And the defects were not inert. Propagating wildly, they collided, combined, and interacted. A migrating point defect could trace out a line; a shifting line could trace out a plane; where two planes crossed, a line was formed, to make more planes and lines. Feedback loops of creation and destruction were quickly established, in a kind of spacetime chemistry. There was a time of wild scribbling.
Most of these sketches died as quickly as they were formed. But 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. And the black holes, drifting through this churning soup, provided additional points of structure, seeds around which the little cycling structures could concentrate. 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.
-Exultant, Ch. 37