### Electronic Newsletter -- #2 Spring, 1997

Items for this newsletter should be emailed to the editor: asgrg *AT* hotmail *DOT* com

CONTENTS:
• Subscriptions due;
• Logo competition winners: Michael Ashley and Geoffrey Ericksson (ANU);
• ACGRG2, Sydney, 6-11 July, 1998, First Announcement;
• 6th Monash GR workshop, 11-12 April 1997, Melbourne - report
• GR15, 16-21 Dec 1997, Pune, India (3rd and final circular)
• GR15, Gravitational wave detection session
• ACGRG1 proceedings book announcement & order form
• "Cosmology - Physics of the Universe" book announcement
• Recent Australasian preprints on gr-qc
• News snippets (large scale cosmological anisotropy?);

#### LOGO COMPETITION

The logo competition has been won by Michael Ashley and Geoffrey Ericksson of the A.N.U. for their entry depicting the Penrose diagram of the Schwarzschild spacetime superimposed on a map of Australia. A symbolic beam splitter has been added at t=0 to represent the activities of ACIGA. The resulting logo is thus similar to the cover of the ACGRG1 Proceedings, except that New Zealand and Papua New Guinea do not figure in the logo. This is not meant as a slight to members in those countries, but is simply a reflection of the fact that a logo must be simple, and with all the countries of the region included it becomes too cluttered.

#### 6th MONASH GENERAL RELATIVITY WORKSHOP - REPORT

The Sixth Monash Relativity Workshop was held on April 11-12, 1997 at the Department of Mathematics in Monash University (Clayton), to mark the occasion of Colin McIntosh's early retirement. The workshop, organised by Tony Lun was an intensive action packed two days, with 18 talks, including many aspects of relativity related to Colin's interests in relativity. There were 26 participants from Monash U., La Trobe U., Deakin U., James Cook U., A.N.U., and the Universities of Adelaide, Canberra, Sydney and Waterloo (Canada).

Talks covered such wide-ranging ground as invariants of the Riemann tensor, perfect fluid and shear-free cosmologies and ultra-relativistic fluid dynamics, isotropic singularities, numerical relativity and gravitational radiation, Regge calculus, symmetry techniques applied to differential equations in relativity, black hole perturbations and thermodynamics, the thorny topic of signature change, an axiomatic approach to spacetime structure and computer tools for visualising geometry in relativity. The workshop finished with a joint talk by Colin and his student Khai Vu on "Desolv: a MAPLE package for solving differential equations".

Highlights were the talks by Colin's former students Graeme Sneddon, Leo Brewin and Tony Lun, which gave a glimpse of the enormous work that Colin has done for Australian relativity in building up the group at Monash and in encouraging networking among the various groups in Australia. A number of anecdotes these speakers told vividly reflected the vitality of the group that Colin has built up. We wish Colin all the best in his early retirement to undertake fulltime church activities, and hope that he will still find occasions to drop in on our conferences and maintain some contact with the scene that he has contributed so much to.

#### ACGRG1 BOOK ANNOUNCEMENT


Proceedings of
THE FIRST AUSTRALASIAN CONFERENCE ON
GENERAL RELATIVITY AND GRAVITATION

12-17 February, 1996, Institute for Theoretical Physics,

Editor D.L. Wiltshire

ISBN: 0-86396-430-3. 242 + vi pp. Paperback.

Price A$20 (approx US$16), credit card payments accepted.

Contains 22 articles on classical relativity, numerical relativity, quantum
gravity and gravitational wave detection.

CONTENTS

GRAVITATIONAL WAVE DETECTION
* A cosmological background of gravitational waves produced by supernovae in
the early universe ... D.G. Blair and L. Ju
* The development of technology for high performance laser interferometer
gravitational wave detectors at the UWA ... C.N. Zhao et al.

