Our search for alien life is getting serious. With better telescopes and a growing scientific consensus that we are probably not alone in the universe, we are starting to look farther and wider across the vastness of space for evidence of extraterrestrials.
But it is possible that we are looking for too few signals in too few places. Having evolved on Earth, surrounded by terrestrial life, we assume that alien life would look and behave like terrestrial life.
What if we’re wrong? What if ET was out there waiting to be discovered by the first astronomer willing to open his mind to the possibility that, to us, alien life might seem really strange?
Some scientists are trying to correct our bias on Earth. In a new study that was made available for reading on July 27, a team led by Arwen Nicholson, an astrophysicist at the University of Exeter, attacked a widespread assumption in astronomy. There is a common line of thinking that a distant “exoplanet” – a planet outside the solar system – would need a certain amount of oxygen and hydrogen to sustain life. And those life forms, as they lived, died and evolved, expelled methane gas that accumulated in the atmosphere.
Methane is one of the big things astronomers look for when it comes to evidence of alien life. They call it “biofirma”. But with over 5,000,000 exoplanets confirmed on the official roster and only so many telescopes powerful enough to observe them, astronomers tend to rule out planets that appear nutrient-poor, lacking, say, the hydrogen concentration we have here on Earth.
To test this hypothesis, Nicholson and his team built a sophisticated computer model of a more or less Earth-like planet, populated it with simple simulated microbes, then began extracting hydrogen. The goal: to see if the microbes would survive and if they would still excrete detectable levels of methane as they struggled on their resource-poor planet.
Surprise! The sturdy little organisms resisted. And yes, they still ejected enough methane to be recorded in astronomical surveys at a distance of light years. “These findings help deepen our understanding of the interactions between life and the planet,” wrote Nicholson and his co-authors. “Reduces the need to make unnecessary assumptions about alien life based on life on Earth.”
In practical terms, Nicholson’s study, which was peer-reviewed and accepted for publication in Royal Astronomical Society Monthly Notices– could expand the list of exoplanets that scientists consider worthy of examination for signs of life.
Astronomers are lining up to take turns using NASA’s new James Webb Space Telescope to inspect planets for biological signatures. The priority in this first year of JWST’s activity is the seven possible Earth-sized planets in the TRAPPIST-1 star system, 40 light-years from Earth.
The planets of TRAPPIST-1 are quite far away; it’s not like we had a real chance to visit any potential life on these worlds anytime soon. Astronomers are targeting them anyway, rather than closer but seemingly drier planets, because the TRAPPIST planets seem to be more likely to have all of those nutrients that terrestrial life really favors. “Would you prefer relatively sparse data on a hard-to-observe but truly Earth-like world, or much better data on a nutrient-poor neighboring planet?” this is how Étienne Artigau, an astrophysicist at the University of Montreal who was not involved in Nicholson’s study, described the surveyors’ dilemma.
If Nicholson’s model catches on, however, astronomers may be willing to risk their precious telescope time on a closer planet that has so far seemed a bit hostile to life.
But the study by Nicholson and his co-authors is still just a push towards a more open approach to ET research. She and her team are still assuming that aliens share the same common basic metabolism on Earth. You take in oxygen and hydrogen and expel the methane. “Since we only know about life on Earth, it’s hard not to be swayed by it,” admitted Nicholson.
But we can at least to imagine life forms with totally different metabolisms. “For the planets it could be very different [from] our, different metabolism may be possible than those on Earth, “said Nicholson.” Identifying those possible metabolics will be the key to contemplating life on distant planets. “
The problem is that unless and until we discover a life form with a radically different metabolism, a serious scientist is unlikely to create specially designed methods of investigation to find signs of that kind of life. It’s a chicken-and-egg kind of problem: you can’t look for a thing you don’t know you’re looking for. And few scientists seem eager to design investigations into what are currently imaginary life forms.
“We are always limited by our imagination, which is guided by our experience,” Avi Loeb, a Harvard physicist who was not involved in Nicholson’s study, told the Daily Beast. For all their intelligence, curiosity and training, scientists tend to be extremely cautious when it comes to weird things.
It is that reluctance to probe the unknown that continues our search alien life so closely linked to our understanding of Land life. Institutional conservatism itself may prevent us from recognizing aliens even after we found them.
Take ‘Oumuamua. This is the name astronomers have given to a strange oblong object, up to 3,000 feet long and shiny, that shot through our solar system in 2017. Nobody knows for sure what it was. Likewise, no one should say for sure what it is it wasn’t. But despite ‘Oumuamua behaving as we would expect from an alien spaceship, very few scientists – Loeb is one of them – are urging their colleagues to at least consider the possibility that the strange object was an opportunity for first contact.
Instead, the scientific community simply shrugged as’ Oumuamua sped away. And that’s a problem, Loeb said. “Reality has ways to surprise us, so we should simply look for things or behaviors that are unfamiliar to us.” When a mysterious object zooms in on the solar system, defying easy categorization, perhaps you worry less about categories. Investigate with an open mind.
The same goes for the planetary surveys. To increase our chances of finding alien life, we might search in places where we wouldn’t normally expect life to thrive. It’s a big universe, after all. And it just seems odd by the day as our discoveries pile up.
More and more scientists are coming to the idea that aliens are out there somewhere. Perhaps more scientists need to do this also come to the idea that those aliens could be really weird.
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