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Thursday, August 31, 2006

Choice and 20th Century physics, 1

I continue a series of musings on the question, "does anything at all really happen by chance?" This post is the third on that subject. The first two consider what the Bible has to say on the subject. (Here's the second, which has a link to the first, or, better, click on the "choice" label at the bottom of this post.)

Modern physics seems to say that almost everything that happens to sub-atomic particles is due to chance.

This belief is known as the Heisenberg Uncertainty Principle. (I have posted previously about Werner Heisenberg.) This principle states that it is impossible to determine both the position and speed* of sub-atomic particles precisely. Some positions are more likely than others, and, if you know what you are doing, you can produce a graphed curve describing the likelihood that the particle will have each possible position, but the exact position is uncertain. A similar statement could be made about the speed. As a result, electron positions cannot be known, but are described as wavefunctions, or orbitals. They are often shown as blobs or clouds in chemistry texts.

Does this mean that everything at the sub-atomic level is due to chance? As I see it, not necessarily. It means that nothing at the sub-atomic level can be predicted absolutely by physicists, except as a statement of the probability that certain things will happen, something like predicting that there will be a 30% chance of rain. Unlike (we suppose) weather prediction, which will get better and better as we learn more about what causes weather events, and are better at detecting these causes, prediction at the sub-atomic level has fundamental limits -- it isn't ever going to get any better, if the theory is correct. Just because something can't be predicted doesn't necessarily mean that it's actually random, however.

Einstein was notoriously uncomfortable with this idea. He is said to have quipped (probably in German, not English) "God does not play at dice." (do a Google search on this phrase -- in quotation marks -- if interested.)

Some have speculated that this sub-atomic (quantum) uncertainty is a physical basis for free will. That may be so, but there are at least a couple of problems with this idea. First, just because physicists can't predict something doesn't mean that God doesn't control it. (God must at least allow sub-atomic events, but I suppose it is possible that He really does let some or all of them happen at random. It is also possible that every sub-atomic event is directed and controlled by God.) Second, it is not clear that chance events on the sub-atomic level could be responsible for the brain activity that leads to choices. The sub-atomic, after all, is orders of magnitude smaller than a nerve cell. To have such events change the action of nerve cells, at least one of which would be expected to do something if an individual chooses, would be roughly as if random impacts from dust particles in the air changed the direction of a moving car.

I'll probably have more to say about this later.

Thanks for reading.

*It's really not the speed, or even the velocity, but the momentum, but I'm trying not to be too technical here.

2 comments:

Amy said...

It was good seeing you the other day! I'm glad you are doing well!

Martin LaBar said...

Thanks! I know who you are, I think.