|Five Billion Years of Solitude: The Search for Life Among the Stars – review|
|Thursday, 21 November 2013 15:51|
Astronomy is enjoying a golden age, but why does the search for intelligent life outside our galaxy matter – and will we ever move off-planet?
In "The Light Years", one of the Cosmicomics by Italo Calvino, the narrator sees with his telescope a sign on a galaxy a hundred million light years away that says "I saw you". Aghast, he checks his diary and finds that on that very day 200m years before he had done something that he had always tried to hide. He casts around frantically for a response, contemplating "Let me explain" and "I'd like to have seen you in my place" before settling for "What of it?" A conversation unfolds between the narrator and his distant interlocutor, with even more remote observers pitching into an exchange in which each comment takes hundreds of millions of years to arrive.
Calvino was writing in the 1960s, shortly after the discovery of quasars and at a time when the nature of the universe as we now understand it was coming into view. He turned this to delightful comic effect. But speculation that life exists across huge distances inthe cosmos is not new. In the sixth century BC Anaximander suggested that other worlds were endlessly forming and disintegrating in a universe of infinite extent. A century later Democritus, the laughing philosopher, argued that the never-ending dance of atoms would inevitably lead to countless other worlds and other lives. In the 12th century AD, citing a verse in the Qur'an that describes Allah as Lord of the Worlds, Fakhr al-Din al-Razi wrote of a thousand thousand worlds.
In the 17th century Johannes Kepler, Christiaan Huygens and others began to wonder if improvements to the recently invented telescope would one day enable humans to actually examine some of those other worlds. "There may be yet created several other helps for the eye," wrote Robert Hooke in 1665, "such as by which we may perhaps be able to discover living Creatures in the Moon, or other Planets."
Three hundred and fifty years later our view has expanded in ways Hooke and his contemporaries could not have imagined. We can watch stars forming in nebulae of dust and gas. We can see, via a deep field photograph taken by the Hubble space telescope, 10,000 galaxies, each containing billions of stars, in a patch of sky the diameter of a grain of sand held at arm's length. We have glimpsed a galaxy 13.3bn light years away, as it existed less than 500m years after the big bang. We can detect, though not directly see, the spin of a black hole and the relativistic effects that warp space-time near its event horizon. Every decade, sometimes every year, brings more astounding discoveries. And theorists say we have hardly begun. Perhaps more than 95% of energy and matter is entirely hidden from us. Perhaps ours is one of many universes, each of them like a soap bubble in a much larger multiverse.
A range of places that might possibly be inhabited has also come into view. Exoplanetology, the study of planets orbiting other stars far beyond our sun, is enjoying a golden age. More than 900 exoplanets have been identified, with another 1,000 suspected and new candidates appearing almost every week. Statistical extrapolations suggest there are probably some 20bn Earth-like planets in our galaxy alone. Our understanding of the nature of these distant bodies is advancing by leaps and bounds – recently, astronomers mapped the clouds on a planet 1,000 light years away. Concurrently, the burgeoning field of astrobiology is finding increasingly subtle ways of thinking about what could enable life to originate, evolve and thrive beyond the Earth.
And yet in at least one respect we are no further along than Democritus or Hooke. We have found no trace of other life. This seems strange. Given the age of the universe and its vast number of stars, extraterrestrial beings should be common. As Enrico Fermi put it tersely in 1950: where the hell are they?
In Five Billion Years of Solitude, Lee Billings tells the stories of those who have tried and are trying to answer Fermi's question. Billings communicates scientific and technical detail fluently, and there is much here to please any geek who does not already know how, say, it is possible to see a distant planet next to a star that outshines it as an exploding nuclear bomb does an unlit match.
But there is more to the book than this. Billings has taken great pains to track down and spend time with leading scientists in the search for alien life. He starts with Frank Drake, who began hunting for extraterrestrial intelligence in 1960 and is known for the Drake equation, which identifies the longevity of a technological civilisation as the key factor in whether we will ever observe one or communicate with it. Others include Gregory Laughlin, who throws out challenging, fertile ideas the way a catherine wheel throws out sparks, and Sara Seager of MIT, a leading light in a younger generation of exoplanetologists. And what really gives the book drive is that Billings relates their work to a question facing all of us: how may we best protect and cherish the life we do know on this planet?
Many scientists doubt we'll find intelligent life elsewhere in our galaxy. Why, then, continue the expensive search? The question seems particularly pertinent in the US at a time when that nation, struggling with the consequences of unfunded wars, increasing inequality and an out-of-control financial sector, is being held hostage by forces that are anti-democratic and anti-science.
There are three answers to the question. First, the show ain't over yet. Evidence of life may yet be observed, perhaps by a tell-tale chemical disequilibrium in the atmosphere of a distant planet. This will be fascinating in its own right – perhaps the greatest discovery in history.
Second, whether we find that life is non-existent, vanishingly rare or common in the universe, a better understanding of its parameters will sharpen our thinking about its nature and prospects here on Earth. That understanding could help us think more clearly about how to manage the impact we are having on our planet's biogeochemical system, which we are currently perturbing at least as profoundly as the factors behind some of the great mass extinction events in its history. It could be a small first step towards planetary intelligence.
Third, because in the very long run, as the sun gets hotter, the only way for humans or our successors to survive may be to move off-planet; it actually makes sense to start thinking about this now. Such a vision – "often implied but rarely acknowledged explicitly for fear of cynical ridicule" according to Billings – has guided space exploration since its inception when Konstantin Tsiolkovsky dreamed up the first space rockets in a remote log cabin in the late 19th century. It explicitly informs Starship Century: Toward the Grandest Horizon, a recent volume in which distinguished scientists explore the feasibility of initiating interstellar travel by 2100. They are quite sane, and their vision is not completely implausible, even if it's not wholly peaceable and benign.
In an interview last year Billings suggested that our era will, when seen in the fullness of planetary time, "prove to have been the fulcrum about which the future of life turned for, at minimum, our entire solar system". He argues that though humans possess the unique capacity to extend life and intelligence beyond Earth towards unknown new horizons, there is a better-than-even chance that we will fail to do so. The human story might end as it began – "in nasty, brutish, and short isolation on a lonely, solitary planet". Five Billion Years of Solitude is, in part, his attempt to explain and come to terms with these beliefs.
The physicist and pioneer of quantum computing David Deutsch is a little more hopeful than Billings. In The Beginning of Infinity, Deutsch stresses that for all the astonishing scientific advances to date, our ignorance is still infinite: we just don't know. (If the cartoon character Calvin is right, the surest proof of intelligent life in the universe is that it has not tried to contact us.)
In the meantime, perhaps we should just chill. In "The Universe as Mirror", Italo Calvino's late creation Mr Palomar hopes that meditation on the cosmos will bring him wisdom and equanimity. He returns from his reverie to the normal run of life only to find that he is as vulnerable to muddle, hesitation, blunders and anguish as ever before.
• Caspar Henderson's The Book of Barely Imagined Beings: A 21st Century Bestiary, is published by Granta and out now.
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