Inhomogeneous Cosmologies

During 2-7 July 2017 we are gathering experts in inhomogeneous cosmology for a small workshop of about 30 participants at Nicolaus Copernicus University in Torun, the town where Copernicus was born. We wish to map out the most promising directions for analytical, numerical and observational investigations aimed to take into account both structure formation and cosmological expansion within the constraints of general relativity. A key motivating theme will be to discuss the claim, already investigated in numerous peer-reviewed papers, that "dark energy" as inferred from observations is an artefact of assuming an average Friedmannian expansion. New techniques in numerical relativity are beginning to open new perspectives on these questions. We expect talks on the latest developments, vigorous, constructive debate between "one-percenters" and "order-unity" proponents, and practical hands-on tutorials of the Einstein Toolkit and other free-licensed inhomogeneous cosmology software packages. The workshop sessions will start on the morning of Mon 3 July and continue to late afternoon Fri 7 July.

Due to the limited number of places available, registration by the early registration deadline of 7 April 2017, including a draft abstract, is strongly recommended. If places remain available, late registration will remain open until the late registration deadline of 9 June 2017 - see for details.

Contact: cosmotorun17 at

Organising committee: Boud Roukema, Eloisa Bentivegna, Krzysztof Bolejko, Thomas Buchert, Mikolaj Korzyński, Hayley Macpherson, Jan Ostrowski, Sebastian Szybka, David Wiltshire

Topics will include:

  • exact cosmological solutions of the Einstein equations
  • averaging and backreaction in cosmology
  • numerical cosmological relativity
  • observational tests