Pulsar Timing — Strong Gravity Clock Experiments

Abstract

25 years ago, in summer 1974, Joseph Taylor and Russell Hulse discovered the first binary pulsar, a pulsar in orbit with a compact companion which itself is most likely a neutron star. This pulsar, denoted PSR B1913+16, turned out to be the most exciting laboratory for testing relativistic gravity theories. Before the discovery of PSR B1913+16 all gravity experiments were confined to our solar system with its very weak gravitational fields. Hence, it has been possible to test gravity theories only in the first post-Newtonian approximation. Binary pulsars take us beyond the weak-field context because of their high orbital velocity and/or the strong self-gravitational fields of neutron stars.