Cosmology has come of age as an observational science, based on
the tremendous progress in satellite- and ground-based experiments
that measure the vital statistics of our universe. Perhaps the
most dramatic advances have come in observations of the cosmic
microwave background radiation, but there have also been major
developments in galaxy surveys and supernovae observations. A new
era of high-precision cosmology has dawned, and we can expect
further major advances in our observational knowledge of the
universe. This has raised difficult but exciting challenges for
cosmological theory, which is struggling to keep pace with
observational advances. In this context, it is clearly useful to
provide opportunities for observational and theoretical
developments to be brought together and critically reviewed.
This was the motivation for the conference The Early Universe
and Cosmological Observations: a Critical Review, which was
organized as a follow-on meeting after GR16, the triennial
conference of the International Society of General Relativity and
Gravitation (held in Durban, South Africa, July 2001). The meeting
reviewed current theoretical models of the early universe and the
observational tests of such models. Starting with summaries of the
major achievements of the standard model of cosmology and the
impact of the tremendous growth in cosmological data, the meeting
then turned its attention to open issues and what still needs to
be done in these areas. This was followed by a critical review of
the subject, highlighting unresolved problems and some of the more
fundamental issues which inevitably underlie the relation of
theory to observation. The scientific organizing committee (B
Bassett, B Carter, T Damour, P Dunsby, G Ellis, R Maartens and N
Turok) also attempted to design the conference so as to maximize
open discussion and interaction between participants.
The conference programme was divided into three parts.
(a) Theoretical models of the early universe
Inflationary cosmology: theory and phenomenology A Liddle String-inspired cosmology D Wands From (p)reheating to nucleosynthesis K Jedamzik The cosmological constant problem and quintessence V Sahni Critical review of
inflation N Turok Panel discussion: Braneworld cosmology - is it here to stay? N Deruelle, R Maartens and J-P Uzan
(b) Observational tests of early universe models
CMB anisotropies: recent measurements and interpretation A
Lasenby Measuring global curvature and cosmic acceleration
with supernovae B Schmidt Cosmological weak lensing Y Mellier Observational tests of FRW world models O Lahav Large galaxy surveys D Schlegel Dark matter: theories and observation N Turok
(c) Fundamental open questions: the future
How much will we learn from the CMB? D Langlois The future of extragalactic observations P Coles The future of large-scale structure studies J Frieman Combining general
relativity and quantum theory T Padmanabhan Panel discussion: The nature of cosmology - critical reflections N Deruelle, J Ehlers, G Ellis and M MacCallum
This issue of Classical and Quantum Gravity contains nearly
all of the plenary talks of the conference. The panel discussion
on braneworld cosmology reflected the strong impact on cosmology
of recent ideas emerging from string theory/M theory. In
braneworld models, the observable universe is a 3-space (the
`brane') moving in a higher-dimensional spacetime (the `bulk'),
where the extra spatial dimensions are not all necessarily small
or even compact. Standard model matter is confined to the brane,
but gravity propagates in the bulk. The panellists emphasized
that, whether or not the braneworld models survive in the longer
term, they are useful to investigate, since they can give a
qualitative insight into how M theory affects the dynamics of the
universe. Furthermore, in a similar way to inflationary models,
braneworld models develop the synergy between cosmology and
particle physics.
The closing panel discussion on the nature of cosmology considered
several questions arising from the more geometric approach to
general relativity. Many of these points are summarized in the
article Comments: Cosmology, 2001 by G Ellis at the end of
this issue.
The conference was attended by more than 70 local and
international researchers and students from about 10 countries. It
was hosted by the Cosmology research group at the University of
Cape Town, and held from 23 to 25 July 2001. Financial support was
provided by the National Research Foundation of South Africa, the
University of Cape Town Research Committee, ICTP (Trieste) and the
French Embassy. The interest and generosity of these institutions
is gratefully acknowledged. All participants will join us in
thanking the local organizing committee, and especially D
Loureiro, for their great efforts and excellent organization.
Peter Dunsby and George EllisUniversity of Cape Town, South Africa
Roy MaartensUniversity of Portsmouth, UK