Electronic Newsletter -- #4 Summer 1999/2000

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

CONTENTS:

FROM THE PRESIDENT'S DESK:

One and a half years have passed since the last Society meeting so I think it is worth filling members in on relevant events that have occurred.

On the highlights side, ASGRG has been granted cognate society status with the Australian Institute of Physics. This has the immediate benefit for ASGRG members in providing us with a 10% reduction on the AIP annual subscription fee. If you are not already a member of the AIP, now would be a good time to support physics in Australia. As a cognate society we are required to run a mini workshop at AIP Congresses (more on this below) and be represented at the AIP Council meeting each February.

In regard to societies, we should consider whether or not to join FASTS. David Wiltshire, Susan Scott and I attended the recent Science meets Parliament day in Canberra. Though David and Susan both represented the AIP, we did our bit to promote the ASGRG. Membership of FASTS would allow us to be fully represented at such events and have formal input on matters effecting science in Australia.

Of great importance to the gravitational wave detection community is the awarding of the Fourth Amaldi Conference on Gravitational waves to Perth. This major international meeting will be held in July 2001, immediately before the South African GR conference. Hopefully this will encourage visitors from the northern hemisphere to include both meetings in their itineraries.

Given that Amaldi will be held in Perth, we are proposing to postpone the next meeting of our Society, which was to be held in Perth in December 2000, until July 2001 and run it just before the Amaldi meeting but with a one or two day overlap at the end on gravitational wave research. This will assist us in financing ASGRG3 by sharing some costs for visitors and facilities with the Amaldi and will be further incentive for people to have a southern relativity experience. David Wiltshire will expand on this below and explain how we will go about getting your approval for this change.

Unfortunately, not all has been positive. The Australian Consortium for Interferometric Gravitational Astronomy (ACIGA) submitted an application for a Special Research Centre to undertake R&D toward gravitational wave detection. Though being highly praised for the research training environment it would provide, the ARC committee had its doubts about whether the innovative technology could be achieved. Obviously there is much work we have to do in educating the broader physics community on what we have already achieved and are currently doing. One event that will aid us in doing this is the opening, in March 2000, of the new gravitational wave physics laboratory in Gingin, WA, a chosen site for a future long baseline detector. Prof Barish from LIGO will attend as part of an Australian speaking tour so look out for him in your state.

On a further gloomy note, I note that Dr. Peter Szekeres has decided to take early retirement. Peter was the founding president of the ASGRG. His contributions to general relativity and to student education are world renown. We will celebrate Peter's achievement during the GR workshop to be held in association with the AIP Congress.

Well, from now on we hope to circulate this electronic newsletter on a quarterly basis. The editor will ask for articles a week before publication so please submit any news, list of abstracts, jobs available, or upcoming events that you think the GRG community should know about. Until April

- David McClelland

EDITORIAL:

It's 18 months since the last ASGRG newsletter; and the December 1999 issue (this one!) has been delayed in the works. My apologies... It is definitely a difficult time in academia in Australia, with a lot of turmoil. Some of you took part in a letter to "the Australian", relating to the situation at Edith Cowan University (Click here for further details). The follow-up news on that one is that Malcolm Anderson (one of our committee) has left Australia to the University of Brunei in South-East Asia. His new email is manderso@ubd.edu.bn

At the University of Adelaide we are also facing down-sizing. A number of early retirements were sought in the Dept of Physics and Mathematical Physics due to the Department facing a budget deficit of order 25%. Unfortunately this is a familiar story around Australia. (People at Monash have been through all of this not so long ago. At U Queensland they are going through another round, with Mathematics and Physics to be amalgamated.) Anyway, the upshot is that Peter Szekeres is amongst those who have put their hands up for early retirement. He is the last tenured staff member in the Mathematical Physics group. The future of the group is in jeopardy since it is crumbling as the contracts of the younger members expire. What exactly is happening is still not clear at this point, as the Department's problems have been side-lined for the present by debate about a restructuring of the whole Faculty of Science, which you may have seen reported in the press.

