文档介绍：Why Does Time Only Move Forward? (page 48)
Therapies
That Beat
BREAST
CANCER
page 58
June 2008 $
Ethics and Economics of
Climate
Change
Balancing Current Costs
against Future Well-Being
Meteor Mystery
What Really Happened
100 Years Ago in Siberia
Trust Hormone
Neurobiology Reveals
What Makes Us Connect
Photo Frauds
Spot Digital Fakes
© 2008 SCIENTIFIC AMERICAN, INC.
features ■
Scientific American June 2008 n Volume 298 Number 6
POLICY
The Ethics of Climate Change
96 By John Broome
When economists analyze how much to spend
on global warming, they must weigh the value
of our current prosperity against that of the
diminished well-being of our grandchildren.
Image by Jean-Francois Podevin
COSMOLOGY
48 The Cosmic Origins 48
of Time’s Arrow
By Sean M. Carroll
Maybe time’s seemingly unvarying flow forward
is a short-term fluke in a universe where the distant
future and distant past look the same.
MEDICINE 58
58 Gaining Ground on
Breast Cancer
By Francisco J. Esteva and
Gabriel N. Hortobagyi
The newest targeted therapies help doctors to tailor
effective treatments to individual patients.
INFORMATION TECHNOLOGY 72
66 Digital Image Forensics 66
By Hany Farid
Modern software makes image tampering easier
but also enables new methods of detection.
EVOLUTIONARY BIOLOGY
72 What Is a Species? On The Cover
By Carl Zimmer Ethics and economics inform every decision about
Biologists still struggle with that fundamental whether to prevent global warming or let future gen-
but scientifically pivotal question. erations deal with it. Image by Jean-Francois Podevin.
© 2008 SCIENTIFIC AMERICAN, INC. SCIENTIFIC AMERICAN 5
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ASTRONOMY
80 The Tunguska Mystery
By Luca Gasperini, Enrico Bonatti and Giuseppe Longo
Finding a piece of the elusive cosmic body that devastated
a Siberian forest a century ago could help save the earth in
the c