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FEATURES ■ www.SciAm.com SCIENTIFIC AMERICAN 5 SCIENTIFI C AMERICAN December 2007 ■ Volume 297 Number 6 BIOLOGY Are Aliens among Us? By Paul Davies All li fe on Earth is generally understood to have descended from a common a ncestor. But if cells e volved 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. A S T R O N O MY 54 Window on the Extreme Universe By William B. Atwood, Peter F . Michelson and Steven Ritz The GLAS T satellite is about to open up an unexplored region of the electromagnetic spectrum, where dark matter and other mysteries might be seen. ENVIRONMENT 70 Making Carbon Markets Work By David G. Victor and Dann y Cullenward Limiting climate change without damaging the world economy depends on stronger and smarter market signals to regulate ca rbon dioxide. GALLERY 78 Radiant Information By Emily Harrison State-of-the-art light microscopy from the Olympus BioScapes competition illumi nates life exquisitely. GENETICS 84 Diet Advice from DNA? By Laura Hercher Are personalized diets based on genetic tests cutting-edge science or high-tech horoscopes? 6 2 84 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. ON THE COVER 54 78 70 Image by Jean-Francois Podevin © 2007 SCIENTIFIC AMERICAN, INC.
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FEATURES■
www.Sc iAm.com SCIENTIF IC AMERICAN 5
SCIENTIFIC AMERICAN December 2007■ Volume 297 Number 6
BIOLOGY
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.
ASTRONOMY
54 Window onthe Extreme Universe
By William B. Atwood, Peter F. Michelsonand Steven Ritz
The GLAST satellite is about to open up an unexploredregion of the electromagnetic spectrum, where dark
matter and other mysteries might be seen.
ENVIRONMENT
70 Making Carbon Markets Work 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.
GALLERY78 Radiant Information
By Emily HarrisonState-of-the-art light microscopy from the Olympus
BioScapes competition illuminates life exquisitely.
GENETICS
84 Diet Advice from DNA? By Laura Hercher Are personalized diets based on genetic tests
cutting-edge science or high-tech horoscopes?
62
84
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.
ON THE COVER
54
78
70
Image by Jean-Francois Podevin
© 2007 SCIENTIFIC AMERICAN, INC.
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8 SCIENTIF IC AMERICAN December 2007
MORE FEATURES ■
Scientific American (ISSN 0036-8733), published monthly by Scientific American, Inc. , 415 Madison Avenue, New York, N.Y. 10017-1111. Copyright © 2007 by Scientific
American, Inc . All rights reserved. No part of this issue may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying
and recording for public or private use, or by any information storage or retrieval system, without the prior written permission of the publisher. Periodicals postage paid at
New York, N.Y., and at additional mailing offices. Canada Post International Publications Mail (Canadian Distribution) Sales Agreement No. 40012504. Canadian BN
No. 127387652RT; QST No. Q1015332537. Publication Mail Agreement #40012504. Return undeliverable mail to Scientific American , P.O. Box 819, Stn Main,
Markham, ON L3P 8A2. Subscription rates: one year $34.97, Canada $49 USD, International $55 USD. Postmaster: Send address changes to Scientific American, Box 3187,
Harlan, Iowa 51537. Reprints available: write Reprint Department, Scientific American, Inc., 415 Madison Avenue, New York, N.Y. 10017-1111; (212) 451-8877;
fax: (212) 355-0408. Subscription inquiries: U.S. and Canada (800) 333-1199; other (515) 248-7684. Send e-mail to [email protected] Printed in U.S.A.
INFORMATION TECHNOLOGY
90 The Semantic Web in Action By Lee Feigenbaum, Ivan Herman, Tonya Hongsermeier, Eric Neumann and Susie StephensNetworks that handle data more intelligently are already here.
HISTORY OF PHYSICS
98 The Many Worlds of Hugh Everett By Peter ByrneWhatever became of the creator of the now celebrated quantum
theory of multiple universes?
CROSSWORD
106 In Boxes By Patrick MerrellChallenge your knowledge of science and
the past year’s issues of this magazine.
GO TO .COM
98
Cash for Carbon DioxideAn 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 FocusSunny Outlook: Can SunshineProvide All U.S. Electricity?Large amounts of solar-thermal electric sup-ply may become a reality if steam storage technologyworks—and new transmission infrastructure is built.
8NewsDon’t Forget: Drink a Beer—or Two—Daily!Study in rats suggests long-term, moderateconsumption of alcohol improves recall of bothvisual and emotional stimuli.
8 PodcastPlant Passion Truly HotMale cycad plants use heat to attrac t and repel thrips,whose comings and goings fertilize female cycads.
8 BlogGod Is in Your MindNot to put too fine a point on it, but so is everything else.
8 Strange but TrueLess Sleep Means More DreamsMissing sleep tonight may just boost your dreamstomorrow night.
How Artists Portray Exoplanets They’ve Never SeenPlanets outside our solar systemare too faint to be distinguishedfrom the stars they orbit, yetpopular news accounts overflowwith bold, almost photorealisticimages of distant worlds.To find out how it is done, visit usat www.SciAm.com/ontheweb
WANT MORE? Everything described here, plusWeb-exclusive supplements to the articles in thisissue, can be found at www.SciAm.com/ontheweb
G R E G B A C O N S T S c I , N A S A
C O U R T E S Y O F T I M P
Y L E ( p l a n e t m o c k - u p s )
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DEPARTMENTS■
50 InsightsSasquatch is just a legend, right?
Maybe not, anthropologist
Jeffrey Meldrum argues.
108 Working KnowledgeAdaptive cruise control.
112 ReviewsBooks to give, books to get.
114 Ask the ExpertsHow do short-term memories
become long-term memories?
116 Fact or Fiction?Is chocolate poisonous
to dogs?
50
22
30
49
114
Negotiating Climate
Can the new Bali talks on controlling CO2 emissions do more thanKyoto did? Join the debate at www.SciAm.com/ontheweb
116
12 From the Editor
14 Letters
20 50, 100 & 150 Years Ago
22 Updates
24 NEWS SCAN■ AIDS: Can immunosuppressants fight off HIV?
■ Decline in hormonal response to pheromones?
■ Testing for drugs in municipal sewage.
■ Night-vision goggles light up the night.
■ Shock-wave engine pulses to save fuel.
■ More virulent space bacteria.
■ Evolution in a petri dish.
■ Data Points: A smaller ozone hole?
■ The 2007 Nobel Prizes.
OPINION 40 ■ SciAm Perspectives
Do more than talk about the climate.
42 ■ Sustainable Developments By Jeffrey D. SachsSmall steps to big climate progress.
46 ■ Forum By Rob DunnHuman changes to the environment
are accelerating evolution.
48 ■ Skeptic By Michael Shermer How science really works.
49 ■ Anti Gravity By Steve MirskyApples and squeaky cheese.
December 2007
S U S A N D U N C A N
© 2007 SCIENTIFIC AMERICAN, INC.
