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Time-Reversed Acoustics

Arrays of transducers can re-create a sound and send it back to its source as if time had been reversed. The process can be used to destroy kidney >stones, detect defects in materials and communicate with submarines

By Mathias Fink

The Grameen Bank

A small experiment begun in Bangladesh has turned into a major new concept in eradicating poverty

By Muhammad Yunus

The Fate of Life in the Universe

Billions of years ago the universe was too hot for life to exist. Countless eons hence, it will become so cold and empty that life, no matter how ingenious, will perish

By Lawrence M. Krauss and Glenn D. Starkman

Slave-Making Queens

Life in certain corners of the ant world is fraught >with invasion, murder and hostage-taking. The battle royal is a form of social parasitism

By Howard Topoff

Flammable Ice

Methane-laced ice crystals in the seafloor store more energy than all the world's fossil fuel reserves combined. But these methane hydrate deposits are fragile, and the gas that escapes from them may exacerbate global warming

By Erwin Suess, Gerhard Bohrmann, Jens Greinert and Erwin Lausch

Floating in Space

Balloons offer scientists a low-cost, quick-response way to study the upper reaches of Earth's atmosphere and those of other planets

By I. Steve Smith Jr. and James A. Cutts

A Zeppelin for the 21st Century

By developing new aerodynamic computer models and using modern materials, the company that originated zeppelins has returned them to the skies over Europe

By Klaus G. Hagenlocher

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