The Tao of Physics interested and very open, and he told me something that I think is not known publicly because he never published it. He said that he was well aware of these parallels. While he was working on quantum theory he went to India to lecture and was a guest of Tagore. He talked a lot with Tagore about Indian philosophy. Heisenberg told me that these talks had helped him a lot with his work in physics, because they showed him that all these new ideas in quantum physics were in fact not all that crazy. He realized there was, in fact,
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