I have been
taking an online course on astrobiology from the University of Arizona—where
robust astronomical research has been the norm. I have taken a couple of
previous courses from the university's astronomy team and appreciate their teaching
abilities. This course blends their preeminence in astronomy with some of the
latest discoveries of thousands of Earth-like planets around other stars and
the potential for these planets to harbor life in some form; maybe similar to
Earth.
Here is a
question that has repeatedly arisen in the human mind: Is planet Earth alone in
the universe at harboring life, or might there be other life-sustaining worlds?
Is life common, rare, or nonexistent elsewhere in this cosmos? Does intelligent
life exist out there—say, critters as smart as we think we are?
We are getting
closer and closer to finding answers to these questions. As I have posted here
several times, our search is being aided and abetted by the recent discovery of
thousands of planets circling local stars. Without planets, you can't have life
elsewhere.
A consistent search
process for extraterrestrial life was begun a few decades ago—dubbed SETI—the
Search for Extraterrestrial Intelligence. Its premise is that intelligent
civilizations “out there” would have reached a technological capability at some
point—as we have—and would have transmitted electromagnetic signals (EM) into
space; signals that could eventually arrive at Earth. If so, might we receive
them and verify that we're not alone? After all, we've been inadvertently
transmitting EM signals from our planet for decades. Old TV episodes of “I Love
Lucy” are currently flying through interstellar space, just waiting to be
captured by some alien technology; maybe to the amusement of otherworldly
beings.
So SETI was
established decades ago—having been designed to receive some of those alien
civilizations' equivalent TV programs, or, hopefully (and more likely) signals
consciously sent out to inform beings like us that we're not alone. Yet my
online course professor made the point that, although we're searching for outer
space life, SETI is not really designed to locate outer-space intelligent life, but to discover extraterrestrial technology
that is similar to ours.
We haven’t yet
detected a signal, let alone determined the presence of either intelligence or the
existence of life elsewhere. At best we currently can register the presence of
EM signals that would indicate some sort of advanced technological
civilization. One issue in our search for ET that possibly is being dealt with
inappropriately is, Would intelligence “out there” display itself anything like
what on Earth has evolved?
Furthermore, there
is another key question that was posed many decades ago, by a prominent
physicist/astronomer: If there are
other advanced civilizations in outer space, where are they? Why haven't we
already heard from them? This is a troubling question for many cosmologists.
Again, we're not yet able to determine if there is or is not intelligence out
there—we're asking if they have evolved technologies like ours, and, if so,
where are the signals?
I can imagine several
reasons why we've yet to capture a signal that we can confidently say came from
outer space (and maybe never will): (1) The distances are simply too vast;
signals from even the closest stars take many years to reach us; so, were we to
detect a more distant signal, it may have been transmitted thousands of years
ago. Any signal we might receive could be from a distant past, from a civilization that is no longer even existing. Where might our technology be, in another thousand years? Would our
current primitive way of interstellar communication even be useful then?
Other
possibilities next time…
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