The works of Stephen Hawking have influenced many fields, and in particular those of cosmology and quantum gravity, in particular in the context of black holes. Today we are interested in one of his most famous paradoxes concerning, exactly, black holessince the latter would be, according to the team of scientists that we are going to present to you, finally solved.
black holes
In astrophysics, a black hole is such a compact celestial object that the intensity of its gravitational field prevents any form of matter (or radiation) from escaping from it. Such objects can therefore neither emit nor scatter light, and are therefore black, which in astronomy amounts to saying that they are “optically invisible”.
Black holes are phenomena that we do not yet fully understand. Indeed, it is not possible to determine a posteriori what entered the black hole, as you will have understood. And it also works for information. However, view from a distant observer, the information is never completely destroyed since the matter falling into the black hole only disappears after an infinitely long time. So, is the information that formed the black hole lost or not? This question gave rise to a paradox: the information paradox.
the information paradox
In astrophysics, the information paradox is a paradox highlighted by Stephen Hawking in 1976, a paradox which opposes the laws of quantum mechanics to those of general relativity. Indeed, general relativity implies that information could fundamentally disappear in a black hole, following the evaporation of this one. This loss of information implies a non-reversibility and a non-unitary evolution of quantum states, in fundamental contradiction with the postulates of quantum mechanics. We can sum it up like this : Einstein’s general theory of relativity asserts that information about what goes into a black hole cannot come out, while quantum mechanics asserts that it is impossible.
This paradox has given rise to a great deal of research, since it is a very important question in the world of theoretical physics. Famous physicists from all over the world have looked into the matter, offering convoluted explanations. Some scientists had even suggested that aspects of quantum mechanics were wrong. A terrifying prospect for theoretical physicists, since quantum mechanics is one of the pillars on which rests most of our understanding of the Universe. At present however, we are finally able to say that the laws of quantum mechanics and Einstein’s relativity are well and truly compatible, even when it comes to evoking black holes.
The resolution of the paradox
New research claims to have finally solved the information paradox, by showing that black holes have a property they call “quantum hair”. Professor Xavier Calmet, from the University of Sussex, exclaimed “The problem was resolved !”exclusively for BBC News. Professor Calmet and his colleagues claim to have demonstrated that the constituents of the star leave an imprint in the gravitational field of the black hole.
Scientists have named this footprint “quantum hair”as their theory supersedes an earlier idea called the “no hair theorem”, developed in the 1960s. The “quantum hair theorem” of the Professor Calmetpublished in the journal Physical Review Letters, is revolutionary. He not only claims that black holes are not “bald” as previously thought, but he also claims to resolve the Hawking paradox that has deeply troubled physicists ever since. the 1970s. The notion of “quantum hair” would allow information about what goes into a black hole to come out without violating any of the important principles of both theories. It’s about a simple and elegant solution.
Professor Calmet said of his discovery:
It will take time for people to accept it. One of the consequences of Hawking’s paradox was that general relativity and quantum mechanics were incompatible. What we find is that they are completely compatible. So it will take time for people to accept that there is no need for a radical solution to solve the problem.
The research team, which also includes Professor Roberto Casadio de the University of Bologna and Professor Stephen Hsu from Michigan State University, drew on the work of Professor Suvrat Raju of the International Center for Theoretical Sciences in Bengaluru, India. Professor Raju thinks that together they solved Hawking’s paradox. And if you want to know what mysterious message left by Stephen Hawking on his painting could finally be decrypted, you can refer to our previous article on the subject.
