David Peat

118 From Certainty to UncertaintyNewtonian clockwork. Laplace imagined himself standing beside God.This meant that he was no longer a part of the universe. Instead ofbeing a participator within a living cosmos, he stood outside and observedits inner working in a dispassionate manner. This is also an imageof Newtonian science itself. While it was possible to describe themotions of the heavens using mathematics, this “universe” turned outto be less a home in which to live than an object standing before us tobe understood, described, predicted, and controlled. The values andqualities, the tastes and smells of the universe become less important,or essentially irrelevant, when compared to its mathematical descriptionin terms of mass, position, and speed.Newtonian clockwork also had its applications here on earth. Asthe moon orbits around the earth it pulls on the oceans and so producesthe alternation of high and low tides. Such events, the time andheight of tides, are entirely predictable, except for the minor perturbationscaused by irregularities in coastline, the meeting of tidal streamsin estuaries, and so on. But knowing the exact time and height of a tideis important; it even proved to be a key element in the plot of JohnBuchan’s famous spy novel The Thirty-nine Steps. 1Newtonian clockwork appeared, at first sight, to be a perfectmechanism. There was however, a tiny grain of sand hidden deepwithin its wheels and cogs. When it comes to the moon’s motionaround the earth, or the earth’s orbit around the sun, Newton’s lawscan be solved exactly and the appropriate numbers calculated to anyaccuracy desired. But what about the small additional pull of the moonon the earth as the earth orbits the sun? And what is the precise effect1As a boy I remember seeing a tide predictor at the Bidston Hill Observatorynear Liverpool. This great machine, the mechanical forerunner of a computer, occupiedan entire room that was carefully controlled for temperature and humidity.While the moon is the driving force of the tides, other small perturbing effects, suchas the shape of an estuary line or the meeting of opposing currents of water, can alterthe exact height of a tide. These factors were represented in the tide predictor by aseries of cogs and wheels. Through their rotations it was possible to compute tidesfor days and months to come. Again, certainty and predictability had become associatedwith regularity, clockwork, and the ability to strip away inessentials in order todescribe apparently complex phenomena in terms of simple mechanical models.