 3. In your last par you said it: isolated from the rest of the unkiverse exactly the singularity I DO identify with Tom's description of a closed system. And 2Qs: Yours: What is an unknowable closed system? If nothing (including information) comes out it must be pretty unknowable. In that ballgame ou suppose: it turns open from c;osed and then again closed, I assume it disappears from our observation. I see no indication that it keeps the same coordinates when dissappeared as we found kit at when it was open. The coordunates you want to find it at dissipate as well. Not to mention the changes or world ujndergoes to... Mine: RSt: Usually because it doesn't move :) Consider something inside a shielded container in a vacuum... How is move identified in connection with (my version of) closed system (singularity) with no interconnection in space lor time of OUR habiturl system? Assigning coordinates to no-info sounds funny. And the shielded vacuum container is Physics 101. I am on a different track... Regards John M --- Russell Standish [EMAIL PROTECTED] wrote: On Tue, May 02, 2006 at 01:33:37PM -0700, John M wrote: Russell, you 'opem' and 'close' a system? Why woulod you close it, once it is already open? and how would you find it again, when it is closed? Usually because it doesn't move :) Consider something inside a shielded container in a vacuum - many physics experiments are like this. Closedness, of course is an idealisation of the real system. And how do you assess those closed system laws, if no info goes in or out? (need an intelligent design?) As I said - by measuring the system at two points, in between which the system is closed. How the system evolves between those points in time will be closed system evolution. Is OUR time-scale valid to the inside of an unknowable closed system? You decide as you need - see below, What is an unknowable closed system? I segregated the black-hole type phantasms which allow action INTO them - and Hawkins had to make allowance Caution - misspelling Stephen Hawkings' name is considered a sure sign of a crank (I can't seem to lay my hands on the ref here...) even for them to 'release' SOME information as I understand. Well, these things are our brainchildren, not 'ntaure's' so we identify them as we need it. John M Are you saying black holes are meant to be closed systems? I would have thought otherwise, unless it is isolated from the rest of the universe in some way. -- A/Prof Russell Standish Phone 8308 3119 (mobile) Mathematics 0425 253119 () UNSW SYDNEY 2052 [EMAIL PROTECTED] Australia http://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?
How many angels can you fit on a drawing pin? ;) Kim J On 03/05/2006, at 6:17 AM, John M wrote: Does that entire topic really make sense? Or is it just a straw-man debate to get it right? Sometimes I wonder. John M --~--~-~--~~~---~--~~ 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 02-mai-06, à 00:18, Tom Caylor a écrit : Bruno Marchal wrote: Le 25-avr.-06, à 17:37, Tom Caylor a écrit : In fact, closed system and meta element seem to be contradictory. Not necessarily. It could depend of what you mean exactly by closed. Closure for the diagonalization procedure is the key. Diagonalization is the key of the heart of the matter. I will come back on this later. Closed system (Principia Cybernetica): An isolated system having no interaction with an environment. A system whose behavior is entirely explainable from within, a system without input... Mathematically, a closed system contains its boundary, or it contains its limit points. In other words, anything expressable with the given axioms/language is itself a member the system. All right. Topologically they are closure systems, and they provide natural models for both first person and S4 type of modal knowledge theory. A set is included in its closure, the closure of a closure is a closure, etc. Example: a theory (set of formula closed for the application of the inference rules), a closed subset of a topological space (not necessarily Hausdorff), closed subpace of Hilbert spaces. And, back to the original question, closed system and erasing information seem to be contradictory. Why? I'm at an impasse with myself in trying to explain my intuition further. OK. Meanwhile I'm studying up on diagonalization, waiting for your heart of the matter (which I take as just a pun and not referring to physical matter, heaven forbid). Heaven forbid? Comp forbids! ;-) About the heart of the matter I have begun a post but I realize it will be far too long and technical, and I am still searching a way to present that heart of the matter in some swallowable way Of course heart of the matter is an allusion