Laub, who converted from the Jewish to the Catholic faith and changed his name from "Jakub" into "Jakob Johann", first visited High School in Rzeszów.
Soon he established closer contact to Wilhelm Wien, Arnold Sommerfeld, Johannes Stark, and Albert Einstein.
When he travelled to Bern in 1908 to visit Einstein (with whom it corresponded later frequently and was friendly) he found him still working as a patent employee.
After accepting the Argentine nationality (with the Spanish first name variant "Jacobo Juan") he began to work in the Diplomatic service of Argentina.
Laub also published some papers on relativistic effects within gases and in 1910 he wrote one of the first survey articles on relativity.