Complex and Unpredictable Cardano

This purely recreational paper is about one of the most colorful characters
of the Italian Renaissance, Girolamo Cardano, and the discovery of two basic
ingredients of quantum theory, probability and complex numbers. The paper is
dedicated to Giuseppe Castagnoli on the occasion of his 65th birthday. Back in
the early 1990s, Giuseppe instigated a series of meetings at Villa Gualino, in
Torino, which brought together few scattered individuals interested in the
physics of computation. By doing so he effectively created and consolidated a
vibrant and friendly community of researchers devoted to quantum information
science. Many thanks for that!