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Eternally Collapsing Object
An Eternally Collapsing Object (ECO) is a self-gravitating ball of ultrahot plasma which is almost as compact as black holes and yet qualitatively different from true mathematical black holes. In other words, an ECO is a sort of hypothesized quasi-black hole and an alternative to true mathematical black holes. This term was first coined by the Indian astrophysicist Abhas Mitra in 1998. Though Mitra admitted that the general relativistic black hole solutions are correct, he argued that, the so-called black hole candidates discovered by astronomers cannot be true mathematical black holes. He based this assertion on the claimed mathematical proof that, the masses of the black holes obtained as integration constants of pertinent general relativistic differential equations are tacitly zero.〔A. Mitra, J. Math. Phys. 50, 042502 (2009) (American Institute of Physics)〕 Historically, Luis Bel was the first author to claim that the Schwarzschild Singularity is a `point singularity' contrary to the widely held view that the Event Horizon is a surface having a finite area: `A new point of view is presented for which the Schwarzschild singularity becomes a real point singularity on which the sources of Schwarzschild's exterior solution are localized'.〔Luis Bel, Journal of Mathematical Physics,Volume 10, Issue 8, p.1501-1503 (1969) 〕 Physically, Bel's contention implies that the gravitational mass of a Schwarzschild black hole is M=0. Following this, Janis,Newman & Winicour too suggested that the `Schwarzschlid Singularity' may be a point singularity: `A spherically symmetric solution of the Einstein equations is presented that coincides with the exterior (r>2m) Schwarzschild solution, but where the Schwarzschild "sphere" becomes a point singularity'.〔Janis, Allen I.; Newman, Ezra T.; Winicour, Jeffrey, Physical Review Letters, vol. 20, Issue 16, pp. 878-880 (1968) 〕 In other words, the gravitational mass of the exact black holes are zero, and hence the observed black hole candidates must be quasi black holes, an assertion originally made by Jayant Narlikar and Thanu Padmanabhan.〔J.V. Narlikar and T. Padmanabhan, Foundations of Physics, Vol. 18, pp.659-668 (1988)〕
```It is shown that inconsistencies arise when we look upon the Schwarzschild solution as the space-time arising from a localized point singularity. The notion of black holes is critically examined, and it is argued that, since black hole formation never takes place within the past light cone of a typical external observer, the discussion of physical behavior of black holes, classical or quantum, is only of academic interest. It is suggested that problems related to the source could be avoided if the event horizon did not form and that the universe only contained quasi-black holes.
==References==
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