What is missing from Minkowski's "Raum und Zeit" lecture

Abstract

This contribution tries to highlight the importance of Minkowski's ``Raum und Zeit'' lecture in a ``negative'' way, where {\it negative} is taken in the photographic sense of reversing lights and shades. Indeed, we focus on the ``shades'' of Minkowski's text, i.e. what is missing, or misunderstood. In particular, we focus on two issues: (i) why are Poincaré's pioneering contributions to four-dimensional geometry not quoted by Minkowski (while he abundantly quoted them a few months before the Cologne lecture)?, and (ii) did Minkowski fully grasp the physical (and existential) meaning of ``time'' within spacetime? We think that this ``negative'' approach (and the contrast between Poincaré's and Minkowski's attitudes towards physics) allows one to better grasp the boldness of the {\it revolutionary} step taken by Minkowski in his Cologne lecture.