
Variational principles have proven to be surprisingly fertile. For example, Fermat used variational methods to demonstrate that light follows the fastest route from one point to another, an idea which came to be known as Fermat's principle, a cornerstone of geometrical optics...

This revised and enhanced new edition of a well-established textbook provides a balanced overview of various areas of theoretical physics based on the use of variational principles. As well as field theory, the book deals with motion in curved spaces, the cradle of general...

Variational principles have proven to be surprisingly fertile. For example, Fermat used variational methods to demonstrate that light follows the fastest route from one point to another, an idea which came to be known as Fermat's principle, a cornerstone of geometrical optics...