to a section in Smullyan's Forever Undecided which got that name. Speaking of impasse with myself and diagonalization, a thought occurred to me that an instruction that erases information, like a Turing machine goto statement (e.g. Wei Dai's go to the beginning of the tape instruction) ? Why a goto should erase anything ? seems to be a *self-referential* instruction. Maybe this has something to do with the original question and (I maintain) the need for a meta viewpoint, or an open system, to understand it. But then how will you explain how that meta-open system understand anything. You take a risk of being lead to infinite regress (but then see for a case below). The heart of the matter, which will really be the closure of some set for the diagonalization procedure will make it possible to find some fixed point for the meta operation itself, so that it will be possible for a system belonging to a closed system to refer to itself in a relatively correct way, with some probability (normally determined from inside). But now, I must confess (!) that I am discovering that if the Riemann critical zeros really describe a spectrum related to a quasi (?) classical chaotic regime---as it can be suspected from experimental (but still purely mathematical!) evidences---then I could imagine that the prime numbers could eventually describe not only a Universal Wave Function (even if only by pieces but the first person doesn't care as far as those pieces have a positive density) but would also describe a sort of universal wave reduction like if an absolutely external observer was included freely in the number's gift ! So, recursion theory (computer science) allows internal metas, but primes, by their so much irregular behavior could still provide an apparent reduction justifying some external metas. Weird. I tend not to believe in it, though. Who did invite the primes to the banquet? Just thinking aloud. Perhaps my Spring Riemann fever ... 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: why can't we erase information?
Bruno Marchal wrote: Le 02-mai-06, à 00:18, Tom Caylor a écrit : Bruno Marchal wrote: Le 25-avr.-06, à 17:37, Tom Caylor a écrit : In fact, closed system and meta element seem to be contradictory. Not necessarily. It could depend of what you mean exactly by closed. Closure for the diagonalization procedure is the key. Diagonalization is the key of the heart of the matter. I will come back on this later. Closed system (Principia Cybernetica): An isolated system having no interaction with an environment. A system whose behavior is entirely explainable from within, a system without input... Mathematically, a closed system contains its boundary, or it contains its limit points. In other words, anything expressable with the given axioms/language is itself a member the system. All right. Topologically they are closure systems, and they provide natural models for both first person and S4 type of modal knowledge theory. A set is included in its closure, the closure of a closure is a closure, etc. Example: a theory (set of formula closed for the application of the inference rules), a closed subset of a topological space (not necessarily Hausdorff), closed subpace of Hilbert spaces. Bruno, thanks for understanding what I mean by closed. John, I shouldn't have mentioned the closed definition that allows output from the system, because this is not what I mean by closed. My meaning of closed does not allow knowledge from the outside. And, back to the original question, closed system and erasing information seem to be contradictory. Why? I'm at an impasse with myself in trying to explain my intuition further. OK. Meanwhile I'm studying up on diagonalization, waiting for your heart of the matter (which I take as just a pun and not referring to physical matter, heaven forbid). Heaven forbid? Comp forbids! ;-) About the heart of the matter I have begun a post but I realize it will be far too long and technical, and I am still searching a way to present that heart of the matter in some swallowable way Of course heart of the matter is an allusion to a section in Smullyan's Forever Undecided which got that name. I am beside myself ;) Perhaps the interactive step-by-step approach that you've used in the past would be easier for you and more profitable for us. Speaking of impasse with myself and diagonalization, a thought occurred to me that an instruction that erases information, like a Turing machine goto statement (e.g. Wei Dai's go to the beginning of the tape instruction) ? Why a goto should erase anything ? Actually, in reviewing the definition of Turing machine (it's been over 2 decades since I studied it) I agree with you. The