I had pretty well decided we were alone. Surely life from another part of the universe would have shown up by now?
But maybe it already has.
In the way that a constellation’s points of light connect into a picture once you know what you are looking for, clues have been popping up.
· A beam of radio waves coming from the direction of Proxima Centauri, the next star over from our sun.
· A global liquid water ocean beneath the surface of one of Saturn’s moons, and in it four of the six elements key to life as we know it.
· Jupiter’s moon Europa with has vast seas below its icy surface, plus a red tinge that could be caused by frozen microbes.
· Methane gas, which is associated with biological life on Earth found in a soil sample from Mars.
· A gas called phosphine—also associated with biological life on Earth—found high in the clouds of Venus.
· A dot of light moving at almost 200,000 miles an hour (four times the speed of its likeliest explanation, an asteroid).
Stray, oddball observations that bolster wishful thinking? Each sign could be shredded and tossed away as nonsense, but astrophysicists do not give up as quickly as I did. The question many ask about extraterrestrial life is not if but when we will find it. Back in 1997, Carl Sagan said, “There can be little doubt that civilizations more advanced than the earth’s exist elsewhere in the universe.” Just a few years ago, Ellen Stofan, director of the National Air and Space Museum and former chief scientist for NASA, predicted that “definitive evidence” of extraterrestrial life will be found in the next two decades.
So where did that beam of radio waves come from? In 2015, with funding from a Russian billionaire and the intellectual blessing of Stephen Hawking, a project called Breakthrough Listen was launched to look for alien radio waves. So far, the pure, unmodulated tone that was detective five times on April 29, always coming from the direction of Proxima Centauri, is the most exciting and otherwise inexplicable finding. It may turn out to be an artifact of interference, the waves human in origin and bounced about the cosmos—but so far, it cannot be so easily dismissed.
As for the mysterious and speedy dot of light, it was first seen by a telescope atop a volcano in Maui, but other observatories then tracked it, too. The extreme variations in its brightness (tenfold every eight hours) have convinced astronomers that it is either, as Elizabeth Kolbert put it in The New Yorker, “long and skinny, like a cosmic cigar, or flat and round, like a celestial pizza.” It is an interstellar object, many have decided—thus could be the first confirmed interstellar object ever observed in our own solar system. Its name is Oumuamua, Hawaiian for “scout.”
The man surest of Oumuamua’s implications is Avi Loeb, a Harvard astrophysicist. It is not an interstellar object, he insists, but an object manufactured by an alien civilization. The best, most economical, Ockham’s Razor explanation of its weird acceleration pattern, he proposes, is that it is propelled by solar radiation. Extremely thin (no thicker than a millimeter), its large surface acts as a sail—powered by light instead of wind.
Other scientists slammed his theory, so Loeb abandoned the tiresome back-and-forth and wrote his own book, Extraterrestrial: The First Sign of Intelligent Life Beyond Earth. Is he too far out there? We already know that somewhere between 1.5 billion and 2.4 billion planets in our galaxy alone could, theoretically, shelter life. Alan Lightman, author of Einstein’s Dreams, did a quick calculation and “estimated that the fraction of all matter in the universe in living form is roughly one-billionth of one-billionth.” In other words, “if the Gobi Desert represents all
of the matter flung across the cosmos, living matter is a single grain of sand on that desert.” Lightman argues that makes us special, the scribes who record the universe and look for its meaning.
Sara Walker, an astrobiologist and theoretical physicist at Arizona State University, says we might be a little too caught up in our own specialness, our perceptions as self-centered as the old conviction that the planets must revolve around us. We could easily have encountered alien life forms already and failed to recognize them, because we get stuck in our own assumptions.
When Ellen Stofan predicted finding extraterrestrial life in the next two decades, she added, “We know where to look. We know how to look.” Walker is not so sure. We look for life in the way we understand life, she points out. “Oxygen in the atmosphere, we’ve always looked for as an indicator,” but oxygen can be easily created in other ways. “We need a more general definition that doesn’t depend on the specific biochemistry Earth uses.”
Until now, we have just used our own biosphere as the model. This is a bit lazy, and it reminds me of so many other mistakes. The way we used our own bodily reactions to decide that animals that did not flinch felt no pain. The way we used medical research findings from white men’s bodies to make decisions about the health of women and people of color. The way we project our own feelings and assumptions when we are trying to understand other people. Why do we keep doing this?
But I digress. Walker says we first need to expand our definition of “life.” To her, life is “the physics of creativity.” Technology is a sure sign of life, she points out. Her current work involves searching for “laws of life” that apply across the universe, and she feels sure they would involve information. When life emerges from non-living matter, information (a DNA code, for example) is what makes that transformation possible. So we need to figure out how information originates in the universe.
Arik Kershenbaum, author of The Zoologist’s Guide to the Galaxy, thinks natural selection might be a universal law. If so, we could reason our way to other life forms by figuring out what traits would have proved advantageous for them. Here on Earth, for example, intelligence is useful, and he thinks that might hold true across the galaxy.
So if there are forms of life out there that are as smart as we are or far smarter, why have they not shown themselves to us? They have imposed a “galactic quarantine,” suggests Jean-Pierre Rospars. They realize “it would be culturally disruptive for us to learn about them.” Which is accurate, if patronizing.
There is another possible reason for the, er, radio silence. Given life forms’ propensity to wipe themselves out, Loeb wonders if Oumuamua is reaching us light years after its civilization died out. Far from finding that discouraging, he is eager for us to develop the same photon technology and send a vessel to Alpha Centauri, a star system only twenty-five trillion miles away. Maybe it could even carry some of our DNA there.
Then we would be the extraterrestrial life, and we would recognize ourselves.
Read more by Jeannette Cooperman here.