Why do we need to understand gravitational waves to understand mass ?
1956 : John Lighton Synge publishes the first relativity text emphasizing spacetime diagrams and geometrical methods , 1957 : Felix A. E. Pirani uses Petrov classification to understand gravitational radiation , 1957 : Richard Feynman introduces sticky bead argument , 1957 – John Wheeler discusses the breakdown of classical general relativity near singularities and the need for quantum gravity 1959 : Pound – Rebka experiment , first precision test of gravitational redshift , 1959 : Lluís Bel introduces Bel – Robinson tensor and the Bel decomposition of the Riemann tensor , 1959 : Arthur Komar introduces the Komar mass , 1959 : Richard Arnowitt , Stanley Deser and Charles W. Misner developed ADM formalism .