Turing machine leaves behind a memory of its past through its writes to the tape. Maybe I don't understand what Wei Dai was saying with his setting of the head back to the start of the tape. In order to get back to the exact beginning *state* the Turing Machine would have to be instructed to do an inverse of all of the writes it has done and then go back to the start of the tape. seems to be a *self-referential* instruction. Maybe this has something to do with the original question and (I maintain) the need for a meta viewpoint, or an open system, to understand it. But then how will you explain how that meta-open system understand anything. You take a risk of being lead to infinite regress (but then see for a case below). The heart of the matter, which will really be the closure of some set for the diagonalization procedure will make it possible to find some fixed point for the meta operation itself, so that it will be possible for a system belonging to a closed system to refer to itself in a relatively correct way, with some probability (normally determined from inside). I believe that in the meta system, being open requires a paradigm shift in the meaning of understanding. If we just stick to our reductionist meaning of understanding, then we are still closed and we haven't really gone out of the system. This new sense of understanding is what allows us to not go into an infinite or circular regress. It is what allows us to assign *true* meaning in the first place. But now, I must confess (!) that I am discovering that if the Riemann critical zeros really describe a spectrum related to a quasi (?) classical chaotic regime---as it can be suspected from experimental (but still purely mathematical!) evidences---then I could imagine that the prime numbers could eventually describe not only a Universal Wave Function (even if only by pieces but the first person doesn't care as far as those pieces have a positive density) but would also describe a sort of universal wave reduction like if an absolutely external observer was included freely in the number's gift ! So, recursion theory (computer science) allows internal metas, but
Re: why can't we erase information?
Kim, you picked a side-remark, although an important one. In the heat of the debates it seems healthy somtimes to rake a breather and look at the topics with an oprn and unbiased (strangers'? outsiders'?) eye to restore some sanity lost to emotional discourse. Otherwise it is easy to get carried away. I do it all the time. In all lack of 'sanity' John Mikes --- Kim Jones [EMAIL PROTECTED] wrote: How many angels can you fit on a drawing pin? ;) Kim J On 03/05/2006, at 6:17 AM, John M wrote: Does that entire topic really make sense? Or is it just a straw-man debate to get it right? Sometimes I wonder. John M --~--~-~--~~~---~--~~ 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?
Tom Caylor wrote: I am beside myself ;) Perhaps the interactive step-by-step approach that you've used in the past would be easier for you and more profitable for us. Bruno, My beside myself statement was a punny reference to self-reference. I meant that I am looking forward to your post(s) with positive eagerness. Tom --~--~-~--~~~---~--~~ 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 Tue, May 02, 2006 at 01:33:37PM -0700, John M wrote: Russell, you 'opem' and 'close' a system? Why woulod you close it, once it is already open? and how would you find it again, when it is closed? Usually because it doesn't move :) Consider something inside a shielded container in a vacuum - many physics experiments are like this. Closedness, of course is an idealisation of the real system. And how do you assess those closed system laws, if no info goes in or out? (need an intelligent design?) As I said - by measuring the system at two points, in between which the system is closed. How the system evolves between those points in time will be closed system evolution. Is OUR time-scale valid to the inside of an unknowable closed system? You decide as you need - see below, What is an unknowable closed system? I segregated the black-hole type phantasms which allow action INTO them - and Hawkins had to make allowance Caution - misspelling Stephen Hawkings' name is considered a sure sign of a crank (I can't seem to lay my hands on the ref here...) even for them to 'release' SOME information as I understand. Well, these things are our brainchildren, not 'ntaure's' so we identify them as we need it. John M Are you saying black holes are meant to be closed systems? I would have thought otherwise, unless it is isolated from the rest of the universe in some way. -- 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?
