It has been 25 years since my Berkeley colleagues discovered what killed the dinosaurs. What began as a highly controversial interpretation of an experimental measurement has now evolved into the standard explanation of the great extinctions that took place 65 million years ago. And the progress in those 25 years illustrates much about the reality of the scientific method. Two observations: science is not driven by curiosity, but by a sense of adventure; and the scientists role model is not Diogenes, but Sisyphus.
The key discovery was the existence of a thin clay layer near the boundary between rocks of the Cretaceous period (full of dinosaurs) and those of the Tertiary (the age of mammals). Walter Alvarez, a junior member of Berkeleys geology department, noticed that millimeter-sized animals called forams went extinct right at that boundary. He knew the dinosaurs went extinct at about the same time (their disappearance was not well dated), and he speculated that maybe they were killed together. His father Luis Alvarez suggested they measure iridium in the layer, so they solicited help from nuclear chemists Frank Asaro and Helen Michel. The level of iridium they discovered was so high that they were forced to conclude that a comet or asteroid rammed into the Earth, and changed the nature of life.
Was the Alvarez team driven by curiosity? Many say yes, of course they werebut I will convince you that scientists are rarely motivated by it. Curiosity is the impulse to learn something new, and truly curious people spend most of their time reading. In just a few books you can learn a thousand times as much as a top scientist could possibly discover in a lifetime of research.
No, scientists are driven by a sense of adventure, by the desire to be there first, by a hope that for a few days they may be the only people in the world to know some important new fact. Luis Alvarez had scientific heroes, but he also admired and emulated Captain James Cook, who explored the Pacific, and the archeologist Howard Carter, who discovered Tutankhamens golden tomb.
In an adventure, the explorer/scientist doesnt know where he is going, and most of his colleagues probably think he is wasting his time. That was the way I felt about Walter Alvarez 25 years ago, and I wasnt alone. A senior geologist tried to persuade the young assistant professor Alvarez to abandon his ridiculous project, lest it embarrass the department. The quixotic project (he thought) held no prospect for tenure. Christopher Columbus endured similar ridicule. Indeed, the toughest part of innovative research is keeping your own belief in your trek, at a time when people you respect are snickering.
Another danger of scientific exploration is attack by natives: the referees who reject your articles and give poor evaluations to your proposals. Twenty-five years ago I sensed paleontologists complaining, What right does a physicist have to land on our island? Unlike his hero Captain Cook, Alvarez survived these attacks, although to this day there are some aborigines lurking in the jungle hoping to get off a good shot. The Alvarez team survived the tribulations with courage and energy. Want a good image of the Luis Alvarez that I remember? Think of Indiana Jones.