“We’re aware it’s a very out-there theory,” said Olivia Curtis, a postdoctoral fellow at the Penn State Extraterrestrial Intelligence Center. She was talking about two days of whiteboards and lecture halls at MIT, where more than two dozen scientists took up an odd question: could an alien civilization have built a Dyson sphere around a black hole?
Curtis led the paper that came out of the gathering, the Dyson Minds 2025 Workshop. Penn State, MIT and The Ultraintelligence Foundation ran it. The paper appeared in Publications of the Astronomical Society of the Pacific. Astronomers, astrophysicists, AI experts, engineers and industry people sat in the same rooms.
From stars to black holes
A Dyson sphere is a hypothetical structure that an advanced civilization could build to harvest energy from a natural source. Physicist Freeman Dyson popularized the idea in the 1960s, first as a megastructure around a star. Finding one would suggest a civilization at Level II on the Kardashev Scale, one able to harness its sun’s energy.
The workshop asked what happens if the source is a black hole. Curtis said the idea sounds less like science fiction as people start to think about putting data centers in space. A life form hunting for the biggest energy gradient it could find, she said, would naturally end up at the center of its galaxy. Supermassive black holes sit at the heart of most galaxies, and the jets from them carry more energy than millions of Suns.
How close is too close?
A black hole is not a giant vacuum, Curtis said. Only past the event horizon do you get stuck. A sphere would sit far outside that line. She compared it with the Gargantua black hole in the film Interstellar and its accretion disk: the structure would be about 1,000 times farther away than that. Radiation is the real limit. A satellite needs to be roughly a parsec, about 3 light-years, from the black hole or it would melt.
Distance causes trouble of its own. If the sphere works like a giant data center, signals take a long time to cross it. Builders could beam data, and observers on Earth might catch periodic bursts as orbits line up and point our way. Or they could do something stranger. “It turns out that at these distance scales, if you want to transmit a zettabyte of information, it’s just faster to sling your hard drive at it,” Curtis said.
Looking for outliers
Curtis’s own work searches for infrared signatures around black holes. Scientists already know what the region should look like, she said, so the job is hunting for outliers. One target is data from the Event Horizon Telescope Team, which imaged the black hole in galaxy M87 in 2019 and Sagittarius A*, at the center of the Milky Way, in 2022. Current algorithms may be smoothing over odd blips in that data, she said, because they are built to produce a pretty picture.
No evidence of a Dyson sphere around a black hole has turned up so far. The workshop did lay out what to look for. Curtis does not expect aliens to be the answer. “Aliens are always the last solution,” she said, but searches like this tend to turn up something nobody had thought of.
