The Nature of Consciousness: Consciousness, Life and Meaning

Natural Selection for Universes

In 1970 the British mathematician Jacob Bronowski introduced the concept of "stratified stability". Stratified stability is a simpler form of evolution than natural selection. Evolution in the universe at large occurs because combinations of nonliving particles, atoms, molecules, etc form ever more complex structures: the laws of nature "prune" the ones that are not stable, or, equivalently, the laws of nature (such as gravity and electromagnetism) determine which of these more complex structures are stable enough to "survive". The surviving ones then combine to form even more complex structures, to which the same "selection" process applies. Stratified stability is nonbiological selection, or, equivalently, biological selection (the one studied by Darwin) is a special case of selection of stable structures.

Refining Guth's vision, the Russian physicist Andrei Linde came up with a "chaotic inflationary" model ("Nonsingular Regenerating Inflationary Universe", 1982). Linde realized that Guth's inflation must litter the universe with bubbles, each one expanding like an independent universe, with its own Big Bang and its own Big Crunch.

Linde's model is "chaotic" because it assumes a chaotic initial distribution of the scalar field: instead of being uniform, the original scalar field was fluctuating wildly from point to point. Inflation therefore began in different points at different times and at different rates.

Regions of the universe that are isolated by a length greater than the inverse of the Hubble constant cannot be in any relation with the rest of the universe. They expand independently. Any such region is a separate mini-universe. In any such region the scalar field can give rise to new mini-universes.

One mini-universe produces many others. It is no longer necessary to assume that there is a "first" universe.

Each mini-universe is very homogeneous, but on a much larger scale the universe is extremely inhomogeneous. It is not necessary to assume that the universe was initially homogeneous or that all its causally disconnected parts started their expansion simultaneously.

One region of the inflationary universe gives rise to a multitude of new inflationary regions. In different regions, the properties of space-time and elementary particles may be utterly different. Natural laws may be different in each mini-universe.

The evolution of the universe as a whole has no end, and may have no beginning.

The "evolution" of mini-universes resembles that of any animal species. Each mini-universe leads to a number of mini-universes that are mutated versions of it, as their scalar fields are not necessarily the same. Each mini-universe is different, and mini-universes could be classified in a strict hierarchy based on a parent-child relationship.

This mechanism sort of "reproduces" mini-universes in a fashion similar to how life reproduces itself through a selection process. The combinatorial explosion of mini-universes can be viewed as meant to create mini-universes that are ever better at "surviving".

Each mini-universe "inherits" the laws of its parent mini-universe to an extent, just like living beings inherit behavior to an extent through genetic code. A "genome" is passed from parent universe to child universe, and that "genome" contains instructions about which laws should apply. Each genome only prescribes a piece of the set of laws governing the behavior of a universe. Some are random. Some are generated by "adaptation" to the environment of many coexisting universes.

At the same time, expansion means that information is being propagated like in a neural network through the hierarchy of expanding universes.

It may also be that a universe is not born just out of a parent universe, but of many parent universes. A region of the universe expands because of the effect of many other regions. This is similar to what happens with neural networks.

With a little imagination, the view of the chaotic inflationary theory can be interpreted in this way:

The expansion of a new region may be determined by many regions, not just one.

Each region somehow inherits its laws from those regions.

The laws in a region may change all the time, especially at the beginning.

The laws determine how successful a region is in its expansion.

Different expansion regions with different laws can communicate. They are likely to compete for survival.

Adaptation takes a toll on expansion regions. Regions die. Branches of regions become extinct.

Obviously, this scenario bears strong similarities with biological scenarios.

Another theory that presupposes evolving universes is the one advanced by the US philosopher Quentin Smith ("A Natural Explanation of the Existence and Laws of Our Universe ", 1990) and by the US astrophysicist Lee Smolin ("Did the Universe Evolve?", 1992). Smolin thinks that black holes are the birthplaces of offspring universes. Each black hole of a universe is a conduit to transfer information to new baby universes. However, the constants and laws of Physics are randomly changed in the new universes, just like the genome of offspring is randomly mutated. Black holes guarantee reproduction and inheritance. Universes that do not give rise to black holes cannot reproduce: there is therefore also a kind of "natural selection" among Smolin's universes. In this scenario, our universe's delicate balance of constants and forces is the result of evolution.

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