Scientists at Lawrence Berkeley National Laboratory have figured out how energy can be extracted from a rotating black hole to accelerate particles to near-light speeds. The simulation results showed that the black hole produces "negative energy" through the Penrose process, which accelerates the body near the event horizon. This is reported by Science Alert.
It is known that black holes, which have an accretion disk, generate jets (jets) of relativistic plasma escaping from the poles. Since the black hole has a powerful attraction, scientists have developed several hypotheses about where the energy comes from, allowing the jets to leave the gravitational field. It is believed that a rotating black hole has a special region of space-time - the ergosphere, which is located between the event horizon and the static limit, that is, the boundary below which the body can no longer be at rest and moves towards the rotation of the black hole.
In the ergosphere, processes take place that allow the body to extract the rotational energy of the black hole in order to give itself sufficient acceleration. According to the Penrose process, the body can split into two parts, one of which must fall beyond the event horizon. If two fragments have certain speeds, a special position relative to each other and fly along the correct trajectories, then the fall of one fragment transfers the energy of the other part, greater than the energy that the body originally possessed. To an outside observer, it looks as if the body was divided into a part with positive energy and a part with "negative energy", which, when falling beyond the horizon, decreases the angular momentum of the black hole. As a result, the first fragment flies out of the ergosphere, "taking" the rotation energy of the black hole.
Another mechanism, called the Blanford-Znaek process, is provided by the magnetic field that creates the accretion disk. It also requires an ergosphere, where an electric field and a potential difference between the equator and the poles of the black hole occur. In other words, a black hole is somewhat reminiscent of a unipolar generator, but this process requires the presence of cascades of electron-positron pairs.
The simulation results showed that both of these processes take place in the ergosphere of a black hole. Scientists have simulated the behavior of a plasma, in which particle collisions do not play a special role, in the presence of a strong gravitational field generated by a black hole. As a result, electrons and positrons began to appear in the system, which contributed to the generation of energy in the electromagnetic field, emitted in the form of jets. Meanwhile, some particles, apparently, slowed down the rotation of the black hole, falling beyond the event horizon, that is, they had "negative energy", according to the Penrose process. However, the fraction of energy recovered in this way was very small.