Two replies in one message, to Michel and Gavin. I hope that this will count as my second in the week ending today, Sunday, so I have another two slots in the week beginning tomorrow, Monday.
Saturday, September 24, 2011, 11:07:58 AM, Michel wrote: > Thanks also to Robin Faichney for the example of information in > physics, that I would comment a bit (not joking). > I can understand that a two states system such as a spin can be viewed > as carrying a bit of information. > This is a good example of application of information theory to a > physical system. This class of examples is nice because it takes > benefit from the rigorous definitions available in the field, which > can be found in textbooks (Cover, Renyi, etc.). > However, since we assumed that information theory is a subfield of > information science (in addition to be a subfield of probability > theory), we also need very simple examples of information outside the > field of information theory. Michel, maybe that was a bad example, misleading because of its binary nature. My understanding is that physical information is material form, re-conceptualised, and so the spin state, like every other physical attribute, not just the binary ones, IS information (non-semantic information), as and when it suits us to view it that way, i.e. to focus on form rather than substance. Historically, the concept of non-semantic information, or "pure pattern", arose in the context of information theory, but to focus on form is a basic human capacity, and given the concept of non-semantic information, however that arises, it is a small step to apply it to material form, which thus becomes pure pattern whose transformations are governed by the laws of physics. So material form is like data and the totality of physical laws is the program that operates upon it. The operations are, in principle and in general, reversible, and so physical information is conserved, like matter and energy. (I believe there is a strong consensus within physics that physical information is conserved in quantum mechanics.) In a certain sense the laws of physics "stand in" for substance, which is what constrains material form in our ordinary thinking. When we think in terms of pure patterns constrained by physics, every physical entity embodies its own description, and (which is to say almost the same thing) encodes the outcomes of all of its potential interactions. This is a very powerful way of thinking. Gavin: I agree with you that there is no such free-standing, "thing-in-itself" as information, but that doesn't invalidate the concept, far from it. Information is, in my view, basically form, and form doesn't exist without substance, but we work with form, ignoring substance, all the time, and achieve great things by so doing. -- Robin Faichney <http://www.robinfaichney.org/> _______________________________________________ fis mailing list fis@listas.unizar.es https://webmail.unizar.es/cgi-bin/mailman/listinfo/fis
