Energetics of a rotating charged black hole in 5-dimensional gauged supergravity (2009)
Prabhu, Kartik, Dadhich, Naresh
We investigate the properties of the event horizon and static limit for a charged rotating black hole solution of minimal gauged supergravity theory in (1 + 4) dimension. It turns out that unlike the...
Why do we live in four dimension? (2009)
We perceive the dimension of physical spacetime we live in through physical experiments and hence it is pertinent to probe the dimension in which the fundamental physical forces exist and act? In...
Inhomogeneous Imperfect Fluid Spherical Models without Big-Bang Singularity (2008)
Abstract. So far all known singularity-free cosmological models are cylindrically symmetric. Here we present a new family of spherically symmetric non-singular models filled with imperfect fluid and...
Focusing versus defocusing properties of truly naked black holes (2008)
Dadhich, Naresh, Zaslavskii, Oleg B.
We study the properties of the congruence of null geodesics propagating near the so-called truly naked horizons (TNH) - objects having finite Kretschmann scalar but with diverging tidal acceleration...
Entropy Bound and Causality Violation in Higher Curvature Gravity (2008)
Neupane, Ishwaree P., Dadhich, Naresh
In any quantum theory of gravity we do expect corrections to Einstein gravity to occur. Yet, at fundamental level, it is not apparent what the most relevant corrections are. We argue that the generic...
On Kaluza-Klein spacetime in Einstein-Gauss-Bonnet gravity (2008)
Molina, Alfred, Dadhich, Naresh
By considering the product of the usual four dimensional spacetime with two dimensional space of constant curvature, an interesting black hole solution has recently been found for...
On gravitational dynamics (2008)
We prove the theorem: The second order quasi-linear differential operator as a second rank divergence free tensor in the equation of motion for gravitation could always be derived from the trace of...
Isothermal spherical perfect fluid model: Uniqueness and Conformal mapping (2007)
Naresh Dadhich Inter, Naresh Dadhich
We prove the theorem: The necessary and sufficient condition for a spherically symmetric spacetime to represent an isothermal perfect fluid (barotropic equation of state with density falling off as...
A Duality Relation for Fluid Spacetime (2007)
Naresh Dadhich, L. K. Patel, Ramesh Tikekar
We consider the electromagnetic resolution of gravitational field. We show that under the duality transformation, in which active and passive electric parts of the Riemann curvature are interchanged,...
An ansatz for spacetimes of zero gravitational mass: global monopoles and textures
Formation of a black hole from an AdS spacetime (2007)
We shall first discuss motivation for higher dimension even for classical description of gravitational dynamics and then construct a black hole out of an anti-deSitter (AdS) spacetime by prescribing...
Origin of matter out of pure curvature (2007)
Dadhich, Naresh, Maeda, Hideki
We propose a mechanism for origin of matter in the universe in the framework of Einstein-Gauss-Bonnet gravity in higher dimensions. The recently discovered new static black hole solution by the...
Singularity: Raychaudhuri Equation once again (2007)
I first recount Raychaudhuri's deep involvement with the singularity problem in general relativity. I then argue that precisely the same situation has arisen today in loop quantum cosmology as...
Matter without matter: novel Kaluza-Klein spacetime in Einstein-Gauss-Bonnet gravity (2006)
Maeda, Hideki, Dadhich, Naresh
We consider Einstein-Gauss-Bonnet gravity in $n(\ge 6)$-dimensional Kaluza-Klein spacetime ${\ma M}^{4} \times {\ma K}^{n-4}$, where ${\ma K}^{n-4}$ is the Einstein space with negative curvature. In...
A Unified View of the Basic Forces (2006)
In this essay we wish to seek a unifying thread between the basic forces. We propose that there exists a universal force which is shared by all that physically exists. Universality is characterized...
Maeda, Hideki, Dadhich, Naresh
We obtain a new exact black-hole solution in Einstein-Gauss-Bonnet gravity with a cosmological constant which bears a specific relation to the Gauss-Bonnet coupling constant. The spacetime is a...
