Hans Ringström
Professor in mathematics
Hans Ringström conducts research into mathematical problem which arise in Einstein's general theory of relativity. He is especially interested in problems relating to cosmology, the study of the universe as a whole. The standard model of the universe is based on two assumptions: homogeneity and isotropy. This means that at any one point in time, there is no difference between different points in space (homogeneity), nor is there a difference between different directions (isotropy). These assumptions become reasonable on a scale relevant to cosmology, where it is meaningful to consider galaxies as small.
The assumptions of homogeneity and isotropy reduce Einstein's equation to one, mathematically simple problem. The conclusion is that the universe started with a Big Bang and will either expand forever or collapse again. These models correspond well to observations that have been made. However, to ensure that they are reasonable you need to prove that they are robust. Consequently, a central theme of Ringström's research is the attempt to answer the question of what the conclusion becomes when you abandon these assumptions. Do you get a Big Bang with an arbitrarily strong gravitational field? What happens to space-time if you take an initial state corresponding to a standard model of the universe and alter it slightly?