Suppose, for example, that instead of the collected works of Shakespeare, we set our sights on something a bit less daunting, say, a 500-word essay I wrote the other day – about two, double-spaced pages in length. Further, suppose we perform the experiment with a computer instead of a monkey. Computers can generate thousands of random strings of characters per second and check their own work. Finally, instead of using a single computer, let’s run many in parallel, and we’ll stop when any one of the computers first completes the essay.
Suppose we had one computer for every atom in the universe (this is a thought experiment, so let’s think big). We’ll let the computers run from the beginning of the Big Bang to one hypothesized end of the universe known as the Big Freeze. Now we can ask: what is the chance one of the computers will type the essay in that time frame?
The answer? The chance is so small there’s nothing we can meaningfully compare it with. For more details, see http://www.uh.edu/engines/epi2924.htm.
In fairness, this result isn’t beyond comprehension. It’s surprising to most people, but the math is elementary. Where we’re led into the world of incomprehensibility is when we look at the complexity of, for example, the human body, where we can reasonably ask if the universe has been around long enough to generate the twenty thousand or so human genes found in DNA, each metaphorically equivalent to an essay. The alphabet of life consists of only four letters (nucleotide bases), but the twenty thousand essays are typically much longer than 500 words. Looking at purely random variations, the situation is stupefyingly worse than trying to randomly type a 500-word essay.
So what are we to make of this? First of all, random typing isn’t a good comparison with the way evolution operates. While evolution uses random mutations to create life, it doesn’t do so by trying everything until it finds something that works. Evolution functions in a more orderly fashion. We don’t fully understand all the steps along the way – for example, why molecules bind together to form life in the first place – but evolution most certainly does not act like monkeys typing on keyboards.
Yet having said this, I do think there’s a cautionary tale here. We tacitly assume that the earth’s been around long enough for randomness to do its magic. But when we work the numbers, it calls into question whether “long enough” has really been “long enough” to create something as immensely complex as human life. Remember, we’re not just talking recipes but the way the recipes work together to keep everything functioning. While I argue that the very existence of human consciousness is beyond comprehension, the fact that human life could come about randomly in the amount of time since the Big Bang only adds to the incomprehensibility.