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were just about the size (relative to the pan) and the shape of the cyclonic storms of the temperate
regions, even a twisting ribbon of fast-flowing water that unmistakably corresponded to the only
recently discovered jet stream. Fultz's dishpan, without a doubt, showed the essential elements of actual
weather.
What did one learn from the dishpan? It was not telling an entirely true story: the earth is not flat, air is
not water, the real world has oceans and mountain ranges and for that matter two hemispheres. The
unrealism of the model world was dictated by what atmospheric theorists were able to or could be
bothered to build in effect, by the limitations of their modeling technique. Nonetheless, the model did
convey a powerful insight into why the weather system behaves the way it does.
The important point is that any kind of model of a complex system a physical model, a computer
simulation, or a pencil-and-paper mathematical representation amounts to pretty much the same kind of
procedure. You make a set of clearly untrue simplifications to get the system down to something you
can handle; those simplifications are dictated partly by guesses about what is important, partly by the
modeling techniques available. And the end result, if the model is a good one, is an improved insight
into why the vastly more complex real system behaves the way it does.
But there are also costs. The strategic omissions involved in building a model almost always involve
throwing away some real information. Oceans and mountain ranges do affect the earth's weather, even
if they are hard to put in a dishpan. And yet once you have a model, it is essentially impossible to avoid
seeing the world in terms of that model which means focusing on the forces and effects
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