Space and Physics
PUBLISHED
4
Nothing escapes black holes, but over the decades researchers have worked out ways to get some energy out of them. Some happen naturally, and some energy can be stolen in clever ways. Now, researchers have worked out novel approaches to use black holes as power sources, suggesting that they can be used as either batteries or nuclear reactors.
The assumption of this study is a Schwarzschild black hole – one that has no electric charge or angular momentum. So, it’s neutral and it doesn’t spin. By dropping charged particles on it, the black holes can be made to have a static electric field – and suddenly, you have the makings of a battery.
The team imagined the black hole in a cavity from which electrical charge can be put in and then extracted in a slow controllable way, and with impressive efficiency. This theoretical black battery could transform up to 25 percent of its mass into electrical energy.
As batteries go, the system would be compact. The black holes they consider would weigh at most around the whole atmosphere of our planet (1,000 trillion tons) and would be not much bigger than an atom. So, easy to fit into a mobile phone if you have the ability to lift something the weight of an asteroid.
The team showed that it is possible to fully charge and fully discharge such a battery without violation of any black hole laws, but it is not an eternal system. As the black hole expands after every cycle, it will eventually reach the size of the cavity that contains it, making the battery unavailable.
A battery is not the only option to create energy with high efficiency from a black hole. The team realized that you can create electricity by throwing alpha (α) radiation into a black hole. This is a nucleus of helium and it is a common enough product of radioactive decay.
The team showed that if this radiation was aimed at a black hole, it could be possible to turn 25 percent of the mass of the alpha radiation into kinetic energy brought away from a positron, the antimatter version of the electron.
“This process can at most amplify the kinetic energy of α-decay hundreds of times. Interestingly, the optimal mass of such a black hole reactor is just located inside the window of primordial-black-hole-originated dark matters,” the team wrote in the paper.
The existence of such black holes is yet to be proven, and there is the factor that we do not know how to contain them – but if we find them and can control them, get ready for high-efficiency electricity.
A paper reporting these findings is published in the journal Physical Review D.
