Quantum Legacies: Dispatches From an Uncertain World

by David Kaiser

  My mother rarely calls to talk about my research. One of the few exceptions occurred in April 2010, when she asked, “Do you agree with Stephen Hawking?” That’s usually an easy question to field. On topics ranging from the behavior of black holes to the structure of the early universe, a safe answer is usually “Yes.” But that wasn’t what my mother was asking about. She was eager to learn whether I agreed with Hawking that trying to contact aliens would be a bad idea. Any extraterrestrial civilization that could receive our communiqués and act on them, Hawking warned, might show up on our doorstep looking to stay—and not in that friendly houseguest sort of way. “Such advanced aliens,” Hawking surmised, might be “looking to conquer and colonize whatever planets they can reach.”1 In no time at all, the word spread from Hawking’s voice synthesizer to the world’s blogosphere. Soon even my mother was calling.

  And so it was that the word “aliens” seemed to be on everyone’s lips and screens that spring, just in time to mark the fiftieth anniversary of SETI, the Search for Extraterrestrial Intelligence. Though philosophers and poets have long dreamed about alien intelligences, the modern history of SETI began with a brief article in the leading scientific journal, Nature. Two astrophysicists at Cornell University, Giuseppe Cocconi and Philip Morrison, postulated in 1959 that there might exist one uniquely well-suited frequency, nestled in the microwave region of the electromagnetic spectrum, at which intelligent civilizations might seek to communicate with us. Frank Drake, an astronomer at a newly established radio astronomy observatory in West Virginia, reasoned along similar lines. In 1960, he conducted his own search of the skies, under the code name “Project Ozma,” hoping to catch some telltale sign of intelligence chiming in at the special frequency. He was greeted mostly with hiss; one heart-thumping squawk, he later determined, came not from the sky but from a top-secret military installation nearby. Not easily discouraged, Drake attracted other colleagues to the topic, and the search for ET began.2

  Cocconi’s and Morrison’s Nature article makes for fascinating reading today. The article appeared less than two years after Sputnik had been launched, and it combined hardheaded calculation with an almost giddy optimism, the “can-do” and “gee-whiz” spirit that often marked the early years of the space age. Why look for signals from aliens? Because there are so many stars out there, Cocconi and Morrison explained. Many are similar to our Sun. Thus, Earth-like conditions, in which our own species evolved, might be fairly common throughout the galaxy. Cocconi and Morrison were further convinced that those myriad civilizations had likely developed “scientific interests” and “technical possibilities much greater than those now available to us.” Where there are Earth-like conditions, they reasoned, there could be life. Where there was life, there would be science.3

  Throughout their brief paper, Cocconi and Morrison performed a strange rhetorical loop-the-loop. Given the state of our science and technology, how should we anticipate that advanced aliens would try to contact us? Humans had recently learned about a process in hydrogen atoms that emitted microwaves at a particular frequency: the so-called “21-centimeter line,” first measured in a Harvard laboratory in 1951. Since hydrogen was the simplest and most abundant element in the universe, surely it provided a “unique, objective standard of frequency, which must be known to every observer in the universe,” Cocconi and Morrison wrote; after all, we already knew about it. According to their calculation, the frequency of that special line lay in a sweet spot of the electromagnetic spectrum, away from naturally occurring sources of background noise. Given the universal nature of the special frequency, aliens might reasonably expect any civilization to design sensitive receivers tuned to that frequency early in their development of radio astronomy, as indeed we had done. Therefore, the only “rational” choice the aliens could make would be to broadcast their messages at that frequency, confident that some day we would follow the same scientific-technological developmental pathway that they did—or that we imagined they did, given our own recent experiences. Reasoning about others was inevitably a projection of ourselves.4

