Walther Heinrich Wilhelm Ritz (22 February 1878 – 7 July 1909) was a Swiss theoretical physicist. He is most famous for his work with Johannes Rydberg on the Rydberg–Ritz combination principle. Ritz is also known for the variational method named after him, the Ritz method. Life Walter Ritz's father Raphael Ritz was born in Valais and was a well-known painter. His mother, born Nördlinger, was the daughter of an engineer from Tübingen. Ritz was a particularly gifted student and attended the municipal lyceum in Sion. In 1897, he entered the polytechnic school in Zurich, where he studied engineering. Soon, he found out that he could not live with the approximations and compromises associated with engineering, and so he switched to the more mathematically accurate physical sciences. In 1900, Ritz contracted tuberculosis, possibly also pleurisy, which he later died from. In 1901 he moved to Göttingen for health reasons. There he was influenced by Woldemar Voigt and David Hilbert. Ritz wrote a dissertation on spectral lines of atoms and received his doctorate with summa cum laude. The theme later led to the Ritz combination principle and in 1913 to the atomic model of Ernest Rutherford and Niels Bohr. In the spring of 1903, he heard lectures by Hendrik Antoon Lorentz in Leiden on electrodynamic problems and his new electron theory. In June 1903 he was in Bonn at the Heinrich Kayser Institute, where he found in potash a spectral line that he had predicted in his dissertation. In November 1903, he was in Paris at the Ecole Normale Supérieure. There he worked on infrared photo plates. In July 1904 his illness worsened and he moved back to Zurich. The disease prevented him from publishing further scientific publications until 1906. In September 1907 he moved to Tübingen, the place of origin of his mother, and in 1908 again to Göttingen, where he became a private lecturer at the university. There he published his work Recherches critiques sur l'Electrodynamique Générale, see below. As a student, friend or colleague, Ritz had contacts with many contemporary scholars such as Hilbert, Andreas Heinrich Voigt, Hermann Minkowski, Lorentz, Aimé Cotton, Friedrich Paschen, Henri Poincaré and Albert Einstein. He was a fellow student of Einstein in Zurich, while he studied there. Ritz was an opponent of Einstein's theory of relativity. Ritz died in Göttingen and was buried in the Nordheim cemetery in Zurich. The family tomb was lifted