Is life an accident? Intelligent Design argues that the complexity and efficiency of nature imply a creator. One of the most famous of such arguments is William Paley's "watchmaker analogy" published in 1802. The analogy roughly translates to "design implies designer" using a watch as an example. The argument goes as far back as around 50 B.C., when it was first introduced by Cicero in De Natura Deorum:
"When you see a sundial or a water-clock, you see that it tells the time by design and not by chance. How then can you imagine that the universe as a whole is devoid of purpose and intelligence, when it embraces everything, including these artifacts themselves and their artificers?"
Darwin was fascinated by this idea as a student. However, upon developing the theory of natural selection, he believed he had answered Paley's question. Darwin's theory of evolution has since framed much of science. Additionally computers and modern mathematics have demonstrated complexity resulting from simple rules, over and over again: one example is in dynamical systems, or fractals.
Richard Dawkins, a well-known atheist, author of The Blind Watchmaker, wrote a computer program that, using only a few rules, generated shapes resembling shrimp and insects.
He was surprised at the output of his code, as this was certainly not his intention. He used this result to demonstrate that in fact such things can happen accidentally.
Although science provides some explanation, not everyone is able to drop the idea that life could only exist as a result of a higher power, or creator. It still seems amazing that something so complicated and powerful as the human eye could have come about by chance. A similar example is given in the following video:
Although I'd expect most atheists find this video amusing instead of a "nightmare," no one can deny that in many ways Earth is perfectly suited for life, as if it were made for us.
Thus far, searches for Extra Terrestrial Intelligence have revealed that complex life is very rare in our universe. Not only is Earth the only planet we know of to support complex life, if conditions were tweaked ever so slightly, Earth may have been yet another barren rock in our solar system. The distance from the sun, lack of meteors, tilt, even the size of the moon are all factors, and in our case, each parameter is just right.
In developing theories of the universe, scientists look at an even bigger picture: how is it that intelligent life was able to develop in our universe? By the anthropic principle, in understanding our universe, we must take into account that we are in it. String theory can generate hundreds of possible universes, and many scientists believe, in some form or another, that hundreds, or in fact an infinite number, of universes can and will exist. It is possible by probability that millions of universes were created, as ours was, before conditions would allow life. The fine-tuned universe refers to an assertion that were our universe only slightly different, that is, had there been a small change in several of the approximately 26 dimensionless physical constants, our universe would be completely different, and in almost all cases, would not be conductive to matter forming. Neuroscientist Larry Abbott wrote:
"the small value of the cosmological constant is telling us that a remarkably precise and totally unexpected relation exists among all the parameters of the Standard Model of particle physics, the bare cosmological constant and unknown physics."
As is the case with Earth, were things only slightly different life may have never formed in the universe at all, which makes it even more amazing that it did.
Just as Darwin's theory replaced bewilderment with theory and reason, theoretical physicist Lee Smolin proposed a theory around 1980 that makes these tiny and unbelievable probabilities a little more reasonable. His theory is sometimes called cosmological natural selection (CNS). He suggested that black holes may be a means by which universes create universes (i.e. universes reproduce). A black hole does contain a singularity at the center and relativity predicts that the initial state of the universe at the beginning of the Big Bang was a singularity. Most importantly, by Smolin's theory, the physics of one universe is passed on to daughter universes created by black holes in that universe, leading to a process analogous to natural selection that favors universes with black holes. Such universes should dominate, and therefore a universe with favorable conditions such as ours is more likely to exist because of such conditions.