According to the traditional model, black holes are defined solely on the basis of their mass and their angular momentum or speed of rotation. Once its progenitor has collapsed (a massive star, for example), its memory is lost forever. All that would be left then would be a quiescent black hole, almost featureless . According to this concept, all the matter that forms or falls into the hole disappears completely and is inaccessible to an external observer.
However, Thomas Sotiriou, a physicist at the International School for Advanced Studies (SISSA) in Trieste, disagrees with this view. ” Black holes, according to our calculations, can have hair, ” explains the researcher referring to a famous statement by physicist John Wheeler, who stated that “black holes lack hair”, that is, they do not have information. and that only mass and angular momentum are needed to describe them .
Although the “bald” black hole model is consistent with general relativity theory, it might not be consistent with some extensions of Einstein’s popular theory. Hence, Sotiriou and his colleagues have carried out a series of new calculations that allowed them to focus on the matter that normally surrounds real black holes, those observed so far by astrophysicists. The pure and simple black hole of the Kerr hypothesis develops a new “charge” (what we call the ‘hair’) that is anchored to the surrounding matter and probably the entire Universe.
Experimental confirmation of this new hypothesis could come from observations made with interferometers , instruments capable of recording gravitational waves. “According to our calculations, the growth of hair from the black hole is accompanied by the emission of distinctive gravitational waves ,” Sotiriou clarifies. In the future, recordings from that instrument could challenge the Kerr model and expand our understanding of the origins of gravity, astrophysicists predict in a paper just published by Physical Review Letters .
