ET Inspections—Part 2

...Continuing a fanciful visit to Earth from outer-space visitors looking for signs of intelligence here...

Visit 4, 700 million years ago. Volcanoes had burst through Snowball Earth's ice crust, spewing carbon dioxide into the atmosphere, causing the planet to warm once again. (In a similar fashion, we humans are now spewing carbon dioxide into the air, causing another global warming event.) At that time, our space visitors would have encountered microbial life forms that were very primitive. Nothing larger than a few microns, and certainly not intelligent. Nothing much of interest going on here at that time.

Visit 5, 400 million years ago. This would have been tens of millions of years after what scientists call the Cambrian Explosion, when millions of multi-cell critters had evolved. Many primitive animals and plants were flourishing across Earth. They were fantastically varied and our visitors would have been amazed at it all, but still have noted no intelligent life forms. None of those creatures appeared to be likely to build a space ship, let alone a stone hammer.

Visit 6, 100 million years ago. Outer-space callers would have found a tropical planet, with huge, reptile-like creatures crawling on land and swimming in its oceans. Countless kinds of plants would be thriving everywhere. Earth was bursting with life, yet no sign of technology could be found. Even though those giant lizards ruled the planet, our guests would conclude that intelligent life (at least smart enough to make rockets) was not there, and maybe never would be. All signs pointed to the fact that Earth life had settled into a stable, unchanging mode. Little did the visitors know that, had they come calling 35 million years later, life on the planet would be struggling to survive, in the aftermath of an asteroid crash that wiped out some 80% of all species.

Visit 7, six million years ago. At this time our extraterrestrial callers would find that Earth was populated by mammals—especially an intriguing one that walked on two legs. They would note the planet was changing rapidly, oscillating from hot periods to times when glaciers covered nearly half of the globe. Although the upright hominids appeared to possess the potential for intelligence, their technology consisted only of crude chunks of stone. Would they advance? Time would tell.

Visit 8, today. Our space travelers would discover a planet seething in hominids, who occupy every corner of the globe. They'd note abundant examples of technology that have rendered the lives of the hominids convenient and comfortable. Their structures are everywhere, as proof of their capabilities. They even have made the first tentative steps to leave the planet and investigate nearby worlds.

Yet something appears to be awry. Many of the planet's life forms are no longer healthy and thriving, but are threatened by the overzealous activities of the over-populous hominids. There is evidence that, in their push to extend their technologies, they have foolishly polluted their world. Yes, our visitors would discover a relatively advanced species, but would doubt that it has sufficient intelligence to survive much longer. The ET travelers conclude that these hominids are yet too savage... they fight incessantly among themselves and are trashing their lovely planet. 

Maybe if they returned in a couple of hundred years, they would find that these dominant hominids either smartened up and got their act together, or made themselves extinct. Whatever fate might await this “intelligent” species, the visitors have faith that the planet has previously survived worse catastrophes, after which life took a new tack and once again flourished.

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...