134 citations · 918 across the 58 of their papers we have counts for
18 papers · 1 filter
Accelerated expansion of the Universe and the Higgs true vacuum
Muhammad Usman, Asghar Qadir
Scalar fields which are favorite among the possible candidates for the dark energy usually have degenerate minima at . In the presented work, we discuss a two Higgs do…
Do the Ricci and energy-momentum tensors have "duality'' in the context of their Lie symmetries?
Hina Khan, Asghar Qadir, K. Saifullah +1
The Ricci and energy-momentum tensors have the same algebraic symmetries. In the Einstein equations they look ``dual'' to each other, in that interchanging them and inverting the g…
Asymptotic Behaviour of the Proper Length and Volume of the Schwarzschild Singularity
Asghar Qadir, Azad A. Siddiqui
Though popular presentations give the Schwarzschild singularity as a point it is known that it is spacelike and not timelike. Thus it has a "length" and is not a "point". In fact,…
K-Slicing the Reissner-Nordstrom Spacetime: Some New Observations
Asghar Qadir, M. Sajid, Azad A. Siddiqui
There were problems encountered in extending the K-slicing of the Schwarzschild and Reissner-Nordstrom (RN) spacetimes [1, 2] to the extreme case, when charge equals mass (in gravi…
On the definition of matter collineations
Asghar Qadir, K. Saifullah
It is shown that when the stress-energy tensor of a spacetime is diagonal and is written in the mixed form, its collineations admit infinite dimensional Lie algebras except possibl…
Conformal Ricci collineations of static spherically symmetric spacetimes
Ugur Camci, Asghar Qadir, K. Saifullah
Conformal Ricci collineations of static spherically symmetric spacetimes are studied. The general form of the vector fields generating conformal Ricci collineations is found when t…
Comments on matter collineations of plane symmetric, cylindrically symmetric and spherically symmetric spacetimes
Asghar Qadir, K. Saifullah
Comments are made on some recently published papers on matter collineations of plane symmetric, cylindrically symmetric and spherically symmetric spacetimes.
Primordial Black Holes in Phantom Cosmology
Mubasher Jamil, Asghar Qadir
We investigate the effects of accretion of phantom energy onto primordial black holes. Since Hawking radiation and phantom energy accretion contribute to a {\it decrease} of the ma…
A Proposal for Determining the Energy Content of Gravitational Waves by Using Approximate Symmetries of Differential Equations
Ibrar Hussain, F. M. Mahomed, Asghar Qadir
Since gravitational wave spacetimes are time-varying vacuum solutions of Einstein's field equations, there is no unambiguous means to define their energy content. However, Weber an…
Approximate Noether Symmetries of the Geodesic Equations for the Charged-Kerr Spacetime and Rescaling of Energy
Ibrar Hussain, F. M. Mahomed, Asghar Qadir
Using approximate symmetry methods for differential equations we have investigated the exact and approximate symmetries of a Lagrangian for the geodesic equations in the Kerr space…
Approximate Symmetries of Lagrangians for Plane Symmetric Gravitational Wave-Like Spacetimes
Ibrar Hussain, Asghar Qadir
Using Lie symmetry methods for differential equations we have investigated the symmetries of a Lagrangian for a plane symmetric static spacetime. Perturbing this Lagrangian we expl…
On Quantum Effects Near a Black Hole Singularity
Asghar Qadir, Azad A. Siddiqui
It is pointed out that the claim made by Joshi and Joshi [1], has not been rigorously demonstrated by them. A simpler and more correct proof is provided.
Second-Order Approximate Symmetries of the Geodesic Equations for the Reissner-Nordström Metric and Re-Scaling of Energy of a Test Particle
Ibrar Hussain, Fazal M. Mahomed, Asghar Qadir
Following the use of approximate symmetries for the Schwarzschild spacetime by A.H. Kara, F.M. Mahomed and A. Qadir (Nonlinear Dynam., to appear), we have investigated the exact an…
Homotheties of Cylindrically Symmetric Static Manifolds and their Global Extension
Asghar Qadir, M. Sharif, M. Ziad
Cylindrically symmetric static manifolds are classified according to their homotheties and metrics. In each case the homothety vector fields and the corresponding metrics are obtai…
General Formula for the Momentum Imparted to Test Particles in Arbitrary Spacetimes
Asghar Qadir, M. Sharif
Ehlers and Kundt have provided an approximate procedure to demonstrate that gravitational waves impart momentum to test particles. This was extended to cylindrical gravitational wa…
The Relativistic Generalization of the Gravitational Force for Arbitrary Spacetimes
Asghar Qadir, M. Sharif
It has been suggested that re-expressing relativity in terms of forces could provide fresh insights. The formalism developed for this purpose only applied to static, or conformally…
Similarities Between Classical Timelike Geodesics in a Naked Reissner-Nordstrom Singularity Background and the Behaviour of Electrons in Quantum Theory
Asghar Qadir, Azad A. Siddiqui
It is generally assumed that naked singularities must be physically excluded, as they could otherwise introduce unpredictable influences in their future null cones. Considering geo…
Note on flat foliations of spherically symmetric spacetimes
Viqar Husain, Asghar Qadir, Azad A. Siddiqui
It is known that spherically symmetric spacetimes admit flat spacelike foliations. We point out a simple method of seeing this result via the Hamiltonian constraints of general rel…