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Is the Earth the Most Special Planet in the Universe, After All?

Kirk Durston


As a small boy, I thought the earth was flat…and it ended ten miles away behind the tall wooden fence at Sticky’s Drive-in. The fence, of course, was to keep people from falling off the edge of the world. No one had put this idea in my head; it was simply the way I perceived the world before anyone told me differently.

A dirt road ran between our farmyard and a large forest that provided endless possibilities for my imagination. Though I was not permitted to enter it as a preschooler, my powerful curiosity got the best of me, and I sneaked into the forbidden forest one evening as the sun was setting. A short ways in, I discovered a path that ran from West to East. It seemed patently obvious to me that this was how the sun got back to the East after it set in the West. The terrible, burning disk flaming down the path was something I thought too terrifying to even look upon, so I quickly but quietly (lest it be coming already) slipped deeper into the forest.

Many people in ancient times thought the sun, moon, and stars revolved around the earth. It was simply the way the world appeared from their perspective. Contrary to popular belief, however, the Bible never taught that the earth is flat, nor that it is the center of the universe. We often speak of the sun setting or the moon rising, even though we know they do not actually revolve around the earth. We are simply speaking from our own frame of reference.

I have often looked up into the night sky in awe of the incredible vastness of the universe, contemplating how infinitesimally minuscule our planet is among billions of galaxies and galactic clusters. In the 1970s I managed to fit first and second year astronomy courses into my undergraduate physics program and purchased my first telescope … a 6″ Newtonian. Back then, astronomer Carl Sagan was a regular guest on the Johnny Carson show. He promoted the idea that there are billions of planets in the universe. Evolutionists, with unquestioning faith, believed that the evolution of life was inevitable, making life on other worlds quite possible. Earth, according to the science of the day, was nothing special at all.

Consequently, I was surprised to read a recent article for Forbes by astrophysicist Ethan Siegel, “Humanity May Be Alone in the Universe.” He suggests that our planet might be the only one in the universe that has ever contained a technologically advanced civilization. His thinking is based on a paper earlier this year by Erik Zackrisson and colleagues, “Terrestrial planets across space and time.” They estimate a total of 8 x 10^20 terrestrial planets in the observable universe.

Not all terrestrial-like planets are habitable or can even permit liquid water at the surface. Furthermore, X-rays, extreme UV radiation, and flares make it unlikely that planets around M-dwarf stars are habitable; this removes 98 percent of the terrestrial planet candidates. If super-earths with high gravitational fields are removed, Zackrisson et al. estimate that about 2 x 10^18 habitable planets remain in the observable universe. In addition, they note other factors that would further reduce the number of habitable planets, such as cosmic rays, Oort cloud comet perturbations, interactions with interstellar clouds, the effects of dark matter, and radiation threats to life. They also point out that the vast majority of habitable planets would be far too young to have evolved advanced life, leaving only a tiny fraction of candidates.

That introduces another problem to overcome. Even if one has a habitable planet, there is no guarantee that life will be found there. Zackrisson et al. state:

If the probability for the emergence of intelligent life is sufficiently small, we could well be the only advanced civilization in the Milky Way.

In a paper published earlier this year in Astrobiology, Frank and Sullivan conclude that if the probability of evolving a technological species is greater than 10^-24, then we may not be alone in the universe, given the number of terrestrial planets estimated by Zackrisson et al.

That minimum probability value exposes a very large problem.

The probability of obtaining even the simplest life form is considerably less than that. For example, in his book The Logic of Chance: The Nature and Origin of Biological Evolution, evolutionary biologist Eugene Koonin has shown that the probability of merely attaining RNA replication and translation (a necessary requirement for even the simplest life) is less than 10^-1018. He concludes that it is highly unlikely to occur anywhere in the universe. His preferred explanation is that we are one of the lucky universes among a near-infinite number of universes. My own work in bioinformatics supports Koonin’s probabilistic conclusions that no life should be expected in this universe if it is a one-shot deal. For example, the probability of obtaining, in a single search, any one of 10^92 functional sequences for the Ribosomal S7 structural domain (necessary for translation from RNA to proteins) is roughly 10^-100.

Seigel points out that in order to develop a technologically advanced civilization, three major steps must occur. First is the commencement of a simple life form, which requires evolving not just one, but a few hundred mutually specified proteins capable of combining together to form a living cell. For this to take place, the right proteins must fortuitously occur on the same planet, and at the same time and location on that planet. Then, life must survive long enough to evolve intelligence. The third step is to become technologically advanced. The likelihood of these three steps prompts Seigel to write, “the huge uncertainties make it a very real possibility that humans are the only spacefaring aliens our Universe has ever known.”

From a materialistic, evolutionary perspective, our technologically advanced civilization is almost certainly unique in the universe. Indeed, if the origin of life is so improbable that we should not even be here, then it seems we are faced with an interesting choice. The first option is to grant Koonin’s theory that we won a lottery against mind-staggering odds, requiring a near infinite number of unseen, untestable universes. The second option arises out of our observation that the universe and this particular planet seem to be incredibly fine-tuned to support life. It may be more rational, therefore, to conclude that there is, in fact, just one Creator who is greatly interested in Earth and its inhabitants. So the choice is between an infinite number of universes to explain our monstrous stroke of luck, or a Creator of the cosmos who has a purpose in mind for humanity. I suggest we go with Ockham’s Razor and opt for the latter.

So it seems that things have come full circle since I was a child. Now, when I stare up into the cosmos, my childhood assumption that the cosmos revolves around Earth is long gone, of course. But Earth is the center of the universe in a very different sense. As the home planet of an astonishingly improbable, technologically advanced society, it is an anomaly of gigantic proportions. Compared to any alternative, I think it vastly more likely that the appearance of design we see everywhere in nature points to a Master Designer, Creator of space, time, matter, energy, and the laws of physics that govern them.

Photo credit: Kirk Durston.
Cross-posted at SQyBLu/Contemplations.