Extraterrestrial

by Avi Loeb

  Second, it is quite possible that they will worry about their reception by our species as much as we may worry over their intentions. Whatever information they have concerning life on Earth, it will be partial and much of it terribly out of date. Just as terrestrial astronomers look back into time when they look out into space, so do extraterrestrial astronomers. The laws of physics, after all, will apply to our alien counterparts’ technologies no less than they apply to ours, and based on everything we have learned to date, this suggests that the distances traveled will encourage modesty. Consider that all of humanity’s interstellar vehicles are doomed to one-way journeys; the same will likely prove true for the extraterrestrial.

  Third, I have to imagine that among the alien intelligence we eventually encounter, there will be a few existentialists. I don’t think that is a fantastical concept. Just as the intellectual history of humanity allowed the existential school of thought to flourish on Earth, informing what came after it, I suspect the same will prove true for alien intelligence. I believe that they, no less than us, will have spent a civilization’s lifetime confronting life’s most stubborn mysteries, the ones that are impossible to move from the miraculous to the mundane.

  There is no mystery more fundamental than the meaning of life. Some of us are cast in the role of Hamlet, some of us in the roles of Rosencrantz and Guildenstern, but all of us experience the sensation of striding across a stage without a script. It is the rare human and, I suspect, sentient being who never seeks an answer to the question: What’s it all about?

  Early in my life I turned to the existential philosophers, especially Albert Camus, for guidance. Among his works, one that resonated with me was The Myth of Sisyphus. According to Greek mythology, Sisyphus was punished by the gods and forced for all eternity to roll a heavy boulder up a hill only for it to roll back down once he managed to get it nearly to the top. Camus believed that this was analogous to the absurd condition of man, who was likewise caught in a perpetual cycle as he tried to understand an inexplicable world. Sentient life’s common circumstance, to live and die without ever learning why, was, Camus believed, absurd. I believe that other sentient beings—who are bound by intellectual limitations, just as we are—will inevitably arrive at the same conclusion: life is absurd.

  It is difficult to remain arrogant in the face of the absurd. Humility is the more apt posture. The more we see evidence of humankind cultivating humility when confronted with the awesome, the more we have reason to anticipate the same from extraterrestrial civilizations.

  Over our history, humans have repeatedly sought to fight for causes that were more inspiring than their private lives—usually causes having to do with terrestrial concerns, such as nationality and religion. To take another example chosen at random, during the Second World War, Japanese soldiers were willing to sacrifice their lives for the sake of their emperor, Hirohito. But in view of our recent realization that there are approximately a zetta (or 1,000,000,000,000,000,000,000) of habitable planets in the observable universe, the emperor’s status cannot be more significant than that of an ant hugging a single grain of sand on a huge beach. And what is true of an emperor is no less true for a soldier or anyone else on Earth.

  We would do well to look up and look beyond that grain of sand.

  Perhaps, rather than behaving like outsize actors in puny roles, we should adopt the perspective of spectators and simply enjoy the dazzling show all around us. And in the broad spirit of stopping to smell the roses (or inspect the seashells), there is much for the spectator to enjoy, both on Earth and off it. If the rich spectacle of events on our planet is insufficiently inspiring, we can use our telescopes to witness an even wider variety of dramas. Within the next decade, the Vera C. Rubin Observatory conducting the Legacy Survey of Space and Time, a ten-year effort to repeatedly photograph more than half of the night sky, will deliver five hundred petabytes of images from our cosmic environment. I dream that one of the survey’s results will be a new streaming-media subscription service—this one broadcasting the entire universe.

  Not all of us can remain spectators, of course. Some of us will aspire to make a difference. The ways to contribute—and I will always argue that no pursuit holds as much promise of contribution than the sciences—are myriad, but it will help if we give ourselves an objective commensurate with our capacity to wonder, and to hope.

  …

  Pondering the values of other civilizations ultimately allows us to understand and refine our own. The effort also captures the promise of ‘Oumuamua’s wager.

  Bet that humanity has recently brushed with extraterrestrial technology, and we fundamentally shift what we seek and what we expect to find out in the universe. Similarly, we shift those things we could aspire to undertake that would make a difference not just to our world but to the universe at large. Live as if we know there is, or has been, intelligent life in the universe other than our own, and we redefine some of the missions of humanity.

  Personally, I have always been driven by the desire to understand something new about the universe that would change our cosmic perspective and stimulate our aspirations for space. I assign a meaning to my life by using the spectator perspective of an astronomer to motivate new challenges for our civilization on the cosmic stage. Given our many engineering accomplishments on Earth, a broader perspective could lead us to develop new technologies, ask new questions, establish new disciplines, and see our role in a larger habitat.

  Among all astronomical data, the discovery of alien life could have the greatest impact on our broad outlook. And what if we have already made that discovery? What if, like so many of science’s brushes with insights that profoundly change how we see the world around us and our place within it, the only thing preventing us from adopting that broader outlook is our own reluctance to accept optimistically ‘Oumuamua’s wager?

