Our Good-Enough Universe

Covering the whole history of the universe naturally raises some Big Questions. We’ll consider some of these over the coming year, along with generous portions of memorable milestones, anecdotes, and curious facts.

Before we get to January 1, here’s a Big Question: why is the universe we live in well-suited for intelligent life? The answer may be related to the answer to another question: why are living things so well-adapted? Why do their various parts work together so well? The Ancient Greeks pondered this question. Some of them (Aristotle, for example) thought it was just the nature of living things to be well-adapted. But some of them offered a materialist explanation: animals with all sorts of combinations of different parts had once existed, but only some of them survived for us to see them. Lucretius, who was sort of the Roman version of Carl Sagan and Richard Dawkins (if Sagan and Dawkins had written in dactylic hexameter) wrote:

“ten thousand tribes of mortals poured forth,

fitted together in all kinds of forms, a wonder to behold. ….

as many heads without necks sprouted forth,

and arms wandered naked, bereft of shoulders,

and eyes roamed alone, impoverished of foreheads.”

But only a small fraction of these monsters – the accidentally well-adapted ones –survived. This sounds like Darwin’s theory of “survival of the fittest,” but in Darwin’s theory, the process is cumulative, and organisms get better and better adapted over time. (You can find biologist John Rees reviewing this history, and sticking up for the pre-Darwinian theory – call it “survival of the viable” – here. Also, literary critic Stephen Greenblatt reviews just how explosive the rediscovery of Lucretius was for the European Renaissance.)

Nowadays, a significant number of physicists defend a similar theory. The same process f inflation that generated our universe automatically generated vast numbers of other universes; only a small fraction of these, including ours, are fit to live in. Here’s one physicist, Leonard Susskind, doing the Lucretius thing:

“Every possible environment has its own Laws of physics, its own elementary particles, and its own constants of nature. Some environments are similar to our own but slightly different, For example, they may have electrons, quarks, and all the usual particles, but with gravity a billion times stronger than ours. Others have gravity like ours, but contain electrons that are heavier than atomic nuclei. Still others may resemble our world except for a violent force … that rips apart glaxies, molecules, and even atoms. Not even the three dimensions of space are sacred … [there may be] worlds of four, five, six, or even more dimenions.” [p.20]

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