- Kaufman, Marc.
First Contact.
New York: Simon & Schuster, 2011.
ISBN 978-1-4391-0901-4.
-
How many fields of science can you think of which study something
for which there is no generally accepted experimental evidence
whatsoever? Such areas of inquiry certainly exist:
string theory
and
quantum gravity
come immediately to mind, but those are
research programs motivated by self-evident shortcomings in the
theoretical foundations of physics which become apparent when our
current understanding is extrapolated to very high energies.
Astrobiology,
the study of life in the cosmos, has, to date, only one exemplar
to investigate: life on Earth. For despite the enormous diversity of
terrestrial life, it shares a common genetic code and molecular
machinery, and appears to be descended from a common ancestral
organism.
And yet in the last few decades astrobiology has been a field which,
although having not so far unambiguously identified extraterrestrial
life, has learned a great deal about life on Earth, the nature
of life, possible paths for the origin of life on Earth and
elsewhere, and the habitats in the universe where life might be
found. This book, by a veteran Washington Post
science reporter, visits the astrobiologists in their native
habitats, ranging from deep mines in South Africa, where organisms
separated from the surface biosphere for millions of years have been
identified, Antarctica; whose ice hosts microbes the likes of
which might flourish on the icy bodies of the outer solar system;
to planet hunters patiently observing stars from the ground and
space to discover worlds orbiting distant stars.
It is amazing how much we have learned in such a short
time. When I was a kid,
many imagined that Venus's clouds shrouded a world of steamy
jungles, and that Mars had plants which changed colour with
the seasons. No planet of another star had been detected, and
respectable astronomers argued that the solar system might have
been formed by a freak close approach between two stars and
that planets might be extremely rare. The genetic code of
life had not been decoded, and an
entire domain
of Earthly life, bearing important clues for life's origin, was
unknown and unsuspected. This book describes the discoveries which
have filled in the blanks over the last few decades, painting
a picture of a galaxy in which planets abound, many in the
“habitable
zone” of their stars. Life on Earth has been found to
have colonised habitats previously considered as inhospitable
to life as other worlds: absence of oxygen, no sunlight, temperatures
near freezing or above the boiling point of water, extreme acidity
or alkalinity: life finds a way.
We may have already discovered extraterrestrial life.
The author meets the thoroughly respectable scientists
who operated the life detection experiments of the Viking Mars
landers in the 1970s, sought microfossils of organisms in a
meteorite from Mars found in Antarctica, and searched for
evidence of life in carbonaceous meteorites. Each believes
the results of their work is evidence of life
beyond Earth, but the standard of evidence required for such
an extraordinary claim has not been met in the opinion of
most investigators.
While most astrobiologists seek evidence of simple life forms
(which exclusively inhabited Earth for most of its history),
the
Search
for Extraterrestrial Intelligence (SETI) jumps
to the other end of evolution and seeks
interstellar communications from other technological
civilisations. While initial searches were extremely limited
in the assumptions about signals they might detect, progress in
computing has drastically increased the scope of these
investigations. In addition, other channels of communication,
such as very short optical pulses, are now being explored. While
no signals have been detected in 50 years of off and on searching,
only a minuscule fraction of the search space has been explored,
and it may be that in retrospect we'll realise that we've had
evidence of interstellar signals in our databases for years in the
form of transient pulses not recognised because
we were looking for narrowband continuous beacons.
Discovery of life beyond the Earth, whether humble microbes on other
bodies of the solar system or an extraterrestrial civilisation
millions of years older than our own spamming the galaxy with its
ETwitter feed, would arguably be the most significant discovery in
the history of science. If we have only one example of life in the
universe, its origin may have been a forbiddingly improbable
fluke which happened only once in our galaxy or in the entire universe.
But if there are two independent examples of the origin of life (note
that if we find life on Mars, it is crucial to determine whether it
shares a common origin with terrestrial life: since meteors exchange
material between the planets, it's possible Earth life originated on
Mars or vice versa), then there is every reason to believe life is as
common in the cosmos as we are now finding planets to be. Perhaps
in the next few decades we will discover the universe to be filled
with wondrous creatures awaiting our discovery. Or maybe not—we
may be alone in the universe, in which case it is our destiny to
bring it to life.
November 2013 