On Wed, Feb 01, 2012 at 09:17:41PM +0100, Evgenii Rudnyi wrote: > On 29.01.2012 23:06 Russell Standish said the following: > > > >Absolutely! But at zero kelvin, the information storage capacity of > >the device is precisely zero, so cooling only works to a certain > >point. > > > > I believe that you have mentioned once that information is > negentropy. If yes, could you please comment on that? What > negentropy would mean?
Scheodinger first pointed out that living systems must export entropy, and coined the term "negative entropy" to refer to this. Brillouin shortened this to negentropy. The basic formula is S_max = S + I. S_max is the maximum possible value for entropy to take - the value of entropy at thermodynamic equilibrium for a microcanonical ensemble. S is the usual entropy, which for non-equilibrium systems will be typically lower than S_max, and even for equilibrium systems can be held lower by physical constraints. I is the difference, and this is what Brillouin called negentropy. It is an information - the information encoded in that state. Try looking up http://en.wikipedia.org/wiki/Negentropy > > In general, I do not understand what does it mean that information > at zero Kelvin is zero. Let us take a coin and cool it down. Do you > mean that the text on the coin will disappear? Or you mean that no > one device can read this text at zero Kelvin? > I vaguely remembered that S_max=0 at absolute zero. If it were, then both S and I must be zero, because these are all nonnegative quantities. But http://en.wikipedia.org/wiki/Absolute_zero states only that entropy is at a minimum, not stricly zero. In which case, I withdraw that comment. Cheers -- ---------------------------------------------------------------------------- Prof Russell Standish Phone 0425 253119 (mobile) Principal, High Performance Coders Visiting Professor of Mathematics hpco...@hpcoders.com.au University of New South Wales http://www.hpcoders.com.au ---------------------------------------------------------------------------- -- 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 everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.
