61 research outputs found
Quantum Singularities Around a Global Monopole
The behavior of a massive scalar particle on the spacetime surrounding a
monopole is studied from a quantum mechanical point of view. All the boundary
conditions necessary to turn into self-adjoint the spatial portion of the wave
operator are found and their importance to the quantum interpretation of
singularities is emphasized.Comment: 5 pages, revte
Properties of four numerical schemes applied to a scalar nonlinear scalar wave equation with a GR-type nonlinearity
We study stability, dispersion and dissipation properties of four numerical
schemes (Iterative Crank-Nicolson, 3'rd and 4'th order Runge-Kutta and
Courant-Fredrichs-Levy Non-linear). By use of a Von Neumann analysis we study
the schemes applied to a scalar linear wave equation as well as a scalar
non-linear wave equation with a type of non-linearity present in GR-equations.
Numerical testing is done to verify analytic results. We find that the method
of lines (MOL) schemes are the most dispersive and dissipative schemes. The
Courant-Fredrichs-Levy Non-linear (CFLN) scheme is most accurate and least
dispersive and dissipative, but the absence of dissipation at Nyquist
frequency, if fact, puts it at a disadvantage in numerical simulation. Overall,
the 4'th order Runge-Kutta scheme, which has the least amount of dissipation
among the MOL schemes, seems to be the most suitable compromise between the
overall accuracy and damping at short wavelengths.Comment: 9 pages, 8 Postscript figure
Quantum Probes of Spacetime Singularities
It is shown that there are static spacetimes with timelike curvature
singularities which appear completely nonsingular when probed with quantum test
particles. Examples include extreme dilatonic black holes and the fundamental
string solution. In these spacetimes, the dynamics of quantum particles is well
defined and uniquely determined.Comment: 12 pages, RevTeX, no figures, A few breif comments added and typos
correcte
One-dimensional nuclear dynamics in the time-dependent Hartree-Fock approximation
The time-dependent Hartree-Fock theory is applied to the large amplitude dynamics of slabs of spin and isospin symmetric nuclear matter. The slabs are translationally invariant in two transverse dimensions, and with the simplified effective interaction used in this work, the problem is reduced to a set of coupled nonlinear equations for time-dependent functions of a single spatial variable. By specification of appropriate initial conditions, large amplitude oscillations of a single slab, the scattering of a slab from an external potential barrier, and collisions of two slabs have been investigated. The results evidence a wide variety of dynamic phenomena, including fusion, compound nucleus formation, dissipation, strongly damped collisions, shock wave propagation, and fragmentation. The microscopic aspects of the dynamics, the relation to fluid mechanics, and the practical and conceptual problems arising from the theory are discussed in detail
A Numerical Study of Transient Mass Transport through a Circular Hole Connecting Two Semi-Infinite Media
NUMERICAL STUDY OF CONVECTION-DIFFUSION-REACTION EQUATIONS FOR LARGE DAMKOHLER AND CELL REYNOLDS NUMBERS
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