The main area of my research is: basic topics in classical relativity theory, in particular the application of exact solutions of Einstein's equations in cosmology. From past research, I still have some expertise with other types of exact solutions (in rotating matter in particular) and in algebraic programming; I am also interested in the history of physics. In cosmology, since 2001 I have been collaborating with Charles Hellaby from the University of Cape Town. Together, we published several papers on the structure formation in the Universe using the Lemaitre--Tolman model (see my list of publications).

At present, my PhD student Krzysztof Bolejko is extending this approach to the more general Szekeres model. Exact models allow us to follow the evolution of structures from the early times up to the present. As long as we believe that general relativity is the correct theory of gravitation, we are not in danger of running out of the allowed range, as routinely happens in perturbative calculations. The advantage of exact models over numerical simulations is that exact models provide a complete description not only of physics, but also of the geometry of the process, and allow, for example, the study of light propagation through the structures.

In basic relativity, my most recent work was on the existence of configurations of charged dust that avoid singularities during their evolution, see item 35 in the list.

I am the author of two books, both published with Cambridge University Press: a monograph on inhomogeneous cosmological models (item 1), and a basic textbook on relativity and relativistic cosmology, written jointly with my former master and PhD advisor, Jerzy Plebanski (item 2).

I am also a member of the Editorial Board of the journal General Relativity and Gravitation, since 1989 (with a break in 2002 -- 2005). In the journal, since 1996 (again with a break in 2002 -- 2005) I am responsible for 'Golden Oldies' -- the series of reprints of classic old papers on relativity; summary of my contributions to this series may be found here .

A more extended summary of my activities (both research and free time) can be found in my private web page here.