Extraterrestrial

by Avi Loeb

  Unlike most equations, Drake’s was not designed to be solved. Rather, it was intended to serve as a framework for thinking about how many intelligent civilizations might occupy our universe. It is unlikely we will ever be able to plug in values for all of the variables, let alone determine their output.

  While Drake was not alone in formulating a framework for seeking extraterrestrial intelligence—Ronald Bracewell came up with a different approach in 1960 and Sebastian von Hoerner, a German astrophysicist, yet another in 1961—his was the one that has since, for good or ill, become the touchstone for SETI science.

  I say for ill because Drake’s equation focuses solely on the transmission of communication signals; he limited his aspirations to finding N and from it the number of interstellar communications that would establish the existence of extraterrestrial intelligence. This exclusive interest in communication predicts the equation’s second limitation, epitomized by its variable L, which represents the length of time an intelligent species would be able to produce such signals. Consider, for example, that our species has been producing pollutants that are detectable by certain telescopes for centuries but radio signals for mere decades.

  Both N and L point to a deeper problem with the Drake equation. For all its value as the first systematic effort to identify the variables involved in estimating and thereby directing efforts to find extraterrestrial intelligence, the equation’s very formalism was perhaps its biggest limitation. When SETI scientists failed to come up with evidence of alien radio signals, critics were happy to declare the equation—and all of SETI—whimsy through and through.

  In 1992, in keeping with the search for N, the U.S. government gave 12.25 million dollars to NASA to initiate a radio astronomy program. The very next year, SETI funding was ended. At the time Congress withdrew its support and the funding, one senator, Richard Bryan of Nevada, declared, “Millions have been spent and we have yet to bag a single little green fellow.” There are few more succinct statements of the ignorance and flawed assumptions that have hampered humanity’s pursuit of the answer to “Are we alone?” The sum spent was paltry, comparatively, and the bar set for evidence of success was absurd.

  That said, the early SETI researchers rarely helped their own cause. Their near-exclusive focus on seeking radio and optical signals has set unhelpful presumptions, scientific and popular, as to what such exploration looks like and what sorts of projects merit funding. Only recently have we witnessed growing interest in seeking biosignatures, such as oxygen and methane in the atmosphere and large-scale algal blooms in distant oceans, and technosignatures, such as markers of industrial pollutants in planetary atmospheres and localized heat islands that suggest urban settlements.

  In the search for extraterrestrial intelligence, the members of this niche are still finding their footing, and the broader scientific community that ought to be supporting them largely is not. Human science still needs to mature—in regard to SETI as well as other frontiers of our limited imagination.

  …

  I keep a file drawer in my office that is labeled, simply, IDEAS. It holds a single hanging file in which I keep manila folders. Sometimes the file is overstuffed, sometimes less so. In each folder are a few sheets of paper displaying equations. These reflect problems and questions that occur to me and that are worthy of answers. They often keep me company during my walks in the backyard of my home and the nearby woods. At the risk of sounding clichéd, I usually come up with them during my shower. (Recently, after a Dutch film crew visited our shower in an attempt to document my inspiration, my wife bought me a waterproof pen and whiteboard.)

  Well before I had a drawer for collecting ideas, let alone undergraduates, graduate students, and postdocs to share these ideas with, I was gathering them. They have served as seeds from which my own research has grown. To date, those seeds have yielded more than seven hundred published papers, six books (including the one in your hand), and a growing number of now-confirmed predictions touching on the birth of stars, the detection of planets beyond our solar system, and the properties of black holes.

  This is not to say that I am guided by imagination alone. All my studies reflect an unshakable guiding principle: contact with data. I avoid mathematical speculations, or what I call “theory bubbles.” Too often astrophysics can lose itself in theories that float free of any evidence, taking funding and talent with them. There is one reality out there and we are very far from exhausting all of its anomalies.

  As I have told generations of students, it is dangerous to wander into work on abstractions that hold little to no promise of feedback from data. I am sure many of them have felt that it is equally dangerous to pursue lines of research or advance conclusions that are against the scientific mainstream. I think that this reaction is not only a shame—it is also dangerous.

  While the past several decades have offered much encouragement to the search for extraterrestrial life, I am repeatedly struck by the extent of what remains untried, undertheorized, underfunded, and, among a broad swath of scientists, deemed best left unmentioned. When I describe to my colleagues the reactions of my undergraduates to the two thought experiments that opened this book, many of them chuckle. I think that we should pay closer attention and ask ourselves if there isn’t a professional truth hiding in plain sight of the students’ responses.

  Unlike what trends on social media, scientific progress is measured by how close a proposed idea is to evidence-established truth. That widely accepted fact suggests that physicists would measure their success by how well their ideas align with data rather than by how popular those ideas are. But that is not what we discover when we survey the landscape of theoretical physics. Fashions frequently dictate funding, sometimes despite anything close to a commensurate return on investments.

