[ExI] Alien 'Dyson spheres' could be harvesting the power of black holes

[John Grigg]

"Aliens could place a large satellite in a stable orbit around a black hole
and then collect X-ray energy using something akin to solar panels, study
coauthor Tomotsugu Goto, also of National Tsing Hua University, told Live
Science.

They might also build a ring-like structure around the black hole or
totally surround it with platforms, much like in Freeman Dyson's original
proposal, Goto added, though each of these would be increasingly complex
and challenging to construct.

In either case, a black hole could radiate up to 100,000 times more energy
than a star like the sun, meaning that a celestial species would have a lot
of power to work with, the researchers wrote in a paper published July 1 in
the journal *Monthly Notices of the Royal Astronomical Society*
<https://academic.oup.com/mnras/article-abstract/506/2/1723/6312510>.

After being absorbed and used, the energy from a cosmic object would have
to be reradiated or else it would build up and eventually melt the Dyson
sphere, as Dyson noted *in his 1960 paper*
<https://science.sciencemag.org/content/131/3414/1667>. This energy would
be shifted to longer wavelengths, so a Dyson sphere around a black hole
might give off an unexplainable energy signature in the ultraviolet or
infrared, the researchers said.

Several instruments, including NASA's space-based Wide-field Infrared
Survey Explorer (WISE) and the Pan-STARRS telescope in Hawaii, have
cataloged billions of objects during their detailed surveys of the night
sky, Goto said. Should Dyson spheres around black holes actually exist,
it's possible that their telltale signs have already been recorded by such
detectors, he added."
https://www.livescience.com/alien-dyson-spheres-suck-black-hole-energy.html
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