True intelligence is not an easy gang to join, but once you’re in, you’re in for life—the life of the universe. If some civilizations, even a very tiny fraction, make it to this quasi-immortal state, then the number of sentient civilizations should be growing over time, and the universe must be increasingly permeated with intelligence. This is not an opinion, it’s a calculation, and it leads me to a kind of “cosmic optimism.” It is possible to be highly optimistic about the cosmic prospects for technological intelligence, while hopeful but uncertain about the human future. Even if our own civilization is somehow doomed, there may be a bright future for life and consciousness. Perhaps there is, as Franz Kafka put it, “plenty of hope, an infinite amount of hope—but not for us.” I really don’t know if our long-term prospects are great, but I think the prospects for intelligence in the universe are promising. There is plenty of hope for the future, but whether we get to be a part of that is up to us.12
There is another kind of comfort that comes with belief in a universe widely inhabited by mind. It absolves us of the weighty responsibility of possibly being the only cosmically aware life-forms in the universe. Novelist Doris Lessing began her masterful space-fiction series, Canopus in Argos: Archives, with this dedication:
For my father, who used to sit, hour after hour, night after night, outside our house in Africa, watching the stars. “Well,” he would say, “if we blow ourselves up, there’s plenty more where we came from!”
If we really are alone and we somehow blow it here on Earth, wiping ourselves out through war or overpopulation, then we are not only behaving self-destructively but robbing the universe of an ability to ponder and explore itself. A widely inhabited universe lets us off the hook.
I also find it comforting that there are likely beings out there who have evolved powers of reason far beyond ours. It is exciting, and strangely encouraging, to realize that this universe is surely capable of producing “minds that are to our minds as ours are to those of the beasts that perish.”13 They may have found the answers to some of our most difficult and persistent questions, such as the basis of morality, the nature of consciousness, the mystery of free will, and how these all relate to the laws of physics. Our deepest philosophical and spiritual questions, such as “Why?” and “How ought we to live?” seem to be intractable. We are smart enough to conceive of these questions, but we cannot answer them. This may reflect that there are no definitive answers. Maybe that is the nature of reality, and we just need to live with it. Or this may have to do with the dim level of awareness and marginal intelligence we have achieved. Maybe we are just not too bright compared with true intelligence.
In the decades since Project Ozma, our searches have become orders of magnitude more powerful, and where Frank Drake once turned his radio dial by hand, our receivers now automatically sift through millions of radio channels simultaneously. Large swaths of sky have been scanned, at least for short periods, and more than a thousand individual stars, deemed promising prospects, have been targeted. The quest has been extended beyond the radio frequencies, now including optical searches for alien messages that might come in the form of laser pulses. So far, nothing has broken the frightening silence of those infinite spaces. Oh, there have been a few briefly exciting false alarms, but in all this time not a blip, squeak, or peep has been detected that can be repeatedly found by independent observers, clearly came from beyond Earth, and has properties that reveal an intelligent design. Yet, if you consider all the stars in our area of the galaxy, all the possible frequencies that could be scanned, all the possible times you could have had a telescope trained on them over the last half century, you realize that we have still barely scratched the surface.
Immersion in SETI takes the edge off the present, makes me worry a little less about the here and now. Is this escapism or an enlarged realism? The mind is diverted away from quotidian worries and toward searches and solutions that will unfold over the coming decades and evolutionary scenarios that play out over untold eons. When pondering life’s efforts to connect with distant life, you can’t help but gain some increased identity with Earth’s four-billion-year-old biosphere, a resilient beast that is going through some awkward transition phase now but is not credibly threatened with extinction. And you can’t help but wonder what, if we survive the coming century, we might become.
