Theodor Franz Eduard Kaluza was born in Germany on November 8, 1885. He is most remembered for his part in the Kaluza-Klein theory.

Kaluza went to university in Königsberg, where he studied mathematics. He finished his doctorate in 1909, and stayed to teach at Königsberg, where he was not thought highly of. He was not promoted for 20 years.

His greatest achievement was his theory of the unification of Einstein's gravitational theory with Maxwell's electromagnetic theory. It was, in fact, something that Einstein had been attempting for a long time.

Einstein had introduced the concept of time as the fourth dimension several years before, and Kaluza went even further. He introduced yet another dimension - a spatial dimension. Here lies the originality of his work - the introduction of the fifth dimension. Kaluza wrote to Einstein in 1919 of his theories to unite gravity and electromagnetism into one theory, and Einstein encouraged him, so that in 1921, Kaluza published Zum Unitätsproblem der Physik (On the unity problems of physics). Einstein was impressed with Kaluza's theory and spoke highly of it. In the fifth dimension, gravity and electromagnetism, which had seemed so separate, fit like a glove.

With the introduction of quantum mechanics, the Kaluza-Klein theory faded from public consciousness. Quantum physics could describe the world so perfectly, without the need of an abstract fifth dimension. But more than half a century later, the Kaluza-Klein theory made a vicious comeback, and is the basis for many later higher-dimensional theories, such as Superstring theory.

In 1929, Kaluza was at last made Professor, of Kiel. In 1935 he was given full professorship at Göttingen. He died on January 19, 1945.