Hi all, Since Joe asked, I will add my two cents. Interpreting these interesting results will be confusing unless we untangle two different though linked conceptions of information: the intrinsic statistical entropy of the signal vs the relationship that constraint on that signal statistic has to extrinsic work imposed on it to achieve this constrained state. The former is often described as syntactic information and the latter roughly corresponds to semantic information (though I don't like to use these terms because of their contamination by linguistic assumptions).
The standard measure of information as it is relevant to the Maxwell's demon thought experiment, and which has been explored in the past by such luminaries as Szillard, Brillouin, Landauer, etc., is what is at stake in this study. I believe that this information-energy conversion reflects the relation between potential (micro)states of the system (signal, channel, medium) under consideration and a constrained variant state, such that this reduction in degrees of freedom is the basis for the decreased uncertainty obtained. Since the constrained informational state of a physical medium is one that is necessarily displaced from its ground state there is an implicit energetic potential. As Landauer (1991) pointed out "Information is physical." It's not just a mathematical abstraction. Where this can be confusing is that more colloquial uses of the term also implicate its referential property, which is bracketed from consideration in the sort of physically-minded analyses like the ones alluded to here. If we consider this additional referential aspect and its role in the reported study we will need to bring into consideration all the additional computational and manipulative apparatus and the physical work involved to precisely assess the effect. As the commentary article by Van den Broeck points out, this effectively dwarfs the microenergetics that is the focus of the study. I like his comparison to the energy disparities of current fusion experiments. But of course the final referential step is interpretation of these results by experimenters, since the instruments are only transducing signals. So one shouldn't worry that somehow this suggests that meaning might be equivalent to energy. There are many other important considerations here that I have skipped over such as the submicroscopic nature of this effect. It is important to recognize the counterintuitive nature of such atomic scale effects, that for example have become increasingly important for understanding molecular processes within living cells. It is at this scale that we may find important applications of these findings. On Fri, Jan 15, 2016 at 1:23 AM, Xueshan Yan <y...@pku.edu.cn> wrote: > Dear Colleague， > > Right? Wrong? We had better have some judgments criterions. If it is true > that information can be converted to energy, we can ask geneticist, human > communication researcher etc. to give some significant answer from their > practical work, empty talk here is endless. > > We can have the conclusion that information can be converted to matter > from teleportation study, does anyone accept it？ > > Best， > > Xueshan > > ------------------------------ > *From:* fis-boun...@listas.unizar.es [mailto:fis-boun...@listas.unizar.es] > *On Behalf Of *Joseph Brenner > *Sent:* Friday, January 15, 2016 3:51 PM > *To:* fis > *Subject:* [Fis] Fw: Toyabe 2010 [ Information converted to energy ] / > Van denBroeck 2010 Thermodynamics of Information: REQUEST TOTERRENCE DEACON > > Dear Folks, > > I do not wish to be negative, but I think this example is contaminated by > a homunculus. There are so much energy coming into the system from various > sources that the alleged result is not surprising. I would be glad to be > wrong but the decision should be up to someone like Terry with far greater > knowledge than I. > > Thank you, > > Joseph > > > ----- Original Message ----- > *From:* John Collier <colli...@ukzn.ac.za> > *To:* fis <fis@listas.unizar.es> > *Sent:* Friday, January 15, 2016 8:09 AM > *Subject:* [Fis] Toyabe 2010 [ Information converted to energy ] / Van > den Broeck 2010 Thermodynamics of Information / Cartlidge 2010 Information > converted to energy > > Stan Salthe sent the item below to Pedro and myself, but not to the list, > as he had used up his posting allotment. With the permission of both of > them, who think that this is an important issue, I am posting some brief > comments I made back to Stan, as well as Stan’s email content, in the hope > that the issue will get more discussion this time.(I posted a link to the > 2010 article when it came out.) The relevant material starts below the > line, and Stan’s email forwarded from Malcolm Dean is below that. It > concerns the use of changed boundary conditions to move things rather than > energy differences, suggesting that information can be used instead of > energy to cause changes in a system (another way of looking at this is that > information can be a force in itself, not merely a constraint on other > actions). In particular, the final state has greater free energy than the > initial state (it is in end state potential energy of the manipulated > particles in an electric field), the energy arising from the manipulation > of the boundary conditions based on the particle location. The original > authors described this as *information-to-energy conversion.