Tuesday, February 9, 2010

Randomness


I am working on a book about evolution and Creation. I'd like to coordinate my blogs with the book and I am just starting. I may find eventually I want to change things, but I hope to at least make some progress this way.

It might seem strange to start a book about evolution with Brownian (random) motion of atoms, but that is what I am thinking of doing. A major problem we face in understanding evolution is in the concepts of chance and randomness, design and non-design, and agency and non-agency. We can add to the problem when philosophy becomes involved, because this discipline uses the terms "necessity" and "contingency." These terms are sometimes used in place of non-random and random. I think it is important to stay as simple as we can, which is hard enough. I'd like to talk about the physical description of random. If you think in the way of philosophical terms, I'd like you to drop that for a while.

In 1827, the botanist Robert Brown noticed pollen particles floating in water under a microscope, or so the story goes. They showed a jiggling type of motion, neither sitting still nor moving in a smooth path (something like the blue line in the picture here).

At the time, scientists did not even know if separate atoms existed. Some thought they did, but others didn't, and they were not proven.

Scientists came to speculate that we could use these random movements to understand physical phenomena. Though we could not see the atoms, we could guess that they were each separate and had movement in various directions. This is what Albert Einstein did in a famous 1905 paper, Investigations on the Theory of the Brownian Movement, to prove the existence of atoms. Then, to complete the cycle, we could take all of the atoms as a whole, using the probabilities of each of them put together to even better understand their movements. This is what Ludwig Boltzmann and James Clerk Maxwell did. They worked out what is called the "Maxwell-Boltzmann distribution, which describes velocity of gas atoms or molecules in terms of statistical, probabilistic distributions."

I'll go further in talking about atoms and the categories of design I mentioned above next time, but I want to make the point about physical "randomness" here. Atoms have internal thermal energies that make them move in these zigzag patterns which we can't even theoretically predict. These are inherently random. What's more, we have found with quantum physics that particles within atoms, such as electrons, are not determined to exact positions and momentums by measurements, but have probabilities of being at certain places.

Perhaps the concept of "random" is difficult for us because we want to be in control, and to know all the answers. Humans do amazing things and they constantly strive to do more. That is a wonderful thing--look at all we have done and the diseases we have cured. But our drive must not be so strong that we can no longer find humility.

No comments: