hi cosmo-torun For this Friday I propose a combined workshop and "Kosmologia" lecture. The one-line sound-bite is: "dark energy is the ordinary, relativistic, negative curvature of voids, which FLRW doesn't allow". 13:00 Fri 22 Mar: Virialization-induced curvature as a physical explanation for dark energy Abstract: "Dark energy" occurs during the redshift range over which the Universe becomes virialised, i.e. inhomogeneous, meaning that the homogeneous model should fail. Adding virialisation-induced negative curvature (of voids) to an Einstein-de Sitter (Omega_m = 1, Omega_Lambda = 0) model brings its d_L(z) relation close to that of the standard, Newtonian-void LambdaCDM model. Dark energy is most simply interpreted as an artefact of forcing voids to be flat, Newtonian voids. URL: http://arXiv.org/abs/1303.4444 For official "Kosmologia" hours, the doktoranci should stay a little longer for discussion. pozdr boud