NUMERICAL RELATIVITY
* Post-Newtonian smooth particle hydrodynamics
... M.C. Thompson and J.J. Monaghan
* Einstein equations in the null quasi-spherical gauge: Progress report
... Robert Bartnik
* Spectral collocation methods for solution of Einstein's equations in null
quasi-spherical coordinates ... Andrew H. Norton
* Computational methods in the physical interpretation of Robinson-Trautman
spacetimes ... Daniel A. Prager and Anthony W.C. Lun
* Using Riemann normal coordinates in numerical relativity
... Leo Brewin
* An application of Regge calculus to axisymmetric initial data
... A.P. Gentle and L.C. Brewin

MATHEMATICAL RELATIVITY AND CLASSICAL GRAVITATION
* The cosmological singularity
... Peter Szekeres
* The gravitational effects of cusps on cosmic strings
... Malcolm R. Anderson
* Square of general relativity
... D.V. Gal'tsov
* Remarks on the Yilmaz and Alley papers
... Edward D. Fackerell
* On the key functions of axisymmetric gravitation
... P.C. Waylen
* Debye potentials for the massless Dirac equation in algebraically special
spacetimes ... Philip Charlton
* Gauge invariant perturbations of black holes using the modified
Newman-Penrose formalism ... Joe F.Q. Fernandes and Anthony W.C. Lun

QUANTUM GRAVITY
* How wrinkled is the surface of a black hole?
... Rafael D. Sorkin
* Quantum cosmology, supersymmetry, and the problem of time
... Hugh Luckock
* Solving the fine-tuning problem of inflation
... Andrew Matacz
* Quantum gravity: A brief review
... Tze-Chuen Toh
* Holonomies in quantum gravity
... E.E. Wood
* Pregeometric modelling of the spacetime phenomenon
... Reginald T. Cahill and Christopher M. Klinger
* Polarisation of instantons in the SO(4) gauge theory results in gravity
... M.Yu. Kuchiev


#### BOOK ANNOUNCEMENT

        (Order from World Scientific or your local distributor)

COSMOLOGY: THE PHYSICS OF THE UNIVERSE
Proceedings of the 8th Physics Summer School,
Australian National University, 16 January - 3 February, 1995

