According to standard physics textbooks, quantum mechanics is the theory of the microscopic world. It describes particles, atoms and molecules but gives way to ordinary classical physics on the macroscopic scales of pears, people and planets. Somewhere between molecules and pears lies a boundary where the strangeness of quantum behavior ends and the familiarity of classical physics begins. The impression that quantum mechanics is limited to the microworld permeates the public understanding of science. For instance, Columbia University physicist Brian Greene writes on the first page of his hugely successful (and otherwise excellent) book The Elegant Universe that quantum mechanics “provides a theoretical framework for understanding the universe on the smallest of scales.” Classical physics, which comprises any theory that is not quantum, including Albert Einstein's theories of relativity, handles the largest of scales.