Mathematician Louis Crane from Kansas State University (USA) concluded that aliens can use spaceships that get energy from Hawking radiation. A preprint of the article has been published in the arXiv repository.
On board such devices should be microscopic black holes emitting gamma radiation, which can be detected with telescopes. The scientist believes that this is the only way to create a starship moving at near-light speed.
As Crane writes in his work, the diameter of an artificial black hole should reach about 2.8 attometers (2.8 x 10 to minus 19). Such a black hole will exist for a century and generate enough energy to accelerate the ship to relativistic (near-light) speeds in 10 years. It will be hotter than any other natural object, emitting particles and gamma rays with energies in excess of 16 gigaelectronvolts.
Thus, to an outside observer, the receding ship will look like a point source of gamma radiation with an increasing shift of electromagnetic radiation to the red long-wavelength side of the spectrum (redshift) due to the Doppler effect. When the starship turns around for deceleration, for another observer at the destination, the ship will have a decreasing blueshift.
According to the researcher, such a technology is still unattainable for humanity. To create an artificial black hole that can be used as an energy source, it is necessary to overcome technical difficulties that cannot be solved with the help of modern technologies. Such a problem is the focusing of the energy of a gamma laser to the scale of the atomic nucleus, as well as the reflection of gamma radiation. At the moment, it is impossible to say whether they can be solved at all and what a spaceship using the energy of a black hole will be like.
Crane suggests that astronomers have already identified objects that are candidates for such starships, including several hundred sources of high-energy gamma rays, the nature of half of which remains unknown. According to the scientist, humanity needs to think seriously about the problem of creating black holes, since such a common goal will give meaning to the existence of people. "It can counteract nationalism and xenophobia," the researcher writes.