Dr. Rituparno Goswami
Senior Lecturer & Gravitational Physicist
Astrophysics & Cosmology Research Unit
University of Kwazulu Natal Durban, SA
Abstract:
In nature, Black Holes have a troublesome sibling called "Naked
Singularity". When a massive star collapses under its own gravity, the
entire mass of the star concentrates at the centre, making the central
density infinite. This is a singularity in the spacetime where density and
curvature diverge. It was conjectured by famous physicist Sir Roger
Penrose, that such singularities must always be hidden within Black holes,
from which nothing can escape. Therefore it is never possible to "see"
these singularities and thus they are "censored" from all observers in the
universe. As yet, no proof for this Censorship Conjecture is available and
rigorous calculations show that it is not always true. The final fate of a
collapsing massive star is either a black hole or a visible naked
singularity. These naked space-time singularities may even provide a
laboratory in the cosmos where one could test the unification possibilities
of basic forces of nature.
Solutions of spherically symmetric spacetimes in modified gravity
Abstract:
The common picture of the Universe is that it is made up of spherical or
approximately spherical stellar objects immersed in vacuum. These spacetime
objects produce gravitational fields that are approximately spherically
symmetric and can be represented as spherically symmetric solutions to the
gravitational field equations. We investigate the problem of spherically
symmetric spacetimes in the context of modified gravity and in particular
we focus on f(R) theories of gravity.