  One needn’t be a psychoanalyst or hold a PhD in cultural studies to discern a sweet, quiet yearning throughout Cocconi and Morrison’s article. Not only were advanced extraterrestrial civilizations likely to exist, they asserted. But also the aliens were probably gentle, benign elders, monitoring our stellar neighborhood “expecting the development of science near the Sun” and “patiently” beaming out their signals to us, ever hopeful that our return beacon might announce that “a new society has entered the community of intelligence.”5 Before Morrison began his work on SETI, he had served on the wartime Manhattan Project to design nuclear weapons. He inspected both Hiroshima and Nagasaki just weeks after the bombings in 1945 as part of the first scientific survey team. Seared by the experience, Morrison turned his energies to the budding arms-control movement. During the early 1950s, he was hounded by red-baiting critics for what they considered radical “world government” ideas.6 No wonder he turned to the skies soon after in search of a more rational, welcoming community of civilizations.

  Figure 14.1. Above, Astrophysicist Giuseppe Cocconi gives a lecture at CERN, 1967. (Source: Courtesy of CERN.) Left, Astrophysicist Philip Morrison. (Source: AIP Emilio Segrè Visual Archives, Physics Today Collection.)

  SETI thus emerged as a by-product of the nuclear age. Drake, the radio astronomer, picked up where Cocconi and Morrison left off. To help organize discussions for a small workshop on SETI in 1961, he jotted down an equation, now known as the “Drake equation.” He wanted some means of estimating how likely it might be that advanced alien civilizations were out there. Variables included the average rate at which new stars form; the fraction of those stars that form planets; the fraction of those planets that develop conditions suitable for life; and so on. The final term in his equation, L, denoted the average lifetime of alien civilizations.7 Where Cocconi and Morrison’s paper reflected the hopeful buoyancy of the early space age, Drake’s equation bore the marks of its Cold War origin. For Drake as for nearly all his colleagues, L was always a stand-in for all-out nuclear war. Cocconi and Morrison assumed that life led inexorably to science. Drake continued: science led inexorably to nukes.

  Paul Davies tackles the air of inevitability that animated the SETI pioneers in his book The Eerie Silence: Renewing Our Search for Alien Intelligence (2010). Trained as a theoretical physicist, Davies now works in cosmology and astrobiology and heads the Beyond Center for Fundamental Concepts in Science at Arizona State University. (Some of his most influential early work refined physicists’ notion of the vacuum. He literally knows everything about nothing.) His main caution in the book is not to confuse necessary and sufficient conditions. The presence of water or amino acids on some distant planet seems necessary for life (at least for life as we know it); but their mere presence is far from sufficient for life to emerge. Same with the existence of Earth-like planets orbiting Sun-like stars. At the time that Cocconi, Morrison, and Drake were formulating their search strategies, astronomers had no direct evidence of planets outside our solar system. Today astronomers have identified thousands of these “exoplanets,” and improvements in observing techniques promise to reveal many more. Davies rightly points out, however, that even if exoplanets do turn out to be exponentially plentiful in our galaxy, the spark of life might prove to be an even more exponentially improbable occurrence. The easy leap made in the early days of SETI—from stars to planets to life to intelligent life—was never more than a conjecture. Hence, Davies concludes, the “eerie silence”—no confirmed SETI contacts despite fifty years of concerted listening—might simply mean that life as we know it is rare, not that civilizations inevitably self-destruct in nuclear holocaust.8

  Figure 14.2. Frank Drake (standing, second from right) and other members of the original Project Ozma team gathered at the National Radio Astronomy Observatory in Green Bank, West Virginia, for a reunion in 1985, shown here posing in front of the Howard E. Tatel eighty-five
-foot radio telescope used in the original 1960 Ozma experiments. (Source: Courtesy of NRAO/AUI/NSF.)

  Davies revisits other assumptions behind the early SETI work. Where Cocconi and Morrison assumed that intelligent civilizations would inevitably pursue scientific investigations, Davies counters that science is not universal, even here on Earth. Moreover, the old idea, common in the 1950s and 1960s, that basic science leads inevitably to improved technology seems difficult to square with humans’ own historical record. Ancient Chinese civilizations developed astounding technologies but little of what might look like Western-style science. If science and technology could follow such contingent paths just among members of our own species over a relatively short time period (cosmologically speaking), why should we assume that extraterrestrial civilizations would march, lockstep, from intelligence to science to technology?

