Contact Optimists vs. Unique Earthers
Of the three fundamental questions asked by astrobiologists,
the question of the second genesis of ETIL, is the one we ask next. We ask
about the possibility that intelligent
living creatures currently inhabit earthlike planets somewhere in the cosmos.
To date no empirical evidence exists that extraterrestrial intelligence exists.
Despite more than three decades of active SETI (Search for Extraterrestrial
Intelligence) research, no radio or visual contact has occurred. If we rely
solely on empirical evidence, then we have no reason to believe that anyone
else is out there.
Space
researchers are divided into two camps. The Contact
Optimists contend that simple reasoning would suggest that the universe
should be teeming with life. Those holding the Uniqueness Hypothesis, in contrast, suggest that the earth is
probably the first and only home for a technological civilization. Until
recently, the lack of empirical evidence combined with the high improbability
of a repeat of earth’s evolutionary history seemed to give the edge to the
uniqueness hypothesis, to the unique earthers (Brin, 1983).
The
unique earth hypothesis depends on the assumption of the improbability that
just the right prebiotic contingencies would fall into place to make the spring
from non-life to life possible, and the low probability that the contingencies
that made the evolution of intelligent life on earth could be repeated in
sequence. Two of the most prominent evolutionary biologists, Stephen Jay Gould
and Francisco Ayala (Gould 1989; Ayala 2004), have argued that if you replay
earth’s evolutionary tape again and again, it will never produce the same result.
“The chemical origin of life seemed to depend on such an improbable sequence of
events, similar to throwing a die over and over and getting a six every time,
that biologists were inclined to think that life elsewhere must be a very rare
occurrence,” writes David Darling (Darling 2001, p.121).
Contact
optimists, while recognizing the improbability problem, counter with the idea
of big numbers. Because the number of possible locations in this vast universe
for evolution to get started is so large, the number of possible repeats of
earth’s biological history is also large. In contrast to the unique earth
biologists, contact optimism has grown among astronomers. “Most of the
speculation about life in the universe came from astronomers, who were generally
positive about the idea simply because they thought there were probably so many
planets around. With billions of potential homes, surely life couldn’t be that
scarce,” comments Darling (Darling 2001, p.121). He concludes, “Almost beyond
doubt, life exists elsewhere” (Darling 2001, p.xi).
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| Contributed by: Ted Peters
|
