There was a time, back when astronomy put Earth at the center of the universe, that we thought we were special. But after Copernicus kicked Earth off its pedestal, we decided we were cosmically inconsequential, partly because the universe is vast and about the same everywhere.Smith, however, takes exception to this "principle of mediocrity":
Astronomer Carl Sagan put it this way: “We find that we live on an insignificant planet of a humdrum star.” Stephen Hawking was even blunter: “The human race is just a chemical scum on a moderate-sized planet.”
The universe, far from being a collection of random accidents, appears to be stupendously perfect and fine-tuned for life. The strengths of the four forces that operate in the universe — gravity, electromagnetism, and the strong and weak nuclear interactions (the latter two dominate only at the level of atoms) — for example, have values critically suited for life, and were they even a few percent different, we would not be here.This expansion value, in fact, is fine-tuned to a precision of one part in 10^10^123. It's a number impossible to comprehend.
The most extreme example is the big bang creation: Even an infinitesimal change to its explosive expansion value would preclude life.
The frequent response from physicists offers a speculative solution: an infinite number of universes — we are just living in the one with the right value. But modern philosophers such as Thomas Nagel and pioneering quantum physicists such as John Wheeler have argued instead that intelligent beings must somehow be the directed goal of such a curiously fine-tuned cosmos.Smith goes on to explain why intelligent life is not likely to exist on other planets, no matter how many of them there are. He gives several reasons for this, but there are reasons he doesn't mention as well. Here are a few: A planet suitable for life has to have the right mass, period of rotation, be the right distance from its star, and have on it the right elements in ample supply. A life-sustaining planet must also have a moon of the proper size, it has to orbit a star of the right size and age, and be located in the right kind of galaxy and in the right place in the galaxy. In addition to all this it has to have been extremely lucky to have avoided life-destroying meteor impacts and other cosmic disasters.
Some of my colleagues strongly reject this notion. They would echo Hawking: “I can’t believe the whole universe exists for our benefit.” Yes, we all have beliefs — but beliefs are not proof. Hawking’s belief presumes that we are nothing but ordinary, a “chemical scum.” All the observations so far, however, are consistent with the idea that humanity is not mediocre at all and that we won’t know otherwise for a long time. let us be grateful for the amazing gifts of life and awareness, and acknowledge the compelling evidence to date that humanity and our home planet, Earth, are rare and cosmically precious.It seems that in light of the overwhelming evidence of fine-tuning more and more philosophers and scientists are abandoning the Sagan/Hawking position and coming around to Smith's point of view that life on earth is extraordinary, and that as huge as the universe is we are quite possibly the only intelligent beings in the whole of its vastness. It's a breath-taking thought.