Suppose we woke up tomorrow to learn that extraterrestrial life had been discovered. What difference would that make? Set aside the extreme scenarios of popular fiction. The truth will probably be more mundane – not massive spaceships suddenly filling the sky but, instead, microorganisms found deep inside an ice-covered Moon, a non-random radio signal from a distant star system, or the ruins of a long-dead alien civilisation. What difference might those discoveries make? Would they strengthen or weaken our faith in God, or science, or humanity? Would they force us to re-evaluate the importance of our own lives, values and projects?
In academic philosophy today, an interest in extraterrestrial life is regarded with some suspicion. This is a historical anomaly. In Ancient Greece, Epicureans argued that every possible form of life must recur infinitely many times in an infinite universe. In the 17th, 18th and 19th centuries, as modern astronomy demonstrated that our Earth is just another planet and our Sun just another star, the default hypothesis among informed observers was that the Universe is filled with habitable planets and intelligent life. One principal argument for this ‘pluralism’ was philosophical or theological: God (or Nature) does nothing in vain, and therefore such a vast cosmos could not be home to only one small race of rational beings.
My goal here is to explore some unexpected implications of the discovery of extraterrestrial life, and my conclusions are very speculative: extraterrestrial life would lend non-decisive support to several interesting and controversial philosophical positions. The discovery of life elsewhere would teach us that, while the Universe does have a purpose, human beings are irrelevant to that purpose. Aliens might well worship a God who is indifferent to us.
We know that life has emerged once. Why should it be so momentous to learn that it has emerged twice? The reason is that finding life elsewhere would radically change our picture of the Universe. At any point in time, humans will have explored only a tiny fraction of our galaxy, let alone the whole Universe. If life has emerged only once in that small sample, then it is possible that life on Earth is unique. (We might then use anthropic reasoning to explain why we inhabit the Universe’s only inhabited planet: where else could observers find themselves?) But suppose we discover that life has emerged twice within our tiny sample – once on Earth, then again somewhere else. It would follow that life must have emerged a vast number of times across the galaxy. The discovery of independently emerging life would thus teach us that life is ubiquitous. And that discovery could have very significant implications. (The restriction to ‘independently emerging’ life is necessary because life found on meteors, asteroids, Mars or the Moon might have the same origin as life on Earth.)
One perennial set of philosophical questions concerns the nature of values, norms and reasons. Are they objective, universal, mind-independent realities, or merely subjective, relative, mind-dependent human constructions? Normative non-naturalists claim that there are universal, objective, mind-independent facts about value, reason and morality that are not specific to any particular human culture, nor even to human nature in general. Any suitably sophisticated moral agent would perceive the same moral facts and be motivated by them. This strong objectivism is a minority position in contemporary ethics, but one that is gaining respectability – thanks in particular to recent work by the philosophers Thomas Nagel, T M Scanlon and the late Derek Parfit.
Normative non-naturalism combines several distinct claims. Moral statements assert facts; those facts are not reducible to the natural facts discovered by science; and some moral statements are true. When I say that murder is wrong, I claim that murder has the non-natural property of wrongness. If murder is wrong, then it does possess that property.
The normative non-naturalist position is anomalous within a purely naturalist worldview that recognises only the natural facts and properties postulated by science. Secular non-naturalists argue that normative non-naturalism is not as anomalous as it seems, because we already need non-natural facts to explain logic, mathematics or the normativity inherent in good scientific practice itself. Theists argue instead that normative non-naturalism makes much more sense if we already acknowledge a God who transcends the natural world. Either God creates the moral facts along with everything else, or God creates the Universe in response to independently existing normative facts. We will return to the link between theism and non-naturalism.
My central claim is that the discovery that life is ubiquitous would support normative non-naturalism. This is because, if life is ubiquitous, then we need non-naturalism to explain an otherwise puzzling fact. Given the vast number of potentially inhabited planets in the Universe, we would expect at least one extraterrestrial species to have either visited us or transformed the galaxy in ways that were clearly visible. Yet we see no one. Where is everybody? This is the Fermi Paradox, named for the physicist Enrico Fermi who posed the question in 1950.
