[1] Albert Einstein recommended him as his successor for a professorship at the German Charles-Ferdinand University of Prague, a position which he held from 1912 until 1938.
[3] In 1938, he was invited by Harvard University to America as a visiting lecturer on quantum theory and the philosophy of modern physics.
The Germans having invaded Czechoslovakia as he was about to begin his scheduled lecture tour, Frank, a Jew, never returned to his position at Prague.
[5] Astronomer Halton Arp described Frank's Philosophy of Science class at Harvard as being his favorite elective.
It is apparent why Mach's Principle, stated in this fashion, does not fit with Einstein's conception of the retardation of all distant action.