ABSTRACT
In the general framework of critical phenomena, all systems that share the same relevant symmetries, dimension of space, and interaction range are supposed to exhibit a certain degree of universality at the critical point. Though the transition point itself and contributions of critical (long-wavelength) fluctuations to various physical properties are system specific, the dependence on detuning from the critical point, the decay of correlation functions at criticality, and the amplitude ratios are system independent. We do not attempt here a comprehensive discussion of critical phenomena that can be found elsewhere.∗ We rather apply these ideas to the superfluid-normal transition, mention the main results, and discuss their significance.
