by Sam Kean
Since Drake first sketched out the equation in 1961, two fundamental developments have reshaped our understanding of the problem. First, the numbers on the left-hand side of the equation (representing the amount of stars with habitable planets) have increased by several orders of magnitude. And second, we have been listening for signals for decades and heard nothing. As Brin puts it: “Something is keeping the Drake Equation small. And the difference between all the people in the SETI debates is not whether that’s true, but where in the Drake panoply the fault lies.”
If the left-hand values keep getting bigger and bigger, the question is which variables on the right-hand side are the filters. As Brin puts it, we want the filter to be behind us, not the one variable, L, that still lies ahead of us. We want the emergence of intelligent life to be astonishingly rare; if the opposite is true, and intelligent life is abundant in the Milky Way, then L values might be low, perhaps measured in centuries and not even millennia. In that case, the adoption of a technologically advanced lifestyle might be effectively simultaneous with extinction. First you invent radio, then you invent technologies capable of destroying all life on your planet, and shortly thereafter you push the button and your civilization goes dark.
The L-value question explains why so many of METI’s opponents—like Musk and Hawking—are also concerned with the threat of extinction-level events triggered by other potential threats: superintelligent computers, runaway nanobots, nuclear weapons, asteroids. In a low L-value universe, planet-wide annihilation is an imminent possibility. Even if a small fraction of alien civilizations out there would be inclined to shoot a two-kilogram pellet toward us at half the speed of light, is it worth sending a message if there’s even the slightest chance that the reply could result in the destruction of all life on Earth?
Other, more benign explanations for the Fermi Paradox exist. Drake himself is pessimistic about the L value, but not for dystopian reasons. “It’s because we’re getting better at technology,” he says. The modern descendants of the TV and radio towers that inadvertently sent Elvis to the stars are far more efficient in terms of the power they use, which means the “leaked” signals emanating from Earth are far fainter than they were in the 1950s. In fact, we increasingly share information via fiber optics and other terrestrial conduits that have zero leakage outside our atmosphere. Perhaps technologically advanced societies do flicker on and off like fireflies, but it’s not a sign that they’re self-destructive; it’s just a sign that they got cable.
But to some METI critics, even a less apocalyptic interpretation of the Fermi Paradox still suggests caution. Perhaps advanced civilizations tend to reach a point at which they decide, for some unknown reason, that it is in their collective best interest not to transmit any detectable signal to their neighbors in the Milky Way. “That’s the other answer for the Fermi Paradox,” Vakoch says with a smile. “There’s a Stephen Hawking on every planet, and that’s why we don’t hear from them.”
In his California home among the redwoods, Frank Drake has a version of the Arecibo message visually encoded in a very different format: not a series of radio-wave pulses but as a stained-glass window in his living room. A grid of pixels on a cerulean blue background, it almost resembles a game of Space Invaders. Stained glass is an appropriate medium, given the nature of the message: an offering dispatched to unknown beings residing somewhere in the sky.
There is something about the METI question that forces the mind to stretch beyond its usual limits. You have to imagine some radically different form of intelligence, using only your human intelligence. You have to imagine timescales on which a decision made in 2017 might trigger momentous consequences 10,000 years from now. The sheer magnitude of those consequences challenges our usual measures of cause and effect. Whether you believe that the aliens are likely to be warriors or Zen masters, if you think that METI has a reasonable chance of making contact with another intelligent organism somewhere in the Milky Way, then you have to accept that this small group of astronomers and science-fiction authors and billionaire patrons debating semiprime numbers and the ubiquity of visual intelligence may in fact be wrestling with a decision that could prove to be the most transformative one in the history of human civilization.
All of which takes us back to a much more down-to-earth, but no less challenging, question: who gets to decide? After many years of debate, the SETI community established an agreed-upon procedure that scientists and government agencies should follow in the event that the SETI searches actually stumble upon an intelligible signal from space. The protocols specifically ordain that “no response to a signal or other evidence of extraterrestrial intelligence should be sent until appropriate international consultations have taken place.” But an equivalent set of guidelines does not yet exist to govern our own interstellar outreach.
One of the most thoughtful participants in the METI debate, Kathryn Denning, an anthropologist at York University in Toronto, has argued that our decisions about extraterrestrial contact are ultimately more political than scientific. “If I had to take a position, I’d say that broad consultation regarding METI is essential, and so I greatly respect the efforts in that direction,” Denning says. “But no matter how much consultation there is, it’s inevitable that there will be significant disagreement about the advisability of transmitting, and I don’t think this is the sort of thing where a simple majority vote or even supermajority should carry the day . . . so this keeps bringing us back to the same key question: is it okay for some people to transmit messages at significant power when other people don’t want them to?”
In a sense, the METI debate runs parallel to other existential decisions that we will be confronting in the coming decades, as our technological and scientific powers increase. Should we create superintelligent machines that exceed our own intellectual capabilities by such a wide margin that we cease to understand how their intelligence works? Should we “cure” death, as many technologists are proposing? Like METI, these are potentially among the most momentous decisions human beings will ever make, and yet the number of people actively participating in those decisions—or even aware such decisions are being made—is minuscule.
