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

- ACGRG3, PERTH, 11-13 July, 2001 - DEADLINE FOR ABSTRACTS EXTENDED - PLEASE SEND THEM IN NOW!!!
- BIENNIEL GENERAL MEETING, Perth, 11 July, 2001
- MEMBERSHIP DETAILS ONLINE
- SUBSCRIPTIONS
- BID FOR GR17
- REPORT ON WORKSHOP IN CONJUNCTION WITH AIP'2000
- MEMBERS' NEWS
- MEMBERS' ABSTRACTS AT gr-qc August, 2000 - February, 2001

http://www2.phys.canterbury.ac.nz/ASGRG/ACGRG3/

Previously, there was a deadline of February 28 for the submission of titles and abstracts of talks. However, the response to this has been somewhat disappointing. The deadline is therefore being extended to April 30. Please get those titles and abstracts in.

http://www2.phys.canterbury.ac.nz/ASGRG/members.html

you will find a members' list. Clicking on individual members gives their current contact details. By following a further link private details of the subscription status of any member will be sent to their registered email.

This feature should enable us to update our records more frequently in response to members' input, and to allow members to keep track of their subscriptions.

To avoid problems in future the new version of the membership script programs will be run automatically once a year to give members other than life members details of their current subscription status. Initially the program will be run after this newsletter is sent, and then at the end of July each year.

The new version of the subscription form

http://www2.phys.canterbury.ac.nz/ASGRG/subsform.html

has been simplified so that it does not need to be updated each year. Given that our annual fee is modest, members are encouraged to pay for multiple years, and to fill in the years they are paying for. E.g., now that July 2000 - June 2001 subscriptions are finally being requested, if you wish to pay for July 2001 - June 2002 at the same time, it may simplify matters.

The conferences are traditionally held in the northern hemisphere summer, and thus a Queensland location is the ideal one. As it is a large event most of the organization would be done by professionals.

The bid must be presented at this year's GR16 conference in Durban, and will be on our agenda for discussion at the BGM in Perth. However, given the short timeframe between ACGRG3 and GR16 the following week, if there are any points wish members wish to raise in relation to the bid, they should contact Susan now directly.

The theoretical sessions were wide ranging, covering all aspects of gravitational physics, from mathematical relativity to cosmology and to string theory. Dr Peter Bouwknegt presented an overview of recent results in string theory, while Dr David Wiltshire presented an overview of the now popular "brane world" scenario, in which extra spatial dimensions are either compact but larger than had been previously considered to be the case, or possibly infinite. The more technical talks covered topics including the evidence for a vacuum energy in the universe - "quintessence" - and possible models to explain it, cosmic strings, solutions of Einstein's equations on null characteristics, and mathematical properties of abstract boundaries and singularities, both in Einstein's theory and generalizations which include fields from string theory.

Though small, the meeting was a great success, and we look forward in July, 2001 to both the "4th Edoardo Amaldi Conference on Gravitational Waves" in Perth http://www.gravity.uwa.edu.au/amaldi/amaldi.htm and the "Third Australasian Conference on General Relativity and Gravitation" http://www2.phys.canterbury.ac.nz/ASGRG/ACGRG3/ which is being held this time as a satellite meeting to the international Amaldi conference.

- Congratulations to Robert Bartnik, Malcolm Gray, David McClelland and
Peter Veitch on their respective ARC large grant successes.
- David Wiltshire will be taking up a continuing lectureship at the Dept of Physics and Astronomy, University of Canterbury, Christchurch, NZ from July, 2001.

We list here all abstracts that we are aware of that have been submitted by our members to gr-qc, or which are cross-linked at gr-qc. (We have not searched for abstracts on other Los Alamos archives which are not crosslinked to gr-qc.) If you do not send your papers to gr-qc but would like to have them noted in the newsletters, please send them to the Editor.