  Despite the absence of experimental evidence, the mathematical ideas of supersymmetry, extra-spatial dimensions, string theory, Hawking radiation, and the multiverse are considered irrefutable and self-evident by the mainstream of theoretical physics. In the words of a prominent physicist at a conference that I attended: “These ideas must be true even without experimental tests to support them, because thousands of physicists believe in them and it is difficult to imagine that such a large community of mathematically gifted scientists could be wrong.”

  But go beyond the groupthink and look more closely at these ideas. For instance, supersymmetry. This theory, which postulates that all particles have partners, is not as natural as prominent theorists predicted it would be. The latest data from the Large Hadron Collider at CERN did not find any of the evidence expected at the energy scales it probed to support supersymmetry. Other speculative ideas pertaining to the nature of dark matter, dark energy, extra dimensions, and string theory have yet to be even tested.

  Imagine that the data suggesting that ‘Oumuamua is extraterrestrial technology is stronger than the data suggesting supersymmetry theory is valid. What might follow? Just a bit under five billion dollars was spent to construct the Large Hadron Collider, a particle accelerator built in hopes of attaining confirming evidence of supersymmetry, and running it costs another one billion dollars a year. If the scientific consensus eventually gives up on the theory, it will do so after vast expense and generations of effort. Until we have invested similarly in the search for extraterrestrial intelligence, flat declarations about what ‘Oumuamua is and isn’t should be judged accordingly.

  A host of theories beyond supersymmetry—the multiverse leaps to mind—are given thoughtful, respectful attention in and out of the academy despite the absence of evidence for them. That should give us pause, and not because of the absence of evidence. Rather, it should concern us because of what it reveals about the scientific enterprise itself.

  What stands in our way of the fair consideration of ‘Oumuamua being of extraterrestrial design isn’t the evidence or the method of its collection or the reasoning behind the hypothesis. What most immediately stands in our way is a reluctance to look past the
evidence and reasoning at what should follow. Sometimes the problem lies with the message, sometimes with the messenger, but when both run up against a recipient who is reluctant to listen, a problem greater than evidence and reasoning stands in the way.

  …

  There are many reasons that the search for extraterrestrial life has attracted far less attention and intellectual firepower than many of the anomalies the universe confronts us with. Certainly, the often absurd plotlines of many works of science fiction haven’t helped. But neither have the prejudices of astronomers and astrophysicists—biases that cumulatively have had a chilling effect on new generations of scientists.

  Today, a young theoretical astrophysicist is more likely to get a tenure-track job by pondering multiverses than by seeking evidence of extraterrestrial intelligence. This is a shame, especially because budding scientists are often at their most imaginative during the early phases of their careers. During this fertile period, they encounter a profession that implicitly and explicitly reins in their interests by stoking their fear of standing outside the mainstream of science.

  An earlier generation of theoretical physicists was open to the humility of seeing their theories proven wrong by experimental data. But a new culture, one that thrives in its own theoretical sauce and exercises influence over award committees and funding agencies, is populated by advocates of popular yet unproven paradigms. When scientists double down on supersymmetry despite the Large Hadron Collider finding no evidence for it or when they insist that the multiverse must exist despite there being no data to support the theory, they are wasting precious time and money and talent. And we have not only finite funds to spend, but finite time.

  The irony is that many grown-up scientists once understood this intuitively. After young children open their first checking accounts, they often fall into the trap of imagining the possible amounts of money accumulating there. As they contemplate this purchase and that purchase and all that they wish they could own, they get very excited. But after going to an ATM and learning how much money is actually in their accounts, their castles in the air come crashing down. Not only are their funds insufficient to do all that they were dreaming of, but they finally grasp the slow pace at which those funds accumulate. Usually, children will come away from this disappointment having learned to check their accounts with some frequency and balance their dreamed-of purchases against the hard evidence of confirmable data.

  A scientific culture that has not learned this lesson—that does not require external verification in observable, confirmable data and that advocates for ideas deemed inherently correct due to their mathematical beauty—strikes me as a culture at risk of losing its grounding. Getting data and comparing it to our theoretical ideas provides a reality check and tells us that we are not hallucinating. What is more, it reconfirms what is central to the discipline. Physics is not a recreational activity intended to make us feel good about ourselves. Physics is a dialogue with nature, not a monologue. We are supposed to have skin in the game and make testable predictions, and this requires that scientists put themselves at risk of error.

  In the age of social media, the sciences generally and astrophysics specifically need to recover their traditional humility. Doing so shouldn’t be difficult. Gathering experimental data and ruling out theoretical ideas need to become greater priorities. It is reassuring to be guided by data, and it also promises more tangible, applicable rewards. Rather than spending one’s entire career going down mathematical alleys that will be regarded as irrelevant by future generations of physicists, young scientists should focus on those areas of research where the value of ideas can be tested and cashed in during their lifetimes.

  There is no field of research where the risk-and-reward calculus is greater than in the search for extraterrestrial life. What is more, with just eleven days’ worth of accumulated data gleaned from ‘Oumuamua’s passage, we already have more suggestive, observable evidence than we do for all the fashionable thought bubbles that currently hold sway in the field of astrophysics.

