Archive for December 2nd, 2007


Aliens? Sure, Why Not

December 2, 2007

I’m going to take a break from my usual political banter and dive into the realm of science for a bit.  I’ve recently spent some time reviewing something called the Rare Earth Hypothesis (REH), so I thought I’d comment on it. But first a little background…

Since childhood, I’ve had an interest in astronomy.  This was one of my favorite subjects in grade school and I even decided to take a course as an elective in college.  Even today I can’t help but gaze at the stars while walking the dog.  The incredible magnitude of it all is just fascinating. 

Speaking of college, I guess its worth mentioning (not that it’d be unexpected) that I was a big fan of shows like Star Trek, and during my time there I managed to view just about every episode of TNG.  If I recall correctly, the show was rerun on weekdays at 3PM, so my roommates and I made it a bit of a daily ritual (combined with some healthy doses of marijuana).  I bring it up because I was reminded of it while reading about REH.   As much as Star Trek adheres to some basic principles of science, certainly a healthy portion of the content stretches and suspends disbelief.  romulan.jpgLeaving aside some more ridiculous assumptions like the idea that a human could mate with a being from another world and bear its offspring (or that said being would even come close to resembling a human with a prosthetic attached to its forehead) , Star Trek wouldn’t be Star Trek with out the assumption that there are aliens in the first place. “To seek out new life forms and new civilizations” is in the title sequence, after all.  As would be the case with a lot science fiction, how far are they stretching that fundamental part? 

Just about everyone has pondered the eternal “are we alone” question.  However, I think there is a certain amount of reluctance for serious people to discuss the subject, probably because they’d want to be careful not to be associated with the tinfoil hat crowd. Also, most religions don’t leave room for the idea that there is anything living on any planet beyond the Earth.  But you certainly don’t have to believe in UFOs, Martians, or being visited by little green men to legitimately entertain the idea that amongst the billions of stars that anyone with decent vision can see on a clear night there might be something living.  There are plenty of brilliant people who keep an open mind and consider that the answer to the question of how many worlds out there that contain some level of life could range anywhere from “none” to “billions”, even when everything known about physics, biology, cosmology, chemistry, mathematics, etc. is brought to bear. For advocates of REH, the answer is much closer to “none”, and they make a fairly strong case.

For many people, the creation and existence of life is not a scientific question but a religious one.  For myself, I’ve always considered the possibility that science and religion need not be mutually exclusive.  In fact, maybe it’s our relentless pursuit of knowledge and adherence to the scientific method that would eventually prove that God exists?  I couldn’t help but think about this while reviewing REH.   The idea of the evolution of intelligent life seems miraculous in and of itself, but what the hypothesis proposes is that the factors that created an environment where it could even develop is equally miraculous.  (interestingly, I also found this article: Was the ‘Rare Earth’ Hypothesis Influenced by a Creationist?)

Watching a show like Star Trek for awhile might give one the impression that complex life can arise wherever there is an atmosphere on a planet near a star.  REH considers that it is far more complicated than that, and states that complex life is unlikely to develop on a planet (or even in a solar system) that doesn’t meet a whole list of qualifying criteria.  This would include (but not limited to)…

…and we haven’t yet considered the size, composition, atmosphere, axis and rate of rotation, magnetic field, plate tectonics, etc.of the planet itself.  Considering that complex life may take hundreds of millions or (in the Earth’s case) billions of years to develop, the idea that a relatively stable and safe incubator is needed for this to happen seems pretty intuitive.  Hot stars, for example, die too fast.  A planet without a magnetophere can’t repel solar radiation.  And even if all other conditions were ideal, a single bolide impact could be catastrophic and prohibit complex life forms from emerging.  All this paints a picture that portrays our existence on Earth as sort of a freak occurrence, and that it is highly unlikely that a wide variety of intelligent life could be found in a single quadrant of a galaxy (as assumed on Star Trek).  In fact, what REH advocates would propose is that Captain Kirk could spend 5 years riding around in the Enterprise and find nothing beyond the occasional microbe.

Does this mean that intelligent life doesn’t exist out there?  Hardly.  The REH has its fair share of critics, and primarily the fact that the model assumes that intelligent life could only evolve in an environment like that of Earth is called into question.  voyagerreverse.jpgGiven the fact that we have but one example (us), there are simply too many unknown variables.  Even if our existence was a one in a billion phenomenon, it would allow for billions of civilizations in the known universe, since there are billions of galaxies, each containing billions of stars.  What most scientist agree on, however, is that the occurrence is infrequent enough to allow for the likelihood that 2 civilizations would be in close proximity of one another.  In other words, whoever is out there, we’ll never contact them (or vise versa).  Another variable is time.   Even if one assumes and accelerated process in relation to our own, intelligent beings may require hundreds of millions of years to evolve, but may hold that status for a mere fraction of that.  During the history of the cosmos, untold intelligent beings could have evolved and subsequently died off before the earliest organisms made their appearance on Earth.  Still others could develop long after we’re gone. Humans have been intelligent enough to make themselves visible to interstellar observers for less than 100 years, and even if we’re around for another 10,000 or even a million more, that’s still a mere blink of an eye in a universe that is 13.7 billion years old (which adds another concept, in that one could trace our own evolution not just to the first creatures on Earth, but to the origin of the universe, since the Earth itself wouldn’t exist without the random chain of events that made it possible.  From that point of view, one can argue that it took 13.7 billion years for one known intelligent species to emerge).  All this may serve to explain the Fermi paradox, which asks the general question “Where are they”?

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