In a general sense, if we (the observer) are outside of the system, there is a definition of closed system which allows output from the system, even though there is no input into the system, *if such a configuration is possible*. If there is no output, I agree with you that the system is unknowable. If the observer is inside (part of) the closed system, that's when things get very mystifying. In this case there are non-trivial limits to what we can know about the system, even though we are in it, since our framework of knowing is also part of the system. (For instance, I maintain that in this case we cannot know if information is being erased.) But I don't think that's what your question was referring to. Tom John M wrote: Tom: one excerpt I try to address: Closed system (Principia Cybernetica): An isolated system having no interaction with an environment. A system whose behavior is entirely explainable from within, a system without input... (I skip the rest, including the mathematical closure as irrelevant for my reply). How do you know about such system? What I mean is: if NO interaction reaches or leaves the 'system', (it includes 'information as well) it does not even 'exist' for us. It is more than a 'black hole' which is said to be receptive. A 'closed no-thing'? John M - Original Message - From: Tom Caylor [EMAIL PROTECTED] To: Everything List everything-list@googlegroups.com Sent: Monday, May 01, 2006 6:18 PM Subject: Re: why can't we erase information? Bruno Marchal wrote: Le 25-avr.-06, à 17:37, Tom Caylor a écrit : In fact, closed system and meta element seem to be contradictory. Not necessarily. It could depend of what you mean exactly by closed. Closure for the diagonalization procedure is the key. Diagonalization is the key of the heart of the matter. I will come back on this later. Closed system (Principia Cybernetica): An isolated system having no interaction with an environment. A system whose behavior is entirely explainable from within, a system without input... Mathematically, a closed system contains its boundary, or it contains its limit points. In other words, anything expressable with the given axioms/language is itself a member the system. ...SKIP Tom --~--~-~--~~~---~--~~ 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, you 'opem' and 'close' a system? Why woulod you close it, once it is already open? and how would you find it again, when it is closed? And how do you assess those closed system laws, if no info goes in or out? (need an intelligent design?) Is OUR time-scale valid to the inside of an unknowable closed system? You decide as you need - see below, I segregated the black-hole type phantasms which allow action INTO them - and Hawkins had to make allowance even for them to 'release' SOME information as I understand. Well, these things are our brainchildren, not 'ntaure's' so we identify them as we need it. John M --- Russell Standish [EMAIL PROTECTED] wrote: We can observe a closed system at two points in time t0, t1 say. The system is closed in between, but not at the point of observation, obviously. The evolution of the system between the two observation points must follow closed system laws. Cheers On Mon, May 01, 2006 at 06:42:26PM -0700, John M wrote: Tom: one excerpt I try to address: Closed system (Principia Cybernetica): An isolated system having no interaction with an environment. A system whose behavior is entirely explainable from within, a system without input... (I skip the rest, including the mathematical closure as irrelevant for my reply). How do you know about such system? What I mean is: if NO interaction reaches or leaves the 'system', (it includes 'information as well) it does not even 'exist' for us. It is more than a 'black hole' which is said to be receptive. A 'closed no-thing'? John M - Original Message - From: Tom Caylor [EMAIL PROTECTED] To: Everything List everything-list@googlegroups.com Sent: Monday, May 01, 2006 6:18 PM Subject: Re: why can't we erase information? Bruno Marchal wrote: Le 25-avr.-06, à 17:37, Tom Caylor a écrit : In fact, closed system and meta element seem to be contradictory. Not necessarily. It could depend of what you mean exactly by closed. Closure for the diagonalization procedure is the key. Diagonalization is the key of the heart of the matter. I will come back on this later. Closed system (Principia Cybernetica): An isolated system having no interaction with an environment. A system whose behavior is entirely explainable from within, a system without input... Mathematically, a closed system contains its boundary, or it contains its limit points. In other words, anything expressable with the given axioms/language is itself a member the system. ...SKIP Tom -- A/Prof Russell Standish Phone 8308 3119 (mobile) Mathematics 0425 253119 () UNSW SYDNEY 2052 [EMAIL PROTECTED] Australia http://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?
