The Day Without Yesterday: Lemaître, Einstein and the Birth of Modern Cosmology
IN OCTOBER 1923 Lemaître crossed the English Channel and arrived at Saint Edmund’s House, Cambridge University’s residence for Catholic clergymen. Sir Arthur Stanley Eddington had accepted him for a year’s study at the observatory as a research student in astronomy, and the young priest enthusiastically jumped into his studies. In addition to regularly attending Eddington’s lectures, Lemaître also attended those by Ernest Rutherford, one of the fathers of atomic physics, who first posited the existence of the nucleus and explained the underlying dynamics of radioactivity. Apparently, Rutherford was the better lecturer. Nevertheless, it would be difficult to overstate the importance of Eddington’s influence and inspiration for Lemaître. Short of being able to study directly with Einstein himself, Lemaître landed the next best authority on the subject at the time, the man whose explications of Einstein’s theory were Lemaître’s first introduction to the field. Eddington was the first champion of Einstein’s theory for the English-speaking world. In 1916, at the height of World War I, the Dutch astronomer Willem de Sitter sent Eddington Einstein’s principle papers on relativity (Holland being a neutral country and open to communications). As noted in chapter 1, de Sitter was one of Einstein’s friends and among the very first to begin applying the equations of general relativity to cosmology. Eddington immersed himself in the new theory and immediately understood its importance for astronomy and astrophysics.