Do worlds exist beyond ‘our lonely Eden’?
Tom Momary
"Larger constellations burning, mellow moons and happy
skies,
Breadths of tropic shade and palms in cluster, knots of
Paradise."
ÂTennyson
"Locksley Hall"
Have you ever gazed into a starry summer sky, into the light of
a thousand distant suns, and wondered about worlds? Of those
glittering stars we see, how many have planets circling them at
this moment? Do worlds exist, far beyond our Earth, that breathe
and laugh and hum with life? Is it natural to wonder about these
things  about worlds in space and life and intelligence? We
want to know if we are alone. If among the billions of fires
burning in our galaxy are sprinkled "knots of Paradise."
I have always been on the optimistic side of these questions. I
cannot fathom how, out of 400 billion suns in our galaxy alone,
ours could be the only one with a lively world  the lonely
Eden. The processes that govern the formation of planets and stars
operate throughout the universe. We know that the laws of nature
are everywhere the same. And the elements that go into building
worlds are abundant, and in the same proportions, everywhere. It
seems more likely to me that technical civilizations must be
commonplace. Maybe one even buzzes about near one of those stars we
see serenely twinkling at night.
We cannot say for sure, of course. Not yet. But we can explore
the probabilities for a moment. Follow this through with me, as the
numbers are extremely compelling, though they are only estimates.
The number of technical civilizations in our galaxy depends first
of all on the number of stars in our galaxy (about 400 billion).
And what fraction of those stars are stable and have planets? I
estimate maybe a third, which is not so far-fetched given recent
evidence. If solar systems commonly have about 10 planets (like
ours does) then a trillion worlds exist in our galaxy alone.
Yes, you say, but not all of these planets are warm and happy
places, and you are right. Maybe only two out of 10 planets are
warm and happy places. At this point, we have an estimate of the
number of planets in our galaxy that can support life, something
like 300 billion. Now, in how many of these places has life
actually arisen? We are treading on thinner ice now, but lets say
one third. But, you say, how many of these produces something more
interesting than a ground sloth? Okay. Perhaps only one percent of
these worlds where life arises produces a technical
civilization.
So, now we have that there are a billion planets in our galaxy
where technical civilizations have existed, at least once. All
right, but technical civilizations can be stupid. How many will
actually survive their adolescence and not snuff themselves out in
a mushroom cloud? Even if only one-tenth of 1 percent can survive,
we still have an estimate of a million technical civilizations in
our galaxy alone. (Not to mention that there are about 100 billion
galaxies in the universe). It is hard for me to imagine that this
universe is not positively rippling with life and intelligence. I
based this analysis on the Drake Equation developed by Frank Drake
of UC Santa Cruz, who estimated similar results.
What about actual evidence? In December, the repaired Hubble
Space Telescope looked at the constellation of Orion, where hot,
young stars are being born right now. Hubble imaged hundreds of
young stars and found that more than half of them had
proto-planetary disks, i.e., planets in formation. This is the
first direct evidence that about half of all young stars in the
universe have the potential to form planets. Circumstantial
evidence also supports this contention. And once we have worlds,
life can follow. Why not? It certainly happened here on this
planet.
I do not believe that this has anything to do with Earth having
been visited. The distances between stars are colossal. Travelling
these distances requires incredible energies. And all of the
accounts of UFOs are suspiciously unprovable. There never has been
any evidence to back them up. Not the tiniest shred of a new metal
alloy. Never any "revelations" about science or religion or social
organization. Very few supposed UFOs were even seen by more than
one witness. I do not put my faith entirely in circumstantial
evidence ( I prefer facts) but that is all that such stories have.
It is natural to want to have been visited. Some part of our nature
senses that we are alone. It is a bit of human arrogance, though,
to suppose that in a million worlds scattered throughout space,
aliens would select the speck of dust we call home. I think that
they are out there, but they have not been here.
As astronomy rides on the tide of progress, evidence mounts that
planets are common. Worlds in space? Yes. Repositories of life and
intelligence? Perhaps. We are not the first people to ask these
questions. But we will be the first generation, I believe, to know
the answers. And the discovery of other civilizations will
profoundly affect us. It will hasten the decline of provincial
perspectives and allow us to realize collectively what this
generation must recognize  that we are one planet. One out of
millions.
At this very moment, somewhere in space, clouds float lazily by
in alien skies. Strange oceans break on the shores of unknown
continents. Breezes sweep the thoughts of creatures we cannot even
begin to imagine, living somewhere on another world. Right now.
There may be whispers ranging through the depths of space, speaking
of other places. Other lives. What inspirations burn, I wonder, on
their "knots of Paradise"?
Tom Momary is a third-year grad-uate student studying
Geophysics.