Editor’s note: As a series at ENV, we have been pleased to present "Exoplanets." Daniel Bakken is an engineer who teaches astronomy at the college level, and an entrepreneur in compound semiconductor crystal growth. In a series of articles he has critically examined recent claims about exoplanets beyond our solar system, asking whether our own planet Earth is a rarity, or common, in the cosmos.
As we have seen in this series, which concludes today, at present the idea that the Earth is the only abode of technology in the Milky Way galaxy appears increasingly likely.
The possibility that this may support supernatural intervention by an intelligent designer, or even affirm a classic Christian concept of a Creator, is vehemently rejected by some in the scientific community. Yet these possibilities are suggested by sobering facts about the rarity of the Earth and its environment. Far from perpetuating the caricature of science versus faith, these results fit well with a theistic view of the universe. Those who reject such a view respond by pointing to the possibility of many universes, looking to chance to resolve the evident difficulties.
Thinkers unwilling to entertain theism as an explanation for life also seek to close the door on a traditional concept of God by portraying Christianity in particular as anti-intellectual and anti-science. A recent example is in the 2014 television series Cosmos, where significant airtime was devoted to the persecution by the Church of early scientists. Giordano Bruno, in particular, was held up as a scientific martyr. He was burned at the stake supposedly for proclaiming that there are planetary systems around other stars, and likely people on those planets. Yet in fact it was political motivations that resulted in his being put to death, a result that had nothing whatsoever to do with his views regarding other planets.1
Many scientists see Bruno as a kindred spirit, with his proclamations about life on other planets, and even feel that this pits them in a struggle with organized religion. Another scientific martyr, Galileo Galilei, likewise is seen as being crushed by religion for standing up for science. As with Bruno, however, Galileo’s house arrest came not from his scientific views as much as his challenging the Catholic Church in interpreting Scripture. Instead of clerics refusing to look through the telescope to see the reality of the cosmos, it was in fact his own university colleagues who refused.2 Similarly today, many scientists are persuaded by philosophy, not science, to ignore the reality that the Earth is not a common planet, but a very special one, maybe even unique in the visible universe.
But some researchers have let the data lead them to another conclusion. As David Waltham says in his Prologue to Lucky Planet, entitled "A Tale of Two Planets," "Earth was blessed with incredible good fortune, giving it all the right properties to sustain a complex and beautiful biosphere. It may just be the luckiest planet in the visible Universe."3 He also goes on to say, "Earth is a precious jewel possessing a rare combination of qualities that happen to make it almost perfect for sustaining life,"4 and, "In my view, imaginatively populating our small corner of one galaxy with hundreds of advanced civilizations is just wishful thinking. The scientifically conservative position should be that life is rare and intelligence even more so."5
Many of his colleagues doubt his view, and will say the data are just too sparse to come to such a conclusion. Yet Waltham no longer has doubts that "[t]he evidence points toward Earth being a very peculiar place; perhaps the only highly habitable planet we will ever find."6 For him, "these ideas merely emphasized how wonderful our home is and how lucky we are to exist at all."7 He concludes that "we are probably effectively alone in the Universe,"8 and "we rarely stop to notice what an amazingly beautiful, unique, and, dare I say it, miraculous place it is."9
This Leads to a Prediction
Life doesn’t have a long future on Earth, at least compared to its history. Barring nuclear war, giant asteroid collision with Earth, or a nearby supernova, what is the outlook? Compared to the past 4 billion years, biological activity on our planet is already on the wane.10 Due to the increase in the Sun’s energy output, and the carbonate-silicate cycle that removes CO2 from the atmosphere to compensate, the level of CO2 is already very low for plants, and the amount and diversity of plant life is dropping due to the decline.11 In a few hundred million years, the Earth will not be able to sustain complex plants or, it is likely, humans either. The oceans will eventually boil away, and plate tectonics will end within about 500 million years.12 Looked at this way, biology is over 90 percent into its life span on Earth.
This is curious because humanity seems to have entered the picture at the most opportune moment — and just in time. What if intelligence and technology hadn’t arisen in Earth’s habitability time window? Waltham in Lucky Planet asks "So, how do we explain the remarkable coincidence that the timescale for the emergence of intelligence is almost the same as the timescale for habitability?"13 Researchers Carter and Watson have dubbed this idea the anthropic inequality14 and it seems surprising, if it is not for some purpose.
