A couple of mathematicians proposed a method to determine how much a black hole lacks to reach its final phase. Black holes are among the strangest objects in the Universe and are produced when an enormous mass is compressed to its ultimate density.
Although observations indicate that black holes are abundant in the universe, scientists actually do not understand what occurs inside them. The equations of the general theory of relativity, which are commonly used to understand the physics of the universe, break down in these cases.
"It really is beyond the physics we know," said Juan Antonio Valiente Kroon, a mathematician at Queen Mary College of the University of London and one of the study's authors, in statements to Space.com. Valiente, who acknowledges that to understand what happens inside a black hole you have to invent "new physics," added that, fortunately, the physics of the final stages of a black hole is "quite simple."
Mathematicians have found a solution to the general relativity equations that produced a situation called "Kerr spacetime" and they believe that is what happens when a black hole reaches the final stage of its evolution. In 1963, New Zealand physicist Roy Kerr solved Albert Einstein's field equations to describe the spacetime surrounding a charged and rotating mass. The Kerr solution describes all the black holes that exist in nature.
"Mainly the equations of relativity are so complex that for relativistic systems the only way one can test these equations is through computers," said Valiente. "Solutions like this one, the Kerr solution, are really exceptional," added the mathematician. Kerr spacetime is independent of time, which means that in Kerr space nothing changes with time, that is, time has actually stopped.
A black hole in such a phase is, essentially, stationary. "One could say that once it has reached this stage no other processes occur," said Valiente. In their new study, Valiente and his colleague Thomas Backdhal have calculated a formula that allows determining how close a black hole is to reaching the Kerr state.
Thus, depending on the mass of the object, this can happen very quickly, even in just a few seconds. To apply the formula, scientists would examine the region around the black hole called the event horizon, or event boundary, which is the boundary hypersurface of spacetime. Once mass, or even light, passes within the event horizon of a black hole, it can no longer escape the gravitational pull of the object. Researchers believe their breakthrough could help scientists who build computer simulations of black holes and seek to align them with their observations of actual black holes. "Astronomers think that most galaxies, including our Milky Way, have supergiant black holes at their center," noted Space.com, which added that "some researchers suspect that these are, in fact, Kerr black holes.