E-Book Content
Winners of 2007 BioScapes Photo Contest (page 78) Inventor of
MULTIPLE UNIVERSES page 98
December 2007
ARE WE LIVING WITH
ALIEN CELLS? Did life on Earth arise more than once? Strange forms may still survive
Semantic Web How the Internet Is Getting Smarter
Carbon Markets Making Them Work to Save the Climate
Gamma Rays New Space Telescope Could Change Physics
COPYRIGHT 2007 SCIENTIFIC AMERICAN, INC.
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FEATURES ■ SCIENTIFIC AMERICAN December 2007 ■ Volume 297 Number 6
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BIOL O GY
Are Aliens among Us? By Paul Davies All life on Earth is generally understood to have descended from a common ancestor. But if cells evolved independently more than once, some microbes radically different from all known organisms might still survive in extreme environments of our planet. The search is on for evidence of these strangers.
Image by Jean-Francois Podevin
AS TRONOM Y
54
54 Window on the Extreme Universe
70
By William B. Atwood, Peter F. Michelson and Steven Ritz The GLAST satellite is about to open up an unexplored region of the electromagnetic spectrum, where dark matter and other mysteries might be seen.
EN V IRONMENT
70 Making Carbon Markets Work
84
By David G. Victor and Danny Cullenward Limiting climate change without damaging the world economy depends on stronger and smarter market signals to regulate carbon dioxide.
GA LL ERY
78 Radiant Information By Emily Harrison State-of-the-art light microscopy from the Olympus BioScapes competition illuminates life exquisitely.
G ENE T IC S
84 Diet Advice from DNA? By Laura Hercher Are personalized diets based on genetic tests cutting-edge science or high-tech horoscopes?
w w w. S c i A m . c o m
78 ON THE COVER One can only guess how different cells that evolved independently of conventional life might look or act. Artist Adam Questell has imagined an alien cell that carries its genetic material in twin nuclei.
© 20 07 SCIENTIFIC AMERIC AN, INC.
SCIENTIFIC AMERICAN
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MORE FEATURES ■ INF ORM ATION T ECHNOL O GY
98
90 The Semantic Web in Action By Lee Feigenbaum, Ivan Herman, Tonya Hongsermeier, Eric Neumann and Susie Stephens Networks that handle data more intelligently are already here.
HIS T ORY OF PH YSIC S
98 The Many Worlds of Hugh Everett By Peter Byrne Whatever became of the creator of the now celebrated quantum theory of multiple universes?
CRO S SWORD
106 In Boxes
Cash for Carbon Dioxide
By Patrick Merrell Challenge your knowledge of science and the past year’s issues of this magazine.
GO TO
.COM
An expanded version of the article on carbon markets by David G. Victor and Danny Cullenward can be found at
www.SciAm.com/ontheweb
8 In Focus
How Artists Portray Exoplanets They’ve Never Seen
Sunny Outlook: Can Sunshine Provide All U.S. Electricity? Large amounts of solar-thermal electric supply may become a reality if steam storage technology works — and new transmission infrastructure is built.
Planets outside our solar system are too faint to be distinguished from the stars they orbit, yet popular news accounts overflow with bold, almost photorealistic images of distant worlds. To find out how it is done, visit us at www.SciAm.com/ontheweb
8 News Don’t Forget: Drink a Beer— or Two — Daily! Study in rats suggests long-term, moderate consumption of alcohol improves recall of both visual and emotional stimuli.
8 Podcast 8 Blog God Is in Your Mind Not to put too fine a point on it, but so is everything else.
Everything described here, plus Web-exclusi