Bruno Marchal wrote: Le 25-avr.-06, à 17:37, Tom Caylor a écrit : In fact, closed system and meta element seem to be contradictory. Not necessarily. It could depend of what you mean exactly by closed. Closure for the diagonalization procedure is the key. Diagonalization is the key of the heart of the matter. I will come back on this later. Closed system (Principia Cybernetica): An isolated system having no interaction with an environment. A system whose behavior is entirely explainable from within, a system without input... Mathematically, a closed system contains its boundary, or it contains its limit points. In other words, anything expressable with the given axioms/language is itself a member the system. And, back to the original question, closed system and erasing information seem to be contradictory. Why? I'm at an impasse with myself in trying to explain my intuition further. Meanwhile I'm studying up on diagonalization, waiting for your heart of the matter (which I take as just a pun and not referring to physical matter, heaven forbid). Speaking of impasse with myself and diagonalization, a thought occurred to me that an instruction that erases information, like a Turing machine goto statement (e.g. Wei Dai's go to the beginning of the tape instruction) seems to be a *self-referential* instruction. Maybe this has something to do with the original question and (I maintain) the need for a meta viewpoint, or an open system, to understand it. Tom --~--~-~--~~~---~--~~ 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 notice that erasure of information on a goto instruction occurs only for goto instructions which send the Turing machine to an instruction already executed. Thus the self-reference is a reference to the *past* self of the Turing machine, which in a sense is the only self the Turing machine knows. Tom Tom Caylor wrote: Bruno Marchal wrote: Le 25-avr.-06, à 17:37, Tom Caylor a écrit : In fact, closed system and meta element seem to be contradictory. Not necessarily. It could depend of what you mean exactly by closed. Closure for the diagonalization procedure is the key. Diagonalization is the key of the heart of the matter. I will come back on this later. Closed system (Principia Cybernetica): An isolated system having no interaction with an environment. A system whose behavior is entirely explainable from within, a system without input... Mathematically, a closed system contains its boundary, or it contains its limit points. In other words, anything expressable with the given axioms/language is itself a member the system. And, back to the original question, closed system and erasing information seem to be contradictory. Why? I'm at an impasse with myself in trying to explain my intuition further. Meanwhile I'm studying up on diagonalization, waiting for your heart of the matter (which I take as just a pun and not referring to physical matter, heaven forbid). Speaking of impasse with myself and diagonalization, a thought occurred to me that an instruction that erases information, like a Turing machine goto statement (e.g. Wei Dai's go to the beginning of the tape instruction) seems to be a *self-referential* instruction. Maybe this has something to do with the original question and (I maintain) the need for a meta viewpoint, or an open system, to understand it. Tom --~--~-~--~~~---~--~~ 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?
Tom: one excerpt I try to address: Closed system (Principia Cybernetica): An isolated system having no interaction with an environment. A system whose behavior is entirely explainable from within, a system without input... (I skip the rest, including the mathematical closure as irrelevant for my reply). How do you know about such system? What I mean is: if NO interaction reaches or leaves the 'system', (it includes 'information as well) it does not even 'exist' for us. It is more than a 'black hole' which is said to be receptive. A 'closed no-thing'? John M - Original Message - From: Tom Caylor [EMAIL PROTECTED] To: Everything List everything-list@googlegroups.com Sent: Monday, May 01, 2006 6:18 PM Subject: Re: why can't we erase information? Bruno Marchal wrote: Le 25-avr.-06, à 17:37, Tom Caylor a écrit : In fact, closed system and meta element seem to be contradictory. Not necessarily. It could depend of what you mean exactly by closed. Closure for the diagonalization procedure is the key. Diagonalization is the key of the heart of the matter. I will come back on this later. Closed system (Principia Cybernetica): An isolated system having no interaction with an environment. A system whose behavior is entirely explainable from within, a system without input... Mathematically, a closed system contains its boundary, or it contains its limit points. In other words, anything expressable with the given axioms/language is itself a member the system. ...SKIP Tom --~--~-~--~~~---~--~~ 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 25-avr.-06, à 17:37, Tom Caylor a écrit : Tom Toffoli's paper, Nothing makes sense in computing except in the light of evolution, gives support to the idea that there needs to be some meta element to give meaning or design to this whole swirl of information we see around us. I think this is also why we keep feeling the need to appeal to anthropic thoughts. Tom I'd like to add that I don't think that evolution in a closed system actually supplies a meta element. I'm just pointing out that Toffoli's paper is an example of recognizing that there needs to be a meta element. OK. In fact, closed system and meta element seem to be contradictory. Not necessarily. It could depend of what you mean exactly by closed. Closure for the diagonalization procedure is the key. Diagonalization is the key of the heart of the matter. I will come back on this later. And, back to the original question, closed system and erasing information seem to be contradictory. Why? 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: why can't we erase information?