------------------------------------------------------------------------------ \\ Paper: gr-qc/0009023 From: Reg CahillDate: Fri, 8 Sep 2000 03:47:32 GMT (134kb) Title: Process Physics: Modelling Reality as Self-Organising Information Authors: Reginald T. Cahill, Christopher M. Klinger and Kirsty Kitto Comments: 9 pages, 4 figures \\ The new Process Physics models reality as self-organising relational information and takes account of the limitations of logic, discovered by Godel and extended by Chaitin, by using the concept of self-referential noise. Space and quantum physics are emergent and unified, and described by a Quantum Homotopic Field Theory of fractal topological defects embedded in a three dimensional fractal process-space. \\ ( http://au.arXiv.org/abs/gr-qc/0009023 , 134kb) ----------------------------------------------------------------------------- \\ Paper: gr-qc/0101028 From: Adrian P. Gentle Date: Mon, 8 Jan 2001 20:29:46 GMT (50kb) Title: A brief review of Regge calculus in classical numerical relativity Authors: Adrian P. Gentle and Warner A. Miller Comments: 2 pages, submitted to the Proceedings of the IX Marcel Grossmann Meeting, Rome, July 2-8, 2000 Report-no: LAUR-00-5816 \\ We briefly review past applications of Regge calculus in classical numerical relativity, and then outline a programme for the future development of the field. We briefly describe the success of lattice gravity in constructing initial data for the head-on collision of equal mass black holes, and discuss recent results on the efficacy of Regge calculus in the continuum limit. \\ ( http://au.arXiv.org/abs/gr-qc/0101028 , 50kb) ----------------------------------------------------------------------------- \\ Paper: astro-ph/0010443 From: David Wiltshire Date: Mon, 23 Oct 2000 12:24:15 GMT (36kb) Title: Supernovae Ia, evolution and quintessence Authors: D.L. Wiltshire Comments: 5 pages, 2 figures, aipproc, epsfig. To appear in "Cosmology and Particle Physics", Proceedings of the CAPP'2000 Conference, Verbier, eds. J. Garcia-Bellido, R. Durrer and M. Shaposhnikov, (AIP, 2001) Report-no: ADP-00-49/M95 Quintessence models with a dark energy generated by pseudo Nambu-Goldstone bosons provide a natural framework in which to test the possibility that type Ia supernovae luminosity distance measurements are at least partially due to an evolution of the sources, since these models can have parameter values for which the expansion of the Universe is decelerating as well as values for which it is accelerating, while being spatially flat in all cases and allowing for a low density of clumped matter. The results of a recent investigation (astro-ph/0004138) of current observational bounds which allow for SNe Ia source evolution are discussed. It is found that models with source evolution still favour cosmologies with an appreciable amount of acceleration in the recent past, but that the region of parameter space which is most favoured shifts significantly. \\ ( http://au.arXiv.org/abs/astro-ph/00010443 , 36kb) ----------------------------------------------------------------------------- \\ Paper: gr-qc/0011023 From: Alan Barnes Date: Tue, 7 Nov 2000 13:06:50 GMT (6kb) Title: On Cyclically Symmetrical Spacetimes Authors: Alan Barnes (Aston University Birmingham) Comments: 6 pages, LaTex. (World Scientific style file: sprocl.sty needed) To appear in Proceedings of the Spanish Relativity Meeting (EREs2000), World Scientific Publishing In a recent paper Carot et al. considered the definition of cylindrical symmetry as a specialisation of the case of axial symmetry. One of their propositions states that if there is a second Killing vector, which together with the one generating the axial symmetry, forms the basis of a two-dimensional Lie algebra, then the two Killing vectors must commute, thus generating an Abelian group. In this paper a similar result, valid under considerably weaker assumptions, is derived: any two-dimensional Lie transformation group which contains a one-dimensional subgroup whose orbits are circles, must be Abelian. The method used to prove this result is extended to apply three-dimensional Lie transformation groups. It is shown