All of us have seen extraterrestrials — on TV, in the movie theater, or in computer games. Real ones still elude us.
But from October 16 through 18 last year scientists sent a brief message, repeated nine times, to a nearby red dwarf star that is surrounded by a potentially habitable planet. Though what “nearby” means to astronomers is in this case 12½ light years away. This is how long the message, sent in the high-frequency radio band, will take to get there. And if technology-savvy aliens live there, we could hear from them any time after 2041.
What would happen if we did receive an ET signal has been the subject of much speculation. Some among the New Atheists are hopeful that it would mean the end of religion, at least of Christianity. Others are convinced that as far as religion is concerned, nothing would change. Both extremes strike me as wishful thinking. Contact with aliens will not suddenly wipe out religion. Christianity never had much problem with the idea that an omnipotent God could create other rational beings. In 1277 the bishop of Paris even went so far as to proclaim it heretical to think otherwise.
On the other hand, I do think that proof for the existence of aliens would have major consequences on how we think of ourselves. Even if we try to dismiss the notion, the media would certainly do their best to convince us of it. Surely this would have important pastoral consequences. A few theologians have taken up the challenge to think this through, among them David Wilkinson 1 and Ted Peters 2. A new book about astrotheology, as this field is called, has also been announced for later this year by the Center for Theology and the Natural Sciences in Berkeley.
So much for being prepared. But how likely is imminent contact? If even a conversation at lightspeed takes decades, it is very unlikely that we will meet an alien any time soon. Traveling faster than light is fascinating science fiction. But in the real world it is not merely something that we have not yet invented; it is a violation of fundamental physical laws as we understand them. Scientists are always cautious about never saying never, but in this case we are rather confident that our understanding is correct. Signals can travel at lightspeed, but physical spaceships cannot.
That much was known already in the 1960s, which is why the search for extraterrestrial intelligence, or SETI, concentrated on scanning for electromagnetic radiation. Frank Drake, known for his equation describing the requirements for intelligent life, was an early promoter of not only listening for, but also sending messages. Twenty-five years ago he estimated that there are ten thousand advanced extraterrestrial civilizations in the Milky Way and hoped to hear from one of them by the year 2000 3.
To gain some perspective on this premature optimism, we need to look at the larger issue of how not only science, but also our imagination and self-image as humans affect our thinking about possible aliens. The 1960s were not only the beginning of human space flight, but also of The Jetsons and Star Trek on TV, futuristic architecture, and other symbols of a glorious technological future. Western society seemed to know what progress was, and naturally if there were other beings like us, they would progress along the same lines.
A more important but less conspicuous aspect of this development was a changing view of human uniqueness. Since Copernicus, so the conventional story goes, it had become increasingly clear that we are simply one race on an average planet around an average star in an unremarkable place within the Milky Way. Sometimes this fact has been turned into an argument against Christianity and its claim that we are special in the eyes of God.
I will not comment on the fact that the humility which this discovery ought to engender is rather conspicuously absent among these critics. Rather I want to point out a less obvious problem in the argument why this supposedly diminished role of humans should lead us to conclude that there are thousands of technological civilizations in the galaxy. The assumption behind this narrative is that there are thousands of life forms that are social like humans, have technology like humans, and have desires like humans to communicate with other galactic beings. In other words, this Copernican argument may have seemed to devalue human self-image, but at the same time has replaced it with the galactic pervasiveness of features exactly like the ones we value in ourselves.
Until fairly recently it was mostly astronomers and physicists who talked about extraterrestrial life. But around the turn to the 21st century more evolutionary biologists became interested in this issue as well. Science fiction and art had of course imagined extraterrestrial beings much earlier, but often with little thought how evolution would constrain possible life forms. We still do not know what the evolutionary possibilities are on other worlds, because all life forms on Earth are most likely descended from a single line. Life forms on Earth that inhabit similar environments evolve to look similar to each other, even if they are descended from ancestors that had very little in common. For example, Australian wombats look and live much like groundhogs, even though the two lines of ancestry diverged long ago when dinosaurs were still going strong. This phenomenon is known as convergent evolution. But it does not follow that this will necessarily apply to a planet with a different evolutionary history. Even if the environment there were very Earth-like, its life forms might still be very different from the ones familiar from our home planet.
Physical scientists hope that the large number of potentially habitable planets and moons in our galaxy means that we could shortly make contact with ET. There is an assumption behind this that if evolution is allowed to run its course uninhibited, it would inevitably culminate in spacefaring intelligence. But if we are wrong about the inevitability of convergence, it is entirely possible that there are extraterrestrials with the same or higher degree of organic complexity than humans, but without spacefaring ambitions. Given how different they might be from us it may be a matter of opinion whether we call them intelligent or not, but that will not be a decision that confronts us any time soon; we will have to develop the capability of finding them first. If they are not sending signals, finding them will not be easy. We might eventually learn enough about some extrasolar planets to suspect life-like chemistry. But anything more conclusive, like finding out what their life forms look like, is a very long way in the future.
Another manifestation of the idea that aliens would resemble us in many ways is the assumption that we could actually understand a message that was sent to us. This is far from clear. Although it is possible to conclude on physical grounds that a signal we receive is likely a deliberate transmission, decoding the content is more problematic than we perhaps imagine. Experts interested in sending messages have developed sophisticated concepts of how we might establish some kind of common language. This would start with mathematics and could establish some scientific concepts by pointing to universal mathematical relationships in nature, such as the periodic table of elements. But how we would get from this to anything resembling a natural language is as yet unfathomable, nor do I think that Artificial Intelligence could help us much.
It is also entirely possible that extraterrestrials who share the human-like desire to contact their neighbors are after all so rare and therefore so far away that we can never get in touch with any of them. The size of our Milky Way galaxy is in the range of 100,000 light years. The vast majority of aliens on any of the habitable objects within it would have had to send a message to us long before the beginning of our own recorded history to be arriving today. And if we widen our perspective, we realize that not only is much of the universe far away, but the bigger part of it is theoretically inaccessible. This is a combination of the finite speed of light with the steady expansion of the universe. What goes on beyond this cosmic horizon of information is forever hidden from us.
Is this uncertainty about making contact in itself theologically significant? I am reminded of words from the Chronicles of Narnia by C. S. Lewis. The Lion Aslan, Narnia’s Christ figure, repeatedly tells the children to whom he appears, “I am telling you your story, not someone else’s. I tell no one any story but his (her) own.” What provides me with the story of someone else is this person’s free disclosure, and it is this shared gift that makes it part of my own story. Perhaps something like this is true, beyond the individual meaning, of humanity as a whole.
Maybe the spiritual stories that we call revelation are likewise just our own stories, not someone else’s. And if this is true, then the only way that the stories of extraterrestrial beings will become part of our own is through freely offered self-disclosure on their part.
Alfred Kracher received a Ph.D. in chemistry from the University of Vienna, Austria. He worked at the Natural History Museum in Vienna, UCLA, the Universities of New Mexico and of Arkansas, and at Iowa State University, from where he retired in 2010. Through his professional focus in cosmochemistry and materials science, he also became involved in the search for extraterrestrial life. In addition, he has written papers and articles on the wider social implications of science and its relationship to religion.