Black holes are known to be the villains that have the capability of ending worlds as and when they desire and nothing remains thereafter. This time it had set its eyes on the world of physics itself.

A theory around black holes laid out by Stephen Hawking could have turned the world of physics upside down as it questioned the two pillars on which most of our understanding of the universe rests the theory of relativity and quantum mechanics. One said nothing can escape a black hole, another, based on principles of thermodynamics, states that energy cannot be destroyed and if something goes into a black hole there has to be some information about it.

Scientists now claim to have solved this information paradox and say that these objects are more complex than originally understood. Black holes have a gravitational field that, at the quantum level, encodes information about how they were formed.

A black hole is formed from the death of a star with such a high gravitational field that the matter gets squeezed into the small space under it, trapping the light of the dead star. The gravity is so strong due to the matter being squeezed into a tiny space. Since no light can get out, people can’t see black holes. They are invisible.

Using over decade-long research, scientists found that matter that collapses into a black hole leaves an imprint in the gravitational field of the black hole when quantum gravitational corrections are taken into account. In a paper published in the journal Physics Letters B, Professor Xavier Calmet from the University of Sussex termed this imprint as “quantum hair.” Another paper is due to publish in Physical Review Letters.


While Einstein’s theory of relativity states that what goes into the black hole cannot come out. The gravitational pull of black holes is so strong that not even light can escape, quantum mechanics states that this is not possible since on the microscopic, quantum mechanical level something will escape, this is what is described as Hawking radiation.

The black hole information paradox proposed by Stephen Hawking in 1976 questioned that if you throw something into a black hole, it gains all the information like mass, charge, energy from the object. But what really happens to this information? This information could be encoded on the black hole’s surface.

The information paradox is basically two sides of physics that contradict each other and could have repercussions the world over as they guide our understanding of the universe and deep space exploration.


Professor Xavier Calmet from the School of Mathematical and Physical Sciences along with Professor Roberto Casadio, Professor Stephen Hsu of Michigan State University, and Ph.D. student Folkert Kuipers have demonstrated that the black hole leaves an imprint in the gravitational field of the black hole.

The researchers compared the gravitational fields of two stars with the same total mass and radii but different compositions. At the classical level, the two stars have the same gravitational potential, but at the quantum level, the potential depends on the star’s composition. When the stars collapse into black holes, their gravitational fields preserve the memory of what the stars were made of and lead to the conclusion that black holes do have hair, after all.

“What we found and I think is particularly exciting is that this isn’t necessary. Our solution doesn’t require any speculative idea, instead, our research demonstrates that the two theories can be used to make consistent calculations for black holes and explain how information is stored without the need for radical new physics. It turns out that black holes are in fact good children, holding onto the memory of the stars that gave birth to them,” says Professor Calmet.

This new development provides the mechanism by which information is preserved during the collapse of a black hole and as such resolves one of modern science’s most famous problems.


India today