Paul Gruner

Franz Rudolf Paul Gruner (13 January 1869 in Bern – 11 December 1957) was a Swiss physicist.

The doctorate was awarded to him in 1893 under Heinrich Friedrich Weber in Zurich.

From 1893 to 1903 he taught physics and mathematics at the Free Gymnasium Bern.

In 1894 he was habilitated in physics and became Privatdozent, and in 1904 titular professor in Bern.

[4] He took part in the development of the physics journal Helvetica Physica Acta, was president of the Swiss Meteorological Commission, and due to his Christian faith and rejection of materialism he became a member of the Keplerbund (an association of Christian natural scientists).

There, Einstein met Sauter's friend Paul Gruner, then Privatdozent for theoretical physics.

Einstein held lectures and discussions in Gruner's home and started a letter exchange with him.

When Einstein tried to become Privatdozent himself in 1907, Gruner (now professor for theoretical physics in Bern) supported him.

[9] Gruner and Sauter were among the participants in the relativity conference held on 11–16 July 1955 in Bern in celebration of the 50th anniversary of Einstein's 1905 achievement.

[10] In May 1921, Gruner (in collaboration with Sauter) developed symmetric Minkowski diagrams in two papers, first using the relation

[A 1][A 2] In subsequent papers in 1922 and 1924 this method was further extended to representations in two- and three-dimensional space.

Gruner noted that there is no contradiction to special relativity, since these coordinates are only valid with respect to one system pair only.

in the sense of the Galilei-Newtonian absolute time by analyzing two frames moving in opposite directions, and subsequently claimed to have refuted the principles of relativity.

[A 9] (For an overview on the discussions with the relativity critic Guillaume, see Genovesi (2000)[A 10]).

[A 11] Also Gruner came to the same conclusion as Mirimanoff, and gave him credit for the correct interpretation of the meaning of those "universal frames".