by Lee Billings
Drake turned to what he said was his current favorite, a single orange bloom with three angular petals that tapered to sharp, blood-red points. They looked like fangs. “This one’s a hybrid of two different genuses, Dracula and Masdevallia,” he said. “Cold-growers from the Andes. No one’s seen one like this before, with this red. It wasn’t blooming yesterday. Some of these only blossom one day out of the year, and the next day they’re gone. You’re lucky to be here right now—the flowers aren’t long for this world.” He touched the petals with reverence.
“They die, but they have reincarnation,” Drake went on. “In principle, well-tended orchids are immortal. They reproduce by putting out new growths. Here’s one.” He gestured at a plant that bore no blooms but had several yellowish bulbous shoots hanging from its encasing pot. “This one is quite old. It’s outgrown its container—I should probably transfer it. You can see its new growth in these pseudobulb leads. Once you have two or three of these, you can cut one off and plant it in fertile soil. It becomes a new plant, and that plant will make more, and those plants will make more still. Each one doesn’t live forever, it lives maybe three or four years, but the organism moves on like a wave, constantly generating new growth.”
I told Drake his orchids made me think of L, a technological civilization’s longevity, the greatest uncertainty in his equation. If it was too low, our galaxy could give birth to millions, even billions, of civilizations over its eons-long life, but each one, isolated on a lonely planet, would wither and fall unseen with no chance for cross-pollination. If L was high, then in-bloom civilizations could linger and eventually intermingle, hybridizing their cultures across the light-years. Stability could set in; some would perhaps gain a sort of immortality.
Drake smiled and nodded. The similarity had not escaped his notice.
• • •
Back inside, Drake fished a bag of cashews from his cupboard and offered me a bottle of Sam Adams beer. He opened a can of Coca-Cola, and we sat down on his living room couch to discuss what the future might hold for SETI. Drake said he still thought that a civilization’s average longevity approached 10,000 years, and that some 10,000 alien cultures were probably sitting out there in the Milky Way, waiting to be discovered. He admitted his belief was somewhat faith-based.
“I think 10,000 is plausible, but my estimate shouldn’t be dignified by saying there’s observational evidence that could accurately lead you to that specific number,” he said between mouthfuls of cashews. “The factor of L still remains a total puzzle. We now know the rough fractions of stars with planets, and we’re closing in on the frequencies of habitable planets. Sooner or later we’ll know that number. But something like the lifetime of technological civilizations . . .” He trailed off, and stared for a long moment at the living room’s blue stained-glass window.
Bits of multicolored glass were fused within the window’s field of blue, forming a series of pictograms outlined in metal wire. Sunlight shining through gave the window a phosphorescent glow like an old analog television screen, and the colorful, blocky shapes looked very much like crude pixelated graphics from some lost, early-1980s video game. Drake had devised the design in 1974, when he was in the middle of a two-decade stint as a professor at Cornell University. Drake had initially been drawn to the job in 1964 because at the time Cornell managed the newly opened Arecibo Observatory, our planet’s largest and most powerful single-aperture radio telescope. Soon after arriving at Cornell, Drake became the director of Arecibo, a position he held until 1981. The observatory was built into an immense limestone sinkhole in the jungle of northern Puerto Rico and boasted a 305-meter-wide (thousand-foot) bowl-shaped aluminum dish—big enough, Drake once calculated, to hold more than 350 million boxes of corn flakes. It was also big enough to transmit messages across hundreds, even thousands of light-years. On November 16, 1974, Drake used the massive dish to blast his message on a focused pencil beam of modulated radio waves toward a star cluster called M13, located some 25,000 light-years away, in the constellation of Hercules. With an effective radiance of twenty million megawatts at its specific wavelength, for the three-minute duration of the transmission Drake’s beam outshone the Sun by a factor of 100,000.