  …

  There is value in paying attention to the intuitive leaps that children make, for they do so far more easily than many adults who carry ego-loaded baggage or intellectual prejudices. When my daughters, Lotem and Klil, learned that their father was working to send a StarChip to the vicinity of Proxima b, which sits in the habitable zone of Proxima Centauri, they grew curious, and they grew even more so when I told them the planet is expected to be tidally locked—to always show one side to the star and one side to the dark expanse of space. After a moment’s thought, my younger daughter, Lotem, declared that this being the case, she would need two houses, one on the permanent night side for her to sleep in and the second on the permanent sunset strip where she could work and take her vacations.

  It would be wrong to assume that Lotem’s imagining of interstellar real estate was merely fanciful. Thought experiments consistent with the laws of physics are the very stuff of discovery, the means of working our way toward the solutions to the many anomalies we confront here on Earth and beyond it. In the less rigid thinking of children, we may well find the insights that propel science, and humanity, forward. And one of the worst mistakes we can make is to impose conservative presumptions on the ideas and instincts of others or laud intellectual caution for the wrong reasons.

  Science is first and foremost a learning experience, one that works best by keeping us humble when we make mistakes, like children figuring out the world through their collisions with it. Just like the sharp edges of furniture, anomalies are rarely beautiful when we are first introduced to them. They confound what we think we know, stand in opposition to theories and beliefs we take as given, and resist efforts to make them align neatly with our presumptions. That is precisely when science must give priority to evidence over imagination and follow that evidence wherever it may lead.

  In the late nineteenth century, for example, physicists noticed something weird about “blackbody radiation,” the light emitted by heated objects. The blackbody-radiation spectrum features a single peak whose wavelength depends on temperature: the hotter the object, the shorter the wavelength of peak blackbody emission. Think of stars—small, cool dwarfs are red, warmer stars such as our Sun shine yellow, and the biggest, hottest stars are a sizzling blue. Try as they might, physicists couldn’t explain or accurately model the spectral shifts at high temperatures—until 1900, when Max Planck proposed that objects absorb and emit energy in discrete units, or quanta. This revolutionary insight ushered in quantum mechanics and the era of modern physics.

  No less a genius than Albert Einstein was puzzled by the weird properties of the quantum world, specifically the phenomenon of entanglement and the idea of quantum nonlocality—the mysterious ability of two particles to engage with each other no matter how far apart they are. He grappled with this unusual idea and ultimately referred to it as “spooky action at a distance.” Recent experiments tell us that he was wrong to dismiss this behavior, and it turns out that the more we understand about nonlocality, the more it reveals about the very nature of reality.

  Science at its core demands humility, an understanding that humanity’s imagination is incapable of mapping out the full richness and diversity of nature. But the proper response to humility is wonder and, with it, a desire to open ourselves to a greater range of possibilities.

  Within science, this frequently means making difficult decisions. Choices, often made outside the immediate influence of scientists, channel efforts toward certain possibilities and away from others. For example, while the number of large telescopes on Earth is constantly increasing, there are not enough of them to keep pace with the number of astronomers eager to access them. To adjudicate the competing demands for allocated time, institutions and universities have formed committees and funding agencies. They approve and prioritize submitted requests, applying the committees’ expertise but also, inevitably, their biases and presumptions. I have often thought that all such decision-m
aking bodies should automatically dedicate a significant portion of their resources—say, 20 percent—to high-risk projects. Like a financial portfolio, humanity’s investments in science need diversification.

  Yet many researchers stray far from this ideal, especially after they’ve lost their youthful enthusiasm and ascended the career ladder to tenured positions of prominence. Instead of taking advantage of their job security, they create echo chambers of students and postdocs who amplify their scientific influence and reputation. Honors should be merely the makeup on the face of academia, but they too often become an obsession. Popularity contests are outside the scope of honest scientific inquiry—the scientific truth is not dictated by the number of likes on Twitter but rather by evidence.

  One of the most difficult lessons to impart to young scientists is that the search for the truth can run counter to the search for consensus. Indeed, truth and consensus must never be conflated. Sadly, it is a lesson more easily understood by a student starting out in the field. From then on, year after year, the combined pressures of peers and job-market prospects encourage the tendency to play it safe.

  Astrophysics is hardly the only academic field prone to these forces, but the explicit and implicit encouraging of conservative science is both depressing and concerning, given the extent of anomalies the universe still contains. While it is not obvious to me why extraordinary claims require extraordinary evidence (evidence is evidence, no?), I do believe that extraordinary conservatism keeps us extraordinarily ignorant. Put differently, the field doesn’t need more cautious detectives.

  If the flame of inquiry is to continue, it is incumbent on senior scholars to not only gather to themselves promising young scholars but to cultivate an environment within which the next generations of scientists can nurture discoveries despite their inherently unpredictable nature. Budding scientists are like matches, and the context within which they do their work is like a matchbox—it does no one any good if at the moment you need them to set a new fire, they strike against the side of a worn-smooth matchbox. A long-learned professional lesson is this: if you want to nurture new discoveries, it helps to construct new matchboxes.