Astronomical tests of general relativity

Astronomical tests of general relativity

This thesis is an in depth investigation of the history of the acceptance of Einstein’s Theory of General Relativity by scientists and by the public through the media. It emphasises the key role that Australia played in that acceptance and in the verification of General Relativity.
This contribution came from the 1922 total solar eclipse across the continent as well as the discovery in 2003 at Parkes Radio Telescope of the first, and to this date only, pair of pulsars in mutual orbit. This system provides a unique opportunity to plumb the theory in a much
stronger gravitational field regime than previously. This historical scrutiny provides an insight into scientific revolutions in general. The examination of this particular development may then act as a template for the study of other scientific revolutions. One of the key findings is that the Theory of General Relativity was prematurely accepted. The main argument of the thesis is for 1928 being the year when sufficient evidence existed for
scientists to begin accepting the theory based on gravitational deflection of light instead of
the commonly accepted date of 1919. Emphasis is given to the explorations of the 1922 eclipse parties in Australia and the activities of the eight groups measuring light deflection at this eclipse. This work is gathered together here for the first time. The upshot is that it was
1928 before the results were published in full and a conclusion could be drawn. It is also established that the situation for Mercury needed a much longer time period to near the end of the twentieth century before a decisive verdict could be made. Similar to the situation for light deflection, it is found that 1928 is also the year in which spectroscopic data from spectral line frequency shifts of the Sun and white dwarfs had accumulated sufficiently so that a strong conclusion on the third of the classical tests of General Relativity could be made. From the late 1960s the radio region of the spectrum was employed more
frequently to investigate gravitational deflection. As a result of a subsequent extension of this application to interferometry, the increased precision of experiments provided a greater level of testing. No astronomical test yet has refuted General Relativity and agreement has
been reached at the 0.05% level with one parameter involving the double pulsar. In line with the emphasis of the 1922 eclipse in Australia, the Australian newspapers were gleaned up to 1928 to see how the 1919 British total solar eclipse results were regarded by the media and
the public and to ascertain how the media explained the purpose for those 1922 expeditions in Australia. It is found surprisingly that the newspapers performed admirably in explaining difficult concepts in simple terms for the public during this time. This work provides an historical account of the astronomical tests of General Relativity. More broadly, this thesis demonstrates how the acceptance of a scientific revolution depends on the constant
accumulation of data by many scientists and the communication of those results to the wider community. A century after it began, Einstein’s revolution in thinking provides a suitable model for space and time in the Universe.