Jürg Fröhlich – författare

This book contains selected papers of Jürg Fröhlich, one of the most outstanding mathematical physicists of our time, on the subject of statistical mechanics. In an extensive introduction, Jürg Fröhlich sets his results into a wider context and gives precious information on the genesis of his work from both a historical and a methodological perspective. It is not only an overview of current and future research directions in statistical mechanics, but also relates this subject with other branches of contemporary physics and mathematics.All papers in this collection bear Jürg Fröhlich’s signature in terms of a delicate balance between mathematical rigor and physical significance. They cover thirty years of his work on statistical physics, ranging from the most basic foundational questions in atomism and thermodynamics via the description of phase transitions and critical phenomena up to disordered systems and the study of many-body systems in condensed matter physics, including the quantum Hall effect. The wide range of topics covered in this compendium reflects the breadth of Jürg Fröhlich’s interests, and the last chapters reveal an outlook towards some of his more recent research areas.

This book reviews recent results on low-dimensional quantumfield theories and their connection with quantum grouptheory and the theory of braided, balanced tensorcategories. It presents detailed, mathematically preciseintroductions to these subjects and then continues with newresults. Among the main results are a detailed analysis ofthe representation theory of U (sl ), for q a primitiveroot of unity, and a semi-simple quotient thereof, aclassfication of braided tensor categories generated by anobject of q-dimension less than two, and an application ofthese results to the theory of sectors in algebraic quantumfield theory. This clarifies the notion of "quantizedsymmetries" in quantum fieldtheory. The reader is expectedto be familiar with basic notions and resultsin algebra.The book is intended for research mathematicians,mathematical physicists and graduate students.

Simple random walks - or equivalently, sums of independent random vari­ ables - have long been a standard topic of probability theory and mathemat­ ical physics. In the 1950s, non-Markovian random-walk models, such as the self-avoiding walk,were introduced into theoretical polymer physics, and gradu­ ally came to serve as a paradigm for the general theory of critical phenomena. In the past decade, random-walk expansions have evolved into an important tool for the rigorous analysis of critical phenomena in classical spin systems and of the continuum limit in quantum field theory. Among the results obtained by random-walk methods are the proof of triviality of the cp4 quantum field theo­ ryin space-time dimension d (::::) 4, and the proof of mean-field critical behavior for cp4 and Ising models in space dimension d (::::) 4. The principal goal of the present monograph is to present a detailed review of these developments. It is supplemented by a brief excursion to the theory of random surfaces and various applications thereof. This book has grown out of research carried out by the authors mainly from 1982 until the middle of 1985. Our original intention was to write a research paper. However, the writing of such a paper turned out to be a very slow process, partly because of our geographical separation, partly because each of us was involved in other projects that may have appeared more urgent.

This collection of essays is above all intended to pay tribute to the fact that while QM today is a refined and incredibly successful instrument, many issues concerning the internal consistency and the interpretation of this theory are still not nearly as well understood as they ought to be.In addition, whenever possible these essays take the opportunity to link foundational issues to the many exciting developments that are often linked to major experimental and technological breakthroughs in exploiting the electromagnetic field and in particular, its quantum properties and its interactions with matter, as well as to advances in solid state physics (such as new quantum Hall liquids, topological insulators and graphene). The present volume also focuses on various areas, including new interference experiments with very large molecules passing through double-slits, which test the validity of the Kochen-Specker theorem; new tests of the violation of Bell’s inequalities and the consequences of entanglement; new non-demolition measurements and tests of “wave-function collapse” to name but a few.These experimental developments have raised many challenging questions for theorists, leading to a new surge of interest in the foundations of QM, which have puzzled physicists ever since this theory was pioneered almost ninety years ago.The outcome of a seminar program of the same name on foundational issues in quantum physics (QM), organized by the editors of this book and addressing newcomers to the field and more seasoned specialists alike, this volume provides a pedagogically inspired snapshot view of many of the unresolved issues in the field of foundational QM.