From owner-biophysics@net.bio.net Thu Mar 11 22:00:00 1999 Path: biosci!news.stanford.edu!newsfeed.berkeley.edu!newsfeed.tli.de!newsfeed.nacamar.de!uni-erlangen.de!news-nue1.dfn.de!news-lei1.dfn.de!news-ber1.dfn.de!news.uni-potsdam.de!newsadm From: "Frank Fürst" Newsgroups: bionet.biophysics Subject: Re: Help on a BIO-PHYSICS book Date: Fri, 12 Mar 1999 18:57:55 +0100 Organization: University of Potsdam Lines: 52 Message-ID: <36E955A3.2493FAC5@fuerst.de> References: <7cb4qj$ifr$1@diana.bcn.ttd.net> <36e927c8.0@news4.his.com> NNTP-Posting-Host: pc207-60.biochem.uni-potsdam.de Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Mailer: Mozilla 4.06 [de]C-QXW0310E (Win95; I) Hi, Eric Fairfield wrote: > [...] > > Across all of these pieces of biology, I can't think of a minimum energy > rule that holds up to serious scrutiny. > > I propose the following hypothesis: > > Biological systems do not abide by a minimum energy rule. They function so > that they produce offspring before they exceed the maximum energy available > to their particular environment at a particular time. > I think the main problem with applying a minimum energy rule to biology is that biological systems are biological ones because they are far from equilibrium. And in non-equilibrium systems the standard rules of thermodynamics no longer hold. In model systems not too far from equilibrium, there's a corresponding rule which has been called principle of "maximal production of entropy", but things get really difficult there. [In P.W.Aktins' Physical Chemistry textbook, the long one, is a chapter on non-equilibrium thermodynamics, but for the one who originally posted the question it might be a little difficult to start with that chapter or even book, as he says not to have academic background in the field] If a system is far enough from equilibrium, there exists no state function (i.e. entropy production is not a total differential [hope thats the right english word]). This results in the fact that there's no unique "way down", and that a macroscopic state can be achieved by the system several times in a kinetic experiment: Oszillations (and even chaos) occur, and that's just what we see in biological systems. But of course this is more or less just a kind of explanation of the existence of life, and maybe why it could "build" a thing like evolution. Its diversity, and also the individuals' behaviour, is governed by additional laws, Erics hypothesis points in that direction. Frank -- **************************************************** Frank Fuerst, Institut für Biochemie der Uni Potsdam Im Biotechnologiepark, 14943 Luckenwalde Tel.: +49-3371-681334; Fax.: +49-3371-681339 ffrank@rz.uni-potsdam.de ************************************************ Hi! I'm Signature Virus 99! Copy me into your signature and join the fun! .