Autocatalysis & Homeostasis
…as the networks of interactions grew in complexity, another kind of phase shift was reached, a threshold beyond which certain closed loops of interactions emerged — loops which promoted the growth of other structures like themselves.
This was autocatalysis, the tendency for a structure emerging from a richly connected network to encourage the growth of itself, or copies of itself. And some of these loops happened to be stable, immune to small perturbations. This was homeostasis, stability through feedback.
Thus, through autocatalysis and homeostasis working on the flaws of the young spacetime, an increasingly complex hierarchy of self-sustaining structures emerged. All these tangled knots were machines, fundamentally, heat engines feeding off the flow of energy through the universe… In the new possibilities opened up by closeness, still more complex aggregates grew: simple machines gathered into cooperative “cells,” and the cells gathered into colonial “organisms” and ultimately multicelled “creatures”…
It was, of course, life.
All this had emerged from nothing.
In this universe it would always be this way: structures spontaneously complexified, and stability emerged from fundamental properties of the networks — any networks, even such exotica as networks of intersecting spacetime defects. Order emerging for free…
… The basis of all life in this age was the chemistry of spacetime defects, interconnected geometric churning of points and lines and planes. Most life-forms were built up of “cells,” tightly interconnected, and very stable. But more complex creatures, built from aggregates of these cells, were not quite so stable. They were capable of variation, one generation to the next.
And where there is variation, selection can operate.
… All life-forms must reproduce. Every parent must store information, a genotype, to pass on to its offspring. From this data is constructed a phenotype, the child’s physical expression of that information — its “body.”
In this crowded young universe the most obvious way to transmit such information was through extended quantum structures. Quantum mechanics allowed for the long-range correlation of particles: once particles had been in contact, they were never truly separated, and would always share information.
…But now they found they could usefully form symbiotic relationships with creatures formed of condensate matter: extended structures locked into a single quantum state. A new kind of being ventured cautiously through the light-filled spaces… It was the formation of a new kind of ecology, emerging from fragments of the old and new. But symbiosis and the construction of composite creatures from lesser components were eternal tactics for life, eternal ways of surviving changed conditions.
Thoughtful beings, human and otherwise, would wonder at the endless fecundity of their universe, a universe that spawned life at every stage of existence — and wonder why it had to be so.
Some of them came to understand that it was the universe’s own innate tendency to complexify that had created the richness of structure within it.
Simple laws of molecular combination governed the growth of such intricate, inanimate forms as snowflakes and DNA molecules. But autocatalysis and homestasis enabled simple structures to interact and spin off more complex structures still, until living things emerged, which combined into ever more complicated entities.
… Humans had the good fortune to exist in a universe in which there was no law of conservation of complexity, no limit to its supply.
Stephen Baxter “Exultant”