This essay explores the nature of spontaneous symmetry breaking (SSB) in connection with a cluster of interrelated concepts such as Curie's symmetry principle, ergodicity, and chance and stability in classical systems. First, a clarification of the two existing senses of SSB is provided and an argument developed for a proposal for SSB, in which not only the possibilities but also the actual breakings are referred to. Second, a detailed analysis is given of classical SSB that answers the questions: (i) how (...) we are justified in regarding it as a matter of chance, and (ii) why the breakings in it are equally probable. The answer provides some support to the applicability of ergodicity in special systems (such as ours). (shrink)

Two alternative accounts of quantum spontaneous symmetry breaking (SSB) are compared and one of them, the decompositional account in the algebraic approach, is argued to be superior for understanding quantum SSB. Two exactly solvable models are given as applications of our account -- the Weiss-Heisenberg model for ferromagnetism and the BCS model for superconductivity. Finally, the decompositional account is shown to be more conducive to the causal explanation of quantum SSB.

In 1894 Pierre Curie announced what has come to be known as Curie's Principle: the asymmetry of effects must be found in their causes. In the same publication Curie discussed a key feature of what later came to be known as spontaneous symmetry breaking: the phenomena generally do not exhibit the symmetries of the laws that govern them. Philosophers have long been interested in the meaning and status of Curie's Principle. Only comparatively recently have they begun to delve into the (...) mysteries of spontaneous symmetry breaking. The present paper aims to advance the discussion of both of these twin topics by tracing their interaction in classical physics, ordinary quantum mechanics and quantum field theory. The features of spontaneous symmetry that are peculiar to quantum field theory have received scant attention in the philosophical literature. These features are highlighted here, along with an explanation of why Curie's Principle, though valid in quantum field theory, is nearly vacuous in that context. (shrink)

Questions regarding the formation of the Universe and ‘what was there’ before it came to existence have been of great interest to mankind at all times. Several suggestions have been presented during the ages – mostly assuming a preliminary state prior to creation. Nevertheless, theories that require initial conditions are not considered complete, since they lack an explanation of what created such conditions. We therefore propose the ‘Creatio Ex Nihilo’ (CEN) theory, aimed at describing the origin of the Universe from (...) ‘nothing’ in information terms. The suggested framework does not require amendments to the laws of physics: but rather provides a new scenario to the Universe initiation process, and from that point merges with state-of-the-art cosmological models. The paper is aimed at providing a first step towards a more complete model of the Universe creation – proving that creation Ex Nihilo is feasible. Further adjustments, elaborations, formalisms and experiments are required to formulate and support the theory. (shrink)