Black holes have long been regarded as the villains of physics, capable of absorbing anything within their gravitational pull, be it radiation, stars, humans, or anything else. now this fear might have come to an end as scientists have come up with a theory of quantum hair that could be a possible solution to Stephen Hawkings’ black hole paradox.
What is a black hole?
Albert Einstein, the father of modern physics, first predicted the existence of black holes in 1916 using his general theory of relativity. However, he did not name it. The name was later given by American astronomer John Wheeler in 1967. It is known to be the most terrifying thing, especially to those who know a thing or two about the world of physics.
These are regions in space that have a very high gravitational field, so much so that even light cannot escape. This is the reason that they are practically invisible to the human eye and can only be detected by specialised telescopes.
Black holes take birth from the death of a star having a high gravitational pull. When the star implodes, the matter gets squeezed into a small space under it. These have some mass without occupying any space.
What is the black hole paradox?
In the year 1976, Hawkings came across the fact that an isolated black hole can emit radiation at a temperature that is dependent on its mass, charge, and angular momentum but is independent of its initial state. That is, it would allow physical information to disappear into the hole, allowing several physical states to merge into one.
Why is it called a paradox?
It is considered to be a paradox as it is the combination of two sides of physics; Einstein’s theory of relativity and quantum mechanics.
According to Einstein’s theory of relativity, anything and everything that goes inside a black hole cannot escape it. Not even light can escape its strong gravitational pull.
Whereas quantum mechanics denies this and claims that on a microscopic quantum level, something will escape.
The discovery
Scientists have performed two studies, both concluding that something called “quantum hair” is the answer to Hawking’s paradox.
According to the first study published in the journal Physical Review Letters, the investigators show that black holes are more complex in nature than comprehended earlier and bear information regarding their formation.
Together, Professor Xavier Calmet from the School of Mathematical and Physical Sciences, Professor Roberto Casadio, Professor Stephen Hsu of Michigan State University, and Ph.D. student Folkert Kuipers exhibited that black holes leave an imprint in the gravitational field of the black hole. This left behind imprint is what’s called “quantum hair.”
In this, the team of researchers started by analysing the gravitational fields of two stars having the same mass and diameter but differing compositions. If considering classical physics, the stars are seen to have the same gravitational potential, whereas if looking at the quantum level, their gravitational potential depends on their composition. Also, they observed that when stars collapse into black holes, the gravitational field of the hole keeps the memory of the composition of the stars intact, hence leading to the concept of “quantum hair.”
Professor Calmet described their answer as “very intriguing” since it does not rely on any speculative idea, but rather shows scenarios where two theories can aid inconsistent calculations of the black hole and can explain how information is stored without the need for radical new physics.
He even proposed an analogy, saying that “black holes are like good children, clinging on to the memory of stars that gave birth to them,” he said.A successful study, published in another journal called Physics Letters B, said that the concept of “quantum hair” is the solution to Stephen Hawkings’ black hole information paradox.
The idea proposed by Hawkings in 1976, that as a black hole evaporates, it destroys information about what formed it, goes against a fundamental law of quantum mechanics, which states any process in physics can be mathematically reversed.
In the 1960s, the phrase “black holes have no hair” was fabricated by physicist John Archibald Wheeler while discussing the lack of observable features of black holes, features like total mass, spin, and charge. This is known as the “no-hair theorem.”
According to experts, this discovery of “quantum hair” furnishes a way for information to be stored as a black hole collapses and, as such, resolves one of modern science’s most famous dilemmas.
Professor Calmet further states that since their discovery, black holes have been considered the quintessential way to study the ways to amalgamate Einstein’s theory of relativity and quantum mechanics.
The scientific community has been conjuring the thought that rectifying the paradox would demand a prototypical shift in physics, propelling the potential refashioning of either quantum mechanics or general relativity.
Roberto Casadio, professor of Theoretical Physics at the University of Bologna, elucidated the study by asserting that “a crucial facet is that black holes take birth when compact objects collapse, and then, according to the quantum theory, there is no absolute separation between the interior and the exterior of the black hole.”
“Whereas in classical theory, the horizon acts as a one-way membrane prohibiting anything to go out, and the exterior is, therefore, the same for all black holes of a given mass. This is the classical no-hair theorem, “the professor added.
However, according to quantum theory, the state of the matter that collapses and produces the black hole continues to affect the state of the outside world, albeit in a fashion that is compatible with current experimental constraints. Quantum hair is what it’s called.
This discovery explains how information is kept throughout a black hole’s collapse, solving one of modern science’s most infamous challenges.
Published By : VATSAL KOTHA
Edited By : KHUSHI THAKUR