that the existence of a one-dimensional subgroup with closed orbits restricts the Bianchi type of the associated Lie algebra to be I, II, III, VII_0, VIII or IX. Some results on n-dimensional Lie groups are also derived and applied to show there are severe restrictions on the structure of the allowed four-dimensional Lie transformation groups compatible with cyclic symmetry. \\ ( http://au.arXiv.org/abs/gr-qc/0011023 , 6kb ) ----------------------------------------------------------------------------- \\ Paper: gr-qc/0011054 From: Leo Brewin Date: Wed, 15 Nov 2000 14:12:02 GMT (25kb) Title: Stable evolution of a maximally sliced Schwarzschild spacetime using a smooth lattice Authors: Leo Brewin Comments: 3 pages, 4 eps figures, talk given at MG9, Rome, July 2000 We will present results of a long term stable evolution, to $t=1000m$, of a maximally sliced Schwarzschild blackhole using a smooth lattice method. \\ ( http://au.arXiv.org/abs/gr-qc/0011054 , 25kb ) ----------------------------------------------------------------------------- \\ Paper: gr-qc/0012036 From: Brandon CARTER Date (v1): Sun, 10 Dec 2000 10:18:00 GMT (33kb) Date (revised v2): Mon, 29 Jan 2001 16:06:24 GMT (33kb) Title: Essentials of Classical Brane Dynamics Authors: Brandon Carter Comments: 37 pages, Latex, revised to update references. Based on talk on 5 June, 2000 at Meudon Colloquium ``Motivations for and Implications of Extra Cosmological Dimensions'' (transparencies visible on line at this http URL) Contribution to proc. Peyresq 5 meeting, June 2000, ``Quantum spacetime, Brane Cosmology, and Stochastic Effective Theories'' This article provides a self contained overview of the geometry and dynamics of relativistic brane models, of the category that includes point particle, string, and membrane representations for phenomena that can be considered as being confined to a worldsheet of the corresponding dimension (respectively one, two, and three) in a thin limit approximation in an ordinary 4 dimensional spacetime background. This category also includes ``brane world'' models that treat the observed universe as a 3-brane in 5 or higher dimensional background. The first sections are concerned with purely kinematic aspects: it is shown how, to second differential order, the geometry (and in particular the inner and outer curvature) of a brane worldsheet of arbitrary dimension is describable in terms of the first, second, and third fundamental tensor. The later sections show how -- to lowest order in the thin limit -- the evolution of such a brane worldsheet will always be governed by a simple tensorial equation of motion whose left hand side is the contraction of the relevant surface stress tensor $ bar T^{\mu\nu}$ with the (geometrically defined) second fundamental tensor $K_{\mu\nu}{^\rho}$, while the right hand side will simply vanish in the case of free motion and will otherwise be just the orthogonal projection of any external force density that may happen to act on the brane. \\ ( http://au.arXiv.org/abs/gr-qc/0012036 , 33kb ) ----------------------------------------------------------------------------- \\ Paper: gr-qc/0012047 From: Tevian Dray Date: Wed, 13 Dec 2000 21:53:33 GMT (5kb) Title: Note on Signature Change and Colombeau Theory Authors: Tevian Dray, George Ellis, Charles Hellaby Comments: REVTex, 3 pages; to appear in GRG Recent work alludes to various `controversies' associated with signature change in general relativity. As we have argued previously, these are in fact disagreements about the (often unstated) assumptions underlying various possible approaches. The choice between approaches remains open. \\ ( http://au.arXiv.org/abs/gr-qc/0012047 , 5kb ) ----------------------------------------------------------------------------- \\ Paper: gr-qc/0101010 From: Brandon CARTER Date (v1): Mon, 1 Jan 2001 07:40:03 GMT (16kb) Date (revised v2): Mon, 29 Jan 2001 14:39:43 GMT (16kb) Title: Reflection symmetry breaking scenarios with minimal gauge form coupling in brane world cosmology Authors: Brandon Carter, Jean-Philippe Uzan Comments: 13 pages latex (revised to rectify a couple of sign transcription errors) This article synthesises and extends