The image’s low resolution was a functional necessity; its content was formed from a series of 1,679 frequency pulses in the transmission beam: 1,679 is the product of two prime numbers, 73 and 23. Thoughtful aliens, Drake hoped, would use this hint to correctly interpret the message’s pulses as forming a grid of 0’s and 1’s 73 units high and 23 wide. His stained-glass window displayed the resulting output: a top row of dots establishing a binary counting method, listing numbers one through ten, followed by a second row listing the atomic numbers of hydrogen, carbon, nitrogen, oxygen, and phosphorus, the key chemical elements of all life on Earth. A third section assembled the preceding atomic numbers into chemical formulas for the nucleotides in a molecule of DNA, followed by a schematic depiction of a DNA molecule’s distinctive double helix. A long vertical bar represented the DNA molecule’s sugar-phosphate backbone, and doubled as a binary depiction of 3 billion, roughly the number of nucleotide base pairs within the human genome. The molecule’s image hovered over the head of a stick-figure human being, which was sandwiched between two more binary numbers, 4 billion and 14. Four billion was meant to convey the world population in 1974, and 14, multiplied by the transmission’s wavelength of 12.6 centimeters, was intended to show that the human figure stands 176 centimeters high—just as tall, it turns out, as Frank Drake. The figure stood above the third of nine small dots extending out from one dot very much larger—a representation of our solar system and a hint that we lived on the third planet from our star. Finally, Arecibo itself was depicted as a simplified dish and antenna, with its gargantuan dimensions given in binary notation.
Whether any aliens would comprehend the message is another matter—even for most humans, it was largely indecipherable. When Drake showed it to his peers prior to transmission, he found that their grasp of its content varied widely based on their expertise. Chemists spotted the elements, astronomers discerned the solar system, while biologists and most everyone else recognized the DNA. But not a soul correctly interpreted each and every element of the Arecibo message.
In the years after Drake’s Arecibo transmission, the question of its eventual interpretation was rendered somewhat moot by the realization that, a bit less than twenty-five millennia from now, when the message’s photons should be reaching some 300,000 stars in M13, they will pass instead through empty space. Galactic rotation will have long since carried the star cluster far from the message’s targeted swatch of sky. The pulse of radio waves will continue onward, perhaps passing near a few solitary suns before eventually escaping the confines of the Milky Way. Its fading echo of technology, its low-resolution snapshot of a biology, a culture, will stream on without end though the intergalactic void, long after Earth itself is but a memory.
The Arecibo message was more than the sum of its parts; it arguably represented the pinnacle of Drake’s personal and professional interest in interstellar communication. Indeed, Arecibo Observatory was something of a linchpin for his dreams of messages from faraway lands and strange peoples. Over the years, as the lingering cosmic silence led some SETI practitioners to lower their estimates of L and of the likelihood of civilizations around nearby stars, the giant Arecibo dish became a central justification for continued SETI efforts. Thanks to its existence, the possibility of contact could be preserved in an atmosphere of increasing pessimism: even supposing that our nearest neighbors were halfway across the galaxy, if they possessed and transmitted with something like our own Arecibo, built with early-twentieth-century technology, we could in principle still detect their signals. Arecibo was, for instance, one major rationale for the Allen Telescope Array’s later survey of planet-hosting stars in the Kepler field of view. Most of the Kepler field stars are several hundreds of light-years distant; the ATA would be extremely unlikely to detect
a radio signal from any of them unless the transmitting dish at the other end was at least as large as the one at Arecibo.
Much like the SETI Institute and the ATA itself, Arecibo had seen better days. Around the turn of the millennium, its funding had begun a steady decline as federal agencies such as the National Science Foundation and NASA, struggling with politically driven budget cuts to their own bottom lines, slashed their spending on the Observatory. Private donations, university funding, and a modicum of financial support from the Puerto Rican government did not sufficiently increase to fully offset the resulting shortfalls. In May of 2011, the NSF announced that Cornell University would no longer manage the Observatory, and handed off the responsibility to a consortium of public and private management partners, led by the nonprofit organization SRI International. Rumors circulated that, in the event of no major additional funding sources being found, the new managers would shut down Arecibo Observatory, dismantle the world’s largest radio dish, and return the limestone sinkhole to its natural state. In 2012, SRI International was given stewardship over the ailing ATA as well.
