Abhas Mitra (born 18 June 1955) is an Indian astrophysicist best known for his distinct views on several front-line astrophysics concepts, particularly related to black holes and Big Bang cosmology involving the black hole information paradox.
Mitra has regularly questioned the mainstream cosmological concepts of the Big Bang and black holes. Scientific diaspora including Richard A. Muller came into his favour of his claim of resolution of black hole information paradox presented 13 years before Stephen Hawking. Richard Muller appreciating the claim of Mitra made, remarking: "I think Mitra resolved the paradox before Hawking, and did it in a way that is superior."
He claims to have offered exact proofs that:The so-called black holes cannot be true black holes even within the context of classical general relativity and
The Big Bang solution is illusory and actual universe must be fundamentally different from the Big Bang paradigm.
Consequently, dark energy, his research claims, is an illusion caused by the departure of the complex universe from the simple Big Bang model.
He is an alumnus of the Uttarpara Govt. High School, and the University of Calcutta. He did a part of his PhD work at the University of Kashmir before transferring because of armed insurgency that had erupted in Kashmir. The University of Mumbai conferred upon him the status of a "Distinguished Alumnus".
Though Mitra stresses that the black hole solutions are correct, his contention is that black hole masses, arising from relevant integration constants, are actually zero. His peer reviewed paper published in the Journal of Mathematical Physics supports this contention by showing that Schwarzschild black holes have M = 0. If so,the so-called massive Black Hole Candidates (BHCs) must be quasi-black holes rather than exact black holes; and
during preceding gravitational collapse, the entire mass energy and angular momentum of the collapsing objects must be radiated away before formation of exact mathematical black holes.
And since the formation of a mathematical zero mass black hole requires infinite proper time, continued gravitational collapse becomes eternal, and the so-called black hole candidates must be Eternally collapsing objects (ECOs).
Mitra's papers describe why continued physical gravitational collapse should lead to formation of ECOs rather than true black holes, and the mathematical "black hole" states can be achieved only asymptotically. An ECO is essentially a quasi-stable ultra-compact ball of plasma which is so hot due to preceding gravitational contraction that its outward radiation pressure balances its inward pull of gravity. Mitra is not alone in this conclusion: Robertson and Leiter (2002) reached a similar conclusion in their introduction of the concept of a magnetospheric eternally collapsing object as an alternative to the black hole model.
In 2014, soon after Stephen Hawking called the alleged loss of information in black holes his "biggest blunder", Mitra received widespread attention in the Indian media, claiming that he had been "vindicated", citing that he had apparently refuted Hawking and indicated the same almost 13 years back.
As per the present version of Big Bang paradigm, almost 70% of the mass energy of the universe is due to dark energy whose most likely form is Einstein's cosmological constant. Mitra claims that the cosmological constant is exactly zero.
According to Mitra, a Big Bang universe can expand only linearly; therefore, popular inflationary and cyclic models are actually inconsistent.
Since perfect Hubble flow implies radially outward motion of Test particles receding from one another without any mutual collision, he claimed his research showed that ideal Big Bang model corresponds to zero pressure and temperature. If correct, this implies that the ideal Big Bang model is fundamentally unable to describe the physical universe endowed with pressure and temperature.
He has also questioned the physical reality of dark energy.
According to Mitra, black holes are actually ultra-magnetized and ultra-hot balls of plasma, nicknamed magnetospheric eternally collapsing objects (MECOs) which are something like extremely general relativistic versions of Sun. He claims, accordingly, MECOs can give rise to flares like solar flares and Coronal mass ejections like the Sun. And on October 25, 2015, NASA reported that its NuStar telescope has detected a massive X-ray flare from a supermassive black hole in a certain quasar, and this flare appears to be triggered by emission of corona from very close to the black hole. In an interview to Nature India, Mitra claimed that, emission of such a corona from the so-called black hole suggests that it is actually a MECO and not a true mathematical black hole. In an international workshop entitled "Jet Triggering Mechanisms in Black Hole Sources", organized by Tata Institute of Fundamental Research, Mumbai, India (January 20–23, 2016), Mitra elaborated on this point in the presence of large number of astrophysicists.
Mitra is associated with the Himalayan Gamma Ray Observatory being set up at Han Leh jointly by Tata Institute of Fundamental Research, Bhabha Atomic Research Centre, and Indian Institute of Astrophysics. He is also an adjunct professor in Homi Bhabha National Science Institute since 2010. Mitra is also a member of the International Astronomical Union.