recent work on the cosmological consequences of dropping the usual Z_2 reflection symmetry postulate in brane world scenarios. It is observed that for a cosmological model of homogeneous isotropic type, the relevant generalised Birkhoff theorem establishing staticity of the external vacuum in the maximally symmetric ``bulk'' outside a freely moving world brane will remain valid for the case of motion that is forced by minimal (generalised Wess Zumino type) coupling to an external antisymmetric gauge field provided its kinetic action contribution has the usual homogeneous quadratic form. This means that the geometry on each side of the brane worldsheet will still be of the generalised Schwarzschild anti de Sitter type. The usual first integrated Friedmann equation for the Hubble expansion rate can thereby be straightforwardly generalised by inclusion of new terms involving 2 extra parameters respectively measuring the strength of the gauge coupling and the degree of deviation from reflection symmetry. Some conceivable phenomenological implications are briefly outlined, and corresponding limitations are derived for possible values of relevant parameters. \\ ( http://au.arXiv.org/abs/gr-qc/0101010 , 16kb ) ----------------------------------------------------------------------------- \\ Paper: gr-qc/0101041 From: Neil J. Cornish Date: Wed, 10 Jan 2001 20:04:05 GMT (3kb) Title: Comment on "Gravity Waves, Chaos, and Spinning Compact Binaries" Authors: Neil J. Cornish Comments: 1 page Report-no: MSU-PHYS-200075 Journal-ref: Phys. Rev. Lett. 85, 3980 (October 30th, 2000) Levin (gr-qc/9910040) has shown that spinning compact binaries can be chaotic at second post-Newtonian order. However, when higher order dissipational effects are included, the dynamics will no longer be chaotic, though the evolution may still be unpredictable in a practical sense. I discuss some of the additional work that needs to be done to decide how this unpredictability might affect gravitational wave detectors such as LIGO. \\ ( http://au.arXiv.org/abs/gr-qc/0101041 , 3kb ) ----------------------------------------------------------------------------- \\ Paper: cond-mat/0101291 From: Reinhard PRIX Date: Thu, 18 Jan 2001 18:19:42 GMT (9kb) Title: Relativistic solution of Iordanskii problem in multi-constituent superfluid mechanics Authors: Brandon Carter, David Langlois, Reinhard Prix Comments: 7 pages, LaTeX, Contrib. to "Vortices in Unconventional Superconductors and Superfluids", Dresden, March 2000, ed. G.Volovik Flow past a line vortex in a simple perfect fluid or superfluid gives rise to a transverse Magnus force that is given by the well known Joukowski lift formula. The problem of generalising this to multiconstituent superfluid models has been controversial since it was originally posed by the work of Iordanski in the context of the Landau 2-constituent model for He-4 at finite temperature. The present work deals not just with this particular case but with the generic category of perfect multiconstituent models including the kind proposed for a mixture of He-4 and He-3 by Andreev and Bashkin. It is shown here (using a relativistic approach) that each constituent will provide a contribution proportional to the product of the corresponding momentum circulation integral with the associated asymptotic current density. \\ ( http://au.arXiv.org/abs/cond-mat/0101291 , 9kb ) ----------------------------------------------------------------------------- \\ Paper: gr-qc/0102113 From: Brandon CARTER Date: Wed, 28 Feb 2001 16:02:19 GMT (12kb) Title: Interaction of gravitational waves with an elastic solid medium Authors: B. Carter Comments: 14 pages TeX file of contrib. to proc. Gravitational Radiation, Les Houches 1982, ed N. Deruelle, T. Piran, 455-464 (North Holland, Amsterdam, 1983) Contents. 1. Introduction. 2. Kinematics of a Material Medium: Material Representation. 3. Kinematics of a Material Medium: Convected Differentials. 4. Kinematics of a Perfect Elastic Medium. 5. Small Gravitational Perturbations of an Elastic Medium. \\ ( http://au.arXiv.org/abs/gr-qc/0102113 , 12kb ) -----------------------------------------------------------------------------