“I think we need to rethink the message process so that we are sending a series of increasingly inclusive messages,” Vakoch says. “Any message that we initially send would be too narrow, too incomplete. But that’s okay. Instead, what we should be doing is thinking about how to make the next round of messages better and more inclusive. We ideally want a way to incorporate both technical expertise—people who have been thinking about these issues from a range of different disciplines—and also getting lay input. I think it’s often been one or the other. One way we can get lay input in a way that makes a difference in terms of message content is to survey people about what sorts of things they would want to say. It’s important to see what the general themes are that people would want to say and then translate those into a Lincos-like message.”
When I asked Denning where she stands on the METI issue, she told me: “I have to answer that question with a question: Why are you asking me? Why should my opinion matter more than that of a six-year-old girl in Namibia? We both have exactly the same amount at stake, arguably, she more than I, since the odds of being dead before any consequences of transmission occur are probably a bit higher for me, assuming she has access to clean water and decent healthcare and isn’t killed far too young in war.” She continued, “I think the METI debate may be one of those rare topics where scientific knowledge is highly relevant to the discussion, but its connection to obvious policy is tenuous at best, because in the final analysis, it’s all about how much risk the people of Earth are willing to tolerate . . . And why exactly should astronomers, cosmologists, physicists, anthropologists, psychologists, sociologists, biologists, sci-fi authors, or anyone else (in no particular order) get to decide what those tolerances should be?”
Wrestling with the METI question suggests, to me at least, that the one invent
ion human society needs is more conceptual than technological: we need to define a special class of decisions that potentially create extinction-level risk. New technologies (like superintelligent computers) or interventions (like METI) that pose even the slightest risk of causing human extinction would require some novel form of global oversight. And part of that process would entail establishing, as Denning suggests, some measure of risk tolerance on a planetary level. If we don’t, then by default the gamblers will always set the agenda, and the rest of us will have to live with the consequences of their wagers.
In 2017, the idea of global oversight on any issue, however existential the threat it poses, may sound naive. It may also be that technologies have their own inevitability, and we can only rein them in for so long: if contact with aliens is technically possible, then someone, somewhere is going to do it soon enough. There is not a lot of historical precedent for humans voluntarily swearing off a new technological capability—or choosing not to make contact with another society—because of some threat that might not arrive for generations. But maybe it’s time that humans learned how to make that kind of choice. This turns out to be one of the surprising gifts of the METI debate, whichever side you happen to take. Thinking hard about what kinds of civilization we might be able to talk to ends up making us think even harder about what kind of civilization we want to be ourselves.
Near the end of my conversation with Frank Drake, I came back to the question of our increasingly quiet planet: all those inefficient radio and television signals giving way to the undetectable transmissions of the internet age. Maybe that’s the long-term argument for sending intentional messages, I suggested; even if it fails in our lifetime, we will have created a signal that might enable an interstellar connection thousands of years from now.
Drake leaned forward, nodding. “It raises a very interesting, nonscientific question, which is: Are extraterrestrial civilizations altruistic? Do they recognize this problem and establish a beacon for the benefit of the other folks out there? My answer is: I think it’s actually Darwinian; I think evolution favors altruistic societies. So my guess is yes. And that means there might be one powerful signal for each civilization.” Given the transit time across the universe, that signal might well outlast us as a species, in which case it might ultimately serve as a memorial as much as a message, like an interstellar version of the Great Pyramids: proof that a technologically advanced organism evolved on this planet, whatever that organism’s ultimate fate.
As I stared at Drake’s stained-glass Arecibo message, in the middle of that redwood grove, it seemed to me that an altruistic civilization—one that wanted to reach across the cosmos in peace—would be something to aspire to, despite the potential for risk. Do we want to be the sort of civilization that boards up the windows and pretends that no one is home, for fear of some unknown threat lurking in the dark sky? Or do we want to be a beacon?
ELENA PASSARELLO
Arabella (Araneus diadematus) 1973
from The Normal School
The tiny insect had, in many ways, been Skylab’s star performer.
—Reuters
In early summer, once she has broken from her cocoon and spent a day or so in the huddle of her family, an adolescent cross spider feels ready to fly. She scuttles to some swatch of vegetation that faces outward—a leaf ridge, a twig—and she perches there. Then she lifts a significant fraction of her legs and pulls a silk strand from the spinnerets at the base of her abdomen. Ounce for ounce, that silk is five times the strength of reinforced steel and at least twice as strong as a human femur.
When a June wind blows the silk strand into its current, she follows it with her body: a tiny balloon chasing its string. It is a journey that begins with a considerable jerk and ends only when her silk tether collides with a rooted object—a bush, a fence post. This could be a one-yard trip, or it could send her half a mile away. A half-mile journey to a cross spider is like a man catching a wind from Milwaukee to Madison.