Editors B. Robson, N. Visvanathan and W.S. Woolcock

ISBN: 981-02-2513-X. 531 + x pages. Price: US$82.50. Hardcover. CONTENTS: * Introduction to General Relativity ... M.R. Anderson * Classical Cosmology ... G. Boerner * Particle Physics Applied to Cosmology ... J. Ellis * Dark Matter in Galaxies ... K.C. Freeman * High Red-Shift Galaxies ... R.W. Hunstead * The Very Early Universe ... V.N. Lukash * The Hubble Constant and the Age of the Universe ... J. Mould * Topological Defects ... S.J. Poletti * Cosmological Implications of Nuclear Physics ... D.N. Schramm, C. Copi and X. Shi * The Epoch of Galaxy Formation ... J. Silk * Statistical Aspects of Large Scale Structure ... A.S. Szalay * Gravitational Lensing ... R. Webster and D. Mortlock * An Introduction to Quantum Cosmology ... D.L. Wiltshire  Australasian postings to gr-qc or cross-listings in gr-qc since last newsletter (past 18 months): N.B. The Australasian mirror for the Los Alamos archive is now operational at ------------------------------------------------------------------------------- \\ Paper: gr-qc/9605018 From: phrtc@cc.flinders.edu.au (<phrtc@cc.flinders.edu.au>) Date: Thu, 09 May 96 15:58:46 +0930 Title: Pregeometric modelling of the spacetime phenomenology Authors: Reginald T. Cahill, Christopher M. Klinger (Dept. of Physics, Flinders University) Comments: 13 page LateX, no figures Journal-ref: Phys.Lett. A223 (1996) 313-319 \\ At present we have only the very successful but phenomenological Einstein geometrical modelling of the spacetime phenomenon. This geometrical model provides a container' for other theories, in particular the quantum field theories. Here we report progress in developing a {\em Heraclitean Quantum System}. This is a particular pregeometric theory for space and time in which no classical or geometric structures are assumed, but rather the emergence of such phenomena is sought. \\ ------------------------------------------------------------------------------- \\ Paper: gr-qc/9605029 From: Neil Cornish <cornish@makarova.ph.unimelb.edu.au> Date: Thu, 16 May 1996 21:15:51 +1000 Title: The mixmaster universe is chaotic Authors: Neil J. Cornish (Uni. Melbourne) and Janna J. Levin (UC, Berkeley) Comments: 4 pages, RevTeX, 3 figures included Report-no: UM-P-96/33, CfPA-96-TH-10 \\ For the past decade there has been a considerable debate about the existence of chaos in the mixmaster cosmological model. The debate has been hampered by the coordinate, or observer dependence of standard chaotic indicators such as Lyapanov exponents. Here we use coordinate independent, fractal methods to show the mixmaster universe is indeed chaotic. \\ ------------------------------------------------------------------------------ \\ Paper: gr-qc/9606021 From: Neil Cornish <cornish@makarova.ph.unimelb.edu.au> Date: Tue, 11 Jun 1996 22:10:58 +1000 (148kb) Date (revised): Wed, 29 Jan 1997 00:42:15 +1100 Title: The Princess and the Pea Authors: Neil Cornish (DAMTP, Cambridge), Norm Frankel (Univ. Melbourne) Comments: 5 pages, RevTeX, 6 figures, revised and expanded version Report-no: UM-P-96/45 \\ Like a fairy-tale princess, trajectories around black holes can be sensitive to small disturbances. We describe how a small disturbance can lead to erratic orbits and an increased production of gravitational waves. ------------------------------------------------------------------------------ \\ Paper: gr-qc/9609016 From: Neil Cornish <cornish@physics.unimelb.EDU.AU> Date: Sat, 7 Sep 1996 03:05:39 +1000 Title: The black hole that went away Authors: Neil J. Cornish (Uni. of Melbourne) Comments: 1 page, RevTeX, no figures Report-no: UM-P-96/74 \\ A purported black hole solution in (2+1)-dimensions is shown to be nothing more than flat space viewed from an accelerated frame. \\ ------------------------------------------------------------------------------ \\ Paper: hep-th/9610033 From: Steven Brumby <spb@physics.unimelb.EDU.AU> Date: Mon, 7 Oct 1996 20:48:19 +1000 Title: Global effects in quaternionic quantum field theory Authors: S.P. Brumby and G.C. Joshi (Melbourne Uni.) Comments: 11 pages, no figures, revtex