On Meson Fields and Conformal Transformations

but in 1930 Veblen and Hoffmann' pointed out that it is su%.cient to introduce 6ve coordinates only in the Oat local space-time, and that these may be considered as homogeneous projective coordinates. At that time this method was well known from the theory of projective linear connections. What we do in local-time is just what we ordinarily do if we wish, for example, to deal with projective geometry in a plane. This could be done with two ordinary Cartesian coordinates, but this being very clumsy it is much more preferable to use 3 homogerieous coordinates. The main point is that we introduce in local space-time another more general geometry, here projective geometry instead of affine geometry, and it is surprising that this enlarging of the fundamental group enables us to describe physical phenomena from a more general point of view.