Professor A. K. Raychaudhuri suddenly passed away on 18th June 2005. I have attempted to give a glimpse of his life and work, and more specifically his role as a great teacher and inspiring force to...
Derivation of the Raychaudhuri Equation (2005)
As a homage to A K Raychaudhuri, I derive in a straightforward way his famous equation and also indicate the problems he was last engaged in.
Debnath, Ujjal, Mukhopadhyay, Banibrata, Dadhich, Naresh
It is well known that when a fermion propagates in curved space-time, its spin couples to the curvature of background space-time. We propose that this interaction for neutrinos propagating in early...
On the Gauss-Bonnet Gravity (2005)
We argue that propagation of gravitational field in the extra dimension is motivated by physical realization of second iteration of self interaction of gravity and it is described by the Gauss-Bonnet...
Why Einstein (Had I been born in 1844!)? (2005)
In his monumental discoveries, the driving force for Einstein was, I believe, consistency of concept and principle rather than conflict with experiment. In this spirit, I would like to look at the...
Curvature driven acceleration : a utopia or a reality ? (2005)
Das, Sudipta, Banerjee, Narayan, Dadhich, Naresh
The present work shows that a combination of nonlinear contribution from the Ricci curvature in Einstein field equations can drive a late time acceleration of expansion of the universe. The transit...
A dynamical symmetry of the spherical dust collapse (2004)
Debnath, Ujjal, Chakraborty, Subenoy, Dadhich, Naresh
By linearly scaling the initial data set (mass and kinetic energy functions) together with the initial area radius of a collapsing dust sphere, we find a symmetry of the collapse dynamics. That is,...
Probing Universality Of Gravity (2004)
I wish to expound a novel perspective of probing universal character of gravity. To begin with, inclusion of zero mass particle in mechanics leads to special relativity while its interaction with a...
Universality, Gravity, the enigmatic Lambda and Beyond (2004)
In this essay, I wish to share a novel perspective which envisions universalization as a guide from the classical world to relativistic and quantum world. It is the incorporation of zero mass...
Quantifying energy condition violations in traversable wormholes (2004)
Kar, Sayan, Dadhich, Naresh, Visser, Matt
The `theoretical' existence of traversable Lorentzian wormholes in the classical, macroscopic world is plagued by the violation of the well--known energy conditions of General Relativity. In this...
Scalar and spinor perturbation to the most generalised Kerr-NUT space-time (2004)
Mukhopadhyay, Banibrata, Dadhich, Naresh
We study the scalar and spinor perturbation to Kerr-NUT space-time, that is, Klein-Gordan and Dirac equation therein. The equations are invariant under duality transformation between the...
Universalization as a physical guiding principle (2003)
In this essay, I wish to share a novel perspective based on the principle of universalization in arriving at the relativistic and quantum world from the classical world. I also delve on some...
The critical role of shear in gravitational collapse (2003)
Joshi, Pankaj S., Goswami, Rituparno, Dadhich, Naresh
We investigate here how the shearing effects present within a collapsing matter cloud influence the outcome of gravitational collapse in terms of formation of either a black hole or a naked...
Embedding Diagrams for the Reissner-Nordstr\"om spacetime (2003)
Paranjape, Aseem, Dadhich, Naresh
We consider embedding diagrams for the Reissner-Nordstr\"om spacetime. We embed the $(r-t)$ and $(r-\phi)$ planes into 3-Minkowski/Euclidean space and discuss the relation between the diagrams and...
Non-singular black-holes on the brane (2003)
Shankaranarayanan, S., Dadhich, Naresh
We investigate the possibility of obtaining non-singular black-hole solutions in the brane world model by solving the effective field equations for the induced metric on the brane. The...
The role of the equation of state and the space-time dimension in spherical collapse (2003)
Dadhich, Naresh, Ghosh, S. G., Deshkar, D. W.
