Gamma-ray telescopes could detect spaceships powered by a black hole

A particularly radical idea is that space civilizations could exploit the radiation emitted by black holes (Hawking radiation) to generate energy. On this basis, Louis Crane, a mathematician from Kansas State University (KSU), recently drafted a study suggesting that soundings using gamma telescopes might find evidence of a spacecraft powered by tiny black artificial holes.

The study "Searching for extraterrestrial civilizations using gamma ray telescopes" has recently been put online. This is the second article published by Dr. Crane on the subject, the first of which was co-authored by Shawn Moreland (a KSU physics graduate student) and published in 2009 – "Are Black Spout Spacecraft ??" .

In the first article, Crane and Westmoreland explored the possibility of using Hawking radiation from an artificial black hole. They concluded that it was at the limit of possibility, but that the effects of quantum gravity (which are unknown at the present time) could be problematic. In his last article, Crane took a step forward in describing how the resulting gamma rays that such a system would produce could help in the search for ETI.

The concept of spaceship powered by a black hole was introduced for the first time by the famous science fiction author Arthur C. Clarke in his 1975 novel Imperial Land. A similar idea was presented by Charles Sheffield in his 1978 article "Killing Vector". In both cases, Clarke and Sheffield describe how advanced civilizations could extract energy from rotating black holes to meet their energy needs.

In addition to being a pure gold sci-fi, the ability to exploit a black hole to generate energy would offer considerable benefits. As Dr. Crane has described to Universe Today via email: "An advanced civilization would want to exploit a microscopic black hole because it could inject material and release energy. It could, in particular, propel a spacecraft wide enough to be protected from relativistic speeds.None of NASA's spacecraft concepts has proven viable … This could be the only possibility. "

In addition, the signatures associated with this type of technological activity ("technosignatures") would indicate a very high level of progress. Given the enormous energy requirements needed to create an artificial black hole and the technical challenges associated with its operation, the process would go beyond the scope of a Kardashev-type type II civilization. .

"To produce an artificial black hole, we will have to focus a multibillion-ton gamma laser on the nuclear dimensions," said Dr. Crane. "It's like making as many high-tech nuclear bombs as there are automobiles on Earth. Its magnitude exceeds the current world economy. A civilization that fully utilizes the solar system would have the necessary resources. "

This is not even the least of the technical challenges, most of which are far beyond what humanity is capable of. These include the amount of energy needed to power the gamma ray laser, the storage location of that energy and how these emissions would be concentrated on a space the size of an atom . As Crane said, there are suggestions on how to proceed, but they remain highly speculative.

Besides the concept itself, the idea of ​​a civilization fueled by a black hole is also interesting because of the possibilities it presents for SETI research. As for other signs of technological activity (eg, "technosignatures"), a civilization exploiting tiny artificial black holes created with gamma ray lasers could be detected through a little thing called "overflow" ".

Professor Philip Lubin described this concept in a study conducted in 2016, in which he suggested that one could find evidence of ETI by looking for signs of directed energy. According to Lubin's research on lasers for planetary defense and laser propulsion (for NASA and as part of Breakthrough Starshot), Lubin suggested that errant flashes of laser energy (or "overflow") might indicate a civilization at the forefront of technology.

Similarly, SETI researchers could use gamma ray telescopes to look for signs of overflow caused by gamma ray lasers. "If an advanced civilization already had such spacecraft, the current VHE gamma telescopes could detect it up to 100 to 1000 light-years away if we were in its beam." They could be distinguished from natural sources by their continuous shift. To study this, astronomers should keep time series of frequency curves of point-shaped gamma ray sources, which does not seem to be what they are doing now. "

Perhaps most exciting is the fact that astronomers may have already found signs of some type II Kardashev civilizations using this type of energy production method. As Dr. Crane explained, several point gamma ray sources have been detected in the universe and for which no natural explanation has been given.

Future observations using space telescopes such as the Fermi Gamma Ray Space Telescope (FGST) and ground facilities such as the High Energy Stereoscopic System (HESS) and the Very Energetic Radiation Imaging Telescope System (VERITAS) could reveal whether the sources could actually be artificial.

Coupled with next-generation instruments offering superior resolution and imaging capabilities, gamma laser beam overflows and other potential technosignatures may be available, pending identification. In the meantime, humanity still has a long way to go before it can consider developing this type of technology.

Like Dyson spheres, Alderson disks, space elevators and the ability to move stars, this type II megaproject will simply have to wait for humankind to meet some smaller challenges. Something more our speed, like finding ways to settle on other planets of our solar system or learn to use the Earth's resources in a sustainable way.

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More information:
Search for extraterrestrial civilizations using gamma ray telescopes: arXiv: 1902.09985 [gr-qc] arxiv.org/abs/1902.09985