On a more positive note, we have gained cognate status with the AIP, and will hold a workshop to celebrate Peter Szekeres' contributions to relativity in Adelaide in December, in conjunction with the AIP2000 Congress (further details below). Peter - who turns 60 in August, 2000 - is well-known for his many significant contributions to many areas of relativity, including singularity theory and the colliding gravitational wave solutions and inhomogenous cosmological models which bear his name. We are aiming to produce a Festschrift in conjunction with the Workshop.

At a committee meeting in November, we decided to try to make the newsletters much more frequent (which will mean briefer). We are aiming to make them quarterly, so the next one will be just before Easter. Please send your contributions, abstracts of new papers etc to asgrg@physics.adelaide.edu.au by March 31, 2000.

- David Wiltshire

THIRD AUSTRALASIAN CONFERENCE ON GENERAL RELATIVITY AND GRAVITATION, PERTH

Proposed date: July ***2001***

- Request to membership for approval of dates -

As outlined by David McClelland above, the committee have decided that it would make sense to delay ACGRG3 until July, 2001, so that we may hold it in conjunction with the International Amaldi Meeting on Gravitational Waves. The dates are arranged so that people travelling westwards to GR16 in Durban, South Africa, can stop at ACGRG3 in Perth on the way. We believe this will be convenient for most members. Holding an international meeting in conjunction with ACGRG3 will make for a bigger event, and one to remember no doubt.

The logistics of running the two meetings has yet to be decided. One suggestion is to run them with an overlap of a couple of days. Another suggestion is to run the conferences entirely in parallel, with one shared plenary talk each morning. The exact logistics will be worked out in discussion with the organisers of the Amaldi Conference once we obtain our members' approval for the July, 2001 date.

There were other reasons making a 2000 conference date undesirable - in July 2000 the Marcel Grossman meeting is being held in Rome; while the other logical choice of the mid-semester break in September clashes with the Sydney Olympics, at which time travel for those going through Sydney will be tight. In any case, we will have one 2000 event with the workshop in Adelaide (below).

Since a July 2001 date is 6 months beyond the natural "term" outlined in our Constitution, we are required [clause 15(i)] to get a simple majority of members to consent to this. Please return the remote ballot email to allow us to go ahead with this.

CONSTITUTIONAL AMENDMENTS

A number of constitutional amendments were proposed at our General Meeting in Sydney at ACGRG2, July, 1998. We are required to vote on these by remote ballot before the next General Meeting. Members will be supplied with a separate email with a voting from relating to the proposed amendments and a summary of the discussion for the benefit of those who were not in Sydney.

It is requested that ballots are returned by February 28, 2000.

SUBSCRIPTIONS

Subscriptions for July 1999 - June 2000 are now due. A number of people have arrears. Individual financial statements will be to each member at the same time as this email. Please note that you should be financial in order to vote in the above ballot. Please send you remittance to the Treasurer promptly.

MEMBERS' ABSTRACTS AT gr-qc July, 1998 - December, 1999

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.

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Paper: gr-qc/9807001
Date: Wed, 1 Jul 1998 07:44:03 GMT (9kb)

Title: An explanation of the Newman-Janis Algorithm
Authors: S. P. Drake P. Szekeres
\\
After the original discovery of the Kerr metric, Newman and Janis showed that
this solution could be derived'' by making an elementary complex
transformation to the Schwarzschild solution. The same method was then used to
obtain a new stationary axisymmetric solution to Einstein's field equations now
known as the Kerr-Newman metric, representing a rotating massive charged black
hole. However no clear reason has ever been given as to why the Newman-Janis
algorithm works, many physicist considering it to be an ad hoc procedure or
fluke'' and not worthy of further investigation. Contrary to this belief this
paper shows why the Newman-Janis algorithm is successful in obtaining the
Kerr-Newman metric by removing some of the ambiguities present in the original
derivation. Finally we show that the only perfect fluid generated by the
Newman-Janis algorithm is the (vacuum) Kerr metric and that the only Petrov
typed D solution to the Einstein-Maxwell equations is the Kerr-Newman metric.
\\ ( http://xxx.lanl.gov/abs/gr-qc/9807001 , 9kb)
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Paper: gr-qc/9807028
From: Tevian Dray <tevian@math.orst.edu>
Date: Tue, 14 Jul 1998 18:08:34 GMT (11kb)

