1 Table of Contents: “...In his classic work of geometry, Euclid focused on the properties of flat surfaces. In the age...”

2 Table of Contents: “.... Notation, Notation, Notation -- 12. From Flat Space to Curved Spacetime -- Sidebar 9: A Case of Misuse...”

3 “... tensor and an explicit analysis of the special cases of conformally flat and conformally Einstein spaces...”

4 “... in, for example, the struggle of the famous mapmaker Gerardus Mercator to represent the curved earth on a flat...”