Chiral conformity emerges from the least-time free energy consumption

Abstract

The prevalence of chirally pure biological polymers is often assumed to stem from some slight preference for one chiral form at the origin of life. Likewise, the predominance of matter over antimatter is presumed to follow from some subtle bias for matter at the dawn of the universe. However, rather than being imposed from the start, handedness standards in societies emerged to make things work. Since work is the universal measure of transferred energy, it is reasoned that standards at all scales and scopes emerge to consume free energy. Free energy minimization, equal to entropy maximization, turns out to be the second law of thermodynamics when derived from statistical physics of open systems. This many-body theory is based on the atomistic axiom that everything comprises the same fundamental elements known as quanta of action; hence, everything follows the same law. According to the thermodynamic principle, the flows of energy naturally select standard structures over less-fit functional forms to consume free energy in the least time. Thermodynamics making no distinction between animate and inanimate renders the question of life's handedness meaningless and deems the search for an intrinsic difference between matter and antimatter pointless.

Keywords: chirality; entropy; free energy; natural selection; statistical physics; symmetry.

Figure 1.

Energy level diagram depicts a system evolving through chemical reactions of chiral residues (◐ and ◑). Compounds of the same energy, G_k, relative to the average energy, k_BT, are on the same level in numbers, N_k. Their exchange (curved arrows) is of no consequence, but reactions (vertical arrows) involving compounds with different energy, G_j, in numbers, N_j, coupled with the flux of quanta with energy, ΔQ_jk (wavy arrows), move the system towards thermodynamic balance with its energy-rich surroundings. In general, reactions yield mixed-handed polymers. Only if chiral-pure products turn out to catalyse their own enantioselective polymerization will the multiple mixed-polymer reactions fall behind in furthering the system towards thermodynamic balance.

Figure 2.

Energy level diagram depicts a system evolving into homochirality through chemical reactions of chiral residues (◐ and ◑). Compounds of the same energy, G_k, relative to the average energy, k_BT, are on the same level in numbers, N_k. Their exchange (curved arrows) is of no consequence, but reactions (vertical arrows) with compounds of different energy, G_j, in numbers, N_j, coupled with the flux of quanta with energy, ΔQ_jk (wavy arrows), forward the system towards thermodynamic balance. When the chiral-pure products (on the left and on the right) catalyse their own enantioselective polymerization, the mixed-handed polymers (in the middle) emerging from multiple reactions fall behind irretrievably. By the same token, improvements, for example, in the left-handed synthesis yield ever more powerful autocatalysts that shift the balance ever more in favour of the left-handed polymers.