Title: A New Look at the Ashtekar-Magnon Energy Condition
Authors: Jim Fischer, Tevian Dray
Journal-ref: Gen.Rel.Grav. 31 (1999) 511-526
\\
In 1975, Ashtekar and Magnon showed that an energy condition selects a unique
quantization procedure for certain observers in general, curved spacetimes. We
generalize this result in two important ways, by eliminating the need to assume
a particular form for the (quantum) Hamiltonian, and by considering the
surprisingly nontrivial extension to nonminimal coupling
\\ ( http://xxx.lanl.gov/abs/gr-qc/9807028 , 11kb)
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Paper: gr-qc/9807075
Date: Tue, 28 Jul 1998 17:22:29 GMT (16kb)
Date (revised v2): Thu, 24 Dec 1998 06:43:44 GMT (22kb)
Date (revised v3): Mon, 1 Mar 1999 02:21:37 GMT (22kb)

Title: Operator ordering and consistency of the wavefunction of the Universe
Authors: N. Kontoleon and D.L. Wiltshire
Comments: 9 pages, epsf, revTeX-3.1, 1 figure. In revised version (v2) a new
section etc with additional arguments increases the length of paper by 3
pages of Physical Review; several references added. v3: small typos fixed
Journal-ref: Phys. Rev. D59 (1999) 063513
\\
We demonstrate in the context of the minisuperspace model consisting of a
closed Friedmann-Robertson-Walker universe coupled to a scalar field that
Vilenkin's tunnelling wavefunction can only be consistently defined for
particular choices of operator ordering in the Wheeler-DeWitt equation. The
requirement of regularity of the wavefunction has the particular consequence
that the probability amplitude, which has been used previously in the
literature in discussions of issues such as the prediction of inflation, is
likewise ill-defined for certain choices of operator ordering with Vilenkin's
boundary condition. By contrast, the Hartle-Hawking no-boundary wavefunction
can be consistently defined within these models, independently of operator
ordering. The significance of this result is discussed within the context of
the debate about the predictions of semiclassical quantum cosmology. In
particular, it is argued that inflation cannot be confidently regarded as a
"prediction" of the tunnelling wavefunction, for reasons similar to those
previously invoked in the case of the no-boundary wavefunction. A synthesis of
the no-boundary and tunnelling approaches is argued for.
\\ ( http://xxx.lanl.gov/abs/gr-qc/9807075 , 22kb)
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Paper: astro-ph/9807311
From: Neil John Cornish <N.J.Cornish@damtp.cam.ac.uk>
Date: Thu, 30 Jul 1998 00:00:39 GMT (315kb)
Date (revised v2): Wed, 5 Aug 1998 14:04:14 GMT (315kb)

Title: Measuring the shape of the Universe
Authors: Neil J. Cornish (DAMTP, Cambridge), Jeffrey R. Weeks (Canton)
Comments: 18 pages, 8 figures, AMS LaTeX, Accepted for publication as a Feature
Article in the Notices of the American Mathematical Society
Report-no: Canton-98-2
\\
Since the dawn of civilization, humanity has grappled with the big questions of
existence and creation. Modern cosmology seeks to answer some of these
questions using a combination of mathematics and measurement. The questions
people hope to answer include how did the universe begin?''; how will the
universe end?''; is space finite or infinite?''. After a century of
remarkable progress, cosmologists may be on the verge of answering at least one
of these questions -- is space finite? Using some simple geometry and a NASA
satellite set for launch in the year 2000, the authors and their colleagues
hope to measure the size and shape of space. This review article explains the
mathematics behind the measurement, and the cosmology behind the observations.
\\ ( http://xxx.lanl.gov/abs/astro-ph/9807311 , 315kb)
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Paper: gr-qc/9809082
Date: Wed, 30 Sep 1998 02:28:24 GMT (7kb)