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In his book If the Universe Is Teeming with Aliens … Where Is Everybody? (2002), the science writer Stephen Webb lists 75 answers to Fermi’s question. Some are jokes or variations on a theme. But most are distinct solutions that are not obviously crazy. I group those into four categories:
- Rarity of life: the specific conditions that make life on Earth possible are very rare.
- Rarity of intelligence: even if life is relatively common, the evolution of intelligent tool-making species requires very specific conditions that are extremely rare.
- Cantian(from can’t): even if intelligent tool-making species are relatively common, a feasibility barrier prevents the emergence of starfaring civilisations. Promising species inevitably destroy themselves or encounter resource constraints before they can conquer the stars.
- Wontian(from won’t): even if intelligent tool-making species are relatively common, a motivational barrier prevents the emergence of starfaring civilisations. Every intelligent species who could conquer the stars chooses not to.
Drawing on anecdotal evidence, Webb suggests that physicists, impressed by the vastness of the Universe, typically assume that life is ubiquitous, and therefore favour Cantian or Wontian solutions; meanwhile, biological scientists, impressed by the complexity of life, typically prefer solutions based on the rarity of life or intelligence.
The discovery that life is ubiquitous would obviously rule out any explanation based on the rarity of life. And if we found evidence of intelligent life elsewhere, we would be forced to conclude that intelligence was not rare either. Of course, if we discovered life elsewhere, then in one sense the Fermi Paradox would simply be dissolved; there is no need to explain why we see no evidence of life elsewhere once we do see it! But the deeper puzzle would remain: if life is ubiquitous, why don’t we see much more evidence of alien civilisations? We must still explain what the astrophysicist and science fiction writer David Brin in 1983 called ‘the Great Silence’.
By ruling out rarity-based solutions, the discovery that life is ubiquitous thereby raises the probability of other credible solutions, especially Cantianism and Wontianism. In so doing, it also supports normative non-naturalism.
Even if some species eschew visibility, why should we expect every intelligent species to do so?
Why would intelligent species choose not to make themselves visible? Webb lists 25 distinct Wontian solutions that have been seriously defended. Here are some of them: advanced extraterrestrials keep us isolated in an intergalactic zoo, as subjects of laboratory experiments, or because any inhabited planet is a non-renewable source of information; extraterrestrial environmentalists are either not interested in colonising or transforming the galaxy, or else they believe that this would be wrong; cautious aliens are hiding because they fear that the Universe is silent because some genocidal species destroys anyone who becomes visible; extraterrestrials are postbiological machines with no interest in stars, planets, biological life or communicating with us; aliens have passed through the ‘Singularity’ and disappeared into black holes, transcended to a higher dimension, created a new universe, or migrated to a virtual reality; advanced aliens congregate around black holes where energy is most abundant, or in the cold outer reaches of the galaxy where computational processing is most efficient; and so on.
Any Wontian solution faces one obvious objection. One non-Wontian species – or even one maverick group or individual – could do things that would be clearly visible for a very long time. To solve the Fermi Paradox, Wontian motivations must be universal, not merely very widespread. But surely that degree of uniformity is simply implausible. Even if some species or individuals eschew visibility, why should we expect every intelligent species to do so? Wontians are open to an accusation of anthropomorphism or parochialism – projecting their own individual preferences onto all intelligent beings.
Of course, Cantianism faces a parallel objection. Even if most intelligent, tool-using species face a feasibility constraint, why should we believe they all do? Cantians must defend a universal feasibility barrier. And that natural universality seems as suspect as the Wontian’s motivational one. Isn’t it more likely that, sooner or later, one lucky species will have sufficient time and resources to escape the feasibility constraint? If Wontians can dissolve their parochialism objection, that will give them a significant advantage over Cantians.
Wontians need universal motivations that are not specific to species or individuals. This is where normative non-naturalism comes in. Armed with non-naturalism, Wontians can argue as follows. Objective values are built into the fabric of the Universe; the discovery of those values is essential if one is to understand the Universe sufficiently well enough to manipulate it successfully on a large and lasting scale; and that discovery transforms any rational being’s motivations. Aliens smart enough to conquer the stars will inevitably abandon their previous plans and follow those universal values.
