Relativity, Dimensionality, and Existence

A 100 years have passed since the advent of special relativity and 2008 will mark another important to all relativists anniversary – 100 years since Minkowski gave his talk “Space and Time” on September 21, 1908 in which he proposed the unifi- cation of space and time into an inseparable entity – space-time. Although special relativity has been an enormously successful physical theory no progress has been made in clarifying the question of existence of the objects represented by two of its basic concepts – space-time and world lines (or worldtubes in the case of extended bodies). The major reason for this failure appears to be the physicists’ tradition to call such questions of existence philosophical. This tradition, however, is not quite consistent. In Newtonian mechanics physicists believe that they describe real objects whenever they talk about particles – one of the basic concepts of Newtonian physics. The situation is the same in quantum physics – no one questions the existence of electrons, protons, etc. Then why should the question of existence of worldtubes (representing particles in relativity) be regarded as a philosophical question?