I am Professor and Chair of the Physics Department at Florida Atlantic University. I also have an emeritus position at the Air Force Research Laboratory in New Mexico since retiring from the Air Force in 2009. I started as Chair of Physics at Florida Atlantic University in January 2003.

I obtained my PhD degree in Physics in 1986 under the supervision of John Archibald Wheeler at The University of Texas at Austin. My dissertation in General Relativity introduced Null-Strut Regge Calculus.

Before I came to FAU in 2003, I worked in Los Alamos as a J. Robert Oppenheimer Fellow in 1990, transitioned to a Technical Staff Member in 1993 and was Group Leader of T-6 for six years from 1996-2002.

Research Interests:

I am interested in discrete geometry as applied to (1) classical and quantum gravity, (2) complex network taxonomy via curvature and discrete Ricci flow, and (3) quantum information processing. I also work on problems in black hole astrophysics.

Regge Calculus and Null-Strut Calculus

Regge calculus provides a beautiful discrete representation of gravity wherein the principles of GR are applied directly to the simplicial spacetime. My work in this area is to develop Regge calculus into a well-defined and useful discrete dynamical theory of gravitation.

Complex Networks and Discrete Ricci Flow in Higher Dimensions

We study the dimensional reduction a complex networks by embedding into lower dimensional manifolds. The geometry of the simplicial geometry may be used to characterize the degree of network congestion. We use Regge calculus to define Discrete Ricci Flow in higher dimensions. This diffusive curvature flow can steer network reconfigurations leading to more favorable load balance.

Quantum Geometrodynamics and Discrete Quantum Gravity

I helped develop Quantum Geometrodynamics by quantizing a representation of the true dynamical degrees of freedom. I am also animated by quantizing discrete metric structures based on information-theoretic distance measures. Applications of quantum Regge calculus are also of interest to me. I have had a sustained interest in understanding the structure of discrete diffeomorphisms and the emergence of the continuous theory.

General Relativistic Smooth Particle Hydrodynamics

We have developed the first manifestly covariant hydrodynamics algorithm using the Lagrangian approach of SPH for a relativistic fluid. The contact forces inherent to this discretized fluid model are modeled as  interpolating kernels defined in the frame locally co-moving with the fluid.

Black Hole Astrophysics

My interest has focused on the role gravitomagnetism in astrophysics. Some of my work on supermassive black holes is showcased on the January 1, 1998 cover of Nature on Closing in on a Black Hole.

Numerical Relativity, Experimental and Classical General Relativity

In addition to numerical applications of Regge calculus, I have studied constant mean curvature slices in numerical relativity, and have addressed issues on the numerical stability of Einstein's equations.

Foundations of Quantum Mechanics and Quantum Information Processing

I am keenly interested in information theoretic foundations of QM for discrete systems. My earlier work with John Archibald Wheeler focused on delayed-choice feature of QM, and in 1983 we introduced the use of the use of a photons` orbital angular momentum (OAM) in such experiments. My recent work has focused on the use of OAM and linear momentum (LM) photon wavefronts in Quantum Key Distribution.