For 50 years, scientists have generally agreed that every black hole is exactly the same. New research from the International School for Advanced Studies in Italy has shown that this may not be the case.
Commenting on the mathematical beauty of black holes, physicist John Wheeler, who actually coined the term "black hole," famously said that "black holes have no hair."
What he meant by this was that black holes could only be defined by mass and angular momentum, or the velocity of the black hole's rotation. Angular momentum aside, all black holes look more or less the same.
Roy Kerr developed the "bald" theory of black holes in 1963, as Nature World News reports. However, Kerr's model disagrees with Einstein's scalar-tensor theory.
A research team led by Thomas Sotiriou recently carried out new calculations that challenged this theory. They focused on the matter that surrounds black holes, and found that the matter forces black holes to develop a charge (or a "hair"), which makes black holes possibly more unique than once thought.
"According to our calculations, the growth of the black hole's hair is accompanied by the emission of distinctive gravitational waves," Sotiriou said in the journal Physical Review Letters, where the work was published. In the future, the recordings by the instrument may challenge Kerr's model and broaden our knowledge of the origins of gravity,"
Universe Today points out that the theory by Sotiriou's team has not yet been proven by measurements, so it will be up to astronomers to watch for these charges in future years.