agree. We do need to ask the Martians, or at least seek them out, so we
can be bloody certain that there is nobody already living there before we
start redecorating the place to be more like home.
On Earth this is a time of war and terror. But it’s been a good year in
the rest of the solar system. The real story of our time, in an evolutionary
sense, may not be who started or lost this or that sorry war. This is when
we take our first steps off Earth and gain the ability to seek out cosmic
companionship. Yet, any aliens watching our behavior at the moment
could not be blamed if they were to recommend against our being invited
to join the galactic league of planets. Just remember, as Doris Lessing’s
dad used to say to her (as described in the dedication in Shikasta, “If we blow ourselves up, there’s plenty more where we came from.”
David Grinspoon
Denver, Colorado
July 2004
Preface
Here’s how this book is supposed to start:
“My fellow humans, we stand here today at the edge of a new age of
cosmic discovery that will transform all of our lives. Recent break-
throughs have sparked a scientific revolution in the search for life in
outer space. Any day now, we may meet with success and find proof
that we are not alone in the universe.”
And, indeed, it’s true. Numerous recent findings have helped to ignite
a resurgence in scientific interest in the study of extraterrestrial life.
These include possible fossils found in a rock from Mars, the first dis-
coveries of worlds orbiting distant suns, evidence for the largest liquid-
water ocean in the solar system underneath the icy surface of Jupiter’s
moon Europa, and an astonishingly wide range of newly discovered
organisms living in extreme terrestrial environments previously believed
to be uninhabitable. Together, these announcements have encouraged
renewed hopes for finding alien life and helped to fuel a movement that
some have called “the astrobiology revolution.”
But, in researching this book, I have repeatedly been struck by the
great similarity between our current ideas about alien life and those that
were expressed decades and even centuries ago. Today, our researches
and ruminations are informed by much new information. Still, a book
summing up everything we know about alien life would contain only
one word: nothing. I’ve managed to add an additional 150,000 by fol-
lowing our quests for aliens through history, speculative science, philos-
ophy, and fantasy. After all, if Jerry Seinfeld can do a sitcom about noth-
ing, why can’t I write a book about something we know nothing about?
For me, extraterrestrial life has been a recurring theme from my days
as a teenage space-head to my more recent employment as a profes-
sional planetary scientist funded to study astrobiology. Along the way I
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Preface
picked up academic degrees in the two least practical things I can think
of: philosophy and planetary science. The topic of alien life allows me
to finally combine all of this “useless and pointless knowledge.”
The first popular-science book devoted to the question of extraterres-
trial life was written in 1686. In the preface to his Conversations on the
Plurality of Worlds, the French poet and philosopher Bernard le Bovier
de Fontenelle wrote, “I’ve tried to treat Philosophy in a very unphilo-
sophical manner; I’ve attempted to bring it to the point where it’s neither
too dry for men and women of the world nor too playful for scholars.”
In his day scientists were still philosophers, science was still “natural
philosophy,” and belief in a cosmos full of planets inhabited by intelli-
gent creatures was becoming widespread among European scholars.
Like Fontenelle, I’ve been unphilosophical in places. Many scientific
ideas and truths, to be expressed accurately, must be couched in endless
caveats and qualifications. When I write, a little imaginary scientific
colleague is always pouncing on my shoulder, telling me to clog the sci-
ence at every turn, whispering in my ear, “Provide more detail,” “Show
how we know that,” and “Don’t you dare step out on that limb.” I’ve
freighted with detail and fall from your hands.
I’ve organized the book into three parts: “History,” “Science,” and
“Belief.” In the first section I give a brief history of beliefs about ETs.
Our changing images of extraterrestrials over the eons have reflected our
evolving sense of ourselves and how we humans fit into the universe.
The history I tell is selective and largely intended as a setup for what fol-
lows, to allow us to examine some modern ideas about extraterrestrial
life in a historical context. This part is told in chronological order.
Several topics and events that I mention here, I discuss in more detail
later in the book. After laying down this rhythm track with the major
beats of history, we are free to wander in time without getting lost. The
rest of the book is nonchronological, and I sometimes jump back and
forth in time chasing the thread of an idea.
