Variational methods and gravitational waves
Abstract
A method used to obtain approximate solutions to the Einstein field equations which can be interpreted as containing highfrequency gravitational waves is reviewed. It involves applying Whitham's technique for dealing with the 'twotiming' approximation scheme by means of an averaged Lagrangian. The method is also applied in a somewhat different form in the present work. The problems that arise when it is not assumed that the unperturbed metric is slowly varying are discussed in connection with this application.
 Publication:

Gravitational Waves and Radiations
 Pub Date:
 1974
 Bibcode:
 1974gwr..conf...57T
 Keywords:

 Einstein Equations;
 Gravitational Waves;
 Plane Waves;
 Variational Principles;
 Wave Propagation;
 Approximation;
 Calculus Of Variations;
 Dependent Variables;
 Differential Equations;
 EulerLagrange Equation;
 High Frequencies;
 Perturbation Theory;
 SpaceTime Functions;
 Stress Tensors;
 Astrophysics