  Davies questions the universality of science in one sense: the pursuit of scientific inquiry, the activity of science. An even more radical question concerns the universality of our scientific knowledge. Is our scientific representation of the natural world universal? Cocconi, Morrison, Drake, and their followers throughout the half century of SETI have argued over which regions of the electromagnetic spectrum would be most “rational” to target for a search. They have based their arguments on naturally occurring processes like the 21-centimeter hydrogen line or similar emissions from water molecules. But who is to say that other advanced civilizations—even if they do pursue something like scientific investigation—would carve up the buzzing, blooming confusion of nature in the same way that we do? Is our knowledge path-independent? We now think in terms of atoms, electrons, quantum transitions, and electromagnetic waves. Are those the only ways of making sense of physical phenomena? Is the intellectual history of Western science a universal pathway, some fixed point in the evolution of intelligence everywhere in the cosmos?

  The question of universality enters Davies’s account in a different way. He has chaired the SETI Post-detection Taskgroup of the International Academy of Astronautics. The committee’s charge is to develop a protocol to be followed in the event that someone detects signals of possible extraterrestrial origin. Few topics today elicit as much blog-addled conspiracy talk as purported government cover-ups of UFOs and alien contacts. Davies’s group has therefore aimed to steer a middle path between military-styled secrecy and unfettered airing of every false alarm. The current protocol calls for credible evidence to be shared first with other astronomers by means of the “Central Bureau for Astronomical Telegrams of the International Astronomical Union.” (One can’t help but smile at the name: telegrams to announce the findings, indeed.) The international community of professionals could then vet the evidence and try to rule out possible alternative explanations, like the terrestrial signals that fooled Frank Drake back in 1960. Next, the discoverer of the putative signal should alert the International Telecommunications Union, the International Council of Scientific Unions, and finally the secretary-general of the United Nations. Only after those international associations have been informed should the discoverer announce the finding to the public.9

  Conspicuous in their absence from the long list of “telegram” recipients are any national governments. In large part, that is because SETI activities no longer receive government funding. The US National Aeronautics and Space Administration (NASA) once had a hand in the SETI game, but not anymore. Philip Morrison, of the Cocconi-Morrison search strategy, received the first NASA grant for SETI research in 1975. Soon money was flowing to research groups across the country. With much fanfare, NASA inaugurated its own SETI observational program on Columbus Day in 1992, five hundred years after the explorer reached the New World. All told, NASA spent nearly $57 million on SETI between 1975 and 1993 and had pledged an additional $100 million—modest sums compared to most “big science” appropriations but real money nonetheless. But the US Congress killed all federal funding for SETI one year after the 1992 Columbus Day festivities. Ever since then, SETI activities in the United States and around the world have been supported by private donations.10

  SETI’s difficulties in Congress stemmed in part from a wave of budget-cutting during the fall of 1993. Indeed, the SETI debates proved to be a dress rehearsal for bigger targets. A few weeks after ending government funding for SETI, legislators killed funding for the Superconducting Supercollider. The Supercollider carried a price tag one thousand times greater than NASA’s annual expenditures on SETI, but both were felled by the same axe. Unlike the Supercollider, SETI operations were small and efficient, well managed and on budget. But SETI had few contractors to rally to its defense and little political “pork” to distribute across congressional districts. SETI also fell through the cracks between disciplines. It used tools from physics and astronomy without being central to either field, even as it trod on the toes of biologists, who knew about life, evolution, and intelligence.

