Microreversible recycled chemical systems. Comment on "A Re-Examination of Reversibility in Reaction Models for the Spontaneous Emergence of Homochirality"

TL;DR

This paper defends the concept of microreversible recycled chemical systems as plausible models for prebiotic chemistry, clarifying misunderstandings about their thermodynamics and energy exchanges, and emphasizing their role in maintaining non-equilibrium states.

Contribution

It clarifies the thermodynamic viability of recycled chemical systems and emphasizes the importance of energy exchanges and activation reactions in prebiotic chemistry models.

Findings

Recycled systems can be thermodynamically feasible with proper energy exchanges.

Misunderstandings about activation reactions lead to incorrect conclusions about system feasibility.

Decomposition approach helps understand non-equilibrium steady states in prebiotic systems.

Abstract

The question of the onset of the homochirality on prebiotic Earth still remains a fundamental question in the quest for the origin of life. Recent works in this field introduce the concept of recycling, rather than the traditional open-flow system described by Frank. This approach has been criticized by Blackmond et al. They claimed that such systems are thermodynamically impossible, except in the cases where non-microreversible reactions are introduced, like in photochemical reactions, or under the influence of physical actions (e.g. by crystal crushing). This point of view reveals misunderstandings about this model of a recycled system, overlooks the possibility of energy exchanges that could take place in prebiotic systems, and leads the authors to unawarely remove the activation reaction and energy source from their "non-equilibrium" models. It is especially important to understand what are the concepts behind the notion of recycled systems, and of activation reactions. These points are fundamental to comprehending how chemical systems -- and especially prebiotic chemical systems -- can be maintained in non-equilibrium steady states, and how free energy can be used and exchanged between systems. The proposed approach aims at the decomposition of the problem, avoiding to embrace the whole system at the same time.