It’s a gamble: Even optimists rate the probability of success at only a few percent. And of course radio transmission is only one channel whereby aliens might reveal themselves. But the stakes are high. A manifestly artificial signal—even if we couldn’t decode it—would convey the momentous message that intelligence had emerged elsewhere in the cosmos.
These searches are more strongly motivated than they were in earlier decades. The Kepler space telescope, surely one of the most cost-effective and inspirational projects in NASA’s history, has revealed that most stars in our galaxy are orbited by retinues of planets. There are literally billions of them in the Milky Way with the size and temperature of Earth.
But would these planets have developed biospheres? Or is Earth unique and all others sterile and lifeless? Despite all we know about life’s evolution, its actual origin—the transition from complex molecules to the first replicating and metabolizing systems we would deem to be “alive”—has remained a mystery, relegated to the “too difficult” box. But it is now being addressed by top-ranking scientists. We may soon know whether life’s emergence was a fluke or near-inevitable in the kind of “chemical soup” expected on any planet resembling the young Earth—and also whether the DNA/RNA basis of terrestrial life is special or just one of several possibilities.
In seeking other biospheres, clues will surely come from high-resolution spectra, using the James Webb Space Telescope, and the next generation of 30-plus-meter ground-based telescopes that will come online in the 2020s.
Conjectures about advanced alien life are of course far more shaky than those about simple life. We know, at least in outline, the evolutionary steps whereby nearly 4 billion years of Darwinian evolution led to the biosphere of which we humans are a part. But billions of years lie ahead. I would argue that our remote, posthuman descendants will not be “organic” or biological, and they will not remain on the planet where their biological precursors lived. And this offers clues to the planning of SETI searches.
Why is this? It’s because posthuman evolution will be spearheaded by superintelligent (and supercapable) machines. There are chemical and metabolic limits to the size and processing power of “wet,” organic brains. But no such limits constrain electronic computers (still less, perhaps, quantum computers). For these, the potential for further development could be as dramatic as the evolution from monocellular organisms to humans. So, by any definition of “thinking,” the amount and intensity done by organic human-type brains will be utterly swamped by the cerebrations of AI. Moreover, the Earth’s biosphere is not essential—indeed, it’s far from an optimal environment—for inorganic AI. Interplanetary space will be the preferred arena where robotic fabricators will have the grandest scope for construction, and where nonbiological “brains” may develop insights as far beyond our imaginings as string theory is for a mouse.
This scenario implies that even if life originated only on Earth, it need not remain a trivial feature of the cosmos: Humans may be closer to the beginning than to the end of a process whereby ever more complex intelligence spreads through the galaxy. But in that case there would, of course, be no “ET” at the present time.
Suppose, however, that there are other biospheres where life began and evolved along a track similar to what happened on Earth. Even then, it’s highly unlikely that the key stages would be synchronized. A planet where it lagged significantly behind what has happened on Earth would plainly reveal no evidence of ET. But on a planet around a star older than the Sun, life could have had a head start of a billion years and already transitioned to the futuristic posthuman scenario.
The history of human technological civilization is measured in centuries—and it may be only one or two more centuries before humans are overtaken or transcended by inorganic intelligence, which will then persist and continue to evolve for billions of years. This suggests that if we were to detect ET, it would be far more likely to be inorganic. We would be most unlikely to “catch” it in the brief sliver of time when it took organic form. A generic feature of these scenarios is that organic human-level intelligence is just a brief prelude before the machines take over.
It makes sense to focus searches first on Earth-like planets orbiting long-lived stars (the “Look first under the lamppost” strategy). But science-fiction authors remind us that there are more exotic alternatives. In particular, the habit of referring to “alien civilizations” may be too anthropocentric—ET could be more like a single “mind.”
Breakthrough Listen will carry out the world’s deepest and broadest search for extraterrestrial technological life. The project involves using radio dishes at Green Bank, in West Virginia, and at Parkes, in New South Wales—and perhaps others, including the Arecibo Observatory in Puerto Rico—to search for non-natural radio transmissions, using advanced signal-processing equipment developed by a team based at UC Berkeley. Moreover, the advent of social media and citizen science will enable a global community of enthusiasts to download data and participate in this cosmic quest.
Let’s hope that Yuri Milner’s private philanthropy will one day be supplemented by public funding. I’d guess that the millions watching Star Wars would be happy if some of the tax revenues from that movie were hypothecated for SETI.
But in pursuing these searches we should remember two maxims, both oft quoted by Carl Sagan. First, “Extraordinary claims require extraordinary evidence,” and second, “Absence of evidence isn’t evidence of absence.”
Life in the Milky Way
Mario Livio
Astrophysicist; author, Brilliant Blunders
The question of whether extrasolar life (and extrasolar complex life in particular) exists, is arguably one of the most intriguing questions in science today.
