SETI Reset—Part 1

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…

ET Inspections—Part 1

There is much research and speculation currently going on, regarding the possibility of life elsewhere in the universe. The search is vigorously proceeding, on the part of several scientific disciplines: astronomy, physics, biology, chemistry, and evolution. Now that thousands of planets have been discovered around nearby stars, we know that worlds exist where life might possibly be present. The recent discovery of hardy life forms right here on Earth, thriving in extreme environments (high/low temperatures, dessicated locations, high-acid spots, sunless pockets, etc.), tells us that life can flourish in what are extraordinarily harsh situations; once thought impossible for life to even exist.

At some point in the future, humans will travel to other worlds where life could potentially exist, and we will be inspecting them for possible forms of life. A pertinent question that could be posed is: Would we recognize life of a very different kind, if we visited its world? Just a few years ago researchers would have doubted that life could exist in some of the extreme places found here on Earth. It has prompted scientists to open up to the possibilities of bizarre life forms elsewhere.

Maybe a way to put the search for extraterrestrial (ET) life in a different perspective is to conduct a fanciful thought experiment. Suppose we think about some intelligent outer-space species that might have visited planet Earth to inspect it for life, at different times over our planet's existence. Suppose we look at what these ET visitors would have observed, and what they might have concluded from their inspections.

Visit 1, four billion years ago. That would have been only a half-billion years after Earth had formed. It would be a molten, heaving surface of lava, with spewing volcanoes. No life possible then.

Visit 2, three billion years ago. While cruising our solar system, the visitors would also have checked into both nearby Venus and Mars. All three planets would have been water worlds with thick atmospheres, and were quite warm. Had they looked closely on Earth at that time, they'd have detected some single-cell, simple life forms. Nothing intelligent. Not much going on here, but some possibilities for the far distant future. Would the outer-space visitors have found similar kinds of primitive life on Venus or Mars? It's certainly plausible. We humans may someday find out, when we have conducted our own inspections of our partner planets.

Visit 3, two billion years ago. For millions of years around that epoch, Earth's temperature had dropped far below the freezing temperature of water. Our visitors would have encountered what scientists call “Snowball Earth.” The planet would have been essentially encased in ice. At first glance, it would be doubtful that life could have existed under such conditions, but had the space voyagers probed a little deeper, they'd have found that single-cell critters did live beneath the ice, deep in the oceans. Astronomers today think that similar kinds of life may be found by humans one day in ice-entrapped oceans on Saturn's moon Europa. Still, our ET visitors would just find primitive life here on Earth—no intelligence yet.

More visits next time...