After Luis Alvarez informed a physicist colleague that the absence of Pu 244 in the boundary clay negated the supernova theory, he received the reply: "Dear Luie: You are right and we were wrong. Congratulations." To Luis, this response "exemplified science at its best, a physicist reacting instantly to evidence that destroys a theory in which he previously believed."2 He could never understand why the paleontologists did not react the same way.
He could have taken a lesson from the theory of continental drift, which took decades to find acceptance among geologists. Early in the nineteenth century, mapmakers and others had noted that the coastlines of South America and Africa fit together like two pieces of a jigsaw puzzle. In '9'8, German meteorologist Alfred Wegener extrapolated from this apparent coincidence to develop a full-fledged theory, backed by a volume of geological evidence, that held that continents are not fixed in place on the surface of the globe, but drift about, colliding, welding together, and sometimes separating along a new fracture. Each single piece of evidence that Wegener presented, however, was circumstantial and therefore could be ascribed to coincidence. Furthermore, he could present no plausible mechanism to explain why the continents should have moved. His idea failed to catch on and came to be regarded, at least by American geologists, as having been falsified to the point of being laughable. The most widely used American textbook on earth history during the 1950s did not contain the words "continental drift." A few years later, but before the plate tectonic revolution, the great Canadian geologist J. Tuzo Wilson lectured on continental drift at MIT. The attitude of the faculty (and therefore of most students) was to regard Wilson, a man of impressive dignity, rather like an eccentric uncle—still a member of the family, but not to be taken seriously. Within a few years, however, Wilson was not only vindicated, but rightfully hailed as a hero of the revolution.
Ursula Marvin, professor of astronomy at Harvard, recounted a similar episode when in 1964 she proposed that geologist Robert Dietz (like Wilson, a courageous visionary) be invited to Harvard to speak about his remarkable theory that meteorite impact created the enormous body of igneous (once-molten) rock in Sudbury, Ontario.3 It is one of the world's greatest, and most studied, sources of nickel ore. Among geologists, it was famous as well as mystifying, for, as with dinosaur extinction, none of the many theories that had been proposed for its origin had received general acceptance. Nevertheless, the Harvard graduate students who had worked at Sudbury "staged a boycott . . . intuitively rejecting] impact as unworthy of their magnificent structure and, indeed, a deus ex machina appropriate only to science fantasy"4
In resisting the Alvarez theory, geologists were merely behaving as people have done throughout history. One who has invested time and effort—possibly an entire career—based on the notion that the continents are fixed, or that geologic change is slow and unaffected by cosmic events, when confronted with an entirely different idea, has to cast off years of work and assumptions and possibly even renounce previously published conclusions. Max Planck, the father of quantum mechanics and a Nobelist, summed it up: "An important scientific innovation rarely makes its way by gradually winning over and converting its opponents. . . . What does happen is that its opponents gradually die out and that the growing generation is familiar with the idea from the beginning."5
Another reason that people resist new theories is because the authorities in a field, who by definition have achieved their eminence working within the prevailing paradigm, often say the new theory is impossible, or at least, highly unlikely. After all, if the new theory is correct, then one of theirs may need replacing. In the nineteenth century the great physicist Lord Kelvin, unaware that radioactivity existed to provide a source of heat, pronounced that the earth must have been hot initially and been cooling ever since. Work ing backward, he calculated that the earth could be no more than 20 million years old. His eminence caused this erroneously short time scale to be accepted, delaying for decades recognition that the true extent of geologic time is on the order of 4.5 billion years. (Kelvin also denounced X rays as a hoax.) G. K. Gilbert, chief geologist of the U.S. Geological Survey and the leading geologist of his day, incorrectly concluded that Meteor Crater, Arizona, was not formed by meteorite impact, leading to a dogma that was decades in the unmaking. When the deans of American geology and the faculties of research universities scoffed at the theory of continental drift, budding geologists of the 1950s and early 1960s chose other topics. The history of science is full of the undue influence of magisters— authoritative masters—whose pronouncements receive an uncritical acceptance.
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