Physics and Beyond people could do big things" are gone. But the people who had been there continue to speak to us through this book. The book was published first in German 1969, in English as "Physics and Beyond" (1971) and in French in 1972 (La partie et le tout). Physics and Beyond Physics and Beyond () is a book by Werner Heisenberg, the German physicist who discovered the uncertainty principle. It tells, from his point of view, the history of exploring atomic science and quantum mechanics in the first half of the 20th century. As the subtitle "Encounters and Conversations" suggests, the
Heisenberg model (quantum) respectively. Other approaches do so without Bethe ansatz. The physics of the Heisenberg model strongly depends on the sign of the coupling constant formula_3 and the dimension of the space. For positive formula_3 the ground state is always ferromagnetic. At negative formula_3 the ground state is antiferromagnetic in two and three dimensions, it is from this ground state that the Hubbard model is given. In one dimension the nature of correlations in the antiferromagnetic Heisenberg model depends on the spin of the magnetic dipoles. If the spin is integer then only short-range order is present. A system of half-integer spins