Andrzej Krasiński

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, in the years 2001 -- 2010 I collaborated 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), and also two papers on basic properties of the Szekeres models.
Since 2006, I have been collaborating with Krzysztof Bolejko, who was my PhD student in 2004-2007. We published several papers on more sophsiticated cosmological applications of the LT and Szekeres models, some of them together, some separately. In particular, I was an author or co-author of papers on the existence of configurations of charged dust that avoid the Big Bang singularity during their evolution (items 37 and 38 in the list), correcting misunderstandings about inhomogeneous models that are being propagated in the literature (items 41, 42 and 46), observable consequences of nonsymmetric cosmic flow in the Szekeres and other inhomogeneus models (items 43, 45 and 50), and on geometrical properties of the Szekeres models (items 40, 49 and 51).
At present I am working on detailed comparisons of the $\Lambda$CDM model and the LT models that imitate accelerated expansion of the Universe without introducing "dark energy" (items 52 and 53).
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.
I am the author and co-author of three books, published with Cambridge University Press: a monograph on inhomogeneous cosmological models (item 1), a basic textbook on relativity and relativistic cosmology, written jointly with my former master and PhD advisor, Jerzy Plebanski (item 2), and a monograph on application of exact solutions of Einstein's equations to cosmological problems, written together with Krzysztof Bolejko, Charles Hellaby and Marie-Noelle Celerier (item 3). I am also a co-editor (together with George Ellis and Malcolm MacCallum) of a book, published with Springer, containing a selection of the "Golden Oldies", published previously in the General Relativity and Gravitation Journal (item 4).
I was a member of the Editorial Board of the journal General Relativity and Gravitation, in the years 1989 -- 2013 (with a break in 2002 -- 2005). In the journal, in the years 1996 -- 2013 (again with a break in 2002 -- 2005) I was 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 personal web page here.