Dear Pedro,
You are right: the dimensionality of thermodynamic entropy is Joule/Kelvin. Probabilistic entropy/uncertainty/information is dimensionless and measured in bits. Configurational information (a point of access to measuring meaning) is also measured in bits, but it is not a Shannon entropy (Krippendorff, 2009). It can be considered as a redundancy = reduction of uncertainty = a difference which makes a difference. Best, Loet _____ Loet Leydesdorff Professor, University of Amsterdam Amsterdam School of Communications Research (ASCoR), Kloveniersburgwal 48, 1012 CX Amsterdam. Tel.: +31-20- 525 6598; fax: +31-842239111 l...@leydesdorff.net <mailto:l...@leydesdorff.net> ; http://www.leydesdorff.net/ ; http://scholar.google.com/citations?user=ych9gNYAAAAJ <http://scholar.google.com/citations?user=ych9gNYAAAAJ&hl=en> &hl=en From: fis-boun...@listas.unizar.es [mailto:fis-boun...@listas.unizar.es] On Behalf Of Pedro C. Marijuan Sent: Wednesday, April 11, 2012 10:44 AM To: fis@listas.unizar.es Subject: Re: [Fis] Physics of computing Dear John and colleagues, Nice to hear that you are OK after that dangerous intoxication --our best wishes for your complete recovery! About physical information I think that Landauer clarified the panorama, at least concerning the relationship between information theory and thermodynamics. According to his principle, any logically irreversible transformation of classical information is necessarily accompanied by the dissipation of at least k T ln(2) of heat per lost bit (about 3 x 10 exp -21 Joules at 300 K temperature), where obviously k is the Boltzmann constant and T the temperature. Recently this principle has been verified experimentally (Nature, 8 March 2012, p. 187). By the way, in his past message Loet enters "Watts" in a similar expression (?). To insist, Entropy and Information are dimensionless and do not explicitly incorporate any units... About the quantum management of info theory, it is another matter, quite more tricky. Beyond that immediate physicality, things get quite obscure as our contradictory "meaning" messages witness. The point made by Joseph on an overarching logic, is rather difficult to be maintained --at least in my small province of the biological signaling pathways. Too many logics are used biologically in too many different contexts or niches, either molecularly or neuronally... I bet that they are not susceptible of integration in any logical system. Maybe Inbiosa parties would also disagree with me in this regard. best wishes to all, ---Pedro John Collier escribió: Folks, I have been in the hospital for almost three weeks due to bleeding from warfarin. I had to have three blood transfusions and an operation. I am only now getting my strength back. Some of my comments, therefore, may be dated. "Physical" has a variety of overlapping meanings (a Wittgensteinian family resemblence). For example Quine takes the physical to be anything accessible to the senses or inferences therefrom. Ladyman, Ross, Collier an Spurrett take the physical to be the most fundamental laws of our (part of) the universe. I did not agree with this, among some other crucial points, so I was not a primary author. Information is at least physical in both of these senses. Quine's approach might make it entirely physical. I prefer to relate it to the causal, which always has physical parametres, as far as we know. But there are many ways of approaching this issue, and disentangling them will be a major advance in foundations of information theory. My Best, John Professor John Collier Philosophy, University of KwaZulu-Natal Durban 4041 South Africa T: +27 (31) 260 3248 / 260 2292 F: +27 (31) 260 3031 email: colli...@ukzn.ac.za>>> On 2012/03/16 at 01:19 PM, in message <mailto:4f6321c3.5000...@aragon.es> <4f6321c3.5000...@aragon.es>, "Pedro C. Marijuan" <mailto:pcmarijuan.i...@aragon.es> <pcmarijuan.i...@aragon.es> wrote: Dear discussants, I tend to disagree with the motto "information is physical" if taken too strictly. Obviously if we look "downwards" it is OK, but in the "upward" direction it is different. Info is not only physical then, and the dimension of self-construction along the realization of life cycle has to be entered. Then the signal, the info, has "content" and "meaning". Otherwise if we insist only in the physical downward dimension we have just conventional computing/ info processing. My opinion is that the notion of absence is crucial for advancing in the upward, but useless in the downward. By the way, I already wrote about info and the absence theme in a 1994 or 1995 paper in BioSystems... best ---Pedro walter.riof...@terra.com.pe escribió: Thanks John and Kevin to update issues in information, computation, energy and reality. I would like point out to other articles more focused in how coherence and entanglement are used by living systems (far from thermal equilibrium): Engel G.S., Calhoun T.R., Read E.L., Ahn T.K., Mancal T., Cheng Y.C., Blankenship R.E., Fleming G.R. (2007) Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems. Nature, 446(7137): 782-786. Collini E., Scholes G. (2009) Coherent intrachain energy in migration in a conjugated polymer at room temperature. Science, vol. 323 No. 5912 pp. 369-373. Gauger E.M., Rieper E., Morton J.J.L., Benjamin S.C., Vedral V. (2011) Sustained Quantum Coherence and Entanglement in the Avian Compass. Phys. Rev. Lett., 106: 040503. Cia, J. et al, (2009) Dynamic entanglement in oscillating molecules. arXiv:0809.4906v1 [quant-ph] Sincerely, Walter _____ _______________________________________________ fis mailing list fis@listas.unizar.es https://webmail.unizar.es/cgi-bin/mailman/listinfo/fis -- ------------------------------------------------- Pedro C. Marijuán Grupo de Bioinformación / Bioinformation Group Instituto Aragonés de Ciencias de la Salud Avda. Gómez Laguna, 25, Pl. 11ª 50009 Zaragoza, Spain Telf: 34 976 71 3526 (& 6818) Fax: 34 976 71 5554 pcmarijuan.i...@aragon.es http://sites.google.com/site/pedrocmarijuan/ ------------------------------------------------- Please find our Email Disclaimer here-->: http://www.ukzn.ac.za/disclaimer <http://www.ukzn.ac.za/disclaimer/> _____ _______________________________________________ fis mailing list fis@listas.unizar.es https://webmail.unizar.es/cgi-bin/mailman/listinfo/fis -- ------------------------------------------------- Pedro C. Marijuán Grupo de Bioinformación / Bioinformation Group Instituto Aragonés de Ciencias de la Salud Avda. Gómez Laguna, 25, Pl. 11ª 50009 Zaragoza, Spain Telf: 34 976 71 3526 (& 6818) Fax: 34 976 71 5554 pcmarijuan.i...@aragon.es http://sites.google.com/site/pedrocmarijuan/ -------------------------------------------------
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