Friday, October 13, 2006

Yin and yang

In Comments, brome grass drew our attention to a remarkable Astronomy Picture of the Day that bears an uncanny similarity to the classic Yin-Yang symbol of Eastern philosophy.

What we are looking at is a whole-sky map showing the motion of our local group of galaxies (including the Milky Way) against the cosmic background radiation, the afterglow of the big bang. The computer-generated colors represent the so-called Doppler shift -- the same physical effect employed in a police radar gun to measure relative speed. We are moving toward the "blue" part of the sky, and away from the "red" part, and our motion shows up as a compression or stretching of the measured radiation.

So is the universe congruent with the diagramatic insight of the wise old East? No. The similarity of the sky map with the classic Yin-Yang symbol is an artifact of this particular map projection. Any other projection would have blue and red regions, but their arrangement would not be so evocative.

And therein lies a tale.

Most prescientific explanations of the world are based on the kind of dualities represented by Yin and Yang. Male and female. Day and night. Heat and cold. Active and passive. The Aristoltelian physics of the premodern West employed polarities: heat and cold, dry and wet, and so on. Most prescientific religions embrace some sort of Manichean duality: God/Satan, order/chaos, good/evil, etc.

The opposed qualities of a Yin-Yang scheme are generally mixed, but polarities are key to the thinking of most prescientific people. Many of our contemporaries still view the world in stark polarities: The Shining City on a Hill vs. The Axis of Evil, for example, or the Saved and the Damned.

Modern science takes exception to this rule. Hot and cold, for example, are not two species in opposition, but different kinetic energies of particles along a continuous scale. The same can be said for the map above, which shows a continuous blending of colors (relative velocities).

For those of us imbued with the scientific spirit, the world is not black and white, but brushed with shades of gray. We are suspicious of dualities (natural/supernatural, body/soul, matter/spirit, us/them). On the whole, we are less given to dogmas and True Belief. The success -- so far -- of the scientific way of knowing suggests that the universe more likely anticipates Newton's and Leibnitz's calculus (a language of continuities) than it does the Yin and Yang of Chinese philosophers.