I call this solution to the Fermi Paradox Kantian Wontianism, because the idea that knowledge of universal values is intrinsically motivating for all rational beings is associated with the 19th-century Prussian philosopher Immanuel Kant. (One can be a Kantian in this sense without endorsing any other details of Kant’s philosophy. In particular, Kant himself was not a normative non-naturalist.) Although it is very controversial, this strange view might be our best solution to the Fermi Paradox, especially if we discover life elsewhere.
Wontians need normative facts that reliably motivate all suitably intelligent beings – whatever their biological species. This rules out normative naturalism, where normative facts are reducible to natural facts, and human ethics is derived from our specific evolved human nature. Alien species might have very different natures, and therefore their moral facts would be quite different from ours. Wontians cannot limit their ontology to natural facts. They need non-natural normative facts that transcend biological differences. In the contemporary intellectual landscape, this is controversial but not absurd. While naturalism is the dominant worldview in analytic philosophy, non-naturalism is becoming increasingly philosophically respectable.
Kantian philosophers claim only that the motivations of rational agents should converge insofar as they behave rationally. They admit that actual agents invariably fall short. Wontians must therefore go beyond Kant and argue that, beyond a certain threshold of knowledge or understanding, all rational agents reliably will behave rationally. This might seem simply absurd. Human motivations obviously do not converge. And beings no more sophisticated than ourselves, armed with current technologies such as radio waves or nuclear weapons, surely could attract the attention of very distant observers. Doesn’t our own existence refute the Kantian Wontian claim that all beings who could become visible will reliably respond to non-natural normative facts?
In reply, Kantian Wontians would say that fleeting visibility is not enough to disturb the Great Silence. Even if short-lived alien civilisations were common, the age and size of the Universe are so great that observers in any particular place and time would almost certainly see nothing. The Fermi Paradox arises because we assume that, if there really are vast numbers of aliens out there, then sooner or later one of them will have built a civilisation that lasts. We expect to see that lasting civilisation, and we are puzzled by its absence.
This offers a strange vision of aliens with radically different evolutionary histories converging on values that humans reject
Kantian Wontians can then argue that maintaining a lasting visible civilisation demands a level of understanding of the nature of the Universe that inevitably delivers knowledge of objective and intrinsically motivating values. This is not absurd if one is already sympathetic to normative non-naturalism. If objective values are built into the fabric of the Universe, then perhaps agents can understand that Universe well enough to manipulate it successfully on a large and lasting scale only if they also find those values intrinsically motivating.
But Kantianism alone is not sufficient to save Wontianism. Many possible values would encourage the creation of a visible galactic civilisation. Consider total utilitarianism, which seeks to maximise the welfare of sentient beings. Aliens who recognised this value would seek to transform the galaxy by creating as many happy beings as possible. We would notice if someone had done that!
Kantian Wontians must defend very different values. As we saw earlier, one possibility is environmentalist non-interference – a quietist desire to contemplate the Universe without imposing one’s will on it. Other possibilities include maximising complexity by living unobserved at the edge of a black hole, transcending to a higher dimension, or even a nihilist conviction that nothing is worth doing. These are minority values in contemporary culture, of course, but they are not unintelligible. Kantian Wontians can remain agnostic about the precise content of non-natural values. Anything that rules out lasting visibility will do.
The Kantian Wontian solution to the Fermi Paradox offers a strange vision, where aliens with radically different evolutionary histories converge on values that many actual humans reject. If we are already committed to expansionist values such as welfare maximisation, then we might struggle to take these Wontian values seriously.
The philosopher Robert Nozick suggested in 1981, in a different context, that ‘someone who proposes a non-strange answer shows that he did not understand this question’. (Nozick’s question was: why is there something rather than nothing?) Philosophical questions often call for strange or disturbing answers. Once we discover life elsewhere, Wontianism could be the least strange explanation left on the table. How else can we solve the Fermi Paradox or explain the Great Silence?
If we discovered that life was ubiquitous, then Kantian Wontianism would be the least unsatisfactory solution to the Fermi Paradox, and normative non-naturalism is essential to any successful Kantian Wontian story. Once we grant these conclusions, it then follows that the discovery of independently originating life supports normative non-naturalism – in the modest sense that this new information raises the probability that normative non-naturalism is true. Philosophical claims can be supported by empirical facts in surprising ways.
