Mathematicians find that slicing a pie into fair pieces is harder than divvying up a sheet cake. The problem is that pie cuts are radial, not parallel.

Medieval Islamic artisans developed a process for creating elaborate, nonrepeating patterns now associated with Penrose tiles.

Medieval Islamic artisans developed a process for creating elaborate, nonrepeating patterns now associated with Penrose tiles.

Scientific advice on the subject of how much salmon it is safe to eat has been confusing.

The first gliding mammal winged through forests at least 70 million years earlier than scientists had previously presumed, a new fossil shows. The specimen dates from about 150 million years ago, during the time when birds were developing flight."This changes our view about the early evolution of mammals," says Jin Meng of the American Museum of Natural History in New York City. Scientists had proposed that mammals from that period "lived in the shadow of dinosaurs and were relatively primitive," Meng says. He and his colleagues report the finding in the Dec. 14 Nature.Farmers found the new fo... (p. 417)

A new method for cutting cake yields slices that make everyone equally happy. (p. 390)

Antique whale oil shows that some mysterious compounds that resemble DDT and PCBs are naturally produced. (p. 278)

The first high-resolution images sent by the Mars Reconnaissance Orbiter support the notion that water once flowed across much of the Red Planet. (p. 260)