SETI requires of us patience and sustained attention. The chances of payoff in any given year may be low, but the potential return on investment is incalculably large. Such a project is a challenge for individuals and societies. We respond to urgency and novelty. We focus for a while and then our minds wander off, our attention responding to the next distraction or call to action. In attempting to build a sustained observation program, the founders of SETI are trying to establish an experiment that will run for as long as it takes, over multiple generations if necessary. In so doing, they are calling upon faculties we need to develop in order to begin the transition to one of those long-lived civilizations. In order to do SETI right, we need to start to become that which we seek, engaging ourselves in activities and goals that transcend individual lives. Still, it’s easy to be a little impatient, to want the discovery to come on your own watch.
It’s hard to be dispassionate about the prospect of making contact with, or even becoming aware of, life elsewhere because, as the poet Diane Ackerman writes, “I am life, and life loves life.” Who wouldn’t want to see their faces and shake their… whatever, or even just enjoy their greetings from afar and bask in their distant radio company? I don’t expect actual contact (i.e., face-to-face, or face-to-that-thing-they-look-out-of) to be easy or necessarily good. But a message seems harmless at worst, and it would be so nice to know we’re not alone, to have our faith shored up by revealed knowledge. Even if contact ends up being dangerous, scary, or deeply disturbing, we all just want to know, don’t we?
SETI is a hopeful enterprise. We are on some level aware of our massive double standard: that what we seek is something that has never existed on Earth, and is almost unimaginably different and more highly evolved than our own young, fragile, transitional civilization. In a sense, this search is an act of faith that such a historical outcome is possible. Scientists aren’t supposed to believe in angels or miracles, but we can believe in the possibility of evolved ETs with godlike capabilities and unknown power to transform our species beyond our current troubled state.
As a grad student in 1984, I attended my first SETI conference, the Search for Extraterrestrial Life: Recent Developments, at Boston University. Philip Morrison gave a riveting retrospective on the first twenty-five years of the field that started in response to his 1959 paper. Drake and Sagan both gave inspiring talks. I was impressed by the undimmed optimism of those pioneers who were certain that the search was in its earliest stages and that eventual success was almost assured.
Twenty-four years later, in September 2008, I attended a SETI workshop entitled the Search for Life Signatures, at UNESCO in Paris. Sagan and Morrison were no longer with us, but Frank Drake was there, showing more than a touch of gray, but as sharp and optimistic as ever. This workshop was focused on new developments that gave reason for optimism. We heard about how the Kepler spacecraft that was being readied for launch a few months later would revolutionize our knowledge of habitable planets. (Since then, it has!)
The keynote talk was given by astronomer Jill Tarter, who combined hopeful vision with hard-nosed engineering detail. It is this combination of personal qualities that makes the SETI community so enjoyable to work with. These people are realistic dreamers with their feet on the ground and their eyes wide open, fixed on the stars. Their wild speculations are backed up with solid equations, and they are not just hoping, but searching, searching…
Tarter was a grad student studying astronomy at Berkeley in the 1970s when she became drawn up in the quest. Following Drake’s retirement, she assumed his leadership role in the SETI Institute in Mountain View, California, which, after the U.S. Congress cut o
ff research funding for SETI in 1993, has doggedly and courageously maintained American SETI as a privately supported research effort. In the years since that Paris meeting, I’ve had the opportunity to collaborate with Jill several times on scientific and educational projects. She is one of the most brilliant people I’ve ever had the pleasure to work with, and great fun to share a drink with after a long day at a conference. Tarter has also been a leader in inspiring young people (girls in particular) to take up careers in science. At the Paris meeting, she reported on the first year of operations of the Allen Telescope Array, an ambitious new dedicated SETI observing telescope she helped to create in Northern California, which was projected to expand into by far the most powerful instrument ever created for SETI searches. Since then, it’s had a challenging existence, with expansion plans interrupted by budget troubles, and temporary shutdowns forced by funding problems in 2011 and a nearby forest fire in 2014. Still, it remains in operation.