Normative non-naturalism and Kantianism both seem very anomalous against the background of an otherwise purely naturalist metaphysic. They are much less anomalous if we instead endorse a theist metaphysic. Kantian Wontian theists can argue as follows. Physicists seek a physical ‘theory of everything’ to explain, not only how the Universe works, but why it exists. For all anyone knows, future (or alien) scientists who complete the theory of everything might need to posit God, cosmic purpose or cosmic value. Belief in divine values is exactly the sort of thing that would reliably transform one’s motivations. Aliens who discover why the Universe exists will abandon their previous inclinations, and embrace the purposes of God.
Theism and Kantian non-naturalism are mutually supporting. Both are independently plausible, and each supports the other. If there is a God, then knowledge of God’s purposes might be enough to transform the motivations of all rational beings. Conversely, many arguments for the existence of God implicitly rely on evaluative claims that cannot be reduced to natural facts about this particular Universe. For instance, many theists argue that we must posit a creator God because the existence of this Universe cries out for explanation. This argument is much more compelling if theists can argue that, out of all the possible universes, this one is strikingly valuable. If there is nothing independently special about this Universe, then why not accept its existence as merely a cosmic brute fact? But comparing the value of possible universes makes sense only if we presume non-natural values that transcend those physical universes.
A theme of contemporary philosophy of religion is that our Universe is religiously ambiguous. It can reasonably be interpreted in radically different ways: realist or idealist, naturalist or non-naturalist, theist or atheist. Our currently available evidence radically underdetermines our metaphysics. Religious ambiguity itself might be peculiar to our present human condition. We inevitably and reasonably disagree, but perhaps everyone capable of establishing a galactic supercivilisation will agree. In our present state of religious ambiguity, we have no idea what they will agree about. Atheists take it for granted that space-faring aliens will have outgrown religion. But the Great Silence points in another direction. Kantian Wontian solutions work best if all sufficiently advanced aliens converge on belief in God.
Theism supports Kantianism. By supporting Kantian Wontianism, the discovery that life is ubiquitous thus indirectly supports theism. But what kind of theism? What sort of universe would a Kantian Wontian God create? Could the God of traditional theism create a universe where life was ubiquitous?
Many theist religions stress the cosmic uniqueness of human beings – or even particular events in human history. This suggests that theists must insist that we are alone in the Universe. But another perennial strand of theist thinking points in the opposite direction. If we are alone, then this cannot be the best possible world. If humanity is valuable, then a possible world containing many other rational God-loving species would be better. If life is good, won’t God create a Universe teeming with every possible kind of life? Leibniz thought so, and argued that this best of all possible worlds is infinitely filled with life. (He supported this claim by citing the world of microscopic organisms revealed by the recently discovered microscope.)
If the Universe teems with life, then there are other candidates for the cosmically decisive role previously held only by humans
If life turns out to be ubiquitous, then theists must obviously re-evaluate humanity’s place in the divine plan. But many theists, throughout the centuries, have been confident that this challenge can be met. After all, theists already believe that God has infinite love for every individual creature, and that this does nothing to diminish God’s love for me. Why should it matter that God’s love also extends to innumerably many alien individuals as well?
The discovery of extraterrestrial life would thus support theism in two ways. We saw earlier that independently originating life would raise the probability of two other hypotheses that support theism, namely Kantianism and normative non-naturalism. We now see that ubiquitous life would also allow theists to agree with Leibniz that God has, indeed, created the best of all possible worlds.
However, ubiquitous life would also create new and unexpected problems for theism, by undermining some traditional arguments for divine benevolence and thus making it harder to believe that God cares about us. Theists argue that the best explanation for the existence of this Universe is that it was created by a benevolent God. One prima facie counter-example is offered by widespread, apparently gratuitous evil. This suggests instead a creator who is indifferent to the fate of individual human beings. Theists reply that, unless we suppose that God cares about rationality, knowledge or intelligibility, we cannot explain why this Universe is governed by regular intelligible mathematical laws. The Universe appears to be designed to be understood by its own inhabitants. So far as we know, we are the only inhabitants who could possibly understand it. So we must be essential to God’s plan.
