Theoretical astrophysicist Mario Livio will discuss his new book “The Golden Ratio” at 7 p.m. Wednesday (Feb. 5) in Carey Auditorium at the University of Notre Dame’s Hesburgh Library.p. Livio’s book examines the irrational number phi (1.6180339887), which is known as the golden ratio of antiquity. Phi crops up in more places in art, music and other fields than any number except its better-known cousin pi. Claude Debussy used it explicitly in his music and Le Corbusier in his architecture. There are claims the number was used by Leonardo da Vinci in painting the Mona Lisa, by the Greeks in building the Parthenon and by the Egyptians in building the Great Pyramid of Khufu (Cheops).p. In his book, Livio investigates these and other claims and does not hesitate to debunk myths perpetuated by overzealous enthusiasts he calls “Golden Numberists.”p. There will be a book signing at 6:30 p.m. in the library lounge next to Carey Auditorium and also after the lecture.p. Livio, who is head of science at Baltimore’s Space Telescope Science Institute, also will present a colloquium titled “Cosmology and Life” at 4 p.m. Wednesday in Room 118 of Nieuwland Science Hall.p. The Department of Physics, the Center for Astrophysics and the Society of Physics Students are sponsoring Livio’s appearance on campus.p.