I maintain hope that the universe will show us a sign, that my (I tell myself) scientifically informed faith may be rewarded. Personally, I want this more than anything except perhaps world peace,* and it even seems possible that one could help bring about the other—that contact could catalyze the kind of sea change in human awareness and planetary identity that just might help put a damper on nationalistic and religious conflicts. Such a discovery and its unpredictable effects goes in the category of potential game changers for the human future.
I’ve been waiting for a signal all my life, and although our powers of searching are just beginning to ramp up, I have to admit that I’ve felt my expectations drop somewhat. At least my hopes of a message received in my lifetime have dimmed considerably. Perhaps this is irrational, but we’re talking about hope here. If you try to look at the problem rationally and quantitatively, you know that we have not searched very far or wide, and there is still immense space within which a strong, unambiguous signal may be found. Yet, as the decades pass, I notice the persistent cosmic silence, and I have to deal with the increased likelihood of no signal while I’m here, of never knowing for sure.
As a teenager in the 1970s, I was, appropriately, full of what Shklovsky once called “adolescent optimism,” the exaggerated hope of the early SETI theorists that detection would come almost immediately. I’m still full of many things, but no longer this. I may once have been slightly brainwashed by the radio optimists I grew up around, but I also suspect that this change has more to do with being middle-aged than with any rational consideration of the observations to date.
It seems common for “contact pessimism” to increase as one grows older. Shklovsky and Sagan both became less optimistic as they aged. Both were also influenced by their increasingly dim view of the human future, but for SETI enthusiasts, this change in expectations might have to do with coming to grips with mortality, and becoming resigned to the likelihood of personally missing out on contact. So we egocentrically extrapolate this to the possibility of no signal ever.
My colleague Seth Shostak, senior astronomer at the SETI Institute, reminds me that there is much reason for continued optimism. The power of our receivers is increasing rapidly, in a pattern similar to Moore’s law, by which computer power increases exponentially, doubling every two years. Our electronic ears can listen much farther out into the cosmos with every passing year. Seth says that, given this, we’ll know in twenty years. He’s been saying this for a few years now, and I notice he hasn’t decreased his rough estimate as the years tick by. Still, I agree with his overall point. There is every reason to believe that if there are radio signals, awaiting a slightly more thorough or sensitive search, then the next couple of decades are propitious.
Much that we have learned in over a half century of space exploration seems to tell us that life and complexity are bound to be anything but rare. The basic ingredients and conditions that facilitated the origin and evolution of life here seem to be widespread throughout the universe.
When we started doing SETI, one of the great unknowns was the number of life-friendly planets. We’re finally nailing this down, and the truth is much more consistent with the dreams of the wild optimists who saw a universe teeming with life than with the galactic grumpycats who said we must surely be alone. When Sagan, Drake, and the rest of the Order of the Dolphin tried to quantify the number of galactic civilizations in 1961, they guessed the number of stars with planets to be between 20 and 50 percent, and the number of habitable planets per system to be between one and five, which leads to a predicted number of habitable planets per star of 20 to 250 percent. (It can be over 100 percent if, on average, each star has more than one.) Their guess, it turns out, was pretty good. The big reveal from the Kepler mission is that almost all stars have planets. The first extrasolar planets found were all non-Earths—mostly freakishly huge and hellish “hot Jupiters.” This was expected, since it’s so much easier to detect the star-broiled giants calling attention to themselves on hyperfast orbits. It’s harder to tease out the signal of worlds like ours, smaller, more distant from their stars and cool enough that our kind of chemistry, our brand of self-replication, would stand a chance.
Yet now we’ve started to find the tinier, less flamboyant Earth-class worlds. Preliminary estimates are that something like one in five Sun-like stars has Earth-like planets, defined crudely in terms of size and distance from their star. That’s more than eleven billion planets. More than one for every person alive today. So the planetary population of the galaxy turns out to be within the range guessed by the Dolphins many decades before we had any data. We don’t yet know how many systems have more than one habitable planet—perhaps our own came close to having three.