Any conclusion about information erasure, or entropy, in a given system seems to depend on the particular meaning assigned to the information. Note that assigned is a verb. What I mean when I say this is that I'm pointed to the fact that it takes someone to do it. There's a recurring thought in this thread about information's dependency on an observer (Russell Standish), a language (Hal Finney). Bruno suggests entropy is a 1st person phenomenon. In other words, the assigning of meaning to the information (or variables, constraints, states) requires a person. From a certain point of view it may look locally like an increase in information, but do a change of variables (albeit maybe a horrific one) and viola, information is decreasing. On the other hand, when we talk about information erasure, it seems that we are talking about something different from entropy. Saiba Mitra says that it could be that internal observers can't see information erasure. Ben Udell appealed to the need for a meta viewpoint. Total information erasure has to be in the global context of the whole universe, or Everything. Otherwise you can't be sure you're dealing with information erasure, or if it's simply negative entropy. So you have to be omniscient about the whole universe. Hence my previous reference to the assumption of reductionism and a closed system, i.e. assume you are God. Wei Dai's Turing machine, which acts on instructions to erase information, has to interpret the instructions using a certain language. The command to erase could be interpreted as having a different meaning in another language. Tom Toffoli's paper, Nothing makes sense in computing except in the light of evolution, gives support to the idea that there needs to be some meta element to give meaning or design to this whole swirl of information we see around us. I think this is also why we keep feeling the need to appeal to anthropic thoughts. Tom --~--~-~--~~~---~--~~ 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?
My first sentence looks like I was equating information erasure with entropy, but further down I hope it's clear that I'm treating them as two different concepts. Tom --~--~-~--~~~---~--~~ 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 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: 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: 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 -~--~~~~--~~--~--~---
Re: why can't we erase information?
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. Because of the action of the second law, it actually takes a thermodynamic flux to preserve information - which is why you need to read your old backup tapes an make copies every few years if you want to retain access to your data. Cheers On Sun, Apr 09, 2006 at 12:11:52AM -0700, Wei Dai wrote: If we consider our observable universe as a computation, it's rather atypical in that it doesn't seem to make use of the erase operation (or other any operation that irreversibly erases information). The second law of thermodynamics is a consequence of this. In order to forget anything (decrease entropy), we have to put the information somewhere else (increase entropy of the environment), instead of just making it disappear. If this doesn't make sense to you, see Seth Lloyd's new book Programming the Universe : A Quantum Computer Scientist Takes On the Cosmos for a good explanation of the relationship between entropy, computation, and information. Has anyone thought about why this is the case? One possible answer is that if it were possible to erase information, life organisms would be able to construct internal perpetual motion machines to power their metabolism, instead of competing with each other for sources of negentropy, and perhaps intelligence would not be able to evolve in this kind of environment. If this is the case, perhaps there is reason to hope that our universe does contain mechanisms to erase information, but they are not easily accessible to life before the evolution of intelligence. It may be a good idea to look out for such mechanisms, for example in high energy particle reactions. However I'm not sure this answer is correct because there would still be competition for raw material (matter and energy) where intelligence can still be an advantage. Anyone have other ideas? -- 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: 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 --~--~-~--~~~---~--~~ 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 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. Tim On Apr 10, 2006, at 3:22 AM, Jesse Mazer wrote: 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 -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?
