What was the name of the physicist who called Einstein's work a 'Jewish fraud'?

The physicist who called Einstein’s work a “Jewish fraud” was Philipp Lenard. Lenard was a German experimental physicist who won the 1905 Nobel Prize in Physics for his work on cathode rays, but later became a fierce opponent of Einstein’s theories and a prominent advocate of Nazi racial ideology in science.

Lenard objected especially strongly to relativity and to aspects of modern theoretical physics that relied on advanced mathematics. He promoted “Deutsche Physik,” or “German physics,” which attempted to reject ideas associated with Jewish scientists as racially suspect. Einstein, who was Jewish, became the movement’s most visible target.

Lenard’s hostility was also connected to the history of the photoelectric effect. Lenard’s experiments measured the phenomenon, while Einstein provided the theoretical explanation using light quanta. Einstein received the 1921 Nobel Prize in Physics chiefly for that explanation, not for relativity.

The phrase is often confused with the broader Nazi expression “Jewish physics,” which was used against Einstein and other modern physicists. Lenard was not merely a scientific critic; he became one of the leading public figures behind that antisemitic campaign. His opposition therefore reflected both theoretical disagreement and extremist racial politics.