The first
superstring revolution, in 1984, was responsible for eliminating
11-dimensional supergravity from the list of candidates for the
ultimate theory of nature. The return of
11-dimensional supergravity, in 1995, in
a new guise called M-theory in the second
superstring revolution is more
dramatic than its exit 11 years ago. This is because the duality
relationship between all the known string theories is incomplete without
M-theory. Though this new avatar of 11-dimensional
supergravity entered as
a missing piece in the jigsaw puzzle of string dualities, it quickly
established its special status by demonstrating that most of the string
theories including the chiral ones can be derived from it in some specific
limit. Whatever understanding we have of M-theory, so far, is challenging
enough to make it one of most exciting subjects for `string theorists',
with
new results appearing on the net almost everyday. Publication of `The
World in
Eleven Dimensions', a reprint volume on 11-dimensional supergravity,
supermembranes and M-theory is, therefore, very relevant and timely.
This book contains six chapters and 33 papers which nicely cover of the evolution 11-dimensional supergravity from its pre-Kaluza-Klein supergravity days to its new incarnation as M-theory. The first chapter contains the original paper on 11-dimensional supergravity (Cremmer E, Julia B and Scherk J 1978 Phys. Lett.B 76409) as well as papers on Kaluza-Klein compactification of it down to four dimensions.
Though 11-dimensional supergravity was out of fashion in the late 1980s a small set of researchers kept the subject alive. One of the important developments during that time was the discovery of the supermembrane and its realization as a classical solution to the supergravity equations of motion. Chapter 2 contains some of the important papers on this subject, e.g., a paper by de Wit et al, which is relevant to the matrix theory developments in chapter 6.
Chapter 3, contains an excellent collection of papers on the M-5-brane. Most of these papers are relatively new. This is simply because the utility of M-5-branes was understood only recently. Their dynamics, however, is still largely unknown. This chapter contains papers which use M-5-branes to determine the dynamics of compactified M-theory as well as anomalous couplings due to their chiral worldvolume theory.
Papers in the fourth chapter use kappa symmetry to derive the type IIA superstring by double dimensional reduction of the supermembrane in 11 dimensions and study duality in the membrane theory. Other papers in this chapter set the stage for the return of 11-dimensional supergravity. Configurations of M-branes have proved useful in understanding the dynamics of black holes as well as super-Yang-Mills theories in four dimensions. Chapter 5 contains papers on configurations of intersecting M-branes and their applications in black hole physics.
All the papers in chapter 6 are classic papers in M-theory in the second superstring revolution. Each one of them has led to quantum jumps in conceptual understanding of physics of M-theory. It contains papers by Horava and Witten, Banks et aland Maldacena to name a few.
It is obviously impossible to do justice to all the contributors to this subject in a 500 page reprint volume with a huge amount of literature existing on it in the journals. This is where the experience of the editor (Professor M J Duff) has helped in judiciously choosing landmark papers in this field. It is a pleasure to review this reprint volume which contains almost all the major milestones in the 22-year history of this subject. It can serve as a very useful one-spot reference for advanced readers as well as an excellent fast-track introduction to the subject for new entrants, although background knowledge of supersymmetric field theories and, to some extent, of superstrings is needed. The editor's comments at the beginning of the chapters are quite instructive and, as intended, do indeed give a wider perspective. A list of references at the end of every commentary is extensive though not quite exhaustive. It, however, illustrates quite well the level of difficulty involved in choosing 33 papers out of them.