If he increased the turbulence of a fluid sufficiently by heating it, the turbulence became chaotic, and never settled down to a regular pattern. Later I understand it was found that any three non-linear equations produced the same consequences; in other words you can do without non-linear equations, which in any event are insoluble, and any three imponderables will produce a system that has sensitive dependence on initial conditions. For example: it may be impossible for a mathematician to work out exactly the movement of a pendulum, subject to air-resistance; but we all know that the pendulum will come to rest eventually. It may be impossible to know when an individual radio-active atom will disintegrate, but we all know that a given quantity of radio-active material has a definite half-life. But in the example of the pendulum there is only one imponderable, namely air-resistance; and in the example of radio-active material there are only two imponderables, namely temperature and quantity of material. But increase your imponderables to three, and you have the potential for chaos, or a sensitive dependence on initial conditions With weather systems you have at least three: temperature, pressure and wind-speed.
Similarly with human life as we experience it, the crucial decisions made in early manhood, are always made with far too little experience to enable a balanced judgement to be made. Subsidiary decisions will usually be made on the basis of convention or upbringing; and so it is that fairly trivial factors may well have a deciding influence on the all-important decision as to how to spend one’s life. In other words, one’s ordinary life has a similar dependence on initial conditions, that one finds in weather forecasting, or in the laboratory. Although their influence cannot be reduced to equations, human life is most certainly beset by at least three imponderables, which go to the very heart of the human psyche: namely religion, science and war. And the result is that life is always an adventure, apart from the tramlines of convention; and it is impossible to predict its outcome. The universal Rule is that where you have one or two imponderables, you have predictability. Where you have three imponderables, you have none. And this Rule applies to the whole of creation; to the realm hitherto regarded as the prerogative of science, and to conventional life as well, as we all live it in practice. How refreshing I find it that the dreary argument of causality and determinism is so neatly abolished, by science itself.
If Chaos Theory applies to an individual life, why not ask if it applies to the human community as well? Here we have the same three imponderables, religion, science, and war. And probably many more as well. Why not ask if here too, we do not have the same unpredictability, within the limits of the Divine Providence?