Einstein's Theory

This introduction to The General Theory of Relativity and its mathematics is written for all those, young and old, who lack or have forgotten the necessary mathematical knowledge to cope with already published introductions. Some of these introductions seem, at the start to require only moderately much mathematics. Very soon, however, there are frightful "jumps" in the exposition, or suddenly new concepts or notations appear as if nearly self evident. The present text starts at a lower level than any other, and leads the reader slowly and faithfully all the way to the heart of relativity: Einstein's field equations.One day, early in the Autumn 1985, the seventy three year old philosopher Arne Næss appeared at Professor Gron's graduate course on General Relativity. He immediatly decided that a new type of introduction to the general theory of relativity is needed; an introduction designed to meet the requirements of non-science educated people wanting to get a thorough understanding of this, most remarkable, theory. This book is the result of the combined effort of a philosopher wanting to understand every logical step in the derivation of Einstein's field equations, and an experienced physicist having a thorough knowledge of these steps. Starting from a freshman level in mathematics the reader is guided along the long and winding road to Einstein's field equations, black holes and relativistic cosmology.