The Fall of the Maya: 'They Did it to Themselves'

For 1200 years, the Maya dominated Central America. At their peak around 900 A.D., Maya cities teemed with more than 2,000 people per square mile -- comparable to modern Los Angeles County. Even in rural areas the Maya numbered ...

Astronomers' simulations support dark matter theory

Computer simulations by astronomers support the idea that dark matter—matter that no one has yet directly detected but which many physicists think must be there to explain several aspects of the observable universe—exists, ...

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