Report-no: UM-P-96/88; RCHEP 96/11 \\ We present some striking global consequences of a model quaternionic quantum field theory which is locally complex. We show how making the quaternionic structure a dynamical quantity naturally leads to the prediction of cosmic strings and non-baryonic hot dark matter candidates. \\ ------------------------------------------------------------------------------ \\ Paper: gr-qc/9610037 From: Jonathan Kress <jkress@frey.newcastle.edu.au> Date: Wed, 16 Oct 1996 20:13:27 MDT Title: Debye Potentials for Maxwell and Dirac Fields from a Generalisation of the Killing-Yano Equation Authors: I. M. Benn, Philip Charlton and Jonathan Kress Comments: 35 pages, plain TeX \\ By using conformal Killing-Yano tensors, and their generalisations, we obtain scalar potentials for both the source-free Maxwell and massless Dirac equations. For each of these equations we construct, from conformal Killing-Yano tensors, symmetry operators that map any solution to another. \\ ------------------------------------------------------------------------------ \\ Paper: hep-th/9610194 From: Hilary Booth <hilary@neumann.une.edu.au> Date: Fri, 25 Oct 1996 09:26:24 +1000 (EST) Title: The Dirac-Maxwell Equations with Cylindrical Symmetry Authors: Hilary Booth, Chris Radford (University of New England, Australia) Comments: 17 pages, Latex, 5 figures, psfig, to be published in J. Maths Phys Report-no: 96-125 \\ A reduction of the Dirac-Maxwell equations in the case of static cylindrical symmetry is performed. The behaviour of the resulting system of o.d.e.'s is examined analytically and numerical solutions presented. There are two classes of solutions. The first type of solution is a Dirac field surrounding a charged "wire". The Dirac field is highly localised, concentrated in cylindrical shells about the wire. A comparison with the usual linearized theory demonstrates that this localization is entirely due to the non-linearities in the equations which result from the inclusion of the "self-field". The second class of solutions have the electrostatic potential finite along the axis of symmetry but unbounded at large distances from the axis. \\ ------------------------------------------------------------------------------ \\ Paper: hep-th/9610210 From: Steven Brumby <spb@physics.unimelb.EDU.AU> Date: Mon, 28 Oct 1996 17:25:00 +1000 Title: Implications of quaternionic dark matter Authors: S.P. Brumby, B.E. Hanlon and G.C. Joshi (Melbourne Uni.) Comments: 14 pages, RevTeX, no figures Report-no: UM-P-96/90; RCHEP 96/12 \\ Taking the complex nature of quantum mechanics which we observe today as a low energy effect of a broken quaternionic theory we explore the possibility that dark matter arises as a consequence of this underlying quaternionic structure to our universe. We introduce a low energy, effective, Lagrangian which incorporates the remnants of a local quaternionic algebra, investigate the stellar production of the resultant exotic bosons and explore the possible low energy consequences of our remnant extended Hilbert space. \\ ------------------------------------------------------------------------------ \\ Paper: gr-qc/9611045 From: Robert Bartnik <bartnik@willow.canberra.edu.au> Date: Fri, 15 Nov 96 15:15:17 GMT Date (revised): Thu, 29 May 1997 17:10:14 MDT Title: Einstein equations in the null quasi-spherical gauge Authors: Robert Bartnik (University of Canberra) Comments: 12 pages, LaTeX (revtex, amssymb), revision 18 pages, contains expanded discussion and explanations, updated references Journal-ref: Class.Quant.Grav. 14 (1997) 2185-2194 \\ The structure of the full Einstein equations in a coordinate gauge based on expanding null hypersurfaces foliated by metric 2-spheres is explored. The simple form of the resulting equations has many applications -- in the present paper we describe the structure of timelike boundary conditions; the matching problem across null hypersurfaces; and the propagation of gravitational shocks. \\ ------------------------------------------------------------------------------ \\ Paper: gr-qc/9611063 From: andrewm@maths.su.oz.au