O S M O L O G Y34 The Universe’s Invisible Hand B Y CHRISTOPHER J . CONSELICEDark energy does more than hurry along the expansion of the universe. It also has a stranglehold on the shape and spacing of galaxies.P A L E O N T O L O G Y42 Tracking an Ancient Killer B Y RAYMOND R . ROGERS & DAVID W. KRAUSE The case was cold—the bones in the mass grave were 70 million years old. But critical clues pointed to the killer’s identity.A T M O S P H E R I C S C I E N C E52 Methane, Plants and Climate Change B Y FRANK KEPPLER & THOMAS RÖCKMANNThe surprising discovery that living plants produce a potent greenhouse gas poses new questions for managing global warming.I N F O R M A T I O N T E C H N O L O G Y58 |Making Silicon Lase B Y BAHR M JALALIScientists have at last persuaded silicon to emit laser beams. In a few years, computers and other devices will handle light as well as electrons.I N N O V A T I O N S66 Spice Healer B Y GARY STIXAn ingredient in curry shows promise for treating Alzheimer’s, cancer and other diseases.C O N S U M E R E L E C T R O N I C S70 Digital TV at Last? B Y MICHAEL ANTONOFFAnalog TV broadcasting is set to end in two years, but its legacy could make the digital transition anything but smooth.N A N O T E C H N O L O G Y76 Molecular Lego B Y CHRISTIANE SCHAFMEISTERSmall molecular building blocks that snap together rigidly enable chemists to design and manufacture nanometer-scale structures in virtually any shape.