Title: On Waylen's regular axisymmetric similarity solutions
Authors: Edward D. Fackerell, David Hartley
\\
We review the similarity solutions proposed by Waylen for a regular
time-dependent axisymmetric vacuum space-time, and show that the key equation
introduced to solve the invariant surface conditions is related by a Baecklund
transform to a restriction on the similarity variables. We further show that
the vacuum space-times produced via this path automatically possess a (possibly
homothetic) Killing vector, which may be time-like.
\\ ( http://xxx.lanl.gov/abs/gr-qc/9809082 , 7kb)
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Paper: gr-qc/9810031
Date: Thu, 8 Oct 1998 20:13:29 GMT (23kb)

Title: Geodesic Deviation in Regge Calculus
Miller
Comments: 9 pages. Latex 2e with 5 EPS figures. Submitted to CQG
Report-no: LAUR-98-4237
Journal-ref: Class.Quant.Grav. 16 (1999) 2381-2391
\\
Geodesic deviation is the most basic manifestation of the influence of
gravitational fields on matter. We investigate geodesic deviation within the
framework of Regge calculus, and compare the results with the continuous
formulation of general relativity on two different levels. We show that the
continuum and simplicial descriptions coincide when the cumulative effect of
the Regge contributions over an infinitesimal element of area is considered.
This comparison provides a quantitative relation between the curvature of the
continuous description and the deficit angles of Regge calculus. The results
presented might also be of help in developing generic ways of including matter
terms in the Regge equations.
\\ ( http://xxx.lanl.gov/abs/gr-qc/981031, 23kb)
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Paper: gr-qc/9811063
From: IBRAHIM ARBAB ARBAB <arbab@ictp.trieste.it>
Date: Thu, 19 Nov 1998 10:00:38 GMT (4kb)
Date (revised v2): Mon, 7 Dec 1998 12:26:09 GMT (4kb)

Title: Causal Dissipative Cosmology With Variable G and Lambda
Authors: Arbab I. Arbab, A. Beesham
Comments: revised version, 6 LaTeX pages
\\
A cosmological model with variable G and Lambda is considered in the framework
of Israel-Stewart-Hiscock (ISH) causal theory. Power law as well as
inflationary solutions are obtained. The gravitational constant is found to
increase with time.
\\ ( http://xxx.lanl.gov/abs/gr-qc/9811063, 4kb)
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Paper: gr-qc/9812022
From: Geoffery Ericksson <gbe105@rsphy1.anu.edu.au>
Date: Mon, 7 Dec 1998 05:08:12 GMT (17kb)

Title: Cosmological models with isotropic singularities
Authors: Susan M. Scott, Geoffery Ericksson
Journal-ref: Proc. Int. Sem. Math. Cosmol., Potsdam 1998, Editors: M. Rainer,
H.-J. Schmidt, WSPC, Singapore, pp123-132
\\
In 1985 Goode and Wainwright devised the concept of an isotropic singularity.
Since that time, numerous authors have explored the interesting consequences,
in mathematical cosmology, of assuming the existence of this type of
singularity. In this paper, we collate all examples of cosmological models
which are known to admit an isotropic singularity, and make a number of
observations regarding their general characteristics.
\\ ( http://xxx.lanl.gov/abs/gr-qc/9812022 , 17kb)
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Paper: gr-qc/9812057
Date: Wed, 16 Dec 1998 20:46:57 GMT (72kb)

Title: Apparent horizons in simplicial Brill wave initial data
Authors: Adrian P. Gentle, Daniel E. Holz, Warner A. Miller, John A. Wheeler
Comments: 7 pages, 6 EPS figures, LaTeX 2e. Submitted to Class. Quant. Grav
Report-no: LAUR-98-5276
Journal-ref: Class.Quant.Grav. 16 (1999) 1979-1985
\\
We construct initial data for a particular class of Brill wave metrics using
Regge calculus, and compare the results to a corresponding continuum solution,
finding excellent agreement. We then search for trapped surfaces in both sets
of initial data, and provide an independent verification of the existence of an
apparent horizon once a critical gravitational wave amplitude is passed. Our
estimate of this critical value, using both the Regge and continuum solutions,
supports other recent findings.
\\ ( http://xxx.lanl.gov/abs/gr-qc/9812057 , 72kb)
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Paper: gr-qc/9812083
From: "" <phrtc@flinders.edu.au>
Date: Thu, 24 Dec 1998 01:20:09 GMT (62kb)
Date (revised v2): Mon, 28 Dec 1998 06:40:30 GMT (62kb)