We study the spherically symmetric collapse of a fluid with non-vanishing radial pressure in higher dimensional space-time. We obtain the general exact solution in the closed form for the equation of...
Action based approach to the dynamics of extended bodies in General Relativity (2003)
Anandan, Jeeva, Dadhich, Naresh, Singh, Parampreet
We present, for the first time, an action principle that gives the equations of motion of an extended body possessing multipole moments in an external gravitational field, in the weak field limit....
Cosmological Dynamics of Phantom Field (2003)
Singh, Parampreet, Sami, M., Dadhich, Naresh
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...
Scalar and Spinor Perturbation to the Kerr-NUT Spacetime (2003)
Mukhopadhyay, Banibrata, Dadhich, Naresh
We study the scalar and spinor perturbation, namely the Klein-Gordan and Dirac equations, in the Kerr-NUT space-time. The metric is invariant under the duality transformation involving the exchange...
Traversable wormholes with arbitrarily small energy condition violations (2003)
Visser, Matt, Kar, Sayan, Dadhich, Naresh
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...
Action principle formulation for motion of extended bodies in General Relativity (2002)
Anandan, Jeeva, Dadhich, Naresh, Singh, Parampreet
We present an action principle formulation for the study of motion of an extended body in General Relativity in the limit of weak gravitational field. This gives the classical equations of motion for...
Brane corresponding to the Nariai bulk (2002)
Dadhich, Naresh, Shtanov, Yuri
We consider the five-dimensional bulk spacetime with negative Lambda described by the Nariai metric (which is not conformally flat) and match it with a vacuum brane satisfying the proper boundary...
Gravitational collapse of null strange quark fluid and cosmic censorship (2002)
We study gravitational collapse of the general spherically symmetric null strange quark fluid having the equation of state, $p = (\rho - 4B)/n$, where $B$ is the bag constant. An interesting feature...
A curious electrovac spacetime as $G = 0$ limit of the NUT space (2002)
We take the $G = 0$ limit of the NUT space which yields a non flat space and show that source of its curvature is electromagnetic field generated by the NUT parameter defining the NUT symmetry. This...
Localized gravity on FRW branes (2002)
Singh, Parampreet, Dadhich, Naresh
We study the system of Schwarzschild anti de Sitter (S-AdS) bulk and FRW brane for localization of gravity; i.e. zero mass gravitons having ground state on the brane, and thereby recovering the...
Brane curvature and supernovae Ia observations (2002)
Singh, Parampreet, Vishwakarma, R. G., Dadhich, Naresh
It is well known that modifications to the Friedmann equation on a warped brane in an anti de Sitter bulk do not provide any low energy distinguishing feature from standard cosmology. However,...
Gravitational collapse of Type II fluid in higher dimensional space-times (2002)
We find the general solution of the Einstein equation for spherically symmetric collapse of Type II fluid (null strange quark fluid) in higher dimensions. It turns out that the nakedness and...
Localization of gravity in brane world cosmologies (2002)
Singh, Parampreet, Dadhich, Naresh
The most remarkable and interesting feature of brane world scenario is the use of bulk's curvature to localize gravity on the brane, albeit with fine tuning of the brane and bulk parameters. For FRW...
The Relativistic World: A common sense perspective (2002)
The motivation for relativistic world is built on robust common sense and on general physical principles which are accessible to even a school student. Author likes to call it a farmer's perspective.
Dadhich, Naresh, Turakulov, Z. Ya.
We obtain the most general solution of the Einstein electro - vacuum equation for the stationary axially symmetric spacetime in which the Hamilton-Jacobi and Klein - Gordon equations are separable....
R=0 spacetimes and self-dual Lorentzian wormholes (2001)
Dadhich, Naresh, Kar, Sayan, Mukherji, Sailajananda, Visser, Matt
A two-parameter family of spherically symmetric, static Lorentzian wormholes is obtained as the general solution of the equation $\rho=\rho_t=0$, where $\rho = T_{ij} u^iu^j$, $\rho_t = (T_{ij} -...
