Template:Are You Sure/April 23

• ... that theoretical physicist Max Planck (1858–1947) took singing lessons and played piano, organ and cello, and composed songs and operas, but chose to study physics rather than music, and later was awarded the 1918 Nobel Prize in Physics for his pioneering contributions to quantum physics?

• ... that inventor Edward Hebern (1869–1952) was an early designer and manufacturer of rotor encryption machines; that when Herbern tried to sell his equipment to the US Government, William F. Friedman found at least one method of attack; and that Hebern's company did not prosper, his promotional efforts for it were questioned, and he was tried and convicted for fraud?