Title: Self-Referential Noise and the Synthesis of Three-Dimensional Space
Authors: Reginald T. Cahill, Christopher M. Klinger (Department of Physics,
Flinders University)
\\
Generalising results from Godel and Chaitin in mathematics suggests that
self-referential systems contain intrinsic randomness. We argue that this is
relevant to modelling the universe and show how three-dimensional space may
arise from a non-geometric order-disorder model driven by self-referential
noise.
\\ ( http://xxx.lanl.gov/abs/gr-qc/9812083 , 62kb)
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Paper: gr-qc/9901071
Date: Mon, 25 Jan 1999 18:14:08 GMT (264kb) Title: Simplicial Brill wave
initial data
Comments: 17 pages, LaTeX 2e, 13 eps figures. Submitted to CQG
Report-no: LAUR-99-304
Journal-ref: Class.Quant.Grav. 16 (1999) 1987-2003
\\
Regge calculus is used to construct initial data for vacuum axisymmetric Brill
waves at a moment of time symmetry. We argue that only a tetrahedral lattice
can successfully reproduce the continuum solution, and develop a simplicial
axisymmetric lattice based on the co-ordinate structure of the continuum
metric. This is used to construct initial data for Brill waves in an otherwise
flat spacetime, and for the distorted black hole spacetime of Bernstein. These
initial data sets are shown to be second order accurate approximations to the
corresponding continuum solutions.
\\ ( http://xxx.lanl.gov/abs/gr-qc/9901071 , 264kb)
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Paper: gr-qc/9904045
From: Robert Bartnik <bartnik@stan.canberra.edu.au>
Date: Mon, 19 Apr 1999 10:48:30 GMT (334kb)

Title: Einstein equations in the null quasi-spherical gauge III: numerical
algorithms
Authors: Robert A. Bartnik and Andrew H. Norton
Comments: Latex, 38 pages, 29 figures (360Kb compressed)
Report-no: ISE RR 99/110
\\
We describe numerical techniques used in the construction of our 4th order
evolution for the full Einstein equations, and assess the accuracy of
representative solutions. The code is based on a null gauge with a
quasi-spherical radial coordinate, and simulates the interaction of a single
black hole with gravitational radiation. Techniques used include spherical
harmonic representations, convolution spline interpolation and filtering, and
an RK4 "method of lines" evolution. For sample initial data of "intermediate"
size (gravitational field with 19% of the black hole mass), the code is
accurate to 1 part in 10^5, until null time z=55 when the coordinate condition
breaks down.
\\ ( http://xxx.lanl.gov/abs/gr-qc/9904045 , 334kb)
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Paper: gr-qc/9903056
Date: Mon, 15 Mar 1999 07:32:48 GMT (10kb)

Title: Post-Newtonian Cosmology
Authors: Tamath Rainsford, Peter Szekeres
\\
Newtonian Cosmology is commonly used in astrophysical problems, because of its
obvious simplicity when compared with general relativity. However it has
inherent difficulties, the most obvious of which is the non-existence of a
well-posed initial value problem. In this paper we investigate how far these
problems are met by using the post-Newtonian approximation in cosmology.
\\ ( http://xxx.lanl.gov/abs/gr-qc/9903056 , 334kb)
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Paper: hep-th/9905025
From: Patrick Peter <patrick.peter@obspm.fr>
Date: Wed, 5 May 1999 07:24:18 GMT (18kb)

