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In the seventeenth century there was still some hope that,
even if the Earth was not the center of the Universe, it might be the only "world."
After millennia of philosophical debate, the issue was settled decisively in favor of
"the plurality of worlds."
They might be profoundly different from our planet.
None of them might be as congenial for life.
But the Earth was hardly the only one.
This was the next in the series of Great Demotions,
downlifting experiences,
demonstrations of our apparent insignificance,
wounds that science has delivered to human pride.
Well, some hoped, even if the Earth isn't at the center of the Universe,
the Sun is.
The Sun is our Sun. So the Earth is approximately at the center of the Universe.
But by the nineteenth century, observational astronomy had made it clear
that the Sun is but one lonely star in a great self-gravitating assemblage of suns
called the Milky Way Galaxy.
Far from being at the center of the Galaxy,
our Sun with its entourage of dim and tiny planets
lies in an undistinguished sector of an obscure spiral arm.
We are thirty thousand light years from the Center.
Well, our Milky Way is the only galaxy.
The Milky Way Galaxy is one of billions, perhaps hundreds of billions of galaxies
notable neither in mass nor in brightness
nor in how its stars are configured and arrayed.
Some modern deep sky photographs show more galaxies beyond the Milky Way
than stars within the Milky Way.
Every one of them is an island universe
containing perhaps a hundred billion suns.
Such an image is a profound sermon on humility.
Well, then, at least our Galaxy is at the center of the Universe.
No, this is wrong too.
When the expansion of the Universe was first discovered,
many people naturally gravitated to the notion
that the Milky Way was at the center of the expansion,
and all the other galaxies running away from us.
We now recognize that astronomers on any galaxy
would see all the others running away from them;
unless they were very careful,
they would all conclude that they were at the center of the Universe.
There is, in fact, no center to the expansion,
no point of origin of the Big ***.
Well, even if there are hundreds of billions of galaxies,
each with hundreds of billions of stars,
no other star has planets.
If there are no other planets beyond our Solar System,
perhaps there's no other life in the Universe.
Our uniqueness might then be saved.
Today we have firm evidence for at least
three planets orbiting an extremely dense star,
And we've found, for more than half the stars with masses like the Sun's,
that early in their careers they're surrounded by great disks of gas aid dust
out of which planets seem to form.
Other planetary systems now look to be a cosmic commonplace,
maybe even worlds something like the Earth.
Well, if our position in space doesn't reveal our special role,
our position in time does:
We've been in the Universe since The Beginning (give or take a few days).
We've been given special responsibilities by the Creator.
the radioactive dating of rocks,
the abundance of impact craters on many worlds,
the evolution of the stars,
and the expansion of the Universe each provides compelling and independent evidence
that our Universe is many billions of years old
despite the confident assertions of revered theologians
that a world so old directly contradicts the word of God,
and that at any rate
information on the antiquity of the world is inaccessible except to faith.
These lines of evidence, as well,
would have to be manufactured by a deceptive and malicious deity
unless the world is much older
than the literalists in the Judeo-Christian-Islamic religion suppose.
Ages rolled by before the Earth began.
More ages will run their course before it is destroyed.
A distinction needs to be drawn
between how old the Earth is
and how old the Universe is
The immense interval of time
between the origin of the Universe and our epoch
was two-thirds over before the Earth came to be.
Some stars and planetary systems are billions of years younger,
others billions of years older.
But in Genesis, chapter 1, verse 1,
the Universe and the Earth are created on the same day.
As for humans, we're latecomers.
We appear in the last instant of cosmic time.
The history of the Universe till now was 99.998 percent over
before our species arrived on the scene.
In that vast sweep of aeons,
we could not have assumed any special responsibilities
for our planet, or life, or anything else.
We were not here.
Our commonsense intuitions can be mistaken.
Our preferences don't count.
We do not live in a privileged reference frame.
Well, even if our position, our epoch,
our motion, and our world are not unique,
maybe we are.
We're different from the other animals.
We're specially created.
The particular devotion of the Creator of the Universe is evident in us.
This position was passionately defended on religious and other grounds.
But in the middle nineteenth century Charles Darwin showed convincingly
how one species can evolve into another by entirely natural processes,
which come down to the heartless business of Nature saving the heredities that work
and rejecting those that don't.
"Man in his arrogance thinks himself a great work
worthy [of] the interposition of a deity,
More humble and I think truer to consider him created from animals.
The profound and intimate connections of humans with the other life forms, on Earth
have been compellingly demonstrated
in the late twentieth century by the new science of molecular biology.
Well, even if we're closely related to some of the other animals,
we're different, not just in degree, but in kind
on what really matters: reasoning, selfconsciousness, tool making, ethics,
altruism, religion, language, nobility of character.
human uniqueness has been exaggerated, sometimes grossly so.
Chimps reason, are self-conscious, make tools, show devotion, and so on.
Chimps and humans have 99.6 percent of their active genes in common.
Okay, maybe we're not much,
maybe we're humiliatingly related to apes,
but at least we're the best there is.
God and angels aside, we're the only intelligent beings in the Universe.
But the simple fact is that we have not yet found extraterrestrial life.
We are in the earliest stages of looking. The question is wide open.
If I had to guess — especially considering our long sequence of failed
I would guess that the Universe is filled with beings far more intelligent,
far more advanced than we are.
But of course I might be wrong.
Such a conclusion is at best based on a plausibility argument,
derived from the numbers of planets, the ubiquity of organic matter,
the immense timescales available for evolution, and so on.
It is not a scientific demonstration.
The question is among the most fascinating in all of science.
we are just developing the tools to treat it seriously.
What about the related matter
of whether we are capable of creating intelligences smarter than ourselves?
Computers routinely do mathematics that no unaided human can manage,
outperform world champions in checkers and grand masters in chess,
speak and understand English and other languages,
write presentable short stories and musical compositions,
learn from their mistakes, and competently pilot ships, airplanes, and spacecraft.
Their abilities steadily improve. They're getting smaller, faster, and cheaper.
Every year, the tide of scientific advance
laps a little further ashore
on the island of human intellectual uniqueness with its embattled castaways.
The long-standing view, as summarized by the philosopher Immanuel Kant,
that "without man . . . the whole of creation would be a mere wilderness,
a thing in vain, and have no final end"
is revealed to be self-indulgent folly.
A Principle of Mediocrity seems to apply to all our circumstances.
We could not have known beforehand
that the evidence would be, so repeatedly and thoroughly,
incompatible with the proposition that human beings are at center stage in the Universe.
But most of the debates have now been settled decisively
in favor of a position that, however painful, can be encapsulated in a single sentence:
We have not been given the lead in the cosmic drama.
Perhaps someone else has.
Perhaps no one else has.
In either case, we have good reason for humility.