The discovery that life is ubiquitous weakens this argument. If the Universe is teeming with life, then there are many other candidates for the cosmically decisive role previously occupiable only by human beings. Perhaps God cares that there be some rational beings, but is indifferent to their species, identity or numbers. Or perhaps God cares only for creatures who reach some threshold of wisdom or intellect that humans could never attain. God cares for beings who are sufficiently rational, intelligent, free or lovable. But it is human arrogance to assume that we are among them!
The intelligibility of the Universe is prima facie evidence that God cares for us. Human suffering is prima facie evidence that God does not. The discovery of ubiquitous life tips the balance against divine benevolence, by opening up alternative explanations for intelligibility.
In my bookPurpose in the Universe (2015), I defend a new alternative to both atheism and (traditional) theism. Ananthropocentric purposivism (AP) holds that the Universe has a purpose and that humans are irrelevant to that purpose. If there is a God, then God cares about what matters, but we do not matter to God. Western theism has always combined both God-centred and human-centred elements. While we are created in God’s image, there is a vast distance between our feeble human concerns and God’s incomprehensible divine plan. AP pushes God-centred theism to extremes, abandoning divine benevolence altogether.
If aliens converge on a metaphysical view, it could be something like ananthropocentric purposivism. Perhaps all advanced civilisations are Wontians because they are simply indifferent to anything we care about, including communication with beings such as us. If life is ubiquitous, this might be the best solution to the Fermi Paradox. But it paints a very unsettling picture of our place in the cosmos.
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is professor of philosophy at University of Auckland in New Zealand, and professor of moral and political philosophy at the University of St Andrews in Scotland. He is the author of Purpose in the Universe: The Moral and Metaphysical Case for Ananthropic Purposivism (2015).
by Les Johnson
Figure 1 — The Earth as seen from Apollo 17. (Image courtesy of NASA.)
The aliens are not among us. The truth is out there—and it is that we are not being visited by extraterrestrials. A flying saucer didn’t crash at Roswell, we aren’t reverse engineering alien technology at Area 51, and otherworldly tourists, anatomists or anthropologists are abducting no one from their homes.
I’ve said it and I’ve said it with certainty. Could I be wrong? Yes, and I will be the first to admit my mistake when someone brings forth credible evidence that our planet is being visited by creatures from another world. But until then, I will be a skeptic on this issue.
Carl Sagan said, “Extraordinary claims require extraordinary evidence.” Now, I may not be in the same league as Carl Sagan, but in this case I agree with him completely. Stories of strange lights in the sky, sightings of aircraft performing seemingly impossible acrobatic maneuvers before “shooting straight up,” presumably into space, or recollections of missing time after observing one of these weird aerial phenomena do not qualify as extraordinary evidence.
But what about the pictures? Since there have been cameras, there have been fuzzy pictures of these strange objects in the night sky. Most are obviously fake, some are clearly explainable, and, yes, some are truly puzzling—but a puzzling object seen from an aircraft window does not an alien spaceship make! Much simpler explanations (than alien visitors) are almost certainly waiting in the wings to be proffered.
I don’t want to get into a debate with true believers out there who have seen something they cannot explain, or have read about an encounter that had to be with a creature from another world. Sending me pictures taken with your cell phone camera will not convince me. No, the evidence would have to be something akin to Gort standing on the National Mall for me to be convinced aliens are visiting us.
Why am I so adamant? Why would I take a position that will almost certainly cause many readers to call me “closed minded” and a veritable Luddite? Because the thought of us being visited by aliens from another planet at this time simply is so highly improbable as to be, for all practical purposes, impossible.
Let me be clear. I do believe that there may be other life in the universe. I find the thought of humanity being alone in the universe to be not only depressing, but also arrogant. Surely, if it can happen here, with us, then it can happen elsewhere also. But, almost as certainly, life is rare. Intelligent tool-using life is likely even more rare. It is incredibly unlikely that intelligent, tool using life just happens to come visit us during a brief moment in the history of our species when are beginning to explore space ourselves.
I’d better explain how I come to this conclusion.