Gravity left the bodies of the Skylab III crew without much warning. They had spent the early minutes of the launch pressed into their command module’s “couch” while 7.7 million pounds of rocket thrust pushed away the Earth. Now, a small space separated their thighs from the seat fabric. If not for the straps of their harnesses, the three men would have risen like milkweed to the low ceilings of the transport pod.
It would be several more hours before a dot appeared in the navigational telescope, unmistakably white against the black of space. More hours still, waiting and hovering, until the dot became a shining oblong cylinder, flanked by two giant solar-paneled flags and topped with a windmill-shaped telescope. Skylab. Here was where they would dock themselves: at the gate of this white and black and brilliant gold capsule, which was falling in the orbit of the planet they’d just escaped at nearly one-half mile per second.
Not too long after landing, a cross spider spins her first full web. She casts a line outward, waits to feel it catch, and then secures the other end of the line to the spot where she rests. This creates a single-strand bridge that she can walk across, which she does, reinforcing it with a second bridge line. Once suspended from the center of that bridge, she free-falls, still pumping silk to form a Y-shape. She then pulls strand after strand from her body, spinning and falling, climbing and plummeting, hooking each strand to the crotch of that Y. Soon, a dozen spokes branch from the Y-hub like a silken sunburst.
Without stopping, she turns sideways and circles the spokes, connecting them in 30 cartwheeled spirals. Here is where she switches the gears of her body to produce a stickier silk—viscid enough to trap heavy prey. With this silk she weaves a second spiral. After that’s done, she eats the first spiral, then she eats the hub, and finally she arranges herself in the hub’s place. And though she will never rate a vantage to see her handiwork (even if she could, her eyes can’t focus at such a distance), the young spider has just filled her space with one of our Earth’s most spectacular pieces of craftsmanship, just as versions of herself have done for hundreds of millions of years. It takes her about half an hour.
NASA spent almost a decade designing Skylab’s orbital workshop, and its final blueprint held limited consideration for up and down. Rather than separate the station’s two levels with a solid floor, a crosshatching of beams split the workshop like an open, metallic net. A long blue pole ran through the center, so the men could pull themselves along the workshop’s 48 feet, but the astronauts scrapped the pole shortly after getting their space bearings. They preferred pushing off the walls and steering with their arms, floating through that empty center to travel from the workshop’s fore level—site of the dinner table, the latrine, and the three booths in which they slept bolted to the walls—to the aft level—with its radio and TV equipment, its biophysics lab, its materials processors, and its plastic vial the size of a human thumb containing a young cross spider named Arabella.
A spider was built to strum her web like a guitar. She was built to pluck a radial with one striped tarsal claw and feel how the pull of the world changes the vibration of her web. She was built to spin more sticky strands at web-bottom than at web-top, as gravity makes jumping down to prey less taxing than climbing up to it. She was built to drop a gossamer line and free-fall from danger, to walk the strands of her handiwork upside down, using her weight for propulsion.
For nothing says spider more than this built-in vigilance, this innate knowledge of what pushes her into the Earth and what lifts her away from it. Her legs, claws, mouth, the silk she unspools from inside herself, they all understand—with the hair-trigger sensitivity that comes from eons of experiments—the facts of our massive planet trying to collide with her body.
It wasn’t until the eighth day of the mission that Science Pilot Owen Garriott floated over to Arabella’s little vial. NASA had custom-built her a 15-inch square cage, as narrow as a framed portrait, with a flat glass front. Around the frame were mounts for long fluorescent bulbs and cameras, and at the top
right corner was an attachment point for Arabella’s transport vial, which would create a narrow tunnel for her to pass into the cage. Nobody wanted to risk releasing a tiny spider into the free space of the orbital workshop, which the crew knew had a mind of its own.
She refused to take the tunnel for a full mission day. Though she was only the responsibility of the science pilot, the two other crewmen couldn’t help but keep tabs on her. Pilot Jack Lousma watched Garriott opening Arabella’s vial and floated over to assist. “It didn’t know where it was, poor spider,” he later remembered. Commander Alan Bean, one of the dozen men who have walked on the moon, noted her in his private journal: “Owen got the vial off the cage, opened the door, and shook her out, where she immediately bounced back and forth, front to back, four or five times, then locked onto the screen panels at the box edge. There she sits, clutching the screen.”
The 16-millimeter film of Arabella’s earliest Skylab work depicts not so much a spider as the specter of one—a black-and-gray arachno-ghost. Eight thin strands glimmer about her body: these are her legs. White dots sparkle from a dozen other faint pinstripes: these are her gossamer. In the film, she tries to free-fall and hang an early radial, with tumultuous results. You watch her scurry along a horizontal line, half holding on and half bouncing, until she loses all footing; then weightlessness floats her above the line. A flailing of legs sends her tumbling in the other direction, sinking lower, though there is no “lower” to a spider somersaulting in a cage-in-space. She first flips head over abdomen, then corkscrews, so that her rolling turns sideways. Her legs reach outward in eight directions; then they all move inward, clutching the empty space as one desperate claw. Eventually, she finds the hard purchase of the cage’s corner and tries to locate some stillness there.