Why do naked singularities form in gravitational collapse? (2001)
Joshi, Pankaj S., Dadhich, Naresh, Maartens, Roy
We investigate what are the key physical features that cause the development of a naked singularity, rather than a black hole, as the end-state of spherical gravitational collapse. We show that...
Nariai metric is the first example of the singularity free model (2001)
This is just to point out that the Nariai metric is the first example of the singularity free expanding perfect fluid cosmological model satisfying the weak energy condition, $\rho>0, \rho+p=0$. It...
On naked singularities in higher dimensional Vaidya space-times (2001)
We investigate the end state of gravitational collapse of null fluid in higher dimensional space-times. Both naked singularities and black holes are shown to be developing as final outcome of the...
On the detection of scalar hair (2001)
Banerjee, Narayan, Sen, Somasri, Dadhich, Naresh
It is shown that the conclusion regarding the existence of a scalar hair for a black hole in a nonminimally coupled self interacting scalar tensor theory can be drawn from the that for a scalar field...
Non-conformally flat bulk spacetime and the 3-brane world (2001)
Singh, Parampreet, Dadhich, Naresh
We show that for non-conformally flat bulk spacetime, there exist no bound modes for zero mass graviton on the 3-brane. The brane world model is therefore unstable for the bulk spacetime being...
Gravitational field of a rotating gravitational dyon (2001)
Dadhich, Naresh, Turakulov, Z. Ya.
We have obtained the most general solution of the Einstein vacuum equation for the axially symmetric stationary metric in which both the Hamilton-Jacobi equation for particle motion and the Klein -...
In this lecture I build up the motivation for relativity and gravitation based on general principles and common sense considerations which should fall in the sphere of appreciation of a general...
Field Theories from the Relativistic Law of Motion (2001)
Singh, Parampreet, Dadhich, Naresh
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...
Gravitational collapse of null fluid on the brane (2001)
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 back-reaction of the bulk onto the brane is...
Global monopoles and scalar fields as the electrogravity dual of Schwarzschild spacetime (2000)
Dadhich, Naresh, Banerjee, Narayan
We prove that both global monopole and minimally coupled static zero mass scalar field are electrogravity dual of the Schwarzschild solution or flat space and they share the same equation of state,...
Negative Energy Condition and Black Holes on the Brane (2000)
We propose that for non-localizable energy distribution the relevant energy condition is determined by the gravitational field energy which is negative for positive non-gravitational energy. That is...
Gamma-ray bursts as the birth-cries of black holes (2000)
Joshi, Pankaj, Dadhich, Naresh, Maartens, Roy
The origin of cosmic gamma-ray bursts remains one of the most intriguing puzzles in astronomy. We suggest that purely general relativistic effects in the collapse of massive stars could account for...
On product spacetime with 2-sphere of constant curvature (2000)
If we consider the spacetime manifold as product of a constant curvature 2-sphere (hypersphere) and a 2-space, then solution of the Einstein equation requires that the latter must also be of constant...
Black holes on the brane (2000)
Dadhich, Naresh, Maartens, Roy, Papadopoulos, Philippos, Rezania, Vahid
We consider exact solutions for static black holes localized on a three-brane in five-dimensional gravity in the Randall-Sundrum scenario. We show that the Reissner-Nordstrom metric is an exact...
Spherically symmetric empty space and its dual in general relativity (2000)
In the spirit of the Newtonian theory, we characterize spherically symmetric empty space in general relativity in terms of energy density measured by a static observer and convergence density...
The electrogravity transformation and global monopoles in scalar-tensor gravity (2000)
Bose, Sukanta, Dadhich, Naresh
The electrogravity transformation is defined by an interchange of the ``active'' and ``passive'' electric parts of the Riemann tensor. Such a transformation has been used to find new solutions that...
