Indian Origin researchers find a kink in Hawking’s Black Hole “Soft Hair” Theorem.
Black Holes have been considered among the most mysterious elements of the universe. From space scientists and astrophysicists to common people, Black Holes has been a substance and interest for everyone. Now, a new study has furthered the enigma. According to a special research team led by physicist Gaurav Khanna, Dr. Subir Sabharwal, and their collaborator, Dr. Lior Burko, a special kind of Black Hole does not follow the “Law of Uniqueness” or the “No-Hair” Theorem. Their study shows that extreme blackholes saturated with maximum angular momentum or spin can defy the theorem. How? Read below to find out.
- “No-Hair” Theorem, explained
- What is a Black Hole Hair?
- The “Soft-Hair” Theorem
- Black Hole “Snowflakes”
- Latest Proposals On Black Hole “Hair”
What is the “No-Hair” Theorem?
Proposed by well-known American physicist John Wheeler, following the Einstein-Maxwell equation of electromagnetism and gravitation in general relativity, black holes can be completely characterized by only three parameters: spin or angular momentum, mass, and electric charge. According to this theory, two black holes having the same mass, electric charge, and angular momentum will be indistinguishable by a viewer outside the event horizon. None of the special particle physics pseudo-charges such as leptonic numbers or baryonic numbers are conserved in the black hole. This theorem was conceived for black holes within a four-dimensional spacetime, following Einstein’s theory of general relativity with zero (0) cosmological constant in the presence of electromagnetic fields.
What is Black Hole Hair?
Every object in this universe is incredibly complex and has the characteristics that set them apart from other similar objects. But black holes are relatively simple and can be truly identical if different black holes possess similar mass, spin, and charge. When a black hole consumes a star cluster or anything else, most of the information is lost leaving only a few strands. As this information consists only of mass, spin, and charge, most of the information completely evaporates into space within the black hole for eternity.
But according to the theorem proposed by renowned physicist and scientist Stephen Hawking, subatomic particles might find their way back from a black hole through an exotic quantum process that might result in releasing radiation from the black hole surface. Also known as the Hawking Radiation, this can cause the black hole to lose energy that can lead it to evaporate entirely. This theory is known as the “Information Paradox”.
Watch: Black Hole ‘Information Paradox’ explained
As these radiations do not carry any information, they also evaporate with the black holes. But if this information is stored on the surface, contained in the “stretched horizon”, the Hawking Radiation might be able to carry the information along with them solving the paradox and preserving the reality as it was before the consumption.
The “Soft Hair” Theorem
Internationally renowned scientist and physicist Stephen Hawking, Professor Malcolm Perry, and Professor Andrew Strominger proposed another theorem to explain the mysteries surrounding black holes. Their works on this theorem give a clear implication that black holes have soft hair. Their work published on January 5, 2016, states that some of the information consumed by a black hole can be stored in the electric hairs. Professor Strominger, also stated that these electric hairs might not be “rich enough to store all the information”.
Black Hole “Snowflakes”
Physicist Strominger had been dismantling some of the notions of black holes in the past few years. In one of his theories, he had raised the question: What would happen if a “soft” proton or a particle with no energy is added to the vacuum left behind by an evaporated black hole? Strominger along with Hawking and Malcolm Perry found that the vacuum left by a black hole would have the same energy but different spin after the addition of a soft proton. This indicates that the vacuum left by an evaporated black hole is like a celestial snowflake possessing individual properties based on its history and origin.
This theory is based on a short paper that Hawking published in 2014. The paper states that the event horizon of a black hole where an object would get consumed into a black hole might not be a fixed boundary.
Latest Proposals on the Black Hole “Hair”
The new research work by the team of Professor Gaurav Khanna, Dr. Subir Sabharwal, and Dr. Lior Burko, shows that there can be some black holes that defy the famous “no-hair” theorem. Claiming the new results to be surprising Dr. Burko revealed, “There has to be an assumption of the theorems that are not satisfied” that can explain “how the theorems do not apply in this case.”
This team used some intensive numerical measures to conclude. These simulations include dozens of high-end NVIDIA GPUs (graphics-processing-units), each of them consisting of over 5,000 cores. According to Professor Khanna, “these GPUs can perform as many as 7 trillion calculations per second” each. The work was published in one of the top physics journals, Physical Review D as a prestigious letter.