WE ARE THE ONLY INTELLIGENT LIFE IN OUR GALAXY?

Day 187 of the Lower Puna Eruption.

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The past three postings have been dedicated to life on Planet Earth, beginning with a fearful conclusion that We just might be the only living things in the entire Universe.  I was planning this morning to speculate on the mid-term elections.  However, I usually carry Scientific American in my golf bag, where I have been reading their special issue from September on Humans.

Lo and behold, the next article was WHY WE ARE PROBABLY THE ONLY INTELLIGENT LIFE IN THE GALAXY, authored by John Gribbin, who in 2011 published the book shown to the right, ALONE IN THE UNIVERSE.  Note, however, that seven years later he has qualified this dismal prospect with "probably" and only "in the Galaxy."

Remember, I began this series with PERHAPS WE ARE ALONE.  We could well be more important than we thought.  The fact of our presence might well be so unique that we are the only hope for intelligent life in our Universe, ever.  

Anyway, a graphic which I hope you can read:

If you can't, here are further details indicating how unique and lucky Planet Earth and Homo sapiens are:

• We are here because of a long chain of implausible coincidences—many, many, many things had to go right to result in the situation in which we find ourselves. This chain is so implausible, in fact, that there is good reason to conclude that humans most likely are the only technological civilization in the galaxy.
• When the sun came into being about 4.5 billion years ago, this enrichment had been going on for billions of years in our galactic neighborhood. Even so, the sun contains roughly 71 percent hydrogen, 27 percent helium and just 2 percent metals.  This means that even if we are not the only technological civilization in the galaxy, we must be one of the first.
• Stars older than the sun have even fewer metals and, correspondingly, less chance of making rocky, Earth-like planets.

• The sun is located in a thin disk of stars about 100,000 light-years across: 
• We are roughly 27,000 light-years from the galactic center, a little more than halfway to the rim. By and large, stars closer to the center contain more metals, and there are more old stars there.  (However, these closer solar systems are inundated with X, gamma and cosmic rays, plus intense intense outbursts of radiation from our black hole, Sagittarius A*, which would kill off life. )
• Further:  we are the “galactic habitable zone” extending from about 23,000 to 30,000 light-years from the galactic center—only about 7 percent of the galactic radius, containing fewer than 5 percent of the stars because of the way they are concentrated toward the core.

• All the talk of Earth-like planets obscures another critical distinction. Astronomers have found around 50 of these worlds, but when they say “Earth-like,” all they mean is a rocky planet in the habitable zone that is about the same size as ours. By this criterion, the most Earth-like planet we know is Venus—but you could never live there. The fact that you can live on Earth is the result of fortuitous circumstances.

• It is impossible to say how often such impacts occur to form double systems such as Earth and its moon. But clearly they are rare, and without our satellite we would likely not be here.
• At first, this sounds like good news for anyone hoping to find extraterrestrials—surely if life got started on Earth so soon, it could arise with equal ease on other planets? The snag is that although it started, it did not do much for the next three billion years.

• The more complex cells, the stuff of animals and plants, are known as eukaryotes, and they are all descended from a single merging of cells that occurred about 1.5 billion years ago.
• Then came the dramatic turning point: An archaeon engulfed a bacterium but did not “digest” it. The bacterium became a resident of the new cell, the first eukaryote, and evolved to carry out specialized duties within it, leaving the rest of the host free to develop without worrying about where it got its energy. The cell then repeated the trick, becoming more complex.  

• It is a measure of how unlikely such a single fusion of cells was that it took two billion years of evolution to occur.
• Even then, not much happened for another billion years or so. Early eukaryotes got together to make multicellular organisms, but at first these were nothing more than flat, soft-bodied creatures resembling the structure of a quilt. The proliferation of multicellular life-forms that led to the variety of life on Earth today only kicked off nearly 550 million years ago, in an outburst known as the Cambrian explosion.

• Eventually Homo sapiens evolved, but:
• DNA evidence pinpoints two evolutionary bottlenecks in particular. A little more than 150,000 years ago the human population was reduced to no more than a few thousand—perhaps only a few hundred—breeding pairs. 
• And about 70,000 years ago the entire human population fell to about 1,000 because of a volcano eruption in Indonesia.
• That our species survived—and even flourished, eventually growing to number more than seven billion and advancing into a technological society—is amazing.

• As we put everything together, what can we say? Is life likely to exist elsewhere in the galaxy? Almost certainly yes, given the speed with which it appeared on Earth. Is another technological civilization likely to exist today? Almost certainly no, given the chain of circumstances that led to our existence. These considerations suggest we are unique not just on our planet but in the whole Milky Way. And if our planet is so special, it becomes all the more important to preserve this unique world for ourselves, our descendants and the many creatures that call Earth home.

To again summarize:

1. With so many exoplanets out there in the galaxy, it seems reasonable to hope that life may be prevalent. But a series of unusual coincidences occurred to give rise to our intelligent civilization, and it is quite unlikely such serendipity has taken place elsewhere.
2. The timing of our solar system’s birth in the history of the galaxy was fortuitous, for example, as is our location in the Milky Way. Furthermore, several features of our planet are very rare, and the conditions that sparked the evolution of life here might be irreproducible.
3. Perhaps most unlikely of all was the development of our technological species from those first sparks of life—a feat that is probably unique.

Thus, even if life thrives throughout the Universe, are we the ONLY intelligent life?

But you argue, what about flying saucers, Star Trek and Star Wars?  Well, they are entertainment devices.  Our nearest neighbor is Andromeda.  This galaxy is about 2.5 million light years away.  If a way is found to travel at the speed of light, it would take 4.6 light years to get there and back.  

But we have not yet quite reached 25,000 MPH (got close when our astronauts went around the Moon in 1969), which is only 0.0037% the speed of light, although 30 times faster than a speeding bullet.  Or look at it this way.  We would need to increase the swiftest we've ever gone by a factor 27,000 times to reach the speed of light.  Then can you imagine the fuel necessary to get that far and back?  And cost?

Ah, but you say, we'll someday find a way to travel faster than the speed of light or zoom to distant corners of the Universe through wormholes.  In 1935 Albert Einstein and Nathan Rosen suggested the existence of bridges through space-time.  Read We Can Make It to the Edge of the Observable Universe in a Few Decades and other inspirations.

If you're even halfway serious about this discussion, then you probably would agree that the future of evolution will lead to artificial intelligence and non-carbon "life."  Thus, if we are alone in the Universe, our responsibility could well be to insure that some form of technological pathway can be created to other galaxies.  If legacy is our ultimate objective, certainly forget Mars today, accept our clear vulnerability and instead lay the foundation for what could be future life, whatever that may be.

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