Date: Wed, 27 Nov 96 10:29:14 +1100 Date (revised): Wed, 04 Dec 96 15:38:07 +1100 Title: Inflation and the Fine-Tuning Problem Author: Andrew Matacz (University of Sydney, Australia) Comments: 5 pages in Latex (uses Revtex), no figures. Minor changes to the text only \\ I describe a recently derived stochastic approach to inflaton dynamics which can address some serious problems associated with conventional inflationary theory. Using this theory I derive an exact solution to the stochastic dynamics for the case of a$\lambda\phi^4$potential and use it to study the generated primordial density fluctuations. It is found that on both sub and super-horizon scales the theory predicts gaussian fluctuations to a very high accuracy along with a near scale-invariant spectrum. Of most interest is that the amplitude constraint is found to be satisfied for$\lambda\sim 10^{-5}$rather than$\lambda\sim 10^{-14}$of the conventional theory. This represents a dramatic easing of the fine-tuning constraints, a feature likely to generalize to a wide range of potentials. \\ ------------------------------------------------------------------------------ \\ Paper: gr-qc/9612011 From: Philip Charlton <philipc@frey.newcastle.edu.au> Date: Tue, 3 Dec 1996 22:00:23 MST Title: Dirac symmetry operators from conformal Killing-Yano tensors Authors: I. M. Benn and Philip Charlton Comments: 8 pages, TeX Report-no: 96/28 \\ We show how, for all dimensions and signatures, a symmetry operator for the massless Dirac equation can be constructed from a conformal Killing-Yano tensor of arbitrary degree. \\ ------------------------------------------------------------------------------ \\ Paper: quant-ph/9612016 From: Don Koks <dkoks@physics.adelaide.edu.au> Date: Tue, 3 Dec 1996 14:11:51 +1030 (CST) Title: Entropy and Uncertainty of Squeezed Quantum Open Systems Authors: D. Koks, A. Matacz and B.L. Hu Comments: 36 pages, epsfig, 2 in-text figures included Report-no: ADP-96-42/M50, umdpp 97-63, School of Mathematics and Statistics 96-41 \\ We define the entropy S and uncertainty function of a squeezed system interacting with a thermal bath, and study how they change in time by following the evolution of the reduced density matrix in the influence functional formalism. As examples, we calculate the entropy of two exactly solvable squeezed systems: an inverted harmonic oscillator and a scalar field mode evolving in an inflationary universe. For the inverted oscillator with weak coupling to the bath, at both high and low temperatures,$S\to r $, where r is the squeeze parameter. In the de Sitter case, at high temperatures,$S\to
(1-c)r$where$c = \gamma_0/H$,$\gamma_0$being the coupling to the bath and H the Hubble constant. These three cases confirm previous results based on more ad hoc prescriptions for calculating entropy. But at low temperatures, the de Sitter entropy$S\to (1/2-c)r$is noticeably different. This result, obtained from a more rigorous approach, shows that factors usually ignored by the conventional approaches, i.e., the nature of the environment and the coupling strength betwen the system and the environment, are important. \\ ------------------------------------------------------------------------------ \\ Paper: gr-qc/9701046 From: David Hartley <DHartley@physics.adelaide.edu.au> Date: Tue, 21 Jan 1997 14:12:02 +1030 Title: Tensor distributions on signature-changing space-times Authors: David Hartley, Robin W. Tucker, Philip A. Tuckey, Tevian Dray Comments: 9 pages, LaTeX 2.09 Report-no: ADP 96-41/M49 \\ Irregularities in the metric tensor of a signature-changing space-time suggest that field equations on such space-times might be regarded as distributional. We review the formalism of tensor distributions on differentiable manifolds, and examine to what extent rigorous meaning can be given to field equations in the presence of signature-change, in particular those involving covariant derivatives. We find that, for both continuous and discontinuous signature-change, covariant differentiation can be defined on a class of tensor distributions wide enough to be physically interesting. \\ (http://xxx.adelaide.edu.au/abs/gr-qc/9701046 , 11kb) ------------------------------------------------------------------------------ \\ Paper: gr-qc/9701057 From: Leo Brewin <leo@newton.maths.monash.edu.au> Date: Tue, 28 Jan 1997 01:00:24 MST (195kb) Title: Riemann Normal Coordinates, Smooth Lattices and Numerical Relativity Authors: Leo Brewin Comments: 49 pages, 18 epsf figures, plain tex \\ A new lattice based scheme for numerical relativity will be presented. The scheme uses the same data as would be used in the Regge calculus (eg. a set of leg lengths on a simplicial lattice) but it differs significantly in the way that the field equations are computed. In the new method the standard Einstein field equations are applied directly to the lattice. This is done by using locally defined Riemann normal coordinates to interpolate a smooth metric over local groups of cells of the lattice. Results for the time symmetric initial data for the Schwarzschild spacetime will be presented. It will be shown that the scheme yields second order accurate estimates (in the lattice spacing) for the metric and the curvature. It will also be shown that the Bianchi identities play an essential role in the construction of the Schwarzschild initial data. \\ ( http://xxx.adelaide.edu.au/abs/gr-qc/9701057 , 195kb) ------------------------------------------------------------------------------ \\ Paper: hep-th/9702070 From: Simon Davis <simond@maths.su.oz.au> Date: Sun, 9 Feb 1997 13:29:22 +1100 (EST) (31kb) Title: Scalar Field Theory in Curved Space and the Definition of Momentum Author: Simon Davis Comments: 41 pages, TeX, 3 figures Report-no: DAMTP-R/96/8 \\ Some general remarks are made about the quantum theory of scalar fields and the definition of momentum in curved space. Special emphasis is given to field theory in anti-de Sitter space, as it represents a maximally symmetric space-time of constant curvature which could arise in the local description of matter interactions in the small regions of space-time. Transform space rules for evaluating Feynman diagrams in Euclidean anti-de Sitter space are initially defined using eigenfunctions based on generalized plane waves. It is shown that, for a general curved space, the rules associated with the vertex are dependent on the type of interaction being considered. A condition for eliminating this dependence is given. It is demonstrated that the vacuum and propagator in conformally flat coordinates in anti-de Sitter space are equivalent to those analytically continued from$H^4$and that transform space rules based on these coordinates can be used more readily. A proof of the analogue of Goldstone's theorem in anti-de Sitter space is given using a generalized plane wave representation of the commutator of the current and the scalar field. It is shown that the introduction of curvature in the space-time shifts the momentum by an amount which is determined by the Riemann tensor to first order, and it follows that there is a shift in both the momentum and mass scale in anti-de Sitter space. \\ ( http://xxx.adelaide.edu.au/abs/hep-th/9702070 , 31kb) ------------------------------------------------------------------------------ \\ Paper: gr-qc/9704074 From: Don Koks <dkoks@physics.adelaide.edu.au> Date: Sun, 27 Apr 1997 13:18:00 +0930 (CST) Title: Thermal Particle Creation in Cosmological Spacetimes: A Stochastic Approach Authors: Don Koks, B. L. Hu, Andrew Matacz, Alpan Raval Comments: 17 pages, revtex (aps, eqsecnum), submitted to PRD, April 1997 Report-no: UMDPP 96-116 Journal-ref: Phys.Rev. D56 (1997) 4905-4915 \\ The stochastic method based on the influence functional formalism introduced in an earlier paper to treat particle creation in near-uniformly accelerated detectors and collapsing masses is applied here to treat thermal and near-thermal radiance in certain types of cosmological expansions. It is indicated how the appearance of thermal radiance in different cosmological spacetimes and in the two apparently distinct classes of black hole and cosmological spacetimes can be understood under a unifying conceptual and methodological