Friday, November 25, 2011

The multiverse

Alan Lightman, another Tennessee boy (now at MIT) who works on the interface of science and the humanities, has an essay in the current Harper's called "The Accidental Universe: Science's Crisis of Faith" that explores the implications of recent developments in theoretical cosmology.

I am such a big fan of Alan that I am reluctant to take issue, but let me gently demur from some of what he has to say.

Early in the essay he says: "The history of science can be viewed as the recasting of phenomena that were once thought to be accidents as phenomena that can be understood in terms of fundamental causes and principles. One can add to the list of the fully explained: the hue of the sky…", etc.

Before the advent of science, the default explanation was not "accident." Whatever happened was the will of the gods. "A fine soft day, thanks be to God," say my neighbors in Ireland, and that, I think, pretty much sums up the universal attitude across cultures. When I was a kid I was told that the sky is blue because that is Mary's color. The hue was no accident.

Science began when divine whim gave way to necessary consequences of "fundamental causes and principles." A small distinction, perhaps -- unpredictable divinity and accident are in practice indistinguishable -- but important to the development of Lightman's thesis, and important to how we live our lives.

As Lightman suggests, it has long been the hope of physicists that if fundamental laws can be discovered, then the universe we live in will turn out to be a necessary consequence of those laws. Even our own presence in such a universe would be no accident. Reduction, determinism, and materialism have been pillars of the philosophy of science.

Now, says Lightman, dramatic developments in cosmological thought -- namely, eternal inflation and string theory -- "have led some of the world's premier physicists to propose that our universe is only one of an enormous number of universes with wildly varying properties" that follow essentially at random from the fundamental principles. There is no way physicists can uniquely derive the characteristics of our universe from first principles; thus, the "accidental universe" of Lightman's title. Also, since there is no way to experimentally observe any other universe than our own, the "multiverse" must be taken as a matter faith; thus, the "crisis" of the subtitle.

This has particular relevance, says Lightman, to the so-called "anthropic principle" -- the apparent fact that our universe seems fine-tuned for the possibility of human existence, something made much of by advocates of intelligent design. More on this Monday.