Freeman: Creationists often argue that evolution is a random, exhaustive search through all possible biological combinations. An impossible task that could never have gotten as far as it has in only four billion years.
Scott [Aaronson] believes complex traits like the human brain or a bacterium's tail can evolve in a reasonable amount of time because evolution is not a completely blind process. In fact, evolution has some clever shortcuts.
Imagine this chessboard is blank and Scott's goal is to properly colour it so that no two neighbouring squares are coloured the same. So, how could you do it? Well, there are three different approaches that may spring to mind.
Let's see my avatar, super Scott, here, try to do it [visual of a digitised avatar of Scott by a large digitised chessboard]. If super Scott had the magical powers of an intelligent designer, he could, I suppose, just see in his mind's eye all of the possible colourings and just instantly pick out the one that worked.
Freeman: If it takes just one step for the intelligent designer super Scott to fill each square, it would only take him 64 steps. You could create humans in a matter of minutes if you had this kind of God-like vision.
Aaronson: What else could we do? A brute-force approach just trying every possible colouring, every possible assignment of colours, to all 64 of the squares. Well, there are ways of coloring all the squares of a chessboard. That's about 18 quintillion. He's obviously gonna be at this for quite a while.
Freeman: On this purely random mission, even if super Scott gets all but one square correct, he has to start over again. If organisms evolved like this, it would take millions of times longer than the age of the universe for a single-celled bacterium to evolve into the intelligent life we see today. But evolution works differently. It makes random guesses, but doesn't go back to square one whenever it makes a mistake.
Aaronson: Here, super Scott starts out with a complete random colouring. He can just look for any two squares that are coloured the same, pick two of those at random, and then randomly change the colour of one of them.
Freeman: In this evolutionary approach, super Scott can make corrections along the way without having to start over every time.
Aaronson: But you might wonder how long will this take? Well, it turns out it will take longer than the intelligent designer, that's for sure. On the other hand, not nearly as long as the brute-force approach. With an eight by eight chessboard, this random-mutation approach will take about 5,000 steps.
Freeman: These emerging mathematics of evolution show that complex patterns can arise surprisingly quickly. We've seen that a mindless evolutionary process really can solve the problem, and it can solve it without an inordinate amount of time.
Freeman: Scott doesn't claim he's proven evolution happened, only that it is possible within earth's timeframe.
Aaronson: For me, the scientific attitude is not that there are no mysteries in the world. It's that you don't wallow in mystery. It's that you constantly look for explanations of things, and, you know, if you find a good explanation for something, you go with it, you know, at least until a better explanation comes along.
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