SPACE IS BIG
(Talk about an understatement.) In a previous essay for Baen, I discussed the enormous size of the universe in great detail. To avoid being redundant, I’ll attempt to summarize how big the universe is and why that this is important and relevant to the topic at hand. The Earth is ninety-three million miles from the Sun. If we imagine that the planets in our solar system can be represented by a series of marbles orbiting the Sun in the center of a room, then we can shrink this ninety-three million mile distance to one inch. (Scientists do this and instead of an inch, they call this distance an Astronomical Unit, or “AU.”) On this scale, Jupiter would be five inches from the Sun and the dwarf planet Pluto would be at a mere forty inches. The nearest star, Proxima Centauri, would be about four miles away. And that is the nearest star. The light from Proxima Centauri takes over four years to reach us traveling at 186,000 miles per second. The distance from here to Alpha Centauri is so large that scientists had to invent yet another term to make it easier to comprehend—the light year. One light year is the distance light travels in one year, making Proxima Centauri about 4.2 light years distant. Our galaxy, which contains hundreds of billions of stars, is over one hundred thousand light years across. The nearest galaxy to our own, the Andromeda Galaxy, is over two-and-a-half-million light years away.
Figure 2—The Omega Centauri star cluster contains many stars like our sun. If life were to develop on a planet around one of these stars, it would take 15,000 years for an alien spaceship to get to Earth even if they were traveling at the Speed of Light. (Image courtesy of the NASA and the Space Telescope Science Institute.)
According to what we know about how the universe works, our knowledge of physics, there is a natural speed limit for us and for any aliens out there: the speed of light. 186,000 miles per second is the fastest anything can go. We’ve never observed anything going faster and it appears that it would actually take infinite energy to accelerate anything other than light to that speed. So the best we, or any aliens, can hope to achieve is some speed that is a significant fraction of the speed of light. If we assume that we can get a spacecraft the size of the Space Shuttle to travel 75 percent of the speed of light (which is pretty darn fast, considering that Voyager 1, our fastest spacecraft, is traveling at about 38,000 miles per hour or 0.005 percent the speed of light), then it would require at least 9.35 X 1022 joules of energy. Wow. At that speed, the journey would take about five-and-a-half years and require one hundred percent of humanity’s current global energy consumption for 195 years! All of that energy would have to be somehow provided to the spacecraft. And that’s just to get here from the nearest star. Crossing the gulf from farther away would lengthen the travel time considerably, only making the duration of such journeys even harder to believe when compared to a human, and presumably, alien lifetime.
All right, so an interstellar voyage will take a while and require lots of energy. Surely, out there somewhere, someone or something may have the interest and ability to take the trip. Well, yes, perhaps, but it doesn’t seem very likely.
LIFE IS RARE
In our solar system we know of only one place life exists. Earth. There are claims that fossilized primitive life has been found in meteorites from Mars or elsewhere, but the data is inconclusive and I must invoke Sagan’s requirement once again. Bring on the extraordinary evidence.
We’ve looked out into the cosmos and found that there are many, many stars and we are now learning that planetary systems are common around them. We’ve also found that the vast majority of these stars and planetary systems are inhospitable to life as we know it. (Yes, the “as we know it” part will be a red flag for some. I’m not entertaining the idea of fanciful beings composed of "pure" energy—whatever that is—nor those that normally occupy extra-dimensional spaces. I’m talking about life based on chemistry.) Life is, by its very nature, complex and organized. And for it to develop requires somewhat stable conditions that almost certainly includes a stable planetary orbit. This rules out many of the planets we’ve found around other stars that have wildly elliptical orbits, or orbits that are not circular, which produce wildly varying climactic conditions not suitable for life to exist.
The star itself must be stable and boring. A variable star, one that changes its energy output dramatically over some period of time, would not produce the kind of stability needed for life to develop. Imagine Mars being warm and wet long enough for primitive life to take hold and then it being plunged into its current desiccated state, with these wild extremes repeating on cycles of a few million years each.
The stellar neighborhood must be stable and boring. Having a star explode and go “nova” would be a very bad day for planets circling nearby stars. Massive stellar explosions, called supernova, occur somewhere in the universe virtually every day. Being on a planet within about a thousand light years of a supernova would likely have the same effect as sterilizing surgical equipment, killing not only bacteria but any higher order life.
