This month the king of Sweden will honor these 10 people of science for their achievements. Three of them—Luc Montagnier, Yoichiro Nambu and Paul Krugman—have written for Scientific American.

Physiology or Medicine: Harald zur Hausen of the German Cancer Research Center in Heidelberg, for his discovery that the human papillomavirus causes cervical cancer, and Françoise Barré-Sinoussi of the Pasteur Institute in Paris and Luc Montagnier of the World Foundation for AIDS Research and Prevention in Paris, for their discovery of the human immunodeficiency virus (HIV). In making its choice, the Nobel committee snubbed Robert C. Gallo of the University of Maryland, who proved that HIV causes AIDS.

Physics: Yoichiro Nambu of the University of Chicago, for the discovery of the mechanism of spontaneous broken symmetry, which helps to explain the masses of subatomic particles and the forces acting on them, and Makoto Kobayashi of the High Energy Accelerator Research Organization (KEK) in Tsukuba, Japan, and Toshihide Maskawa of Kyoto University, for the discovery of the origin of broken symmetry, which predicts the existence of at least three families of quarks.

Chemistry: Osamu Shimomura of the Marine Biological Laboratory in Woods Hole, Mass., Martin Chalfie of Columbia University and Roger Y. Tsien of the University of California, San Diego, for their discovery of the green fluorescent protein and its development as a visual tag in bioscience.

Economics: Paul Krugman of Princeton University, for his theories on international trade patterns and geography, which explain why cities are growing and why similar industries clump together.