HBAR ENTROPY (Syllabus: GS Paper 3 - Sci & tech)

Context: Scientists have explored novel quantum effects on the radiation emitted from a black hole due to atoms freely falling into it. 

Key Points

• Scientists have investigated the radiation of atoms falling into a black hole having quantum corrections embedded into it. 
• This investigation of atoms falling into a black hole could throw new light on the efforts of scientists towards unification of quantum mechanics which plays out at the smallest scales of matter and the general theory of relativity propounded by Einstein which is applicable at the largest cosmological scales.
• Their mathematical calculations reproduced earlier results that this radiation is similar to the Hawking radiation (emitted by black holes) and has special features that provide insights to the Einstein principle of equivalence.
• The radiation which arises due to the relative acceleration between the atom and the field surrounding it is generated from the two-level atoms unlike the radiation emitted from the black hole as predicted by Hawking. 
• The amount of disorder known as entropy was calculated for this radiation emitted from the atoms, and this was called the “horizon brightened acceleration radiation entropy” (HBAR entropy).
• While similar work has been undertaken previously, this research stands out due to the finding that the HBAR entropy obeyed the area law along with logarithmic leading order area corrections and the inverse order of area subleading corrections.
• Considering the effects of quantum mechanics on a black hole, Stephen Hawking predicted that they can also emit radiation—termed the Hawking radiation. 
• It has not been possible to detect Hawking radiation till date because the cold radiation from the black holes gets drowned in the 2.7-degree Kelvin cosmic microwave background radiation of the universe.