A rotating black hole is such an extreme force of nature that it drags surrounding time and space around with it. So it is only natural to ask whether black holes could be used as some sort of energy source. In 1969, mathematical physicist Roger Penrose proposed a method to do just this, now known as the “Penrose Process.”
The method could be used by sophisticated civilizations (aliens or future humans) to harvest energy by making “black hole bombs.” Some of the physics required to do so, however, had never been experimentally verified — until now. Our study confirming the underlying physics has just been published in Nature Physics.
Around its event horizon (the boundary around a black hole beyond which nothing, not even light, can escape), a rotating black hole creates a region called the “ergosphere.” If an object falls into the ergosphere in such a way that it splits — with one part falling into the black hole and the other escaping — the part that flees effectively gains energy at the expense of the black hole. So by sending objects or light toward a rotating black hole, we could get energy back.