Traversable wormholes necessarily require violations of the averaged null energy condition, this being the definition of "exotic matter." However, the theorems which guarantee the energy condition… (More)

SAYAN KAR, NARESH DADHICH and MATT VISSER Department of Physics and Centre for Theoretical Studies, Indian Institute of Technology, Kharagpur 721 302, India Inter-University Centre for Astronomy and… (More)

By requiring the linear differential operator in Newton’s law of motion to be self adjoint, we obtain the field equation for the linear theory, which is the classical electrodynamics. In the process,… (More)

We derive the metric for a Schwarzschild black hole with global monopole charge by relaxing asymptotic flatness of the Schwarzschild field. We then study the effect of global monopole charge on… (More)

By resolving the gravitational field into electric and magnetic parts, we define an electrogravity duality transformation and discover an interesting property of the field. Under the duality… (More)

We present a singularity free class of inhomogeneous cylindrical universes filled with stiff perfect fluid (ρ = p). Its matter free (ρ = 0) limit yield two distinct vacuum spacetimes which can be… (More)

We study the general features of the dynamics of the phantom field in the cosmological context. In the case of inverse coshyperbolic potential, we demonstrate that the phantom field can successfully… (More)

We first obtain the analogue of Vaidya’s solution on the brane for studying the collapse of null fluid onto a flat Minkowski cavity on the brane. Since the backreaction of the bulk onto the brane is… (More)

By resolving the Riemann curvature relative to a unit timelike vector into electric and magnetic parts, we define a duality transformation which interchanges active and passive electric parts. It… (More)

From the relativistic law of motion we attempt to deduce the field theories corresponding to the force law being linear and quadratic in 4-velocity of the particle. The linear law leads to the vector… (More)