When I changed offices a year ago, sacrificing some floor space for a
view of the Rocky Mountain Front Range, the burly moving guy
wrestling my filing cabinet full of heavy scientific reprints onto a dolly
inquired, “Can I ask you a question? When I read in the paper that sci-
entists agree on this or that, I wonder who decides what leading scien-
tists all agree on, or what world scientific opinion is. How does that
really work? Is there a commission?” It was a great question. In the
Preface
xxii
“Science” section I present a snapshot of present scientific thought
about ET life. Part of what I’ve tried to do here is to hold up a mirror to
the scientific process, in an attempt to illuminate how we decide what is
true. My wife once compared me and my fellow planetary scientists to
kids on a playground. Everyone is excited about a certain game for a
while and all crowd around. Then somebody at the other end of the
playground says, “Hey, check this out!” and all run over and start play-
ing the new game. In these pages I try to portray the collective thought
process of the scientific community, as ideas ripple through, are tossed
around, put to the test, and are embraced or rejected. Sometimes they
are embraced without being put to the test.
This is not a comprehensive treatment, as I have no wish to write a
fifteen-volume Encyclopedia Galactica. Nor do I wish to be superficial, so I have been highly selective. I skim lightly over topics that have been well
covered in other recent books and dive more deeply into areas that I feel
have been neglected or mistreated elsewhere, or where I think I have
something new to say. More comprehensive treatments of many topics
can be found in the notes on sources and suggestions for further reading,
or my sporadically updated on-line chapter notes at funkyscience.net.
Copious additional illustrations for each
chapter in this book can also be
found at this site.
This book is highly opinionated and biased in numerous ways. In a
raw field like planetary science or astrobiology, any researcher worth
her grant money has opinions about contentious issues that are not
held by all of her colleagues. I do not shy away from expressing my
own nonconsensus views, but I will try to point out when I am doing so
and even endeavor to describe the opposing views and explain why
some researchers hold these erroneous opinions. �
Ï don’t claim to be
objective, unbiased, or correct about everything. This is a combination
of what you’d hear if you sat in on one of my undergraduate lectures
and what I’d tell you if we got talking over a beer afterward. Hopefully,
I’ll at least keep you entertained.
One of the themes of this work is the long, often uneasy relationship
between astronomy and biology, the two scientific fields that must get in
bed together if we want to make real progress in understanding the poten-
tial of this universe to create life in other places. After a century of flirta-
tion, they started going steady in 1960 with a tentative, insecure union
called exobiology. Then, after a thirty-five-year courtship, they finally
took the plunge in the late 1990s in a marriage called astrobiology.
xxiii
Preface
Some scientists have been studying the question of extraterrestrial life
for decades, but until recently it was not considered entirely respectable,
and it could even be a risky career move. The astrobiology movement
represents a shift in attitudes among a scientific community that previ-
ously regarded this study with suspicion or derision. This was fueled
by some exciting new discoveries, but also by a heightened awareness
within NASA that the public and the media respond more to stories
about alien life than to anything else we do. Here, I try to present a first-
hand description, from within my own field of planetary science, of this
large and rather abrupt change in attitude about the scientific search for
ET life.
Last summer, at a friend’s wedding reception in California, I ran into
David Morrison, the head of space sciences at NASA’s Ames Research
Center and a leader in the new astrobiology movement. He asked me
about my new book, and after I briefly described the work in progress
he said, “It sounds like you’re writing a book about astrobiology.” I
tried to explain to him why that wasn’t exactly the case, but we were
both heavily into the wedding spirit, so I probably didn’t do an articu-
late job of it. There are several books about astrobiology—some of
them quite good—and they all begin by saying: “Poised on the edge of
the most momentous breakthrough in human knowledge, scientists
have sparked a revolution that is sweeping the nation like a dance
craze.” Yet, the way I see it, astrobiology is the newest name for an old
quest. Here I will try to put the present moment—and the belief that we
are hot on the trail of aliens, and witnessing the start of a new scientific
revolution—in a wider historical frame.
To me, the study of ET life is as interesting for what it reveals about
our own biases and hidden assumptions as it is for what it reveals
about life in the universe. We strain the boundaries of good science
when we extrapolate to the rest of the cosmos based on our one exam-
ple of a planet with life. We come across many questions that are great
fun to contemplate. Could there be a world ruled by intelligent plants?
Life on a gas world like Jupiter? Planets that are much better suited for life than Earth? Sure. Why not? Such questions force us to refine our
views about intelligence and evolution and push us to define life in a
universal sense, even though all we know is life on Earth.
Because I pay special attention to the limits of science, in a sense this
is not strictly a science book but a work of natural philosophy. By using this term, I want to encourage a certain perspective on the science, an
Preface
xxiv
attitude where we keep ourselves honest by frequently questioning the
framework of assumptions we use. I discuss some new ideas, currently
on the shifting boundary between science and natural philosophy, that
may be helping us to derive a less Earth-bound view of what it means
for a planet to become alive.
Science is attempting a noble new assault on the question of our cos-
mic aloneness. But the question encompasses far more than just science.
