This book is not a systematic course of theoretical physics, it contains only selectedproblems and topics ofthis remarkablescience.Onecannotbut recall here the words ofI.Newton (in his “Universal Arithmetic”): “In learning the Science, Examples are of more use than Precepts.” The book is basedon lectures on additional chaptersof theoreticalphysics given by me in various years at the Department of Physics, Novosibirsk U- versity,Russia,andatScuolaNormaleSuperiore,Pisa,Italy.Themainsource of interest to the problems addressed in the lectures were my own investi- tions, as well as discussions with colleagues and students. The contents of the additional courses varied in time, together with my own interests, and so- timesinaccordancewiththewishesofthestudents.Someproblemsconsidered in the book were included also into general courses. I strived to rely both in the lectures and in the book on qualitative, in- itive arguments, as far as they can be su?cient at all for theoretical physics. An exception in this sense is in the book the chapter on the semiclassical - proximation in complex plane; it appears here by the following reason: in my opinion,acomprehensiblepresentationofthis e?cienttechniqueis practically absent in literature. Unfortunately, in other chapters also, far from always I could avoid calculations. I hope that the book will be accessible and useful for a student who has digestedcommoncoursesofanalyticalmechanics,electrodynamics,andqu- tum mechanics;onlysomesectionsofthelastchapterrequireanacquaintance with the fundamentals ofquantum electrodynamics.Hopefully, even a mature physicist will ?nd something interesting in the book. And not only a theorist.
The diversity of the material covered in the book implies that it is not just for one particular course or fieldThe book contains the analysis of concrete problems in classical mechanics, classical electrodynamics, quantum mechanics, and relativistic quantum mechanicsThere are no intersections in the problems considered and the book does not set out its fundamental principals in the usual pedagogic style as competition Many of the problems and solutions included in this book have never been discussed in print before