Black holes might have a full head of hair.
The theory of "clean" black holes was first brought to the table by Roy Kerr in 1963, but new research suggests the entities may be considerably "dirtier" than Kerr gave them credit for, a, International School of Advanced Studies (SISSA) press release reported.
Black holes have two defining qualities: "mass and angular momentum" (rotation velocity).
"Once their progenitor has collapsed (a high mass star, for instance, that at the end of its life cycle implodes inwards) its memory is lost forever. All that is left is a quiescent black hole, with almost no distinctive features: all black holes, mass and angular momentum aside, look almost the same," the press release stated.
Thomas Sotiriou, a physicist at SISSA, has a different idea of black holes.
"Black holes, according to our calculations, may have hair", Sotiriou said in reference to a statement from the notorious physicist John Wheeler who said the opposite. What Wheeler meant by the statement "black holes have no hair" is that one only needed to describe them through mass and angular momentum.
"Although Kerr's 'bald' model is consistent with General Relativity, it might not be consistent with some well-known extensions of Einstein's theory, called tensor-scalar theories," Sotiriou said. "This is why we have carried out a series of new calculations that enabled us to focus on the matter that normally surrounds realistic black holes, those observed by astrophysicists. This matter forces the pure and simple black hole hypothesized by Kerr to develop a new 'charge' (the hair, as we call it) which anchors it to the surrounding matter, and probably to the entire Universe."
The study came to this conclusion using tools called interferometers, which can read and measure gravitational waves.
"According to our calculations, the growth of the black hole's hair is accompanied by the emission of distinctive gravitational waves. In the future, the recordings by the instrument may challenge Kerr's model and broaden our knowledge of the origins of gravity," Sotiriou said.
