In the search for extraterrestrial life, all ideas are welcome, including exploring for a technosignature that an advanced civilization might produce. Researchers have found potential signs around several dozen stars!
Imagine if we could harness all the energy of our Sun. To do this, we would need to build what scientists call a Dyson sphere. An immense structure – in the form of a bubble, a ring, or even a swarm of satellites – capable of capturing its energy. Humanity is currently not capable of such a feat. But perhaps advanced extraterrestrial civilizations have already achieved it. Astronomers searching for signs of life elsewhere in the universe certainly hope so. That’s why they have embarked on a quest to find a star whose brightness would betray the presence of a Dyson sphere.
However, let’s not kid ourselves. Finding such a star in the vastness of the cosmos, is a bit like looking for a needle in a haystack. But astronomers are persistent. And today, two separate studies claim to have discovered not one, but several dozen serious candidates.
Dyson Spheres Betrayed by Their Infrared Radiation
In the Monthly Notices of the Royal Astronomical Society, researchers from Uppsala University (Sweden) first present the advances of Project Hephaistos. This project is named after the Greek god of blacksmiths as it aims to detect signs of extraterrestrial technology. Not necessarily Dyson spheres, but also traces of industrial pollution in the atmosphere of an exoplanet, for example?
By examining optical and infrared data from satellites, the physicists have developed a method to identify clues that could indicate the presence of a Dyson sphere around a star. Because these structures, the researchers believe,It would radiate heat in the mid-infrared that astronomers might be able to detect.
They applied the method to as many as five million objects in our sky. And what they found was… seven particularly convincing Dyson sphere candidates! For these, they recorded clear emissions in the mid-infrared without any known contaminant or identified natural source that could explain them. However, astronomers point out that the presence of hot debris disks surrounding these Dyson sphere candidates remains a plausible explanation for the observed infrared excess.
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In previous publications, scientists involved in the Hephaestus project reported that they had not been able to find any serious Dyson sphere candidates in over 1,000 galaxies studied. They thus set an upper limit on the proportion of galaxies like our Milky Way that could host an advanced extraterrestrial civilization. According to this work, fewer than one out of 300 galaxies may have given rise to extraterrestrials who developed technological intelligence. The astronomers from the Hephaestus project also searched for stars whose brightness could be dimmed by a Dyson sphere. However, other studies suggested natural explanations. Nevertheless, an upper limit could still be set. The researchers concluded that fewer than one star out of 50,000 within a radius of 100 parsecs from Earth could be surrounded by a Dyson sphere.
Meanwhile, researchers from the International School for Advanced Studies (Italy) present their own results. They, too, sifted through the data in search of excessive infrared emissions. And they found 53 candidate Dyson sphere stars. But they also emphasize the need for caution. Before considering an advanced extraterrestrial civilization, all less exciting explanations will need to be ruled out. For example, the collision between two planets, which could produce a significant amount of debris and radiation possibly similar to that emitted by a Dyson sphere built by extraterrestrials.
To learn more, a closer observation of all these candidates will likely be necessary. Perhaps with the help of the James Webb Space Telescope.