The “Rare Earth.”
The notion that life existed anywhere in
the universe besides Earth was once laughable in the scientific community. Over
the past thirty years or so, the laughter has died away. As the vast scale of
the universe has become clearer, the notion that life could have arisen only on
Earth seems increasingly unlikely. The law of averages alone would suggest that
there must be many places in the cosmos that harbor life.
“Not so fast,” say Peter D. Ward and
Donald Brownlee. These two professors at the University of Washington
argue that the recent trend in scientific thought has gone too far. They suggest
that even if the universe is teeming with life, complex organisms are not
likely to appear on many — if any — planets besides our own. They make their
case in “Rare Earth” (“Rare Earth: Why Complex Life Is Uncommon in the Universe”).
The authors draw on a wide variety of
scientific disciplines, from geology to paleontology to astrophysics, as they
lay out the evidence that Earth may be a singular habitat for animal life.
Indeed, they call this compendium of sciences “astrobiology,” the study of life
throughout the universe. They also admit that all of their conjectures about
how life might evolve on other planets are based entirely on one example — how
life evolved on Earth. But they argue that example is rich enough in detail to
provide clues about how the process might work everywhere.
A long list of factors. Ward and Brownlee acknowledge that life arose fairly quickly on
Earth, and they allow that simple life forms, of the single-cell variety, might
be common on many other planets. But they insist that the evolution that led to
everything from butterflies to redwoods to humans is the result of a peculiar,
and perhaps unique, sequence of events on Earth.
There is a long list of interrelated
factors leading them to this conclusion. They include the presence of the
planet Jupiter in an orbit sufficiently far from Earth to deflect much of the cosmic
debris floating around the solar system. If Jupiter weren't there, or if it
were in a different orbit, a lot of that junk would be crashing into Earth and
extinguishing complex plant and animal life. Only Earth, among the inner
planets of the Solar System, has plate tectonics, a process that serves as a
sort of regulator of our global temperature and provides enough dry land for
complex organisms to inhabit.
They also cite the happy accident of
Earth's position in the galaxy — not too close to the intense radiation of the
central core, not so far away that it is left without the chemical building
blocks of life. And there is the position of the galaxy itself — not in a
globular cluster, not in a metal-poor quadrant, but in just the right spot to
foster the rise of complex life.
'Not the center of the Universe.' “The continued marginalization of Earth and its place in the
Universe now should be reassessed,” the authors write. “We are not the center
of the Universe, and we never will be. But we are not so
ordinary as Western science has made us out to be for two millennia. Our global
inferiority complex may be unwarranted.”
To us who believe in God these new
findings say that, after all, we are very special to Him.