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In the search for extraterrestrial life, we are the real aliens

Jaime Green’s ‘The Possibility of Life’ teaches us that when we look beyond Earth, we are ultimately looking back at ourselves

(Illustration by Mark Pernice for The Washington Post)
6 min

Humans in the early 21st century are a lonely lot. Though our space-based telescopes can see the first nanoseconds of the universe and have found exoplanets seemingly everywhere, we have yet to detect anything we recognize as life beyond our planet. Not even a microbe. The more we learn, the more likely it seems that we’re alone. And yet it was not always that way. Johannes Kepler, who discovered the elliptical orbits of planets around the sun, was convinced by his work that life was abundant in the universe. He even wrote science fiction about alien worlds in the 17th century, to prepare people for what he considered inevitable. For hundreds of years afterward, scientists believed we lived in a universe teeming with life.

As science journalist Jaime Green points out in her new book, “The Possibility of Life: Science, Imagination, and Our Quest for Kinship in the Cosmos,” the 20th century changed all that. Powerful telescopes revealed, disappointingly, that Martian canals were merely geological features and the moon’s craters were devoid of celestial cities. Despite Carl Sagan’s promise that we are not alone, there is no evidence to prove we are not. And thus, humanity has entered its singleton era, searching for life in a universe where we fear there is none. Still, as Green argues persuasively, it’s the search that matters; looking for friends among the stars is what defines us as human.

A wide-ranging and delightful survey, “The Possibility of Life” is the kind of book that makes you exclaim “Wow!” out loud while reading on the bus. To some extent, that’s because Green packs the book with fascinating facts. Did you know, for example, that the secret to Earth’s fecundity might be our gigantic moon? Or that Louis Pasteur, the chemist who proved the germ theory of disease, also busted the myth of life on Mars? Even more mind-blowing, though, is Green’s ability to make us rethink everything we thought we knew about life on Earth.

Her first target is science itself. Green introduces us to ideas from exobiology (the study of life on other worlds) and researchers who study exoplanets (worlds beyond our solar system), pointing out that these fields rely as heavily on science fiction as on mathematical probabilities. “Scientists imagine things every day,” she writes. “They imagine a possible chemical pathway and test it. They imagine the surface of a distant planet about which hardly anything is known and render it as artwork. … We imagine alien life in a similar way through fiction.” The only life we’ve encountered is on our own planet, and thus all our conjectures about life elsewhere are by definition fiction. But that’s okay, Green reassures us. “Science fiction is more than entertainment, it’s a generative act that creates new possibilities of life beyond Earth, as valid and potent as anything we might conjure up in the lab.”

Unlike most science books that touch on sci-fi, “The Possibility of Life” does not trot out cliched references to Isaac Asimov and Arthur C. Clarke. Green isn’t neglecting history — there’s a truly lovely analysis of the forgotten 1937 classic “Star Maker” by Olaf Stapledon — but she focuses largely on contemporary works that engage with recent scientific discoveries. In the process, she upends our expectations about scientific research by putting it on par with the humanities, weaving the two fields together to show us what it means “to be matter and alive.” Maybe this fiction will all turn out to be wrong, Green muses, but our human-centric science might be just as wrong.

With infectious humor and enthusiasm, she explores why aliens might look very similar to humans by dipping into episodes of “Star Trek: The Next Generation.” Then she invites us to contemplate the precarity of existence on a planet without a moon in the alien landscapes depicted by the contemporary sci-fi great N.K. Jemisin, who wrote the “Broken Earth” trilogy. And she helps us wrap our minds around nonhuman language in the work of Ted Chiang, whose short story “Story of Your Life” was the basis for the movie “Arrival.”

N.K. Jemisin offers a hopeful — if fantastical — message of tolerance

As Green peels away our Earthly preconceptions, the book gets truly wild. Why, she asks, do we assume that life on other worlds develops via the same process of evolution that Homo sapiens endured? In conversations with microbiologists, she reveals that there are many other ways life could adapt to its environment. For example, a planet might not have zillions of species competing to be the fittest. Instead, there might be one “species” whose members share genes the way bacteria do, by transferring genetic material between organisms. A blob that learns to walk could share genes with a squiggle that swims, and presto, you’d have a walking blob-squiggle. Or a swimming blob. No sexual selection, no natural selection — just swapping genes in productive chaos.

Green also blows up the widespread idea that advanced alien civilizations will be run by machines. Right now, humans are infatuated with technology. Therefore, scientists and fiction writers fantasize that tech represents an advanced state of civilization. But, Green reminds us, that’s roughly equivalent to insisting that Earth is at the center of the universe. Video games and computers may not turn out to be the most important things to everyone else in the galaxy. We need to keep our minds open and realize that for aliens, “advancement” could mean something completely unexpected.

“The Possibility of Life” is rich with these kinds of insights, teaching us that when we look beyond the gravity well of Earth, we are ultimately looking back at ourselves. Green talks to researchers who are trying to decipher the language of dolphins, suggesting there might already be an alien intelligence right here beside us. At the same time, she acknowledges the loneliness of our position, our hunger to find another species like ours and compare notes. It’s that last bit, the comparing notes, where Green finds hope. Ultimately, the quest for extraterrestrial life reflects a desire to see ourselves from an outside perspective. Inventing aliens — in science and in fiction — gives us an imaginary vantage point from which to see ourselves anew and figure out where we’d like to go next.

The Possibility of Life

Science, Imagination, and Our Quest for Kinship in the Cosmos

By Jaime Green

Hanover Square. 268 pp. $32.99

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