No Smilies on Snow Crystals

Posted on October 1, 2006 in Fact-Dropping Psycho-bunk Reading

This little vignette very nicely describes the nature of the Heisenberg Uncertainty Principle. From Robert L. Park’s Voodoo Science, a fine compedium of “sane” delusions:

Suppose, for example, that you want to clock the speed of an automobile. You could set up two pylons on the side of the road a known distance apart. An observer at the first pylon will press a button that starts a clock running when the car passes; when the car passes pylon number two, a second observer will press a button stopping the clock. The accuracy of the measurement depends on such things as how precisely the pylons are positioned and how quickly observers respond. The effect of these uncertainties can be minimized by simply using a larger separation between the pylons.

But now suppose you also ask where the car was when its speed was measured. The answer is “between the pylons”. The more accurately you determine the automobile’s speed by moving the pylons apart, the less precise you can be about its position. If you want to be more precise about the position of the car, you must move the pylons closer together, making the speed measurement more uncertain.

This trade-off is the classic dilemna of the measurement. Position and motion are said to be “complementary” variables….

What Heisenberg postulated was that there is a fundamental limit on how accurately you can simultaneously know both the position and motion of a particle. That limit, called the Planck constant, is a measure of the graininess of nature.

So it has nothing to do with funny faces on ice crystals appearing when you sing happy songs to them. Tell that to your resident New Age Bipolar-Depression Denier.