News
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PaleontologyRain Forest Primeval? Colorado fossils show unexpected diversity
The size, shape, and riotous variety of fossil leaves unearthed at a site in central Colorado suggest that the region may have been covered with one of the world's first tropical rain forests just 1.4 million years after the demise of the dinosaurs.
By Sid Perkins -
PhysicsU.S. time now flows from atom fountain
The United States has switched to the atomic fountain clock, which sets itself according to the resonant frequency of rising and falling balls of cold cesium.
By Peter Weiss -
PhysicsMagnets trap neutrons for a lifetime
A new device that uses magnets to trap neutrons may enable physicists to measure more precisely how quickly free neutrons decay, a time period with implications for understanding both the weak force and the early universe.