This leads to a prediction. If the Earth is indeed special in its ability to support advanced technological life, and if there is indeed a purpose behind this, future research should continue to show more evidence of uniqueness. If there is no purpose that has guided the existence of the Earth, and its life, then it is likely that the pace of discovery of factors revealing the rarity of the Earth and its life should diminish as research continues. For now, however, it appears that this pace is quickening, and shows signs of increasing into the future if recent history is a guide.
With respect to the Earth, if we were to follow the Copernican principle to its conclusion, we should find ourselves in many ways a typical example of a technological civilization in the cosmos. If we are, indeed, a common example of intelligent, civilized life, then statistically we should expect to find ourselves in a typical environment where that kind of life is possible. As an example, if technological civilizations like ours were possible around a red dwarf, or in a dwarf galaxy, then we should find ourselves in one of those environments, since they are much more common than the one we find ourselves in. Since we find ourselves in an environment that is not typical, but atypical, as I have shown in this series, then it follows that technological civilizations likely require atypical conditions.
The many required — and rare — parameters that technological civilizations apparently need effectively stand the Copernican principle on its head. The mediocrity principle, which has been assumed for so long to apply to the Earth, is refuted by the actual data of other planets and environments. It fails with respect to Earth, and by extension the Copernican principle also fails.
An interesting point about what we’ve learned about habitability suggests that if advanced civilizations are out there, they would quickly discover the same restrictions on habitability in the galaxy and universe as we have. This has an effect of accentuating Fermi’s paradox15, in that it greatly reduces the places to visit, colonize, or at least communicate with in the galaxy. Instead of the whole galaxy, just the galactic habitable zone is available, and within that, only G type stars, of a certain metallicity, and so forth need be considered. Any significantly more advanced alien civilization could, and likely would, either colonize or communicate with all potential life sites in our galaxy in far less than the 50 million years I mentioned previously. Fermi’s paradox, then, is even more potent in accentuating our apparent loneliness in the galaxy.
Having examined some of the data from astrobiology and the study of known exoplanets, what are the probabilities that other planets have the capacity to harbor complex intelligent life that can develop technology? The answer is far more complex than we used to imagine, encompassing the entire history of the universe, which then includes focusing down the galactic environment, the galaxy’s history, star formation, planet formation, life’s requirements, and requirements for advanced technology like available metal ores and free oxygen. At each scale the interactions must be within a narrow range, and statistically modeled, with input from actual data.
As Guillermo Gonzalez states in "Setting the Stage for Habitable Planets," a paper in the journal Life, to answer the question of the probability of other planets harboring life, we "must incorporate the complete history of the universe, including galaxy, star, and planet formation and evolution."16 Further, "cosmology is not irrelevant to the formation and continued existence of habitable planets."17 And, "Change one aspect of a habitable planetary system to make it non-habitable, and it might not be possible to make it habitable again with a single change to a different parameter."18
The view that there may be something or Someone purposeful behind life has also been explored by Gonzalez in The Privileged Planet, co-written with Jay Richards, where they reveal an even deeper connection between the rarity of habitability and the factors that make scientific discovery possible. They make a cumulative case, one that requires unpacking, supported by the new research showing just how special our planet is, and how that relates to our ability to do science.
Given the positive evidence from the current state of this research, and the negative evidence from the search for extraterrestrial life, the most satisfying answer to Fermi’s paradox is that we are alone, and that there is a supernatural reason we are here. Someone decided that life should exist in this universe and made sure that Earth received all the proper protection and environmental benefits it needed to become the home of humankind. The Earth’s uniqueness brings to mind what the prophet Isaiah recorded thousands of years ago:
For thus says the Lord — Who created the heavens, God Himself, Who formed the Earth and made it, Who established it and did not create it to be a worthless waste; He formed it to be inhabited — I am the Lord, and there is no one else.20
(1) Waltham, Lucky Planet, 11-12.
(2) Charles E. Hummel, The Galileo Connection: Resolving Conflicts Between Science and the Bible (Downers Grove, IL: InterVarsity Press, 1986), 91.
(3) Waltham, Lucky Planet, ix.
(4) Ibid, 1.
(5) Ibid., 163.
(6) Ibid., 2.
(8) Ibid., 184.
(9) Ibid., 185.
(10) Ward and Brownlee, The Life and Death of Planet Earth, 106-111.
(11) Ibid., 111.
(12) Ibid., 139, 144-148.
(13) Waltham, Lucky Planet, 120.
(15) Gribbin, Alone in the Universe, 79.
(16) Gonzalez, "Setting the Stage for Habitable Planets," 56.
(19) Gonzalez and Richards, The Privileged Planet, viii.
(20) Isaiah 45:18 (emphasis added).