A S T R O N O M Y
42 Hubble’s Top 10
BY MARIO L IVIO
As they wait for the space telescope to be serviced one last time, astronomers
refl ect on its greatest discoveries over the past 16 years.
B I O M E D I C I N E
52 Stem Cells: The Real Culprits in Cancer?
BY MICHAEL F. CL ARKE AND MICHAEL W. BECKER
The potential for stem cells to turn malignant is known to
be at the root of a handful of cancers and might be
the cause of many more.
P H Y S I C S A N D O P T I C S
60 The Quest for the Superlens
BY JOHN B. PENDRY AND DAVID R . SMITH
Built from “metamaterials” with bizarre optical properties, a superlens could overcome resolution limits
imposed by the wavelength of the illuminating light.
L I F E S C I E N C E
68 What Birds See
BY T IMOTHY H. GOLDSMITH
Evolution endowed birds with a system of color vision surpassing that of all mammals, including humans.
E N E R G Y
76 A Power Grid for the Hydrogen Economy
BY PAUL M. GRANT, CHAUNCE Y S TARR AND THOMA S J . OVERBYE
Cryogenic, superconducting conduits could be connected into a “supergrid” that would simultaneously
deliver electrical power and hydrogen fuel.
F O R E N S I C S
84 CSI: The Reality
BY MA X M. HOUCK
Television’s forensics dramas have led to increased interest in the science of criminal investigations but
may make viewers unreasonable jurors.
I N F O RM A T I O N T E C H N O L O G Y
90 A Farewell to Keywords
BY GARY S TIX
Snap a photo on the go with a mobile phone, and a system for searching the Web will pull in information
about what you see in the picture.
july 2006
SCIENTIFIC AMERICAN Volume 295 Number 1 features
52 Source of
malignancy?
www.sciam.com SCIENTIFIC AMERICAN 7
COPYRIGHT 2006 SCIENTIFIC AMERICAN, INC.

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