Minkowski Institute is inviting colleagues who are interested in joining (as affiliated members of the Institute) its most ambitious research project – to examine rigorously whether gravitational phenomena are noting more than manifestations of the non-Euclidean geometry of spacetime, which would mean that gravitation is not a physical interaction. This project follows strictly Minkowski’s program of geometrizing Physics – after discovering the spacetime structure of the world (all physical objects are, in reality, a forever given web of worldlines in spacetime), Minkowski summarized this program: “The whole world presents itself as resolved into such worldlines, and I want to say in advance, that in my understanding the laws of physics can find their most complete expression as interrelations between these worldlines.” Colleagues who join the project will take part in analyzing the mathematical structure of general relativity with the explicit intention to derive, following Minkowski’s program, all predictions of general relativity by regarding gravitational phenomena as effects of the non-Euclidean geometry of spacetime, without assuming that gravitation is a physical interaction (i.e., without assuming the existence of gravitational energy and momentum). In 1921 Eddington mentioned the possibility that gravitation might not be a physical interaction almost explicitly – “gravitation as a separate agency becomes unnecessary” [A. S. Eddington, The Relativity of Time, Nature 106, 802-804 (17 February 1921)]. The main theme of the Third Hermann Minkowski Meeting on the Foundations of Spacetime Physics this year (https://minkowskiinstitute.org/meetings/2023/) will be the nature of gravitation – whether it is merely spacetime geometry or it is a physical interaction. If interested, contact us at mi@minkowskiinstitute.org or by responding to this message. Vesselin Petkov Minkowski Institute http://www.minkowskiinstitute.org/old/ (the new site of the Minkowski Institute is under construction): http://www.minkowskiinstitute.org http://www.minkowskiinstitute.org/old/gravitation.html Montreal, Canada http://spacetimecentre.org/vpetkov/