The planetary system cannot have too many asteroids and comets careening around because sooner or later one of them will hit the planet bearing life and restart the evolutionary process in much the same way ours was restarted in the event that wiped out the dinosaurs. Fortunately for us, in our solar system, these events are not very common on a timescale of millions of years.
The life-bearing world would have to be in the Goldilocks Zone (not too hot, not too cold) for life based on chemistry as we know it to exist. If the planet is too close to the Sun or if it has the “wrong” atmospheric chemistry, you get the hellish conditions we find on Venus. If it is a little too small or too far away from its star, you get the cold and dry Mars.
And from here it gets more complicated still. There are entire books written on the subject of why the Earth may be unique in its ability to evolve and sustain life. I don’t want to get into that topic here so I will simply summarize the conclusion I’ve reached: The long-term "stable" conditions favorable for the development and evolution of life are exceedingly rare.
INTELLIGENT, TOOL-USING ALIENS ARE VERY, VERY, RARE
Now, Les, how can you possibly know that? Putting one’s religious beliefs aside, life appears to have developed and evolved on planet Earth over about four billion years. (I’ll talk about Deep Time a little bit later. For now, let’s just say that four billion years, that’s 4,000,000,000 years, is a long, long time.) Biologists can show that we humans are merely the latest development of a series of evolutionary processes and historical events spanning this chasm of time. We are not the inevitable byproduct of evolution. There is a common misconception about evolutionary theory that many people believe—that evolutionary processes are somehow guided (self guided?) to create beings of ever-increasing complexity and intelligence until it finally produces an intelligent, self-aware species like us and then, voila! We are here and evolution’s purpose is fulfilled.
Alas, this is not the case. The Theory of Evolution says that species evolve to survive and those physical characteristics that allow a species to survive, prosper and reproduce will propagated and preserved as long as they are useful survival characteristics. If a mutation doesn’t serve a useful purpose in keeping the creature in which the mutation occurred alive long enough to reproduce, then it is not likely to be one that is passed on to future generations.
In evolution, there is another aspect that is often overlooked in general discussion, even by my biologist friends: history. The world is not simply a tug of war between competing species with generations born, living and dying, some passing on their more successful characteristics to future generations. No, events play a pivotal role and some events are true game changers. Arguably one of the most successful species ever to inhabit the Earth, the dinosaurs, had their reign end rather abruptly about 75 million years ago when an errant meteor is thought to have hit the Earth, dramatically changing the climate of the entire planet, making it less hospitable to dinosaurs and more hospitable to the small, furry mammals from whence we descended. This pivotal event in the Earth’s history is the one that allows us to exist and ponder how we happen to be here.
But, as they say, there is more to the story. What characteristics must a species have to build spaceships that would travel between the stars?
Alien life would have to be intelligent in order to figure out how to build spaceships. Okay, so intelligence is a survival trait that has allowed humanity to survive and reproduce. But is it the only trait required for a technological society? Not by a long shot.
Consider dolphins. Many believe that dolphins are intelligent, that they have language and that they experience many of the higher-order thought processes that we previously considered being the sole province of humanity. That’s just great for the dolphins—as they swim around in the ocean, seemingly carefree, playing with each other and amusing human biologists and tourists alike. But without fire they will never be able to alter their environment to build spaceships.
Figure 3—No matter how intelligent dolphins may be, they will not be building spaceships anytime soon. (Image courtesy of Allen McCloud.)
Consider the dolphins again and let’s assume they are, or will be able to be, as intelligent as humans. Even without the fire issue, how will they be able to manipulate their environment to make things without hands and fingers? Better yet, how could they do this without opposable thumbs? Without the ability to grasp, making tools is much more difficult and making complex tools is likely impossible. So, from an evolution-to-space-traveling-species point of view, being a dolphin is a dead end.
What, then, is the likelihood of natural processes creating life and that life evolving a species that is intelligent, capable of using tools, making fire, and curious enough to invent space travel?
It is clearly not zero, after all, we’re in the process of doing just that. But I can say it is a very low probability.
