This publication offers the speculation of soppy subject to scholars on the complex undergraduate or starting graduate point. It presents a easy creation to theoretical physics as utilized to delicate topic, explaining the techniques of symmetry, damaged symmetry, and order parameters; stages and section transitions; mean-field idea; and the maths of variational calculus and tensors. it really is written in an off-the-cuff, conversational sort, that is obtainable to scholars from a various variety of backgrounds. The booklet starts with an easy “toy version” to illustrate the actual importance of loose strength. It then introduces regular theories of section transitions—the Ising version for ferromagnetism and van der Waals idea of gases and liquids—and makes use of them to demonstrate rules of statistical mechanics. From these examples, it strikes directly to speak about order, disease, and damaged symmetry in lots of states of subject, and to provide an explanation for the theoretical equipment which are used to version the phenomena. It concludes with a bankruptcy on liquid crystals, which brings jointly all of those actual and mathematical strategies. The e-book is observed on-line via a suite of “interactive figures”—some permit readers to alter parameters and spot what occurs to a graph, a few enable readers to rotate a plot or different pics in 3D, and a few do either. those interactive figures aid scholars to enhance their instinct for the actual which means of equations. This e-book will arrange complex undergraduate or early graduate students to go into extra complex theoretical reports. it's going to additionally equip scholars going into experimental smooth topic technology to be absolutely conversant with the theoretical points and feature potent collaborations with theorists.