When he first proposed his heretical ideas early in the century, many geologists treated this German meteorologist as if he were a member of the Flat Earth Society. Convinced that the continents were anchored firmly in place, geologists dismissed as preposterous his theory that the earth's major land masses had once been huddled together in a single supercontinent, which he called Pangaea (Greek for "whole earth"), then began slowly drifting apart. Wegener had plenty of evidence, ranging from the jigsaw-like fit of the continents to the discovery of matching fossils on opposite sides of oceans, but he couldn't give a satisfactory explanation of what caused the global breakup.

For years continental drift was held up to derision--until scientists in the 1960s found a plausible mechanism in the earth's internal motions under the ocean floor. Suddenly, Wegener's disreputable ideas became reputable. Renamed plate tectonics, they gave geology a single unifying theory, explaining everything from earthquakes and volcanoes to the formation of mountain ranges and ocean basins. Sadly, Wegener, who perished on the Greenland icecap in 1930 at age 50, didn't live to see it.

For this Swiss-born psychiatrist, death was medicine's dirty secret. American doctors, she learned early on, rarely discussed the subject with the terminally ill, and the idea of administering pain killers or letting patients die at home or with their families around them was almost unheard of. Determined to overthrow this taboo, she interviewed hundreds of dying patients, sometimes in the presence of startled medical students. Her best-selling 1969 book, On Death and Dying, detailed her now popularly accepted conclusions. The dying, she wrote, go through five psychological stages: denial ("No, it won't happen"), anger ("Why me?"), bargaining ("God, just a little longer?"), depression and finally acceptance. Lecturing and writing at a furious pace, she went on to campaign for hospice care in the U.S., gave countless "life, death and transition" workshops around the world and tried to help babies with AIDS. Her current infatuation with mysticism and the afterlife distresses some in the psychiatric community. Even so, though hobbled by several strokes, Kubler-Ross, at 72, remains a powerful voice for the terminally ill and their loved ones.

A minor bureaucrat in Madras, India, Ramanujan tried twice to interest professional mathematicians in his spare-time dabbling with numbers. All too familiar with numerological crackpots, they were profoundly uninterested. But Ramanujan persisted, and his third shot was the lucky one. The eminent Cambridge don G.H. Hardy took the time to decipher the young man's idiosyncratic scrawls and realized he was corresponding with a genius. Unlike trained mathematicians, Ramanujan knew his speculations about numbers were true, so he didn't bother to prove them. That wouldn't do. Hardy brought him to England in 1914, and the pair spent four years working to prove the self-taught mathematician's intuitively brilliant conjectures. Alas, Ramanujan hated England and died of tuberculosis in 1920 at age 32--with so much of his opus left unproved that mathematicians today are still working on it.

The idea that a comet or asteroid might be bearing down on Earth--as in Deep Impact and Armageddon--can be traced to this crusading geologist. Probing Arizona's Meteor Crater in 1956, Shoemaker found a form of quartz that is created only by tremendous impacts. Finding the same telltale mineral in other craters, he concluded that they had been formed not by volcanoes, as most scientists thought, but by large objects hitting Earth. It was only a matter of time, he said, before Earth would be struck again. So he launched the first organized search for big incoming objects, recruiting astronomers to join the hunt and cajoling Congress into funding it. Even the public began to take notice when, in 1994, Comet Shoemaker-Levy 9 (which he co-discovered) crashed into Jupiter in an awesome demonstration of what could happen here.

--By Frederic Golden, Leon Jaroff, Jeffrey Kluger and Michael D. Lemonick