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THE SPARK OF LIFE • SHRIMP FARMING • THE CHEMISTRY OF MISERY LIQUID COMPUTERS Magnetic Fields Build a Computer from Drops of Fluid JUNE 1998 $4.95 Colliding galaxies fuel the blaze of a quasar Copyright 1998 Scientific American, Inc. June 1998 FROM THE EDITORS 6 Vo l u m e 2 7 8 A New Look at Quasars Numb e r 6 52 Michael Disney LETTERS TO THE EDITORS 8 50, 100 AND 150 YEARS AGO 9 NEWS AND ANALYSIS Potato blight (page 20) IN FOCUS Cultured stem cells might repair damaged brains, blood and more. Quasars are the most luminous objects in the universe, not much larger than our solar system but brighter than a trillion suns. Their mere existence challenged physics for years. Black holes swallowing whole stars inside colliding galaxies seem to power most quasars, but many mysteries remain. Newly installed instruments on the Hubble Space Telescope may reveal the answers at last. 11 SCIENCE AND THE CITIZEN Wolves in limbo.... Greenhouse methane is disappearing—why?... Tamoxifen and breast cancer.... Crabby mates. 13 PROFILE Epidemiologist Joel Schwartz warns of dangerous particles in the air. 30 TECHNOLOGY AND BUSINESS A fast Y2K bug fix.... Confidentiality without encryption.... Earthcam.com. 42 The Neurobiology of Depression Charles B. Nemeroff Whatever its cause, depression ultimately arises from biochemical shifts in the brain that provoke aching sadness, loss of pleasure, guilt, thoughts of death and other symptoms. The search for those neurological underpinnings is intensifying and raising the prospects of better treatment for one of the most common mental health disorders. 34 CYBER VIEW A new language for the Web. 40 2 Copyright 1998 Scientific American, Inc. 58 Shrimp