  Beyond the budget cuts and the usual political horse trading, SETI suffered from an image problem. Advocates talked about the “giggle factor.” Grandstanding politicians wondered why the government should spend millions of dollars to search for extraterrestrial intelligence when one could just plunk down “75 cents to buy a tabloid at the local supermarket,” as one Congress member stormed in 1990. Upon introducing the final amendment to kill SETI funding in 1993, one senator proclaimed, “This hopefully will be the end of Martian hunting season at the taxpayer’s expense.” Silicon Valley entrepreneurs and other private philanthropists largely picked up the tab, enabling SETI researchers to keep the project running.11

  With all its talk about aliens, SETI has often been lumped together with occult topics or pseudosciences. Searching for references to Cocconi and Morrison’s article on the internet today, one finds links to the paper alongside books by New Age shamanism expert Carlos Castaneda and mystico-environmentalist tracts on the Gaia hypothesis. In the absence of confirmed contacts, critics charge, the field has been sustained by faith, hope, and speculation. Not so fast, proponents counter. SETI received high marks from three decadal reviews by the US National Academy of Sciences. The drive to improve detection capabilities led to major advances in microwave electronics and signal extraction. Frank Drake’s first SETI search relied on a single-channel receiver. By the mid-1990s, SETI devices could simultaneously scan 250 million channels with state-of-the-art resolution. No wonder the US Federal Aviation Administration and the National Security Agency both expressed interest in SETI spin-offs. Other SETI techniques were quietly incorporated into next-generation methods to simulate the inner workings of thermonuclear weapons.12 SETI still cannot shake the nuclear specter.

  Davies has high hopes for a different kind of spin-off. SETI can inspire greater interest in science and encourage young people to ask big questions: not just about the enormity of space and the evolution of the cosmos but about the human condition and everything that unites us as a species. Davies anticipated Hawking’s dour view of aliens, too. Although SETI does not broadcast signals of its own—it passively monitors for signals from others—Davies endorses “METI,” or Messaging to Extraterrestrial Intelligence. He sees no reason to think that aliens would have any of the anthropomorphic traits (jealousy, colonizing impulses) that Hawking imputes to them. The message Davies would send? “Keep well clear and defend yourself”: we are a helplessly militaristic society and armed to the teeth with nuclear weapons.13 Davies sees Hawking’s aliens in the mirror, and they are us.

  In fact, SETI might make its grandest contribution in the nuclear arena. Rather than pseudosciences or the occult, SETI seems most similar to recent efforts by the US Department of Energy. The overseers of the nation’s nuclear stockpile have had to get creative over the past two decades, designing secure facilities to house vast stores of radioactive waste. Some of the most hazardous by-products of the nuclear age, including isotopes of plutonium, have half-lives that stretch hundreds of thousands of years. The acutely toxic waste will be with us for countless millennia. O
ne challenge is to find nooks and crannies on Earth that might remain geologically stable over those kinds of timescales, into which the waste can be buried. A second challenge is to design symbol systems that might warn our own future descendants, three hundred thousand years from now, not to go digging in bespoiled areas. As Harvard historian Peter Galison has documented, the US nuclear agencies have sought the wisdom of diverse experts—linguists, anthropologists, sculptors—to imagine how we might plausibly communicate with terrestrial beings in the impossibly distant future.14 After all, the Latin alphabet dates back a mere twenty-six hundred years; cuneiform, the oldest known form of human writing, stretches back only a few thousand years before that. Only blind hubris could lead us to imagine that our familiar modes of communication will be recognizable in the year 300,000 CE.

  Alongside the linguists and artists, the nuclear bureaucrats have also enlisted experts in SETI. Struggling to communicate with our own future selves calls for the same kind of radical imagination that SETI requires. Both efforts crisscross the boundaries between disciplines. Both face the challenge of extracting meaningful information from senseless noise. Both require experts to project from what we know about our own civilization to facilitate communication with some distant other. They are mirror images, twin children of the nuclear age, each haunted by the dangling L in Frank Drake’s famous equation.

  15

  Gaga for Gravitation

  A remarkable publishing event occurred in September 1973: the release of a 1,279-page book, weighing more than six pounds, with the simple title Gravitation. Wags were quick to remark that the book was not just about gravitation but a significant source of it. The book acquired several nicknames, including “the phone book” (another reference to its girth) and “the big black book” (for its sleek, modern cover). Most common became “MTW,” named for the authors’ initials: Charles Misner, Kip Thorne, and John Wheeler.1