“In the beginning, the L factor was simply the likely duration that a civilization possessed high technology,” Drake said, turning his attention away from the window and back to the bag’s dwindling supply of cashews. “L really should be the length of time that a civilization has technology that you, that we, can detect. And that muddles everything up, because it means L depends not only on there being a technology to detect in the first place but also on the technological capabilities of the searchers. Look at our own civilization, for example. We’ve had radio for, so far, about one hundred years, which you’d think would give us a minimum L of one hundred. But we’re now becoming far more radio-quiet, so if someone’s looking at us with radio, they might not see us much longer.
“Back in the 1960s, we had powerful military radars, early-warning systems against intercontinental ballistic missiles, things like that,” Drake reminisced. “Those could be detected from nearby stars using equipment similar to what we had back then. I thought at the time that sort of technology would just keep getting more powerful, and that would keep Earth visible practically forever. What actually happened is that technology did get more powerful, but not how I’d expected. It got more efficient. The switchover to digital television has made us much, much less detectable than when we used analog broadcasting, for instance. We send more through coaxial cable and optic fiber than we used to. And most of the ways we transmit radio signals now are almost indistinguishable from cosmic radio noise. All that causes what could have been a big sign of our existence to just vanish. Poof!”
Drake sighed. “These days I think that more-advanced technological civilizations will probably prove more difficult to detect than younger ones,” he said.
On Earth, the high technology developed during the first half of the twentieth century had in the second half spread from developed countries to colonize the entire globe. After harnessing the power of the atomic nucleus, science had turned to the machinery within the nuclei of living cells, bringing forth what promised to be a transformative era of synthetic biology. The world’s human population had more than doubled, driven by bioengineered boosts in agricultural productivity, breakthroughs in medicine, and a host of other science-fueled increases in living standards. Simultaneously, extinction rates of natural species had soared due to environmental disruption and habitat destruction. The land was laced with superhighways, power transmission lines, and fiber-optic communications networks; the sky was crisscrossed with transcontinental jet contrails and the starlike gleams of orbital satellites; the air itself was filled with electromagnetic chatter from radios, televisions, and mobile phones, as well as with rising amounts of carbon dioxide from the frenzied combustion of the planet’s reservoirs of fossil fuel. Rapid, successive revolutions in information technology had made powerful computers networked, ubiquitous, and personal, creating vast virtual realms often only tenuously linked to the world of atoms.
What those changes meant for the future of our culture and our world remained to be seen, though it seemed possible that, given a few centuries’ time, we might not even recognize whatever our descendants had become. I mentioned to Drake that many of the same Silicon Valley tycoons who helped fund the SETI Institute often chattered about a dawning era of even more radical and rapid change, a coming “technological singularity” in which exponential growth in computing power and sophistication would profoundly transform, at minimum, the entire planet. Some techno-prophets spoke worshipfully or fearfully of computers becoming sentient and gaining godlike powers. Others speculated that someday humans would break free of their carbon-based chains by uploading their minds into silicon substrates, where they could, in some manner, live forever. All seemed to agree that if humans themselves weren’t destined to inherit the Earth, they would certainly author whatever ultimately would. A few even conjured up the bygone Space Age dreams of Drake’s youth, envisioning a new golden era of prosperity and exploration in which humans would travel with their intelligent machines throughout the solar system, and perhaps someday to other stars.
“Yeah, I’ve heard all that stuff,” Drake replied. “It would be nice if we made it to Mars. But I don’t hold with the hypothesis that we’ll all slowly become or be replaced by computers. And of all the things we might someday do, I don’t think we’ll ever colonize other stars.”
I asked why not.
