Between May 29 and July 1919, an expedition organized by Cambridge astronomer Arthur Eddington and the Astronomer Royal Frank Dyson photographed first an eclipse of the Sun (May 29) and then, a month later, the stars where the Sun had been during the eclipse. By comparing the two photographs, the deflection of light caused by the Sun’s gravity could be precisely measured. Einstein’ gravity theory predicted a deflection value of 1.75 arcseconds, and Newton’s gravity theory a value half that. The results were announced in November 1919 to a joint meeting of the Royal Society and the Royal Astronomical Society....