* > > > ------------------------------ > > > > I posted a different pointer to this to fis some time ago, but the > reaction from the list was almost nothing, or skeptical, though the main > objection was that we could understand what was going on without using the > information concept. My response to that was that not using the word does > not mean that the concept is not being used. > > > > Of course, if you think that information is always meaningful to some > interpreter (alternatively, always a coding of something that has had > meaning to some mind, or the like) then the argument in the paper is a > nonstarter. I would argue that this puts unnecessary obstacles in the way > of a unified approach to information, and that the issue of the > interpretation of information gets obscured by presupposing information is > carried only by meaningful communication. > > > > John Collier > > Professor Emeritus and Senior Research Associate > > University of KwaZulu-Natal > > http://web.ncf.ca/collier > > > > *From:* Stanley N Salthe [mailto:ssal...@binghamton.edu > <ssal...@binghamton.edu>] > *Sent:* Thursday, 14 January 2016 4:56 PM > *To:* Pedro Marijuan; John Collier > *Subject:* Fwd: Toyabe 2010 [ Information converted to energy ] / Van den > Broeck 2010 Thermodynamics of Information / Cartlidge 2010 Information > converted to energy > > > > > > ---------- Forwarded message ---------- > From: *Malcolm Dean* <malcolmd...@gmail.com> > Date: Thu, Jan 14, 2016 at 6:13 AM > Subject: Toyabe 2010 [ Information converted to energy ] / Van den Broeck > 2010 Thermodynamics of Information / Cartlidge 2010 Information converted > to energy > To: > > http://www.nature.com/nphys/journal/v6/n12/full/nphys1821.html > > > > Nature Physics 6, 988–992 (2010) doi:10.1038/nphys1821 > > *Experimental demonstration of information-to-energy conversion and > validation of the generalized Jarzynski equality* > > Shoichi Toyabe, > > > > Takahiro Sagawa, > > > > Masahito Ueda, > > > > Eiro Muneyuki > > > > & Masaki Sano > > In 1929, Leó Szilárd invented a feedback protocol1 in which a hypothetical > intelligence—dubbed Maxwell’s demon—pumps heat from an isothermal > environment and transforms it into work. After a long-lasting and intense > controversy it was finally clarified that the demon’s role does not > contradict the second law of thermodynamics, implying that we can, in > principle, convert information to free energy2, 3, 4, 5, 6. An experimental > demonstration of this information-to-energy conversion, however, has been > elusive. Here we demonstrate that a non-equilibrium feedback manipulation > of a Brownian particle on the basis of information about its location > achieves a Szilárd-type information-to-energy conversion. Using real-time > feedback control, the particle is made to climb up a spiral-staircase-like > potential exerted by an electric field and gains free energy larger than > the amount of work done on it. This enables us to verify the generalized > Jarzynski equality7, and suggests a new fundamental principle of an > ‘information-to-heat engine’ that converts information into energy by > feedback control. > > > http://www.nature.com/nphys/journal/v6/n12/full/nphys1834.html > > [ <------- Please send this PDF if you have access. -- M. ] > > > > > > > > Nature Physics 6, 937–938 (2010) doi:10.1038/nphys1834 > > *Thermodynamics of information: Bits for less or more for bits?* > Christian Van den Broeck > > Recent advances in the formulation of the second law of thermodynamics > have rekindled interest in the connections between statistical mechanics > and information processing. Now a 'Brownian computer' has approached the > theoretical limits set by the rejuvenated second law. Or has it? > > > > > > http://physicsworld.com/cws/article/news/2010/nov/19/information-converted-to-energy > Physics World, 19 > > > > November 2010 > > ** > > *Information converted to energy* > > Physicists in Japan have shown experimentally that a particle can be made > to do work simply by receiving information, rather than energy. They say > that their demonstration, which uses a feedback system to control the > electric potential of tiny polystyrene beads, does not violate the second > law of thermodynamics and could in future lead to new types of microscopic > devices. > > The experiment, carried out by Shoichi Toyabe of Chuo University in Tokyo > and colleagues, is essentially the practical realization of a thought > experiment proposed by James Clerk Maxwell in 1871. Maxwell envisaged a gas > initially at uniform temperature contained in a box separated into two > compartments, with a tiny intelligent being, later called "Maxwell's > demon", controlling a shutter between the two compartments. By knowing the > velocity of every molecule in the box, the demon can in principle time the > opening and closing of the shutter to allow the build-up of faster > molecules in one compartment and slower ones in the other. In this way, the > demon can decrease the entropy inside the