framework. \\ ( http://xxx.adelaide.edu.au/abs/gr-qc/9704074 , 31kb) ------------------------------------------------------------------------------ \\ Paper: gr-qc/9705079 From: Robert Bartnik <bartnik@stan.canberra.edu.au> Date: Wed, 28 May 1997 17:40:18 MDT (20kb) Title: Shear-free Null Quasi-Spherical Spacetimes Authors: Robert Bartnik Comments: 20 pages, revtex Report-no: UNE-MSCS-96-128 \\ The residual gauge freedom within the null quasi-spherical coordinate condition is studied, for spacetimes admitting an {\em expanding, shear-free} null foliation. The freedom consists of a boost and rotation at each coordinate sphere, corresponding to a specification of inertial frame at each sphere. Explicit formulae involving arbitrary functions of two variables are obtained for the accelerated Minkowski, Schwarzschild, and Robinson-Trautman spacetimes. These examples will be useful as test metrics in numerical relativity. \\ ( http://xxx.adelaide.edu.au/abs/gr-qc/9705079 , 20kb) ------------------------------------------------------------------------------ \\ Paper: hep-ph/9707324 From: R.A.W.Gregory@durham.ac.uk (Ruth A W Gregory) Date: Fri, 11 Jul 1997 14:40:19 +0100 (55kb) Title: Effective action and motion of a cosmic string Authors: Malcolm Anderson, Filipe Bonjour, Ruth Gregory and John Stewart Comments: 24 pages revtex, 12 figures Report-no: DTP/97/5, DAMTP/R-97/27 \\ We examine the leading order corrections to the Nambu effective action for the motion of a cosmic string, which appear at fourth order in the ratio of the width to radius of curvature of the string. We determine the numerical coefficients of these extrinsic curvature corrections, and derive the equations of motion of the worldsheet. Using these equations, we calculate the corrections to the motion of a collapsing loop, a travelling wave, and a helical breather. From the numerical coefficients we have calculated, we discuss whether the string motion can be labelled as rigid' or antirigid,' and hence whether cusp or kink formation might be suppressed or enhanced. \\ ( http://xxx.adelaide.edu.au/abs/hep-ph/9707324 , 55kb) ------------------------------------------------------------------------------ \\ Paper: gr-qc/9708013 From: "" <phrtc@flinders.edu.au> Date: Thu, 07 Aug 97 10:45:47 +0930 Title: Bootstrap Universe from Self-Referential Noise Authors: Reginald T. Cahill, Christopher M. Klinger (Flinders University) Comments: 10 pages, Latex \\ We further deconstruct Heraclitean Quantum Systems giving a model for a universe using pregeometric notions in which the end-game problem is overcome by means of self-referential noise. The model displays self-organisation with the emergence of 3-space and time. The time phenomenon is richer than the present geometric modelling. \\ ( http://xxx.adelaide.edu.au/abs/gr-qc/9708013 , 10kb) ------------------------------------------------------------------------------ \\ Paper: gr-qc/9708039 From: Leo Brewin <leo@newton.maths.monash.edu.au> Date: Tue, 19 Aug 1997 02:58:16 MDT Title: An ADM 3+1 formulation for Smooth Lattice General Relativity Authors: Leo Brewin Comments: 18 pages, plain TeX, 5 epsf figues, gzipped ps file also available at this http URL A new hybrid scheme for numerical relativity will be presented. The scheme will employ a 3-dimensional spacelike lattice to record the 3-metric while using the standard 3+1 ADM equations to evolve the lattice. Each time step will involve three basic steps. First, the coordinate quantities such as the Riemann and extrinsic curvatures are extracted from the lattice. Second, the 3+1 ADM equations are used to evolve the coordinate data, and finally, the coordinate data is used to update the scalar data on the lattice (such as the leg lengths). The scheme will be presented only for the case of vacuum spacetime though there is no reason why it could not be extended to non-vacuum spacetimes. The scheme allows any choice for the lapse function and shift vectors. An example for the Kasner$T^3\$ cosmology will be presented and it
will be shown that the method has, for this simple example, zero discretisation
error.

