Uncertainty

The pace of farm life slows down this time of year. There’s still plenty to do, but things aren’t as urgent. And by 5:30 or so it’s too dark outside to do anything, which leaves me a lot more time for reading now.

It’s nice to have time for books again. I’m gradually reducing the big stack that I accumulated over the summer.

I’ve just finished David Lindley’s Uncertainty, a fascinating history of the development of quantum mechanics during the early part of the last century. Until scientists like Bohr and Heisenberg blew up classical physics, scientists believed that all effects had causes and that with perfect information about the present, one could precisely predict the future. But the quantum physicists proved that at the subatomic level reality is unpredictable. Things happen for no reason. At the quantum level we can determine only the probability of an event. There is an inherent element of chance, unpredictability, uncertainty. It seems that subatomic particles have personalities and they don’t obey the classical rules. So even though at the visible level things seem orderly and predictable, when we drill all the way down we find arbitrariness.

Of course these discoveries have been disconcerting to those who don’t like the idea that uncaused events occur. Einstein went to his grave refusing to believe it could be true.

But I kind of like knowing that all of nature, at its core, is a cloud of uncertainty. As Jonathan Fields says (in an entirely different context), “There is no such thing as possibility, without uncertainty.” I’ve never accepted the idea that we are just machines. Maybe nothing is. Maybe all of the things we take for granted as “certain” are in reality just very highly probable. (Of course I do appreciate the fact that classical physics still works just fine once we leave the subatomic world. It’s nice to be able to count on gravity, for example).

At the end of the book the author makes a fascinating observation, one new to me, and it is worth quoting:

There can be no going back to the old days of absolute determinism, when, as the Marquis de Laplace hoped, knowledge of the present would bring complete knowledge of  the past and the future.

Cosmically speaking, that may be a good thing. The Laplacian universe can have no moment of birth, because any set of physical conditions must arise, logically and inevitably, from some prior situation, and so on ad infinitum. Nothing uncaused can happen

But the quantum universe is different. Ever since Marie Curie wondered at the spontaneity of radioactive decay, ever since Rutherford asked Bohr what made an electron jump from one place in an atom to another, the recognition has grown that quantum events happen, ultimately, for no reason at all.

So we reach an impasse. Classical physics cannot say why the universe happened, because nothing can happen except that prior events caused it to happen. Quantum physics cannot say why the universe happened, except to say that it did, spontaneously, as a matter of probability rather than certainty….We come to a paradox that Bohr would have loved: it’s only through an initial, inexplicable act of quantum mechanical uncertainty that our universe came into being, setting off a chain of events that led to our appearance on the scene, wondering what initial impetus led to our existence.

Of course the philosophical (and theological) implications of that are obvious. And that is enough fodder to keep a nerdy farmer’s brain itching for a long time.