Discrete inhomogeneous relativistic cosmology.
Contact person: Prof. Kjell Rosquist (kr@fysik.su.se)

(a) In a new approach to cosmology, we employ a mean field philosophy to study cosmological evolution and to estimate observational quantities. One advantage, compared to traditional schemes, is the close connection to the observed discrete matter distribution which is used as an input in the evolution equations. Another advantage is that we use only a minimum of assumptions. In particular, no symmetries, such as isotropy or homogeneity, need to be imposed at the outset.
(b) Cosmological observations depend on light beams from distant sources. The beams are focused by the spacetime curvature. In the standard Friedmann cosmology, the curvature is determined by the Ricci tensor which represents the part of the curvature which is determined locally by the matter. In the real universe, however, the curvature is dominated by the Weyl curvature which represents the vacuum part of the curvature. The aim of this project is to investigate the influence of the Weyl curvature on the focusing of light beams in order to obtain a better basis for the interpretation of cosmological observations.
Working on the above projects can include the development of the theory and/or to study luminosity-redshift relations which can be compared with observational data such as those coming from supernova measurements.