If you include stars that are not as Sun-like, adding in the more abundant red dwarf stars, and a sprinkling of other types, then we’re talking about perhaps more than fifty billion habitable planets in our galaxy alone. That’s nearly one for every person who has ever lived. This provides an astounding number of places where things could happen.
Combine this with what we’ve learned from the extremophile organisms on Earth, displaying the tremendous resourcefulness of life to thrive in so many kinds of environments and to extract free energy from its surroundings wherever it exists. These “lovers of extremes” have given us, more than just an expanded appreciation of life’s limits, a sense of the impressive diversity of life’s skills. They’ve taught us that organisms can tap into a huge assortment of alternative energy sources. There are, for example, creatures who are living off the hydrogen coming from nuclear decay in rocks a mile underground. This is impressive, and quite encouraging for the prospect of life on other planets.
All these discoveries encourage us to think that we live in a biophilic universe, one that is widely productive of life. Our galaxy is chock-full of potential Edens. So where are they?
The Meaning of Silence
A century is nothing in the life of a star, a planet, or a species. Yet the people who started SETI are growing old and dying without receiving so much as a whisper from the stars. We’ve heard plenty of noise but no signal.
What does this really tell us? Some will say not much, because we, and our search, are so young and green. Success would mean everything. Failure means very little. Or does it? Is there any message in all this silence? It may be true that we’ve only scratched the surface; still, we scratched it and there was nothing there.
It’s become a truism, a mantra, that “absence of evidence is not evidence of absence.” Yet a search that turns up nothing is different from no search at all. The question is how do you interpret it? A negative result could always mean you’re just looking in the wrong way. Still, the silence does tell us something about the kind of universe we live in. Most Sun-like stars in our immediate vicinity (within a few tens of light-years), we can now say, do not have a certain type of aliens, behaving a certain way, on their surrounding planets. If space were full of noisy neighbors cranking their radios, we would have heard them by now. Our galaxy doe
s not have civilizations occupying nearly every Sun-like star and broadcasting strong radio signals.
Beyond this narrow conclusion, we can only speculate and argue over the significance of the negative results. There is no shortage of speculation or argument. An extensive literature offers to interpret this “great silence” and the closely related Fermi paradox: If there are aliens out there in abundance, then surely some portion of them must be technically very advanced, and capable either of fantastic works of stellar engineering, sending messages, or ships to colonize the entire galaxy. If that is the case, then why haven’t we heard from or seen them? This conundrum is named the Fermi paradox after physicist Enrico Fermi,14 who, legend has it, posed the question to his Manhattan Project colleagues over lunch one day in Los Alamos in 1943: “Where are they?”
Fermi was known for his simple but deceptively instructive questions, which often concealed deeper lessons and have spawned a whole class of questions-as-thought-experiments that scientists call Fermi questions.15 When we geeks get together for a hike or a beer, these kinds of questions come up: How long would it take a bullet train to get to Alpha Centauri? Which is larger, the number of atoms in a human body or the number of stars in the universe? Before you know it, we’re reaching for our pens and scribbling “quick and dirty” calculations on napkins. Part of why Fermi is a geek god is that he was a master of this kind of thinking. When Fermi asked his colleagues, “Where are they?” he was implying more than a wistful look toward the heavens. He was suggesting a calculation. If you make a few reasonable assumptions about the behavior and capabilities of advanced aliens, it’s easy to show that their presence in our universe should be obvious. The fact that it’s not is then the paradox.
What are these assumptions? That a civilization slightly more technically advanced than ours should be able to travel between the stars, and that, having done so, they, or their offshoots, would keep doing so. Even if such travel takes millions of years, they should have had more than enough time to explore or occupy the entire galaxy. Given the age of the universe and the number of places where life could get started, even if a minuscule number of these places produced advanced alien civilizations with this behavior, we should have seen them by now.
Earth in Human Hands Page 34
