From Wikipedia:

The

**fecund universes** hypothesis of

cosmology advanced by Lee Smolin, also called

**cosmological natural selection** theory, suggests that a process analogous to biological

natural selection applies at the grandest scales. Smolin summarized the idea in a book aimed at a lay audience called

*The Life of the Cosmos*.

The theory surmises that a collapsing

black hole causes the emergence of a new universe on the "other side", whose fundamental constant parameters (

speed of light,

Planck length and so forth) may differ slightly from those of the universe where the black hole collapsed. Each universe therefore gives rise to as many new universes as it has black holes. Thus the theory contains the evolutionary ideas of "reproduction" and "mutation" of universes, but has no

*direct* analogue of natural selection. However, given any universe that can produce black holes that successfully spawn new universes, it is possible that some number of those universes will reach

heat death with unsuccessful parameters. So, in a sense, fecundity cosmological natural selection is one where universes could die off before successfully reproducing, just as any biological being can die without having offspring.

^{[4]
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Fractals in theoretical cosmologyIn the realm of theory, the first appearance of fractals in cosmology was likely with

Andrei Linde’s "Eternally Existing Self-Reproducing Chaotic Inflationary Universe"

^{[5]} theory (see

Chaotic inflation theory), in 1986. In this theory, the evolution of a scalar field creates peaks that become nucleation points which cause inflating patches of space to develop into "bubble universes," making the universe fractal on the very largest scales.

Alan Guth's 2007 paper on "Eternal Inflation and its implications"

^{[6]} shows that this variety of

Inflationary universe theory is still being seriously considered today. And inflation, in some form or other, is widely considered to be our best available cosmological model.

Since 1986, however, quite a large number of different cosmological theories exhibiting fractal properties have been proposed. And while Linde’s theory shows fractality at scales likely larger than the observable universe, theories like

Causal dynamical triangulation^{[7]} and Quantum Einstein gravity

^{[8]} are fractal at the opposite extreme, in the realm of the ultra-small near the

Planck scale. These recent theories of

quantum gravity describe a fractal structure for

spacetime itself, and suggest that the dimensionality of

space evolves with

time. Specifically; they suggest that reality is 2-d at the Planck scale, and that spacetime gradually becomes 4-d at larger scales. French astronomer

Laurent Nottale first suggested the fractal nature of spacetime in a paper on

Scale Relativity published in 1992,

^{[9]} and published a book on the subject of Fractal Space-Time in 1993.

^{[10]}
French mathematician

Alain Connes has been working for a number of years to reconcile

Relativity with

Quantum Mechanics, and thereby to unify the laws of

Physics, using

Noncommutative geometry. Fractality also arises in this approach to

Quantum Gravity. An article by Alexander Hellemans in the August 2006 issue of Scientific American

^{[11]} quotes Connes as saying that the next important step toward this goal is to "try to understand how space with fractional dimensions couples with gravitation." The work of Connes with physicist

Carlo Rovelli^{[12]} suggests that time is an emergent property or arises naturally, in this formulation, whereas in

Causal dynamical triangulation,

^{[13]} choosing those configurations where adjacent building blocks share the same direction in time is an essential part of the 'recipe.' Both approaches suggest that the fabric of space itself is fractal, however.