Despite all the reasons why it's a truly terrible idea, humanity still seems desperate to actively seek out alien life. NASA recently created a new department dedicated to searching for alien life, and one of the increasingly popular avenues for this search is looking for "technosignatures," the distinctly artificial byproducts of advanced civilization. One of those technosignatures is the spaceships the aliens are cruising around in, or more accurately, the radiation emanating from the engine of the galactic hot-rod. A new paper from Dr. Louis Crane, a mathematician at Kansas State University, argues that the most likely interstellar engines are powered by artificial black holes, the gamma-ray radiation signatures of which we'd be able to see. In fact, Crane says, we may have already detected them.
Black hole spaceships, if possible at all, would require a civilization that was already at Type II on the Kardashev scale, which would mean they had achieved total mastery over the energy output of their entire solar system. Why would they need to be that advanced? Because making a black hole is one of the harder things a civilization could accomplish. In an email exchange with Universe Today, Dr. Louis Crane wrote:
“To produce an artificial black hole we would need to focus a billion ton gamma ray laser to nuclear dimensions. It’s like making as many high tech nuclear bombs as there are automobiles on Earth. Just the scale of it is beyond the current world economy. A civilization which fully utilized the Solar System would have the resources.”
In her recent paper, titled Searching for Extraterrestrial Civilizations Using Gamma Ray Telescopes, Dr. Crane acknowledges that black hole spaceships would be far out of reach for any civilization at the development level of humanity, and that it is impossible to say for certain whether an advanced civilization could ever solve the problems necessary to build a black hole spaceship. However, Crane says that a black hole engine may be the only means of interstellar travel capable of powering a ship that could shield its inhabitants from the many hazards of space travel. She writes:
Only with a much denser power source than anything yet tried would it be possible to shield a habitat from the radiation of space and accelerate it continuously to provide a livable human environment. A black hole can convert matter into energy, so it would be the ultimate power source. An artificial black hole, although extremely difficult to produce or control, would open possibilities that nothing we can currently conceive would equal. We think that it should be investigated as far as it can be.
In terms of investigating, Dr. Crane says that we could use gamma ray telescopes to detect the radiation from black hole spaceships. The ships would, she says, produce a very distinct pattern gamma radiation that would be easily distinguishable from natural phenomena.
Interestingly, she says that we have detected mysterious points of unexplained gamma radiation coming from the galactic center—an area likely to house potential civilizations due to the extremely high density of stars. These mysterious gamma ray emissions are puzzling due to their lack of associated X rays and the intensity of their energy output, which, so far, no known phenomena can explain. Dr. Crane suggests that these points of gamma rays be observed over the following decades to see if they begin to show the distinctive patterns predicted with black hole spaceships.
And what then? If we found evidence of extraterrestrial civilizations that are using black holes to power their ships, while we're still lighting stuff on fire to spin turbines, we better hope they don't notice us looking at them. Contact with such a species probably wouldn't result in a good time. On the other hand, just knowing that such technology was possible, and that we're not alone out here, could be the impetus for us to focus on claiming our destiny among the stars. Or we'd hurl a couple nukes at them, just to show them who's boss, and that, as they say, would be that.