The modern search for extraterrestrial life requires unique thinking. Researchers must be open-minded and creative enough to imagine something beyond our current knowledge of the universe. At the same time, to be taken seriously, researchers must be skilled enough to analyze sophisticated astronomical images using supercomputers, artificial intelligence, and other means.
That’s exactly what the researchers behind Hephaestus, a Swedish-based project trying to identify signs of extraterrestrial life in the universe, are: a team of prolific astrophysicists who share a dream that the observable universe may hold traces of far-flung civilizations that we don’t yet know about.
Earlier this year, the group Published a paper The study used machine learning to sift through a large dataset of infrared images of a Dyson Sphere, a network of alien satellites that harvest energy from stars. The idea is old, but the scientists’ AI-heavy approach was new.
“If we want to do this, we need to try things we’ve never tried before,” says the Hephaestus Project leader. Eric Zachrisson.
In their paper, the Hephaestus project identified seven stars that appear to be surrounded by something like a Dyson sphere, which are potential candidates for further study.
Just two months after the announcement, another research team Questioned the results of Project HephaestusThe truth has yet to be revealed.
What is a Dyson Sphere?
Many great hypotheses come from science fiction, and this is especially true in the search for alien civilizations. Freeman Dyson attributes the original idea of a Dyson sphere to Olaf Stapledon.
After all, Stapledon’s epic 1937 science fiction novel Star Maker, Contains only brief mentions About an alien civilization capable of harvesting the energy of the stars. From this idea, Dyson imagined that any technologically advanced society would inevitably become dependent on the sun as a plentiful and stable source of power.
Zachrisson said a common misconception about a Dyson sphere comes from its name: It’s likely that a Dyson sphere isn’t actually a sphere at all. Instead, it’s a web-like network of satellites orbiting a star. The satellites collect energy from the star in the same way that solar panels collect light energy from the sun.
Read more: What does extraterrestrial life mean and why are experts searching for it?
Challenges in identifying potential Dyson spheres
When Project Hephaestus went to search for the Dyson Sphere, they programmed their model to find stars that were partially obscured by what appeared to be energy-harvesting satellites, and to eliminate any results that could be explained by corrupted data or known “astrophysical phenomena.”
“The problem is that there are some common objects that give us infrared excess,” Zachrisson explains. “We want to eliminate those.”
Images from the seven candidates for the project show what looks like a shaggy rug with chocolate shavings sprinkled on its surface — the intense heat generated by nuclear fusion reactions in certain stars — and it’s these chocolate shavings that interest researchers.
Like other solid objects, they hide the star’s intense heat from view, but each intriguing piece also emits a discernible amount of infrared radiation that matches the “waste heat” that the researchers predict energy-collecting satellites would emit.
read more: The secret origins of the search for extraterrestrial intelligence
Could space dust explain mysterious infrared images?
A British team led by astrophysicist Tongtian Leng, who cast doubt on the results of the Hephaestus mission, proposed a different theory: The researchers say that the Hephaestus chocolate bits are the result of interference from a hot, dusty foreground galaxy. Essentially, the phenomenon is not caused by an extraterrestrial civilization, but by irradiated space dust.
Zacklison acknowledges that three of the candidates appear to be hot, dusty galaxies, but the mystery remains unsolved.
“The question is, what do we not yet know? The jury is still out,” he said.
When Wren and his co-authors published their critique, the possibility of a nearby alien civilization seemed to have once again lost some permanence in the collective imagination of xenophiles. But Project Hephaestus’ four other candidates are still waiting to be confirmed or disproved. And whatever the evidence, one haphazard result is unlikely to deter explorers, especially with new methods emerging.
“Radio SETI dates back to the 1960s,” Zachrisson says, referring to the acronym Search for Extraterrestrial Intelligence (SETI). “We didn’t have infrared telescopes then. Astronomy has entered the era of big data, and we have a database of billions of objects in the sky.”
read more: New SETI tools expand search for intelligent life in the universe
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Gabe Allen is a Colorado-based freelance journalist focused on science and the environment. He is a 2023 Pulitzer Center reporter and is currently a master’s student at the University of Colorado Center for Environmental Journalism. His bylined articles have appeared in Discover Magazine, Astronomy Magazine, Planet Forward, The Colorado Sun, Wyofile, and Jackson Hole News&Guide.
