Homochirality and the need for energy.
The mechanisms for explaining how a stable asymmetric chemical system can be formed from a symmetric chemical system, in the absence of any asymmetric influence other than statistical fluctuations, have been developed during the last decades, focusing on the non-linear kinetic aspects. Besides the absolute necessity of self-amplification processes, the importance of energetic aspects is often underestimated. Going down to the most fundamental aspects, the distinction between a single object-that can be intrinsically asymmetric-and a collection of objects-whose racemic state is the more stable one-must be emphasized. A system of strongly interacting objects can be described as one single object retaining its individuality and a single asymmetry; weakly or non-interacting objects keep their own individuality, and are prone to racemize towards the equilibrium state. In the presence of energy fluxes, systems can be maintained in an asymmetric non-equilibrium steady-state. Such dynamical systems can retain their asymmetry for times longer than their racemization time.
Plasson
Raphaël
R
Nordita, Roslagstullsbacken 23, Stockholm, Sweden. rplasson@nordita.org
Brandenburg
Axel
A
D019418:Evolution, Chemical; D005118:Extraterrestrial Environment; D008433:Mathematics; D008956:Models, Chemical; D013237:Stereoisomerism; D013816:Thermodynamics