Binary Stars as Evidence Against Ritz's Relativity (Articles by Willem de Sitter) In 1908 Swiss physicist Walter Ritz proposed a ballistic relativity theory in which the velocity of a source of electromagnetic radiation is additive to the velocity of light. Ritz died in the following year at age 31. In 1913 Dutch mathematician, astronomer, and cosmologist Willem de Sitter published a series of articles related to binary star observations which he said provided evidence for a constant speed of light, thus disproving Ritz's relativity. Below are the first four articles in the de Sitter series.

Ein astronomischer Beweis für die Konstanz der Lichgeshwindigkeit (An Astronomical Proof for the Constancy of the Speed of Light) Physik. Zeitschr. 14, 429, (1913) German | Scanned | English Translation A Proof of the constancy of the velocity of light Proceedings of the Section of Sciences - Koninklijke Academie van Wetenschappen -- te Amsterdam, 15, 1297 (1913). HTML Copy

Über die Genauigkeit, innerhalb welcher die Unabhängigkeit der Lichtgeschwindigkeit von der Bewegung der Quelle behauptet werden kann. (About the accuracy, within which the independence of the speed of light from the movement of the source can be stated.) Physik. Zeitschr. 14, 1267, (1913) German | Scanned | English Trans On the constancy of the velocity of light Proceedings of the Section of Sciences - Koninklijke Academie van Wetenschappen -- te Amsterdam, 16, 395 (1913). HTML Copy

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