DEEP TIME IS UNDERESTIMATED
(Yes, that is another understatement.) We humans in the developed world have, on average, a lifespan of fifty to eighty years. We have recorded history going back a few thousand years. There is archeological evidence that humans have been around for one hundred thousand years; most of that time was spent in the “survival mode” without a whole lot in the way of civilization being built, let alone spaceships.
In the context of the history of the Earth, recorded human civilization occupies about 0.00008 percent of Earth’s history. Let me put that another way—the sum total of human civilization, in years, rounds to zero when considering the age of the Earth, let alone the age of the universe.
Current estimates place the age of the universe at about 13.75 billion years. That’s 13,750,000,000 years for those of you who like to see all the zeros. The earliest stars in the universe probably didn’t give rise to life because the early universe was lacking most of the elements in the periodic table – including most of those we require for our physical bodies to exist. Elements lighter than iron, including the carbon, nitrogen and oxygen which, when combined with hydrogen, make up much of the stuff from which we are made, were formed inside those early stars as their fusion processes converted primordial hydrogen and helium into them. Elements heavier than iron had to wait for massive stars to explode as novae or supernovae in order to be created. It took time for these processes to occur and it is because of them that we are here. To again quote Carl Sagan, “We are made of star stuff.”
The Earth is about 4.5 billion years old. In that time, evolution has produced many species, some of which have been quite successful—from an evolutionary point of view. Consider again, for example, the dinosaurs. They reigned supreme over the Earth for about 180 million years, disappearing about 75 million years ago. According to fossil and genetic evidence, modern humans have been around for only about 100,000 years, or 0.1 million years. Hmmm. 75 million versus 0.1 million—it sounds like those dinosaurs had a pretty good run.
But what does this have to do with alien visitors? Well, if you strictly play a numbers game and look at the age of the Earth, not even considering the age of the universe, what is the probability that alien visitors who are, by all alleged accounts, no more than a few hundred years ahead of us technologically, would just happen to start paying a visit to the Earth when we humans are here to see them? Looking at our fractional time of existence on the planet, which is roughly 100,000 divided by 4,500,000,000 (0.00002 or 0.002 percent), the chances are slim that they would be here at a time when humans exist at all. Slimmer still is the chance of them happening by when we have a technological civilization. If we liberally define a “technological civilization” as one in which we know that the Earth revolves around the Sun, then we can date its beginning with the publication of De revolutionibus Orbium Coelestium (On the Revolutions of the Celestial Spheres) by Nicolaus Copernicus in 1543—merely ~500 years ago. What is the chance we’ve been visited by aliens since that time? Roughly 500/4,500,000,000 = 0.0000001 or 0.00001 percent. Folks, that is a pretty small number.
Figure 4—A diagram of the solar system as Copernicus envisioned it. (From his 1543 book, De revolutionibus Orbium Coelestium.)
Let me be blunt: the chance of an alien species evolving, developing intelligence with the physical characteristics that allow them to make fire and use tools, evolving to the point at which they can travel through space (obeying nature’s speed limit), crossing immense distances, and just happening to reach Earth at a time that we, too, are starting to explore space is, within any reasonable rounding error, ZERO.
At this point, some might say, “But Les, you are now underestimating the effect of deep time! Science and technology are advancing at an amazing pace. Who’s to say that ET hasn’t found a way to tap the quantum vacuum energy (or some other breakthrough). Look how much we’ve accomplished in the last 500 years—maybe the extraterrestrials are a thousand years ahead of us technologically.”
My conclusion is unchanged. Look at the odds. It wouldn’t make a difference if they were 50,000 years ahead of us technologically. The odds of them being here, now, and with a technology that we would recognize are too small to worry about. Might such a super civilization have visited the Earth in the past? Perhaps. If so, then it is far more likely that they arrived to find an Earth populated with dinosaurs and not human beings.
Actually, I truly wish they were here. I’d like to think that the universe abounds with intelligent, tool-using species that travel between the stars. I want there to be a Federation of Planets (thank you Gene Roddenberry) with myriad species learning from each other and exploring the great unknown that is the universe. I am not so naïve to assume that in such a future there wouldn’t be conflict. I can put up with conflict in my wish list for the future; though I doubt there would be massive interstellar wars given the impracticality of interstellar travel to begin with. But that is another essay waiting to be written. . . .
Copyright © 2011 by Les Johnson