“I don’t think computers can have fun,” he said. “I think joy is a quality not available to computers. But what do I know?” He laughed. “Interstellar travel, on the other hand, I’ve worked on that quite a bit. Putting a hundred humans around a nearby star costs about a million times as much as putting them in orbit in your own system. You’d have to be pretty rich to pull that off.
“Let’s say you have two colonies ten light-years apart—that’s probably the typical distance between habitable planets, I’d guess. The fact is, you can’t really go faster than about a tenth of light-speed. At speeds higher than that, if you hit anything of any substance whatsoever, the amount of energy released approaches that of a nuclear bomb. So you’re limited to about ten percent, a speed we currently can’t come anywhere close to, and that means you’re looking at journey times of at least a hundred years. The distances, times, and speeds are daunting, but the most daunting thing of all is the cost. Take something the size of a Boeing 737 plane, which is about the smallest that might make a reasonable crewed expedition, and send it at a tenth the speed of light to a nearby star, okay? Now just work out the kinetic energy that’s in it. It turns out to be about equal to two hundred years of the total electric power production in today’s United States. And that’s assuming a one-way trip, where you don’t even slow down and enter orbit on the other end. The inherent difficulty of interstellar travel is one of the big reasons why looking for things like radio signals is so appealing.”
“So you think we’re stuck in the solar system,” I said, thinking of distant days when the swollen red Sun would sterilize Earth. “This is it?”
“Yeah, I think so,” Drake somberly replied. “You have to admit, though, that it’s pretty good while it lasts.”
Drake ate the last of his cashews, picked up his can of Coca-Cola, and tilted its lip to clink against the neck of my beer bottle. We drank to L and to all those who sought to make it a larger number.
A Fractured Empire
When Project Ozma was unveiled in 1960, it created a deep rift among astronomers. Some loved the idea of scouring the skies for other galactic civilizations, while others thought it the worst form of pseudoscience. In SETI’s defense, Otto Struve drafted an influential letter circulated among the upper echelons of the global astronomy community.
In the letter, Struve emphasized that planets were probably common around other stars, and that, while the likelihood of life or intelligence emerging on any particular world was unknown, “an intrinsically improbable single event may become highly
probable if the number of events is very great. . . . There is every reason to believe that the Ozma experiment will ultimately yield positive results when the accessible sample of solar-type stars is sufficiently large.” Humanity, he reasoned, could no longer consider itself alone and anonymous on the cosmic stage.
Astronomy was at a turning point, Struve wrote. The Space Age had thrust the field into “a state of turbulence, uncertainty, and chaotic expansion unknown in the history of mankind,” one increasingly funded by massive government coffers. Astronomers could capitalize on that newfound abundance by embracing the search for extraterrestrial life and intelligence, mustering a new age of discovery rivaling that of the Enlightenment. Or, they could just muddle along pursuing nothing but the status quo, leaving a less impressive record for future historians, one defined “by the team work of many competent but not especially brilliant scientists, by the evident confusion of ideas, by the competitive aspects of our research and its political overtones.” The truth, as it so often turns out, would lie somewhere in between.
Struve’s admonishment was on my mind when, a few days before my meeting with Drake, I attended a gathering of scientists and journalists 125 miles north of Santa Cruz, at the Marconi Conference Center in Tomales Bay. Built in 1913 by the Italian radio pioneer Guglielmo Marconi, the Center had in a previous life been the world’s first trans-Pacific receiving station, though it now served as the site of an annual interdisciplinary conference held by the University of California, Berkeley’s Miller Institute for Basic Research in Science. It was a warm sunny Saturday afternoon, with small boats and Jet Skis dotting the narrow bay’s emerald waters, but the conference-goers were all sitting in a stuffy, darkened room, spellbound by a tall, smartly dressed man, thin and angular, with dark hair, wide green eyes, and a hawkish nose. He was talking excitedly, occasionally stammering in his rushing words, making gangling gesticulations in front of PowerPoint slides on a projector. He was Greg Laughlin, the forty-four-year-old astrophysicist and professor at UC Santa Cruz.
