Phase Transitions in Quantum Spin Systems with Isotropic and Nonisotropic Interactions

@inproceedings{Dyson1956PhaseTI,
title={Phase Transitions in Quantum Spin Systems with Isotropic and Nonisotropic Interactions},
author={Freeman J. Dyson and Elliott H. Lieb and Barry},
year={1956}
}

A basic subtlety in the study of statistical mechanics is the following: In nature, we observe abrupt changes in certain basic physical quantities, such as the magnetization of a magnet, but the statistical mechanics of systems with finitely many degrees of freedom is typically real analytic in all external variables. The resolution of this apparent paradox is that the abrupt changes are only approximately abrupt: True discontinuities only occur in the limit of an infinite system. For this… CONTINUE READING