While we don’t know with any certainty whether the emergence of life on an extrasolar planet requires conditions similar to those on Earth, the presence of liquid water on a rocky surface is thought to be a generic necessity for life-producing chemistry to operate. This assumption has led to the concept of a habitable zone (HZ)—that “Goldilocks” not-too-hot, not-too-cold region around a star where the temperature and atmospheric pressure allow for liquid water to exist on the planet’s surface. The idea of the HZ, in turn, has brought the question of how many Earth-size planets in the HZ exist in our Milky Way Galaxy to center stage.
Amazingly, during the past few years, observations (primarily by the Kepler space observatory) have accumulated sufficient statistics to solve this piece of the puzzle. Even conservative estimates, published in 2014, put the number of roughly Earth-size planets orbiting Sun-like stars in the HZ (in the Milky Way) at about 10 billion!
The publication of this empirically based estimate marked a critical point at which the quest for extrasolar life transitioned from mere speculation to an actual science. The realization that exoplanets could—in principle, at least—support life has turned the search for extrasolar life almost into an obsession for many astronomers. Plans for this field envisage a two-pronged attack:
A series of upcoming telescopes (in space and on the ground) will look for biosignatures—characteristics imprinted by life processes—in the atmospheres of planets in the HZ of their host stars.
Russian billionaire Yuri Milner announced in July 2015 a $100-million decadal project called “Breakthrough Listen” aimed at providing the most comprehensive search for alien communication (an extension of SETI) to date.
There is little doubt that the determination of the number of planets able to host life will stay news for at least a few decades. The only discovery in this domain that will eclipse these findings will be the actual detection of extrasolar life. We are, for the first time in human history, on the verge of potentially eliminating the last obstacle to Copernican modesty. We have discovered that neither our place in the galaxy nor our galaxy itself is special. Darwin has further shown that humans are a natural product of evolution by means of natural selection. The discovery of extrasolar life will demonstrate that e
ven that last claim to being special will have to be abandoned.
There Is (Already) Life on Mars
Michael I. Norton
Harold M. Brierley Professor of Business Administration, Harvard Business School; co-author (with Elizabeth Dunn), Happy Money: The Science of Smarter Spending
Members of the Mashco-Piro tribe—previously viewed as one of the few remaining “uncontacted” peoples—have recently emerged to make increasing contact with the outside world. But this is a less than heartwarming story: As is so often the case with such contact, members of the tribe are vulnerable to unfamiliar diseases, such as influenza. These active efforts to become “contacted” create a problem for countries like Brazil, which have initiated far-sighted “no contact” policies to allow such tribes to choose seclusion. As José Carlos Meirelles, an indigene-protection agent in Brazil, put it: “If they are seeking contact, we must welcome them in the best manner possible. We must take care of their health, block out the boundaries of their territory, give them some time to adjust to the madness of our world.”
Lately we’ve also learned more about the role of Catharine Conley, “planetary protection officer” at NASA, who has the job not of finding life on Mars but of protecting Mars from life on Earth. Scientists agree that life exists on Mars, if only in the form of microbes from Earth that took an accidental interplanetary ride. Despite the best efforts of NASA—which include sterilizing and sometimes even baking spacecraft—some life slips through. Much like the “no contact” policies for uncontacted peoples, NASA has protocols that keep rovers on Mars far from “special regions” where bacteria from Earth might thrive.
But what happens when life on Mars chooses not to wait? All of recorded history shows that life tends to find life—or more likely in this case, lichens tend to find lichens. Surely we should apply the lessons learned from centuries of genocide (accidental and intentional) of indigenous peoples on this planet to nascent forms of life on Mars. “If they are seeking contact, we must welcome them in the best manner possible. We must take care of their health, block out the boundaries of their territory, give them some time to adjust to the madness of our world.”
The Breathtaking Future of a Connected World
Chris J. Anderson
Curator, TED conferences, TED Talks; author, TED Talks: The Official TED Guide to Public Speaking
Our planet is growing itself a brain. That process is accelerating, and the project will determine the future of humans and many other species.
The major Internet and space technology corporations, among others, have confirmed multibillion-dollar investments to bring low-cost broadband Internet to every square meter of Earth’s surface within ten years. They are building the railway tracks and freeways of the 21st century—but at global scale, and with breathtaking speed.
Five billion human minds are therefore about to come online, mostly via sub-$50 smartphones. And unlike the two billion who preceded them, their first experience of the Internet may not be clunky text but high-resolution video and a fast connection to whatever grabs their imagination.
This is a social experiment without historical precedent. Most of us built our Internet habits on top of years of exposure to newspapers, books, radio, and TV. Many of those soon to come online are currently illiterate. Who is going to win their attention and with what consequences? Local language versions of social media, Wikipedia, Porn? Video games? Marketing come-ons? Government propaganda? Addictive distractions? Free education? Conversations with mentors in other countries empowered by realtime machine translation?