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. And yes you need to observe it. Entropy is undefined without an observer. 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?
From: Russell Standish [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 18:34:42 +1000 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. And yes you need to observe it. Entropy is undefined without an observer. Cheers 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. 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 --~--~-~--~~~---~--~~ 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: 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 decrease in the entropy of a few neural connections in my brain. This is accompanied by a relative large increase in entropy of my body which I have to make up for by consuming some low entropy organic material. Whether the entropy the thing I observe is increased or decreased by the observation is a different question. Brent Meeker --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
why can't we erase information?
If we consider our observable universe as a computation, it's rather atypical in that it doesn't seem to make use of the erase operation (or other any operation that irreversibly erases information). The second law of thermodynamics is a consequence of this. In order to forget anything (decrease entropy), we have to put the information somewhere else (increase entropy of the environment), instead of just making it disappear. If this doesn't make sense to you, see Seth Lloyd's new book Programming the Universe : A Quantum Computer Scientist Takes On the Cosmos for a good explanation of the relationship between entropy, computation, and information. Has anyone thought about why this is the case? One possible answer is that if it were possible to erase information, life organisms would be able to construct internal perpetual motion machines to power their metabolism, instead of competing with each other for sources of negentropy, and perhaps intelligence would not be able to evolve in this kind of environment. If this is the case, perhaps there is reason to hope that our universe does contain mechanisms to erase information, but they are not easily accessible to life before the evolution of intelligence. It may be a good idea to look out for such mechanisms, for example in high energy particle reactions. However I'm not sure this answer is correct because there would still be competition for raw material (matter and energy) where intelligence can still be an advantage. Anyone have other ideas? --~--~-~--~~~---~--~~ 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?
It does seem a little confusing how to quantify information when the universe itself is regarded as a computation. Some flies buzzing around the horses may make a difference in the horse race. If the flies are erased, then that issue is settled, which seems to count as a decrease of uncertainty and therefore as an _increase_ of info. How does one arrive at a result for net change of info? The settlement of questions by imaginary erasure of all 'extraneous' factors, elimination of 'details,' reductive abstraction, etc., seems to be a basic working step for treating a scenario under a probability-theoretic viewpoint. Would the real erasure of those factors count in the same way as an increase of information? It seems like an increase of info at least in the case where we do remember the real things that we've erased or annihilated. Anyway, trying to arrive at a result for net change of information seems to require adopting some meta viewpoint, though I don't know, I'm not well versed in information theory. On the other hand, when we treat things as being samples surfaces of more opaque things even when we do know somewhat about what is or isn't under those surfaces, then factors/details which have been settled tend to get put into question or veiled such that it's uncertain what difference they make, and that's a decrease in info which seems to be a basic working step for treating a scenario under a statistical-theoretic viewpoint. When we feign ignorance about how things will be affected, that's an imaginary addition possible factors. Would a real adding of possible factors, uncertainty, count as a decrease in info? It seems like a decrease of info at least in the case where we do remember that those factors weren't previously there. Are these problems real? Maybe a universe doesn't allow for change of information that requires some sort of meta viewpoint to calculate. On the other hand, maybe I just don't know what I'm talking about. Best regards, Ben Udell - Original Message - From: Wei Dai [EMAIL PROTECTED] To: everything-list@googlegroups.com Sent: Sunday, April 09, 2006 3:11 AM Subject: why can't we erase information? If we consider our observable universe as a computation, it's rather atypical in that it doesn't seem to make use of the erase operation (or other any operation that irreversibly erases information). The second law of thermodynamics is a consequence of this. In order to forget anything (decrease entropy), we have to put the information somewhere else (increase entropy of the environment), instead of just making it disappear. If this doesn't make sense to you, see Seth Lloyd's new book Programming the Universe : A Quantum Computer Scientist Takes On the Cosmos for a good explanation of the relationship between entropy, computation, and information. Has anyone thought about why this is the case? One possible answer is that if it were possible to erase information, life organisms would be able to construct internal perpetual motion machines to power their metabolism, instead of competing with each other for sources of negentropy, and perhaps intelligence would not be able to evolve in this kind of environment. If this is the case, perhaps there is reason to hope that our universe does contain mechanisms to erase information, but they are not easily accessible to life before the evolution of intelligence. It may be a good idea to look out for such mechanisms, for example in high energy particle reactions. However I'm not sure this answer is correct because there would still be competition for raw material (matter and energy) where intelligence can still be an advantage. Anyone have other ideas? --~--~-~--~~~---~--~~ 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?
