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 book explains variational principles and charts their use
throughout modern physics. The heart of the book is devoted to the
analytical mechanics of Lagrange and Hamilton, the basic tools of any
physicist. The book also offers simple but rich first impressions of
Einstein's General Relativity, Feynman's Quantum Mechanics, and more
that reveal amazing interconnections between various fields of physics.