- Posted
09.28.04
- NOVA
We
Earthlings have seen no credible signs that there are beings elsewhere in the
universe that match us in smarts. Yet are there?
Paleontologist Peter Ward,
coauthor of Rare Earth: Why Complex Life is Uncommon in the Universe,
points to evidence that intelligent life must be exceedingly rare.
Other
scientists, however, think that advanced life is common—Carl Sagan estimated a
million intelligent civilizations in our galaxy alone. So NOVA asked
astrophysicist Neil deGrasse Tyson to play devil's advocate in a conversation
with Ward.
Neil
deGrasse Tyson (left) and Peter Ward square off in a friendly debate. EnlargePhoto credit: © Daniel Deitch
(Tyson) / © WGBH Educational Foundation (Ward)
TIME
IS OF THE ESSENCE
Neil
deGrasse Tyson (NdGT): Peter, when you combine the fossil record on Earth with all
that we know of biology and evolution, what can we expect as we look for
intelligence elsewhere in the cosmos?
Peter
Ward (PW): There
are maybe 30 million species on the planet today—10 to 30 million. If we look
at the fossils, there are hundreds of millions of species in the past. And one
time on Earth has intelligence arisen to the point where we can build a radio
telescope (which is the definition of intelligence to a radio astronomer). One
time out of hundreds of millions of possibilities. That's an astronomically
small number of intelligences that have arisen—just one.
NdGT: At
last tally, there are several hundred billion stars in the Milky Way galaxy and
perhaps 100 billion galaxies in the universe. Yet according to your book, we're
just cold, dark, and alone.
PW: No,
we're not alone; we're lonely. There's a big difference between being alone and
being lonesome.
