Speaker: Michiya Mori (Univ. Tokyo)

Title: Optimal version of the fundamental theorem of chronogeometry

Time/Date: 4:45-6:15pm, May 21 (Tue), 2024.

Room: 126 Math Sci Building (It will be also online. The Zoom link is the same as before. If you don't have one, please ask Kawahigashi.)

Abstract: We study lightlikeness preserving mappings from the 4-dimensional Minkowski spacetime to itself under no additional regularity assumptions like continuity, surjectivity, or injectivity. We prove that such a mapping is either (i) an affine mapping and can be written by means of Lorentz transformation, or (ii) of one of two special degenerate types and its image is contained in a "small" subset of the spacetime. This is joint work with Peter Semrl (University of Ljubljana).