On the bearing of the Principle of Relativity on Gravitational Astronomy

Willem de Sitter was a Dutch mathematician, physicist and astronomer. Professor de Sitter was one of the first to consider the implications of the Special Theory of Relativity for his field of astronomy; the Special Theory was only of interest to mathematicians because no practical relevance of it could be found in the first decade after its publication in 1905. De Sitter was possibly the first person after Einstein to make application of General Relativity to astronomy, because he was one of the first people to hear of Einstein's new theory. When Einstein sought a description of the universe in terms of the General Theory, Einstein sought a single solution to his field equations that was a description of universe. His static model with its cosmological constant seemed to be the solution that he sought.