Astrobiology, I believe, is leading the way in helping the scientific com-
munity to, once again, think like natural philosophers, harkening back
to a time when science was not distinct from philosophy, when the uni-
verse was not carved up into the turf of separate disciplines and subdis-
ciplines each speaking its own specialized language, and when even the
lines between our study of the physical universe and our spiritual quests
were not so finely drawn.
After I’ve lulled you into submission and taught you to respect my
authority as a scientist, then hopefully you won’t notice when, in the
“Belief” section, I start crawling farther out on various unsupported
limbs, where the juiciest fruit is often found. In this section I allow
myself more freedom to discuss my own beliefs. There is such a thing as
scientifically informed intuition, and I rely more on this inexact tool in
the last section of the book. My explanations and justifications are
inevitably looser than those found in the “Science” section. I’m saying
this now to give myself license, so look out.
Here I discuss our efforts to theorize about, and even communicate
with, intelligent aliens living on planets circling distant stars. I also
grapple with the widespread beliefs that aliens are already here study-
ing us or perhaps even infiltrating our societies.
True confession: The whole time I have been writing this book I have
had as a companion looking over my shoulder a three-and-a-half-foot-
tall, large-headed, green alien with big black eyes. He is not flesh-and-
blood or even silicon-and-plasma but a squeaky-squeezy plastic inflatable
hanging by a string from the ventilation pipe, yet he serves to remind me
that, at least as a cultural phenomenon, aliens are indeed among us. I
don’t attempt a comprehensive survey of the history and current phe-
nomena of ufology, but I offer a montage of my impressions and experi-
ences with some true believers.
After I discuss some of the more fringe ideas about aliens that perme-
ate modern culture, I speculate on some future possibilities. What
might intelligent life become, eventually, on Earth or elsewhere, and
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Preface
what are the implications, both scientific and spiritual, of these far-
future evolutionary possibilities for the ultimate role of life and mind in
our universe?
• • •
In writing this book I feel as though I’ve been abducted by aliens and
abruptly returned to Earth after two years, hoping
my friends, family,
cats, and scientific and musical colleagues will remember who I am. A
great many people have helped me on this interrupted journey.
For helpful comments on earlier drafts I thank Mark Yanowitz,
Jason Salzman, Rebecca Rowe, Mark Bullock, John Spencer, Lester and
Betsy Grinspoon and the Rev. Dr. Jeff Moore. Jake Bakalar provided
detailed and insightful editing and Kevin Zahnle (a.k.a. Thrak) con-
tributed perceptive and amusingly exasperating commentary on the
entire manuscript. Fortunately for me, Kevin found all six mistakes in
the first draft.
I thank my colleagues at the Southwest Research Institute for putting
up with my strange schedule and being generous with their insights and
expertise. In particular Hal Levison, Alan Stern, Robin Canup, Bill
Ward, Henry Throop, Clark Chapman, and Luke Dones have enlight-
ened me on various topics touched on in this book. Needless to say,
none of them are to be blamed for any mistakes or opinions.
For conversations, correspondence, suggestions and sources I thank
Steven Dick, Anthony Aveni, Harry Cooper, Larry Klaes, Andy
Chaikin, Glen Webster, David Deamer, Jim Head, John Lewis, George
Musser, Ken Croswell, Ben Bova, Amir Aczel, Peter Grinspoon, Josh
Grinspoon, Tim Ferris, Carl Pilcher, Nick Schneider, Dorion Sagan,
Penny Boston, John Bally, Larry Esposito, Fran Bagenal, Bruce Jakosky,
Don Hunten, Sean Solomon, Dirk Schulze-Makuch, John Scalo,
Alexander Zaitev, Martha Hausman, Chris O’Brien, Ginny Sutherland,
Tom Donahue, Nicolai Kardashev, Philip and Phyllis Morrison, Frank
Drake, Peter Ward, Don Brownlee, Chris McKay, Simon Conway
Morris, Ronald Weinberger, John Mack, Tim Pickard, Dennis Overbye,
Guillermo Lemarchand, Doug Vakoch, Jacques Vallee, Jack Mustard,
Athena Andreadis, Andy Spencer, Shaun Brooks, Rick Griffith, Bob
Pappalardo, Guy Consolmagno, John Rummel, Mike Meyer, David
Morrison, Chris Chyba, Jeff Kargel, Damon Santostefano, Helen
Thorpe, Peter Heller, and Dan Sjogren.
Preface
xxvi
Borin Van Loon provided inspired artwork that graces some of these
pages.
Thanks to Jim and Harriet Campbell for the peace and hospitality of