Title: Dynamics and integrability property of the chiral string model
Authors: Brandon Carter, Patrick Peter
Comments: 7 pages, 2 eps figures included, uses ReVTeX
Report-no: DARC/99-09
Journal-ref: Phys.Lett. B466 (1999) 41-49
\\
The effect of fermionic string conductivity by purely right (or purely left)
moving zero modes'' is shown to be governed by a simple Lagrangian
characterising a certain chiral'' (null current carrying) string model whose
dynamical equations of motion turn out to be explicitly integrable in a flat
spacetime background.
\\ ( http://xxx.lanl.gov/abs/hep-th/9905025 , 18kb)
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Paper: gr-qc/9905082
From: "" <phrtc@flinders.edu.au>
Date: Fri, 21 May 1999 03:58:47 GMT (18kb)

Title: Self-Referential Noise as a Fundamental Aspect of Reality
Authors: Reginald T. Cahill, Christopher M. Klinger (Department of Physics,
Flinders University)
Comments: 7 pages, Latex, 3 ps figures. Contribution to the 2nd International
Conference on Unsolved Problems of Noise, Adelaide 1999
\\
Noise is often used in the study of open systems, such as in classical Brownian
motion and in Quantum Dynamics, to model the influence of the environment.
However generalising results from G\"{o}del and Chaitin in mathematics suggests
that systems that are sufficiently rich that self-referencing is possible
contain intrinsic randomness. We argue that this is relevant to modelling the
universe, even though it is by definition a closed system. We show how a
three-dimensional process-space may arise, as a Prigogine dissipative
structure, from a non-geometric order-disorder model driven by, what is termed,
self-referential noise.
\\ ( http://xxx.lanl.gov/abs/gr-qc/9905082 , 18kb)
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Paper: gr-qc/9905090
Date: Mon, 24 May 1999 07:55:49 GMT (13kb)

Title: Wave functions for arbitrary operator ordering in the de Sitter
minisuperspace approximation
Authors: D.L. Wiltshire
\\
We derive exact series solutions for the Wheeler-DeWitt equation corresponding
to a spatially closed Friedmann-Robertson-Walker universe with cosmological
constant for arbitrary operator ordering of the scale factor of the universe.
The resulting wave functions are those relevant to the approximation which has
been widely used in two-dimensional minisuperspace models with an inflationary
scalar field for the purpose of predicting the period of inflation which
results from competing boundary condition proposals for the wave function of
the universe. The problem that Vilenkin's tunneling wave function is not
normalizable for general operator orderings, is shown to persist for other
values of the spatial curvature, and when additional matter degrees of freedom
\\ ( http://xxx.lanl.gov/abs/gr-qc/9905090 , 13kb)
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Paper: math.DG/9906017
From: Neil Cornish <njc@astro.princeton.edu>
Date: Wed, 2 Jun 1999 16:46:10 GMT (547kb)

Title: On the eigenmodes of compact hyperbolic 3-manifolds
Authors: Neil J. Cornish, David N. Spergel
Comments: 8 pages, 10 figures. Submitted to Experimental Mathematics
Subj-class: Differential Geometry MSC-class: 53C80
\\
We present a simple algorithm for finding eigenmodes of the Laplacian for
arbitrary compact hyperbolic 3-manifolds. We apply our algorithm to a sample of
twelve manifolds and generate a list of the lowest eigenvalues. We also display
a selection of eigenmodes taken from the Weeks space.
\\ ( http://xxx.lanl.gov/abs/math/9906017 , 547kb)
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Paper: astro-ph/9906401
From: njc@astro.Princeton.EDU
Date: Fri, 25 Jun 1999 04:10:55 GMT (481kb)
Date (revised v2): Sat, 26 Jun 1999 20:15:09 GMT (481kb)

Title: A small universe after all?
Authors: Neil J. Cornish, David N. Spergel (Princeton University)
Comments: 4 pages, RevTeX, 7 Figures
\\
The cosmic microwave background radiation allows us to measure both the
geometry and topology of the universe. It has been argued that the COBE-DMR
data already rule out models that are multiply connected on scales smaller than
the particle horizon. Here we show the opposite is true: compact (small)
hyperbolic universes are favoured over their infinite counterparts. For a
density parameter of Omega_o=0.3, the compact models are a better fit to
COBE-DMR (relative likelihood ~20) and the large-scale structure data (sigma_8
increases by ~25%).
\\ ( http://xxx.lanl.gov/abs/astro-ph/9906401 , 481kb)
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Paper: gr-qc/9907039
From: Brandon CARTER <carter@mesiob.obspm.fr>
Date: Fri, 9 Jul 1999 14:08:43 GMT (30kb)