  The main benefit from an encounter with superior beings would be the opportunity to ask them the fundamental question that has been bothering us for ages: What’s the meaning of life? I hope to live long enough to be around for their answer, stemming from numerous millennia of acquired scientific knowledge. But at the same time, I worry that the pace of humanity’s advance to the answer will be hampered by our arrogance, which has often made it easier for us to cling to our grain of sand rather than look up into the expanse of stars.

  12

  Seeds

  If, when confronted with ‘Oumuamua’s wager, we decide to bet on the object being the product of extraterrestrial intelligence rather than simply a weird rock, that raises another question: How much are we willing to place on this wager?

  For starters, consider the least ambitious bet humanity could make: We could simply accept that we missed an opportunity to properly examine the first interstellar traveler that humankind ever spotted and resolve to be better prepared in the future so as not to miss the next one. Preparation could proceed along several tracks, including coming up with a way to capture an image of the next wildly anomalous object that passes through our solar system, perhaps even to capture the object itself. But preparation would also entail increasing every capacity, intellectual and technological, to be able to study and make sense of what we find. The results of such a modest bet are staggering to contemplate—the discovery of another civilization’s technology might help us reach goals that we have long aspired to.

  Astro-archaeology would be one such initiative—but our efforts shouldn’t stop there.

  Take seriously the hypothesis of ‘Oumuamua’s alien technology origin, and we must also take seriously the challenges that we are likely to face in our next encounter with extraterrestrial technology or life. Once we find conclusive evidence of extraterrestrial life in the universe, there will be a predictable international debate about whether and how to react. How do we prepare for this debate? How do we anticipate and plan for the communication SETI has been seeking for decades—or for any other evidence of extraterrestrial intelligence, for that matter?


  Bet that ‘Oumuamua was an exotic rock and nothing more, and on the day that more such evidence presents itself clearly, we will scramble to construct the necessary tools. The first will probably be the academic field of “astro-linguistics” to confront the challenge of an intergalactic means of communication. Other fields would follow, such as “astro-politics,” “astro-economics,” “astro-sociology,” “astro-psychology,” and so on.

  Bet that ‘Oumuamua was of alien technology origin, however, and we could start tomorrow to establish such fields.

  There are other, relatively unambitious bets we could make on ‘Oumuamua’s alien technology origins. For instance, upon discovering conclusively that we are not alone in the universe, we will also quickly discover that existing terrestrial international law provides us no thought-out framework to respond to an extraterrestrial encounter. Indeed, among the most modest of all the optimistic bets that humanity could place on ‘Oumuamua being of alien technology origin would be the establishment of international protocols and oversight—likely under the umbrella of the United Nations—regarding our efforts to search for and find evidence of extraterrestrial life and communicate with extraterrestrial intelligence. Even a nascent treaty agreed to by all terrestrial signatories would provide a framework for how we, as a species, respond to an encounter with a mature intelligence that is billions of years more advanced than we are.

  What would be the most ambitious wager humanity could place on ‘Oumuamua? It would be something sufficient to ensure terrestrial life’s survival.

  A more ambitious bet would be to learn from what we imagine a more mature civilization might have attempted. To take the small scientific leap and allow the possibility ‘Oumuamua was extraterrestrial technology is to give humanity the small nudge toward thinking like a civilization that could have left a lightsail buoy for our solar system to run into. It is to nudge us not just to imagine alien spacecraft but to contemplate the construction of our own such craft.

  Alien spacecraft might include robots equipped with 3D printers and artificial intelligence, which would allow them to use raw materials they scooped up elsewhere to make artificial objects based on blueprints from their home planet. This serves the purpose of avoiding catastrophes at one location by making copies of the same precious content at other locations. The advantage of 3D printing of life from raw materials on a target planet is that natural biological systems with DNA as we know it live a finite lifetime. Even the most cautiously stored building blocks of life may disintegrate in a few million years. Machinery capable of constructing life once it reaches its destination can last much longer.

  Perhaps we should be working along the same lines even before we obtain conclusive evidence that we are not the only or even the most intelligent life in the universe.

  As a child, I would search for the spherical seed heads of dandelions, bring them up to my face, and blow as hard as I could. Just as nature intended, the seeds scattered far and wide. Two weeks later, I would see new seedlings pushing up from the soil. Could civilizations preserve themselves from extinction by doing something similar? Might extraterrestrial civilizations have already tried? And could this also be a way to preserve life in the universe?

  Recall ‘Oumuamua’s slight deviation from the path explicable by the gravity of the Sun alone. Something else pushed it, and I have hypothesized that this something else was the force of sunlight on an extraterrestrial lightsail. But even assuming the object to have been optimally designed for this purpose, it deviated only slightly. The reason is that the force of the Sun is barely capable of accelerating a lightsail craft to just a thousandth of the speed of light even if it starts its journey as close as ten times the solar radius (which is the closest we have yet managed to send a craft, the Parker Solar Probe, the robotic spacecraft launched in 2018 to study the corona of the Sun). We would need a far greater force to propel our seeds of terrestrial life in sufficient number and across the universe. Something less like the radiation of our Sun—and more like a star exploding in a supernova.