The field equation from Newton's law of motion and absence of magnetic monopole (1999)
Singh, Parampreet, Dadhich, Naresh
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,...
New classes of black hole spacetimes in 2+1 gravity (1999)
Bose, Sukanta, Dadhich, Naresh, Kar, Sayan
The electrogravity transformation is applied to the three-dimensional Einstein field equations to obtain new multi-parameter families of black hole solutions. The Ba\~{n}ados-Teitelboim-Zanelli black...
Domain Walls in Kaluza-Klein spacetime (1999)
Patel, L. K., Dadhich, Naresh, Tikekar, R.
Three families of exact solutions of Einstein field equations are found. Each family contains three parameters. Two of these families represent thick domain walls in a five dimensional Kaluza-Klein...
Global monopole as dual-vacuum solution in Kaluza-Klein spacetime (1999)
Dadhich, Naresh, Patel, L. K., Tikekar, R.
By application of the duality transformation, which implies interchange of active and passive electric parts of the Riemann curvature (equivalent to interchange of Ricci and Einstein tensors) it is...
Gravoelectric-dual of the Kerr solution (1999)
By decomposing the Riemann curvature into electric and magnetic parts, we define the gravoelectric duality transformation by interchange of active and passive electric parts which amounts to...
Electromagnetic duality in general relativity (1999)
By resolving the Riemann curvature relative to a unit timelike vector into electric and magnetic parts, we consider duality relations analogous to the electromagnetic theory. It turns out that the...
Exact solutions for null fluid collapse in higher dimensions (1999)
A large family of inhomogeneous non-static spherically symmetric solutions of the Einstein equation for null fluid in higher dimensions has been obtained. It encompasses higher dimensional versions...
Higher Dimensional Analogue of McVittie Solution (1999)
Patel, L. K., Tikekar, R., Dadhich, Naresh
A generalization of the McVittie solution, representing spacetime of a mass particle placed in (n+2) dimensional Robertson-Walker universe is reported.
On the Brown-York quasilocal energy, gravitational charge, and black hole horizons (1999)
Bose, Sukanta, Dadhich, Naresh
We study a recently proposed horizon defining identity for certain black hole spacetimes. It relates the difference of the Brown-York quasilocal energy and the Komar charge at the horizon to the...
A simple shear-free non-singular spherical model with heat flux (1999)
We obtain an exact simple solution of the Einstein equation describing a spherically symmetric cosmological model without the big-bang or any other kind of singularity. The matter content of the...
Dual spacetimes, Mach's Principle and topological defects (1999)
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...
Oscillating non-singular relativistic spherical model (1999)
Dadhich, Naresh, Raychaudhuri, A. K.
A particular choice of the time function in the recently presented spherical solution by Dadhich [1] leads to a singularity free cosmological model which oscillates between two regular states. The...
A spacetime dual to the NUT spacetime (1998)
Nouri-Zonoz, Mohammad, Dadhich, Naresh, Lynden-Bell, D.
By decomposing the Riemann curvature into electric and magnetic parts, a duality transformation, which involves interchange of active and passive electric parts, has recently been proposed. It was...
On Electrogravity Duality (1998)
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...
A duality relation for fluid spacetime (1998)
Dadhich, Naresh, Patel, L. K., Tikekar, Ramesh
We consider the electromagnetic resolution of gravitational field. We show that under the duality transformation, in which active and passive electric parts of the Riemann curvature are interchanged,...
A duality relation : global monopole and texture (1997)
We resolve the entire gravitational field;i.e. the Riemann curvature into its electric and magnetic parts. In general, the vacuum Einstein equation is symmetric in active and passive electric parts....
Black hole : Equipartition of matter and potential energy (1997)
Black hole horizon is usually defined as the limit for existence of timelike worldline or when a spatially bound surface turns oneway (it is crossable only in one direction). It would be insightful...
