His father was Gustav Hertz who, along with James Franck, was awarded the Nobel Prize in Physics 1925 for their experiments on inelastic electron collisions in gases.

[2] Hellmuth graduated from the elite Schule Schloss Salem boarding school in 1939 at the age of 19 years with the highest grade in mathematics and physics.

[3] The same year, he was conscripted into the German Army (Wehrmacht) and served as a soldier for Nazi Germany in World War II.

In 1943 he was captured in the North African theatre by US troops and brought to America, where he was placed in a prisoner-of-war camp until 1946.

Instead, he got a job at the Department of Physics in Lund University in Sweden with the assistance of James Franck and the Nobel laureate Niels Bohr, who were both friends of Gustav Hertz.