Oxygen is an essential element for life as we know it, but it may also be a key factor in detecting intelligent extraterrestrial civilizations.
A recent study by astronomers Amedeo Balbi and Adam Frank suggests that planets with oxygen-rich atmospheres are more likely to host advanced technological civilizations than planets with low oxygen levels. The reason is simple: fire.
Fire is essential to many human inventions, such as metalworking, machinery, industry and communications. Without fire, we wouldn’t have radio telescopes, rockets, or spacecraft.
But fire needs oxygen to burn, and not all planets have enough oxygen in the air to sustain combustion. Balbi and Frank estimate that a planet needs a minimum of 16 percent oxygen to support fire, and preferably more than 18.5 percent.
The study, which has not yet been peer-reviewed, argues that oxygen could be a useful technosignature: a sign of technological activity on a distant world.
By searching for planets with high oxygen levels, astronomers can narrow down their search for potential extraterrestrial civilizations. Oxygen can also be detected remotely by observing the spectra of starlight passing through a planet’s atmosphere.
Of course, oxygen alone is not enough to guarantee the presence of intelligent life.
There may be other factors that prevent a civilization from developing or communicating with us, such as environmental challenges, social conflicts, or ethical choices. And there may be other ways to realize technology without fire, such as using alternative energy sources or materials.
But oxygen could be a good starting point for exploring the possibility of extraterrestrial intelligence.
As Balbi and Frank write in their paper, “Oxygen may not be strictly necessary for the rise of technological civilizations, but it certainly helps a lot.