It’s certainly possible to imagine a beautiful scenario in which, for the first time in history, every human can have free access to the world’s greatest teachers in his or her own language; people discover the tools and ideas to escape poverty and bigotry; growing transparency forces better behavior from governments and corporations; the world starts to benefit from billions of new minds able to contribute to our shared future; global interconnection begins to trump tribal thinking.
But for all that to have even a chance of happening, we need to get ready to engage in the Mother of all attention wars. Every global company, every government, and every ideology has skin in this game. It could play out in many different ways, some of them ugly.
What’s unique and significant is that we have a roadmap. It’s now clear that we will not need to physically wire the planet. Satellites, possibly aided by drones and balloons, are about to get the job done a lot faster. We can therefore be certain that a massive transformation is about to hit. We’d better get ready.
Everything Is Computation
Joscha Bach
Cognitive scientist, MIT Media Lab/Harvard Program for Evolutionary Dynamics
These days we see a tremendous number of significant scientific news stories, and it’s hard to say which has the highest significance. Climate models indicate that we are past crucial tipping points and irrevocably headed for a new, difficult age for our civilization. Mark van Raamsdonk expands on the work of Brian Swingle and Juan Maldacena and demonstrates how we can abolish the idea of spacetime in favor of a discrete tensor network, thus opening the way for a unified theory of physics. Bruce Conklin, George Church, and others have given us CRISPR/Cas9, a technology that holds promise for simple and ubiquitous gene editing. “Deep learning” starts to tell us how hierarchies of interconnected feature detectors can autonomously form a model of the world, learn to solve problems, and recognize speech, images, and video.
It is perhaps equally important to notice where we lack progress: Sociology fails to teach us how societies work; philosophy seems to have become infertile; the economic sciences seem ill-equipped to inform our economic and fiscal policies; psychology does not encompass the logic of our psyche; and neuroscience tells us where things happen in the brain but largely not what they are.
In my view, the 20th century’s most important addition to understanding the world is not positivist science, computer technology, spaceflight, or the foundational theories of physics. It is the notion of computation. Computation, at its core, and as informally described as possible, is simple: Every observation yields a set of discernible differences.
These we call information. If the observation corresponds to a system that can change its state, we can describe those state changes. If we identify regularity in those state changes, we are looking at a computational system. If the regularity is completely described, we call this system an algorithm. Once a system can perform conditional state transitions and revisit earlier states, it becomes almost impossible to stop it from performing arbitrary computation. In the infinite case—that is, if we allow it to make an unbounded number of state transitions and use unbounded storage for the states—it becomes a Turing machine, or a Lambda calculus, or a Post machine, or one of the many other mutually equivalent formalisms that capture universal computation.
Computational terms rephrase the idea of “causality,” something that philosophers have struggled with for centuries. Causality is the transition from one state in a computational system to the next. They also replace the concept of “mechanism” in mechanistic, or naturalistic, philosophy. Computationalism is the new mechanism, and unlike its predecessor, it is not fraught with misleading intuitions of moving parts.
Computation is different from mathematics. Mathematics turns out to be the domain of formal languages and is mostly undecidable, which is just another word for saying “uncomputable” (since decision making and proving are alternative words for computation, too). All our explorations into mathematics are computational ones, though. To compute means to actually do all the work, to move from one state to the next.
Computation changes our idea of knowledge: Instead of justified true belief, knowledge describes a local minimum in capturing regularities between observables. Knowledge is almost never static but progresses on a gradient through a state space of possible worldviews. We will no longer aspire to teach our children the truth, because, like us, they
will never stop changing their minds. We will teach them how to productively change their minds, how to explore the never-ending land of insight.
A growing number of physicists understands that the universe is not mathematical but computational, and physics is in the business of finding an algorithm that can reproduce our observations. The switch from uncomputable mathematical notions (such as continuous space) makes progress possible. Climate science, molecular genetics, and AI are computational sciences. Sociology, psychology, and neuroscience are not: They still seem confused by the apparent dichotomy between mechanism (rigid moving parts) and the objects of their study. They are looking for social, behavioral, chemical, neural regularities, where they should be looking for computational ones.
Everything is computation.
Identifying the Principles, Perhaps the Laws, of Intelligence
Pamela McCorduck
Author, Machines Who Think; The Edge of Chaos; Bounded Rationality: A Novel; This Could Be Important; co-author (with Edward Feigenbaum), The Fifth Generation
The most important news for me came in mid-2015, when three scientists—Samuel J. Gershman, Eric J. Horvitz, and Joshua B. Tenenbaum—published “Computational rationality: A converging paradigm for intelligence in brains, minds, and machines” in Science. They announced that something new was under way: an effort to identify the principles of intelligence, just as Newton once discovered the laws of motion.
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