Comer Duncan

Bowling Green State University

gcd@chandra.bgsu.edu

The sixth annual Midwest Relativity Conference was held at Bowling Green State University in Bowling Green, Ohio on Nov. 1-2, 1996. There were about 50 participants, most of whom gave talks. Each talk was 15 minutes long. For the most part the topics covered fell into the following categories: 1) Numerical Relativity, 2) Mathematical Relativity, 3) Observational Topics, 4) Quantum Gravity, and 5) Alternative Theories of Relativity.

* Numerical Relativity.* There were quite a few talks which utilize
numerical techniques, but several were more or less devoted to issues
which center on the numerical implementation of Einstein's theory in
two and three spatial dimensions, with and without matter. Beverly
Berger discussed evolutions of symmetric cosmologies, showing
the tracking of regions of large curvature using her symmetric
code. David Garfinkle talked about a new symplectic algorithm for the
evolution of mixmaster spacetimes which accurately evolves to late
times. Jorge Pullin gave an overview of the successful 'close
approximation' for colliding black holes and discussed its salient
features and applications. Serge Droz discussed a numerical
investigation of black hole interiors. Keith Lockitch reported on his
investigations of how to numerically construct a family of
asymptotically flat initial data sets which are axisymmetric and
geodesically complete as counter-examples to the cosmic censorship
conjecture. Comer Duncan gave a talk about a new hyperbolic solver
for vacuum axisymmetric spacetimes which combines the Geroch manifold
of trajectories approach with a symmetric hyperbolic form of
Einstein's equations, and discussed a numerical implementation and
tests on weak gravitational waves. Mark Miller reported his
investigations into the utility of Regge Calculus for numerical
relativity, focussing on issues of consistency and stability. Grant
Mathews discussed his work on the appearance of instabilities in close
neutron star binaries.

* Mathematical Relativity.* There were a wide variety of topics in
mathematical relativity. Ulrich Gerlach discussed some recent work on
a variety of topics, including paired accelerated frames, diffractive
scattering, and achronal spin. Jean Krisch reported on some work on
string fluid stress energy. Steve Leonard talked about the appearance
of tail effects for various types of fields in curved spacetimes. Ted
Quinn reported his investigations into an axiomatic approach to
electromagnetic and gravitational radiation reaction. Shyan-Ming
Perng talked about his research on conserved quantities at spatial
infinity. Ed Glass discussed the calculation of the Bondi mass from
Taub numbers, while Jim Chan discussed radiative falloff in
non-asymptotically flat spacetimes. Juan Perez-Mercader presented his
views on how self-organized criticality may be expressed in the
universe. Kevin Chan talked about modifications of the spinning BTZ
black hole when the theory contains a dilaton field. Masafumi Seriu
gave an overview of his work to characterize the global geometrical
structure of a space in terms of the spectra of a suitable operator,
including discussion of a measure of closeness of two universes based
on the spectra. There were two talks utilizing torsion. Richard
Hammond discussed gravitation with torsion derived as the exterior
derivative of a second potential, built so that electromagnetism may
be generalized such that the source of the torsion gives rise to the
magnetic dipole moment of the electron. Harry Ringermacher gave a
treatment in which gravity with torsion is present to encode the
electromagnetic field and discussed several solutions.

* Observational Topics.* Mark Beilby gave a talk about methods of
predicting test mass thermal noise by measurement of the anelastic
aftereffect in the context of the LIGO project. Eric Poisson talked
about the dual use of space-based interferometers to measure black
hole parameters and as a means of testing general relativity. Andrew
de Laix gave a treatment of the gravitational lensing signature of
long cosmic strings. Bob Wald gave an overview of some recent work on
galactic and smaller scale gravitational lensing, while Daniel Holz
followed with further developments and some applications. Philip
Hughes discussed some recent high resolution relativistic
extra-galactic jet simulations as a possible probe of aspects of
super-massive black holes.

* Quantum Gravity.* The variety of topics which are quantum related
was quite wide in scope. Leonard Parker gave a talk about his
research on 2D black holes, reporting on his work on the formation and
evaporation of 2D black holes in dilatonic quantum gravity. Louis
Witten talked about the formation and evaporation of naked
singularities in 2D which suggest that the naked singularity will not
exist but instead there would be a large outburst of radiation. Ivan
Booth reported on the cosmological production of charged and rotating
black hole pairs. James Geddes gave a discussion of some recent work
on whether there exists a measure on the space of all paths in
Schroedinger quantum mechanics such that the time evolution of the
system is given by an appropriate path integral. He give an example of
a system for which the answer is no. Hong Liu talked about quantum
hair, instantons, and black hole thermodynamics. Bob Mann then gave a
report on the pair production of topological anti de Sitter black
holes. The talks by Michael Pfenning and Matt Visser were of a
different orientation. Pfenning discussed quantum inequalities in
static curved spacetimes. Visser gave an overview of the violation of
energy conditions at order hbar, showing how the polarization of the
vacuum by the semi-classical gravitational field causes a shift in the
stress-energy which violates all the classical energy conditions.
Rhett Herman talked about the use of the DeWitt-Schwinger
point-splitting technique to construct the stress-energy of a complex
scalar field in curved spacetime.

* Alternative Theories of Relativity.* Ken Seto discussed a special
relativity alternative. Edward Schaefer talked about means of
eliminating black holes from relativity theory.

The Sixth Midwest Relativity Conference included a wide variety of talks, giving ample evidence of the breadth of interests of relativists in and around the midwest. The meeting at Bowling Green demonstrated that the midwest meetings have achieved a stable status.

Thanks to all who attended! The next meeting will be at Washington U. in St. Louis with Wa Mo Suen the prime contact. See you all at the next meeting!

Tue Feb 4 22:28:54 EST 1997