Robert Wichard Pohl (1884 - 1976): Pohl was born in Hamburg, and studied physics in Heidelberg and Berlin, where he completed his doctorate in 1906. He obtained the Habilitation there in 1912 (this is an advanced research degree often required in Germany for an academic career). In 1916, he received the offer of a professorship in Göttingen as the successor to E. Riecke, and was full professor and director of the 1st Physics Institute there from 1920 until his retirement in 1952. He published fundamental results in the newly developing 2nd edition on also including thermodynamics; 18th edition 1983, English translation 1932), and "Optik" in 1941 (from the 9th edition on also including atomic physics; 13th edition 1976). Since 1980, the German Physical Society has conferred an annual prize in his name, the "Robert-Wichard-Pohl Prize" for outstanding achievements in teaching and in physics didactics.Klaus Lüders was born in 1936 in Cologne, Germany. He studied physics in Göttingen, Munich (LMU), Aachen and Karlsruhe, where he completed his doctorate in 1965. He obtained the Habilitation in 1972 from the Freie Universität Berlin, and was professor of experimental physics at the FU Berlin from 1972. He spent research stays among others at Kyushu University in Fukuoka, Japan and at the University of Basel, Switzerland. His areas of specialization include solid-state and low-temperature physics, superconductivity and superfluid helium. Robert Otto Pohl was born in 1929 in Göttingen, Germany. He studied physics in Göttingen, Freiburg and Erlangen, and received his doctorate there in 1957. He was professor of physics at Cornell University from 1968, and Goldwin Smith Professor Emeritus from 2000. He was guest professor at the RWTH Aachen, the TH Stuttgart and the University of Canterbury in New Zealand, among others. His area of specialization is solid-state physics, particularly lattice vibrations in crystalline and amorphous materials. William Dean Brewer was born in 1943 in Boise, Idaho, USA. He studied chemistry and mathematics at the University of Oregon and received his PhD in physical chemistry from UC Berkeley in 1970. He obtained the Habilitation at the FU Berlin in 1975 and was professor of experimental physics there from 1977. His research areas are low-temperature and nuclear solid-state physics, and magnetism in thin films and on surfaces. He has translated over a dozen textbooks and monographs from German to English.