  An exploding star would have a luminosity equivalent to a billion Suns shining for a month. A lightsail weighing less than half a gram per square meter could, propelled by such an explosion, reach almost the speed of light even if it were separated from the exploding star by a hundred times the distance of the Earth from the Sun. This would allow our dandelion craft to reach regions of the universe of which we currently can only dream, thereby dramatically expanding the number of possible planets where the seeds of life might find a home.

  To picture how this might work in practice, imagine a civilization that resides near Eta Carinae, a massive star with a luminosity five million times that of the Sun. To ensure the continuation of life, it could park numerous lightsails around the star and cleverly await the explosion that would launch these sails to almost the speed of light at minimal cost.

  Such a civilization would have reached a level of either patience or profligacy that humanity hasn’t—yet. Massive stars live for millions of years and the exact timing of their explosion is difficult to forecast. Eta Carinae, for example, has a lifetime of a few million years. Predicting its death to the precision of millennia is the equivalent of forecasting anyone’s death to within a year after approaching the average life expectancy.

  The Crab Nebula is the remnant of a supernova explosion observed on Earth in 1054 from a distance of about 6,000 light-years. The remnant contains a neutron star, the Crab Pulsar, near its center that spins 30 times every second and pulsates like a lighthouse. Explosions such as this could be harnessed to propel lightsails to the farthest reaches of the universe.

  ESO

  Such a civilization would also have had to plan ahead to a degree humanity has never proven capable. While its lightsails could be transported to their destination around the aging star well in advance of the explosion using cheap chemical rockets, the journey could take millions of years using that primitive mode of propulsion.

  But it is forethought and patience that present the greatest obstacles. The technology, while formidable, is achievable. We know from our modeling for Starshot that sails must be highly reflective so as not to absorb too much heat and burn up. We can also anticipate how to build such craft to avoid the danger of them being pushed away by the bright starlight prior to the explosion. And to keep these craft from accelerating into paths strewn with stellar debris, they should be designed to fold into needle-like configurations to minimize damage and friction and greatly increase the number of such craft.

  It would be a civilization’s greatest of hedged bets. Conceivably numbering in the trillions, these small lightsail craft built to preserve the building blocks of life could sit like dormant seeds a tremendous distance from an aging massive star, awaiting the inevitable. Even if the civilization that placed them there failed to outrun its great filter, on going supernova, the star would disperse into the universe the possibility for the continuation of life, just like the seeds of a dandelion do.

  Of course, there is no need to be that patient. It is already technologically feasible for humanity to use powerful lasers that will be far more effective than the Sun to push lightsails out into interstellar space. This, of course, is the centerpiece proposal of the Breakthrough Starshot Initiative: a laser beam that produced ten gigawatts of power per square meter would be ten million times brighter than sunlight on Earth and able to send lightsail craft at several tenths the speed of light.

  Without question, this would require a major investment. But the moment we know that we are not alone, that we are almost certainly not the most advanced civilization ever to have existed in the cosmos, we will realize that we’ve spent more funds developing the means to destroy all life on the planet than it would have cost to try to preserve it. Confronted with the ‘Oumuamua wager, we might conclude that humanity’s continued existence is worth the expense.

  …

  Currently, we keep all our eggs in one basket—the Earth. As a result, humanity and ou
r civilization are extremely vulnerable to catastrophe. By spreading multiple copies of our genetic material through the universe, we could guard against that risk.

  This effort would resemble the revolution brought about by the invention of the printing press, which allowed Johannes Gutenberg to mass-produce copies of the Bible and distribute them throughout Europe. As soon as many copies of the book were made, any single copy lost its unique value as a precious entity.

  In the same way, as soon as we learn how to produce synthetic life in our laboratories, “Gutenberg DNA printers” could be distributed to make copies of the human genome out of raw materials on the surface of other planets. No single copy would be essential for preserving our species’ genetic information; rather, that information would be contained in multiple copies. As I write, colleagues of mine at Harvard and elsewhere are working diligently to move the miracle of creating life into the column of mundane accomplishments. Much as physics benefited greatly from laboratory experiments that unraveled the laws that govern the universe, these scientists are attempting to create synthetic life in the laboratory and unravel the multitude of chemical paths that could give birth to life. For example, the Szostak Laboratory, headed by its namesake, Nobel laureate Jack Szostak, is building a synthetic cellular system that evolves, replicates itself, and preserves genetic information according to the mechanisms outlined by Charles Darwin in 1859. Szostak and his team are focused on creating a protocell capable of replication and variation, which means it should be able to evolve; they hope this will lead to the spontaneous emergence of genomically encoded catalysts and structured molecules.

  If it works, this accomplishment would guide us toward the best celestial targets in our astronomical search for life by showing us under which conditions life can emerge. But it might also teach us more about our own selves as life-forms—and give us a much-needed dose of humility in the process.