Technologically-savvy aliens could be powering their society using a hypothetical megastructure called a Dyson sphere to harvest energy from a black hole . A new study suggests that the sphere could emit unusual light patterns, which would allow telescopes to see intelligent beings in other parts of the universe.
According to Space.com, a Dyson sphere would be a speculative structure which would surround a star with tight formations of orbiting platforms to capture starlight and generate power. The idea was first proposed in 1960 by Freeman Dyson, a theoretical physicist. It could be realized by an extraterrestrial spacefaring species that has spread across their star systems and thus requires ever-increasing amounts energy.
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Tiger Yu-Yang Hsiao, an astronomer at National Tsing Hua University in Taiwan, and his colleagues were reading a paper on Dyson spheres. They began to wonder if it was possible to create one around a blackhole instead of a star.
Hsiao said that black holes were one of the most bright objects in the sky.
He said that while we think of black holes as all-consuming and dark, they can also radiate enormous amounts of energy. Material can form a disc when it falls into a dark hole's maw. This is similar to water circling a drain.
Hsiao stated that the disk's gas and dust will spin against one another and heat up through friction, sometimes reaching millions of degrees. This produces light in the X ray portion of electromagnetic spectrum. From the poles of a black hole, huge beams can also be shot.
Black holes compress a huge mass of material into a small area, making them smaller than stars, and thus easier to surround. Hsiao stated that a species who chooses to build a Dyson sphere around black holes can save a lot.
Tomotsugu Toto, a coauthor of the study and also from National Tsing Hua University, said that aliens could place a large satellite into a stable orbit around an black hole, then collect Xray energy using something similar to solar panels.
They could also create a ring-like structure or completely surround the black hole with platforms. This is similar to Freeman Dyson’s original proposal. However, each of these options would be more difficult and complex to construct.
The researchers found that black holes could emit up to 100,000 times the energy of a star like the Sun, which means that celestial species would have plenty of power.
The energy of a cosmic object must be radiated after it has been absorbed. Otherwise, it will build up and eventually melt Dyson spheres, Dyson wrote in 1960. Researchers said that this energy would shift to longer wavelengths so a Dyson-sphere around a dark hole could emit an unexplainable energy signature in ultraviolet or infrared.
Goto stated that several instruments, including NASA's space-based Wide-field Infrared Survey Explorer, (WISE), and the Pan-STARRS telescope, in Hawaii, have catalogued billions of objects through their detailed night sky surveys. He said that Dyson spheres around black hole may exist and that such detectors could have recorded their signs.
Now, the team is developing algorithms to search these databases and find unusual entities that could indicate Dyson spheres. Hsiao stated, "If it can be found, then I would feel ecstatic."
This type of search could prove useful regardless of what results it yields, Macy Huston (a doctoral candidate at The Pennsylvania State University in astronomy who was not involved with the research), told Live Science. They said that even if Dyson spheres are not found, they're likely to discover something.
Black holes pose a unique challenge to mega-engineers from other aliens. Huston stated that gravitational giants are less stable than stars when it comes to their energy production.
While sunlight shines constantly, black holes can have bursts that are followed by periods of silence as they consume smaller and larger amounts of matter. Huston stated that an alien species may need to be aware of large bursts of activity that could cause damage to orbiting structures.
They said that "if a species is searching for something more powerful than stars, this could be it."
Original publication in Live Science