Inhomogeneous imperfect fluid spherical models without Big-Bang singularity (1997)
So far all known singularity-free cosmological models are cylindrically symmetric. Here we present a new family of spherically symmetric non-singular models filled with imperfect fluid and radial...
On ``minimally curved spacetimes'' in general relativity (1997)
We consider a spacetime corresponding to uniform relativistic potential analogus to Newtonian potential as an example of ``minimally curved spacetime''. We also consider a radially symmetric analogue...
An ansatz for spacetimes of zero gravitational mass : global monopoles and textures (1997)
We propose a geometric ansatz, a restriction on Euclidean / Minkowski distance in the embedding space being propotional to distance in the embedded space, to generate spacetimes with vanishing...
On the third law of black hole dynamics (1997)
The third law of black hole dynamics states that the surface gravity (temperature) of black hole cannot be reduced to zero in finite sequence of physical interactions. We argue that the same is true...
On the Schwarzschild field (1997)
General relativity is a non-linear theory with the distinguishing feature that gravitational field energy also acts as gravitational charge density. In the well-known Schwarzschild solution...
Schwarzschild black hole with global monopole charge (1997)
Dadhich, Naresh, Narayan, K., Yajnik, U. A.
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...
Schwarzschild Black Hole With Global Monopole Charge (1997)
Naresh Dadhich, K. Narayan, U. A. Yajnik
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...
A Conformal Mapping and Isothermal Perfect Fluid Model (1996)
Instead of conformal to flat spacetime, we take the metric conformal to a spacetime which can be thought of as ``minimally'' curved in the sense that free particles experience no gravitational force...
Isothermal spherical perfect fluid model: Uniqueness and Conformal mapping (1996)
We prove the theorem: The necessary and sufficient condition for a spherically symmetric spacetime to represent an isothermal perfect fluid (barotropic equation of state with density falling off as...
A Class of Stationary Rotating String Cosmological Models (1995)
We obtain a one parameter class of stationary rotating string cosmological models of which the well-known G$\ddot o $del Universe is a particular case. By suitably choosing the free parameter...
The General Self-dual solution of the Einstein Equations (1994)
Koshti, Sucheta, Dadhich, Naresh
We obtain the most general explicit (anti)self-dual solution of the Einstein equations. We find that any (anti)self-dual solution can be characterised by three free functions of which one is...
Characterisation of orthogonal perfect fluid cosmological spacetimes (1994)
Dadhich, Naresh, Patel, L. K., Govinder, K. S., Leach, P. G. L.
We consider the general orthogonal metric separable in space and time variables in comoving coordinates. We then characterise perfect fluid models admitted by such a metric. It turns out that the...
Uniqueness of the non-singular family and characterisation of cosmological models (1994)
We prove that for an orthogonal spacetime metric separable in space and time in comoving coordinates, the requirements of perfect fluid and non-singularity single out the unique family of singularity...
On Singularity Free Spacetimes--II : mid Geodesic Completeness (1993)
We study the geodesics of the singularity free metric considered in the preceding Paper I and show that they are complete. This once again demonstrates the absence of singularity. The geodesic...
Singularity Free Spacetimes -- I :Metric and Fluid Models (1993)
Dadhich, Naresh, Patel, L. K., Tikekar, R.
We show that the metric for the singularity free family of fluid models [3] can be obtained by a simple and natural inhomogenisation and anisotropisation procedure from Friedman--Robertson--Walker...
Singularity Free Inhomogeneous Models with Heat Flow (1993)
We present a class of singularity free exact cosmological solutions of Einstein's equations describing a perfect fluid with heat flow. It is obtained as generalization of the Senovilla class [1]...
A Conformal Mapping and Isothermal Perfect Fluid Model
Naresh Dadhich Inter, Naresh Dadhich
Instead of conformal to flat spacetime, we take the metric conformal to a spacetime which can be thought of as "minimally" curved in the sense that free particles experience no...