An important factor in the search for extraterrestrials that people underestimated has been revealed: what it's all about
The presence of oxygen in the atmosphere of exoplanets may be much more important for the search for alien life than previously thought. It's not about the mere fact of whether there is oxygen in the planet's atmosphere, but whether there is enough of it to allow technological life to develop there.
This is stated in a study by Amedeo Balbi, an astronomer at the University of Rome, and Adam Frank, an astrophysicist at the University of Rochester. The research has been published on the arXiv preprint portal and is yet to be reviewed by the scientific community.
The search for extraterrestrial intelligence is currently focused on the discovery of high-tech things on distant planets: radio signals, giant glowing cities, interstellar probes, or Dyson spheres.
But to create all these things, two important conditions are needed. The first of them is that aliens are able to work with iron. The second, and more important, brings scientists back to the banal: to work with iron, aliens must be able to ignite the fire that will be needed for all the complex manufacturing processes.
And this is where oxygen plays a very important role. If there is less than 16% or even 18.5% of it in the planet's atmosphere, the flame simply won't burn.
Scientists explain that the lack of fire affects the very survival of civilization. After all, if aliens can't light a fire, they won't be able to cook food, get heat to survive in harsh climates, or travel to colder regions. They will also be deprived of the ability to paint in the dark depths of caves. And these are all important evolutionary milestones.
No fire also means no smelting or metalworking, no energy for machines and no industry that could produce radio antennas, solar panels, or spacecraft.
Such a civilization would never be able to communicate with us or explore space as scientists do on Earth.
In other words, as Balbi and Frank emphasized, astronomers looking for signs of high-tech alien civilizations should focus their efforts on planets with atmospheres rich in oxygen.
At the same time, they do not rule out the possibility that there are civilizations built without the use of fire, but they will be invisible to Earth-based researchers and can only be detected during direct contact in the future.
At the same time, Balbi admitted in an interview with Inverse that it will not be easy to find out how many planets have enough oxygen in their atmosphere to allow aliens to use fire.
"The amount of atmospheric oxygen depends on the interaction of many phenomena, including geology, astrophysics, climate, biology, etc. We are still not able to make reliable predictions for typical planets. We definitely need more data from exoplanets and more theory," he said.
To do this, he said, we need more detailed measurements of exoplanet atmospheres and more computer modeling of how planets form and evolve.