- Pp. 1-33 (33)Matti Pitkanen
In this chapter the key ideas behind Topological Geometrodynamics (TGD) are introduced and an overall view about the structure of the book is given. </p><p> The observation that profoundly changed my life was that if space-time is microscopically a 4-dimensional surface in certain 8-dimensional imbedding space H, one can solve the "energy" problem of general relativity, which is due to the fact that the notions of energy and momentum become ill-defined in curved space-time since the corresponding symmetries are lost. The simple arguments fixing the choice of the imbedding space to be H = M<sup>4</sup>XCP<sub>2</sub>, that is Cartesian product of Minkowski space of special relativity and complex projective space of 2 complex dimensions, are described. Also the basic implications - such as the notion of geometrization of known classical fields in terms of the induction procedure, and the notion of many-sheeted space-time - are described. The basic objections resolved by TGD view about classical fields and their superposition are considered. The relationship of TGD space-time with the space-time of general relativity understood as macroscopic phenomenological concept is briefly depicted. </p><p> TGD leads to several generalizations of existing view about the ontology of physics and these modi cations are described....