The steady wind that attracted Orville and Wilbur Wright to the Outer Banks of North Carolina produces an uncommonly reliable surf. Hour after hour, with mesmerizing monotony, the big waves roll in from the deep ocean. Each liquid mountain swells ominously as it approaches the shore, crests majestically, and breaks with a thundering crash, giving birth to a new, flat wave called a bore, a rushing wall of water with a foaming vertical front. Racing toward the shore, the bore eventually spreads and disperses, hiding the white sand under a blanket of froth.
Three years ago the gulls on the beach witnessed the curious spectacle of an awkward little amphibious craft that was daring the waves by positioning itself right under the largest breakers, where it was drenched and thrown about in a most alarming way. The boat's crew of four men seemed to be heaving mysterious boxes overboard and somehow anchoring them in the pounding surf--but unlike others who come to that lonely beach, they were neither fishing nor trying out some dangerous new sport. They were, in fact, conducting an oceanographic experiment designed to map the water's speed and depth in the vicinity of a bore. Their data would later be used to construct a mathematical description of a bore, an essential ingredient in our knowledge of the complex flow patterns at the edge of the ocean. In this particular case their effort led to an additional, and unusual, scientific payoff: it contributed to a better understanding of the roiling of hot gases on the surface of pulsating stars. Furthermore, it would turn out that the shapes of both ocean waves and star waves are mirrored in the shape of the stream from a faucet splashing into a kitchen sink. Understanding that homely, familiar sight goes a long way toward explaining what happens on the beach and far off in the unreachable depths of the galaxy.
Of course, science doesn't really explain why things are the way they are. The most we can hope for, and we ought to be grateful for achieving so much, is to connect bits of nature's grand design to each other by discovering resemblances among them. "All science," observed Jacob Bronowski, the creator of the memorable television series The Ascent of Man, "is the search for unity in hidden likenesses." When Galileo Galilei discovered the formula for the distance an object falls in a given time, he established a likeness among an infinity of objects, from the bread crumb softly dropping on the carpet to the cascades of Niagara; when Isaac Newton found an unsuspected likeness between the way Earth pulls on an apple and the way it attracts the moon, he discovered the law of universal gravitation; and when James Clerk Maxwell noticed the similarity between electric and magnetic forces, he found the key to his theory of electromagnetism. William Blake expressed the same thought more poetically when he extolled our ability "to see a world in a grain of sand." Early in this century Niels Bohr managed to equal the vast compass of Blake's vision when he likened a hydrogen atom to the solar system, but scientific analogies don't need to be that spectacular to be instructive. To see the heaving of a star in the ocean surf, and both in the kitchen sink, is sufficient proof of the power of analogy. If Bronowski's characterization of science is right, analogy, the ancient device of explaining the unknown by pointing out its resemblance to the familiar, turns out to be one of the most useful instruments in the toolbox of science.