Wei Dai wrote: If we consider our observable universe as a computation, it's rather atypical in that it doesn't seem to make use of the erase operation (or other any operation that irreversibly erases information). The second law of thermodynamics is a consequence of this. In order to forget anything (decrease entropy), we have to put the information somewhere else (increase entropy of the environment), instead of just making it disappear. If this doesn't make sense to you, see Seth Lloyd's new book Programming the Universe : A Quantum Computer Scientist Takes On the Cosmos for a good explanation of the relationship between entropy, computation, and information. Has anyone thought about why this is the case? One possible answer is that if it were possible to erase information, life organisms would be able to construct internal perpetual motion machines to power their metabolism, instead of competing with each other for sources of negentropy, and perhaps intelligence would not be able to evolve in this kind of environment. If this is the case, perhaps there is reason to hope that our universe does contain mechanisms to erase information, but they are not easily accessible to life before the evolution of intelligence. It may be a good idea to look out for such mechanisms, for example in high energy particle reactions. However I'm not sure this answer is correct because there would still be competition for raw material (matter and energy) where intelligence can still be an advantage. Anyone have other ideas? I guess you have in mind some kind of local (micrsoscopic) mechanism for erasing information. The Copenhagen intepretation of QM assumed this, but couldn't solve the problem of the Heisenberg cut. At a large scale, it is not yet settled whether black holes erase information. With a few exceptions, like t'Hooft, physicist assume that the unitary evolution of QM is fundamental. If that's the case, the only place information gets erased is by expansion of the universe. Brent Meeker --~--~-~--~~~---~--~~ 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?
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. - Original Message - From: Wei Dai [EMAIL PROTECTED] To: everything-list@googlegroups.com Sent: Sunday, April 09, 2006 09:11 AM Subject: why can't we erase information? If we consider our observable universe as a computation, it's rather atypical in that it doesn't seem to make use of the erase operation (or other any operation that irreversibly erases information). The second law of thermodynamics is a consequence of this. In order to forget anything (decrease entropy), we have to put the information somewhere else (increase entropy of the environment), instead of just making it disappear. If this doesn't make sense to you, see Seth Lloyd's new book Programming the Universe : A Quantum Computer Scientist Takes On the Cosmos for a good explanation of the relationship between entropy, computation, and information. Has anyone thought about why this is the case? One possible answer is that if it were possible to erase information, life organisms would be able to construct internal perpetual motion machines to power their metabolism, instead of competing with each other for sources of negentropy, and perhaps intelligence would not be able to evolve in this kind of environment. If this is the case, perhaps there is reason to hope that our universe does contain mechanisms to erase information, but they are not easily accessible to life before the evolution of intelligence. It may be a good idea to look out for such mechanisms, for example in high energy particle reactions. However I'm not sure this answer is correct because there would still be competition for raw material (matter and energy) where intelligence can still be an advantage. Anyone have other ideas? --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