Title: Vortex Dynamics in Superfluids
Authors: Brandon Carter
Comments: 39 pages, Latex; contrib. to Topological defects and non-equilibrium
dynamics of phase transitions' ed Y. Bunkov, H. Godfrin, Les Houches Winter
School, February 1999
\\
Superfluid condensates are known to occur in contexts ranging from laboratory
liquid helium to neutron stars, and are also likely to occur in cosmological
phenomena such as axion fields. In the zero temperature limit, such condensates
are describable at a mesoscopic level by irrotational configurations of simple
relativistic perfect fluid models. The general mechanical properties of such
models are presented here in an introductory review giving special attention to
the dynamics of vorticity flux 2-surfaces and the action principles governing
both individual flow trajetories and the evolution of the system as a whole.
Macroscopic rotation of such a condensate requires the presence of a lattice of
quantised vortex defects, whose averaged tension violates perfect fluid
isotropy. It is shown that for any equation of state (relating the mass density
$\rho$ to the pressure $P$) the mesoscopic perfect fluid model can be extended
in a uniquely simple and natural manner to a corresponding macroscopic model
(in a conformally covariant category) that represents the effects of the vortex
fibration anisotropy. The limiting case of an individual vortex defect is shown
to be describable by a (global'') string type model with a variable tension
${\cal T}$ (obtained as a function of the background fluid density) whose
vorton'' (i.e. closed loop equilibrium) states are derived as an exercise.
\\ ( http://xxx.lanl.gov/abs/gr-qc/9907039 , 30kb)
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Paper: gr-qc/9907094
Date: Wed, 28 Jul 1999 08:47:40 GMT (10kb)
Date (revised v2): Sun, 12 Sep 1999 07:41:45 GMT (11kb)

Title: Newtonian and Post-Newtonian approximations of the k = 0 Friedmann
Robertson Walker Cosmology
Author: Tamath Rainsford (University of Adelaide)
Comments: 11 pages, Latex, corrected typos
\\
In a previous paper we derived a post-Newtonian approximation to cosmology
which, in contrast to former Newtonian and post-Newtonian cosmological
theories, has a well-posed initial value problem. In this paper, this new
post-Newtonian theory is compared with the fully general relativistic theory,
in the context of the k = 0 Friedmann Robertson Walker cosmologies. It is found
that the post-Newtonian theory reproduces the results of its general
relativistic counterpart, whilst the Newtonian theory does not.
\\ ( http://xxx.lanl.gov/abs/gr-qc/9907094 , 11kb)
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Paper: gr-qc/9911021
From: Simon Davis <simond@maths.usyd.edu.au>
Date: Sat, 6 Nov 1999 09:26:49 GMT (10kb)
Date (revised v2): Wed, 10 Nov 1999 21:31:54 GMT (10kb)

Title: Higher-Derivative Quantum Cosmology
Authors: Simon Davis
Comments: 11 pages TeX. A term has been removed from equation (13)
Report-no: Report 99-12
\\
The quantum cosmology of a higher-derivative derivative gravity theory arising
from the heterotic string effective action is reviewed. A new type of
Wheeler-DeWitt equation is obtained when the dilaton is coupled to the
quadratic curvature terms. Techniques for solving the Wheeler-DeWitt equation
with appropriate boundary conditions shall be described, and implications for
semiclassical theories of inflationary cosmology will be outlined.
\\ ( http://xxx.lanl.gov/abs/gr-qc/9911021 , 10kb)
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Paper: gr-qc/9911043
From: Simon Davis <simond@maths.usyd.edu.au>
Date: Wed, 10 Nov 1999 23:04:20 GMT (13kb)

Title: The Effect of Higher-Derivative Curvature Terms on String Quantum
Cosmology
Authors: Simon Davis
`