The Spirit of Unification: The Wei of Physics

Abstract

We review, in a historical perspective, developments in physics which led to the emergence of unifying ideas and theories. Some attention is paid to the theoretical programme that started in the second decade of the XXth century and whose objective was to reach a unified description of gravity and electromagnetism. These attempts can be regarded as conceptually akin to the contemporary "theories of everything" which aim to unify all interactions of Nature.