box without transferring energy > directly to the particles, in apparent contradiction of the second law of > thermodynamics. > > Among the many responses to this conundrum was that of Leó Szilárd in > 1929, who argued that the demon must consume energy in the act of measuring > the particle speeds and that this consumption will lead to a net increase > in the system's entropy. In fact, Szilárd formulated an equivalence between > energy and information, calculating that *kT*ln2 (or about 0.69 *kT*) is > both the minimum amount of work needed to store one bit of binary > information and the maximum that is liberated when this bit is erased, > where *k* is Boltzmann's constant and *T* is the temperature of the > storage medium. > Spiral staircase > > Toyabe and colleagues have observed this energy-information equivalence by > varying an electric field so that it represents a kind of spiral staircase. > The difference in electrical potential between successive steps on the > staircase is *kT*, meaning that a thermally fluctuating particle placed > in the field will occasionally jump up a step but more often than not it > will take a step downwards. What the researchers did was to intervene so > that whenever the particle does move upwards they place the equivalent of a > barrier behind it, preventing the particle from falling beyond this point. > Repeating the process allows it to gradually climb the staircase. > > The experiment consisted of a 0.3 µm-diameter particle made up of two > polystyrene beads that was pinned to a single point on the underside of the > top of a glass box containing an aqueous solution. The shape of an applied > electric field forced the particle to rotate in one direction or, in other > words, to fall down the potential-energy staircase. Buffered by the > molecules in the solution, however, the particle every so often rotated > slightly in the opposite direction, allowing it to take a step upwards. > > By tracking the particle's motion using a video camera and then using > image-analysis software to identify when the particle had rotated against > the field, the researchers were able to raise the metaphorical barrier > behind it by inverting the field's phase. In this way they could gradually > raise the potential of the particle even though they had not imparted any > energy to it directly. > Quantifiable breakthrough > > In recent years other groups have shown that *collections of particles > can be rearranged so as to reduce their entropy without providing them with > energy directly. The breakthrough in the latest work is to have quantified > the conversion of information to energy. By measuring the particle's degree > of rotation against the field, Toyabe and colleagues found that they could > convert the equivalent of one bit information to 0.28 kTln2 of energy or, > in other words, that they could exploit more than a quarter of the > information's energy content.* > > > > The research is described in Nature Physics, and in an accompanying > article Christian Van den Broeck of the University of Hasselt in Belgium > describes the result as "a direct verification of information-to-energy > conversion" but points out that the conversion factor is an idealized > figure. As he explains, it regards just the physics taking place on the > microscopic scale and ignores the far larger amount of energy consumed by > the macroscopic devices, among them the computers and human operators > involved. He likens the energy gain to that obtained in an experimental > fusion facility, which is dwarfed by the energy needed to run the > experiment. "They are cheating a little bit," joked Van den Broeck over the > telephone. "This is not something you can put on the shelf and sell at this > point." > > However, Van den Broeck does believe that the work could lead to practical > applications within perhaps the next 30 or 40 years. He points out that as > devices get ever more miniature the energy content of the information used > to control them – *kT* at room temperature being equivalent to about > 4 × 10–21 J – will approach that required to operate them. "Nobody thinks > of using bits to boil water," he says, "but that would in principle be > possible at nanometre scales." And he speculates that molecular processes > occurring in nature might already be converting information to energy in > some way. "The message is that processes taking place on the nanoscale are > completely different from those we are familiar with, and that information > is part of that picture." > About the author > > Edwin Cartlidge is a science writer based in Rome > > > > > > John Collier > > Professor Emeritus and Senior Research Associate > > University of KwaZulu-Natal > > http://web.ncf.ca/collier > > > > ------------------------------ > > _______________________________________________ > Fis mailing list > Fis@listas.unizar.es > http://listas.unizar.es/cgi-bin/mailman/listinfo/fis > > > _______________________________________________ > Fis mailing list > Fis@listas.unizar.es > http://listas.unizar.es/cgi-bin/mailman/listinfo/fis > > -- Professor Terrence W. Deacon University of California, Berkeley
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