Interstellar grains as possible cold seeds of life

Abstract

As long as entropy ceases to play any part in equilibria when the temperature approaches absolute zero, all exothermic reactions—up to the formation of the most complex biopolymers—become thermodynamically profitable. In such conditions the reaction rate starts to play a decisive part in the observability of chemical transformations. According to classical views (Arrhenius law) all reactions should completely stop when T→0 and therefore the cold synthesis of biologically active substances is absolutely excluded. The phenomenon of a low-temperature limit to chemical reaction rates found recently, however, in the studies of radiation-induced polymerisation of formaldehyde^1–3, showing the existence of chemical reactivity even at T→0, obviously caused by quantum-mechanical molecular tunnelling, makes it possible to combine complete suppression of the entropy term in equilibria with an observable rate of exothermic chemical reactions, for example, of chain polymerisation (or any other integration of molecules) induced by light or ionising radiation. Thus molecular tunnelling suggests the possibility of a cold pre-history of life^1–3.