Dr Richard Manchester (ARC Federation Fellow/ATNF)

Einstein's Gravity - Dr Richard Manchester Colloquium

ATNF Marsfield Lecture Theatre

Abstract

2005 has been designated "The World Year of Physics" to mark the centenary of Einstein's "Annus Mirabilis" (Miracle Year) when he revolutionised physics by publishing four great papers on, respectively, the quantisation of light, Brownian motion, special relativity and mass-energy equivalence. A decade later Einstein published the general theory of relativity, which described gravitation as a curvature of spacetime and introduced the idea of
gravitational waves. Pulsars are remarkable celestial clocks, first
discovered in 1967 and believed to be rotating neutron stars. Some pulsars are binary, that is, in orbit around another star, and precise timing measurements on some of these systems have revealed several relativistic effects, enabling tests of gravitational theories. In particular, the detection of orbital decay in the first-known binary pulsar, PSR B1913+16, due to the emission of gravitational waves led to the award of the Nobel Prize in 1993 to its discoverers, Joe Taylor and Russell Hulse. Surveys using the Parkes radio telescope have more than doubled the number of known pulsars. Without doubt, the most exciting discovery was the first known "double pulsar" PSR J0737-3039A/B, which is four times as relativistic as PSR B1913+16. In just two years, this system has provided more stringent tests of gravitational theories than have been possible with nearly 30 years
of data on PSR B1913+16 which show that Einstein got it right! Although these binary pulsars demonstrate the existence of gravitation radiation, up to now there has been no convincing direct detection of these waves. We have embarked on a project known as the Parkes Pulsar Timing Array which has a goal of making a direct detection of gravitational waves. Progress toward reaching this goal will be described.