------------------------------------------------------------------------------


#### NEWS ITEM

                  ALL SPACE IS NOT EQUAL:
PHYSICISTS FIND AXIS THAT GIVES THE UNIVERSE ORIENTATION

Physicists at the University of Rochester and the University of Kansas have
found evidence that flies in the face of the long-held belief that space is the
same in all directions (isotropic). In fact, measurements indicate something
seldom considered by physicists: that the universe has an orientation. The
unexpected finding, determined by measuring the polarization of light as it
travels to Earth from the far reaches of the universe, is the subject of a
paper in the April 21 issue of Physical Review Letters [Phys Rev Lett 78 (1997)
3043].

The work, which may be one of the most fundamental findings about the universe
in recent years, could affect physicists' views about the birth of the universe
and suggests that scientists will need to explore how Einstein's theory of
relativity and the theory of electromagnetism might explain the finding. That's
quite an impact from an effect so tiny that it's betrayed only by light
traveling across most of the observable universe, from 15 billion years ago.
Physicists have dubbed the effect the "corkscrew effect" for the way it twists
light crossing the heavens.

"The big news is that perhaps not all space is equal, for as far back as we can
peer in time," says Borge Nodland of the University of Rochester.

Adds co-investigator John Ralston of the University of Kansas: "The shocking
thing about our result is that there seems to be an absolute axis, a kind of
cosmological north star that orients the universe. We don't really know yet
what this axis represents."

This axis of orientation is not a physical entity but rather defines a
direction of space that somehow determines how light travels through the
universe. In effect, Ralston and Nodland have discovered a direction in space
that is out of the ordinary or different from all other directions. The idea
that any direction of space is in any way "special" has long been taboo among
astrophysicists.

"This work defies the notion that there is no 'up' or 'down' in space," says
Nodland, research fellow at Rochester's Theory Center for Optical Science and
Engineering.

From Earth, the axis of this orientation runs toward the constellation Sextans,
roughly in the direction of Leo and Gemini and high in the southern evening sky
this time of year. The other end of the axis points toward the constellations
Aquila and Equuleus. (Stargazers, of course, will see nothing special when they
look in that direction.) Nodland and Ralston, a professor of physics and
astronomy at Kansas, say the axis might have several interpretations: It could
be an intrinsic property of the universe, or it might indicate that an
undiscovered particle, such as the long- theorized axion, is at work.

The team made the finding by studying the polarization (orientation of electric
fields) of radio waves from 160 distant galaxies as measured in previous
experiments by astronomers around the world. Nodland and Ralston found that the
plane of polarization of the light rotates like a corkscrew as the light
travels through space, and that the orientation of the universal axis that
they've discovered is key to the amount of rotation. The rotation of
polarization depends on the angle at which the light moves relative to the axis
and on the distance the light travels before being measured. The effect is
crudely analogous to that of a crystal that twists light depending on the
direction light is traveling through the crystal.

Astronomers have long known about a somewhat similar effect called the Faraday
effect, which is caused by magnetic fields between galaxies and causes the
plane of polarization of light to rotate as the light travels through space.

Though the cause of the corkscrew effect remains unknown, in their paper the
team constructs a mathematical theory that explains the observations. The data
indicate that light actually travels through space at two slightly different
speeds. Such a mismatch in speeds would cause the polarization plane to rotate
in a well known manner, in a way that physics students see when they pass light
through corn syrup and look at the light with polarizing filters. This
corkscrew effect is far more subtle, though: Light traveling across the heavens
undergoes one full rotation of its plane of polarization about once in a
billion years.

Whatever the cause, the work could have widespread implications. Scientists
have long theorized that the Big Bang was completely symmetric. Says Nodland:
"Perhaps it was not a perfect Big Bang, but a Big Bang with a twist to space
and time." Such a twist would be seen today as a ripple of non-uniformity,
perhaps as the axis (an "axis of anisotropy") represents.

Much more speculatively, the work may provide some of the first experimental
evidence for physicists who have theorized the existence of other universes. If
our universe was asymmetric at creation, and symmetry in the cosmos is
maintained as many physicists believe, it raises the possibility of the
simultaneous creation of another universe with an opposite twist.

The work also seems to run counter to the notions that all space is uniform and
that the speed of light in a vacuum is always precisely the same, key
assumptions of the theory of special relativity.

Though the researchers say there's only a few chances in a thousand that the
result comes from statistical fluctuations, they stress the need for other
scientists to confirm their results.

Questions about the universe and our role in it have fascinated Nodland ever
since he can remember, filling his mind as he took long hikes while growing up
in his native Norway.

"I've always had a passionate interest in the universe and its origins," he
says. "We're on a little planet going around some burning mass that we call a
sun, in a certain region of space. What is this space, and why are we here? The
universe is amazing, and I want to know the most I can about it."

The team's work is funded by the U.S. Department of Energy, the National
Science Foundation, the New York State Energy Research and Development
Authority, and the Kansas Science and Technology Advanced Research (KSTAR)
program.
`