Oxygen is a vital element for life as we know it, but it could also be a key factor for detecting intelligent alien 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 those with low oxygen levels. The reason is simple: fire.
Fire is essential for many human inventions, such as metalworking, machinery, industry, and communication. Without fire, we would not have radio telescopes, rockets, or spacecraft.
But fire requires oxygen to burn, and not all planets have enough oxygen in their air to sustain combustion. Balbi and Frank estimate that a planet needs at least 16 percent oxygen to support fire, and preferably more than 18.5 percent.
The study, which has not yet been peer-reviewed, proposes that oxygen could be a useful technosignature: a sign of technological activity on a distant world.
By looking for planets with high oxygen levels, astronomers could narrow down their search for potential alien 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 could be other factors that prevent a civilization from developing or communicating with us, such as environmental challenges, social conflicts, or ethical choices. And there could be other ways of achieving 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 emergence of technological civilizations, but it certainly helps a lot.