The first, second, and third editions of this book seem to occur at ten
year intervals. The intent is to keep the book up-to-date. Many-body
theory is a field which continually evolves in time. Journals only
publish new results, conferences only invite speakers to report new
phenomena, and agencies only fund scientists to do new physics. Today's
physics is old hat by tomorrow. Students want to learn new material, and
textbooks must be modified to keep up with the times. The early chapters
in this book teach the techniques of many-body theory. They are largely
unchanged in format. The later chapters apply the techniques to specific
problems. The third edition increases the number of applications. New
sections have been added, while old sections have been modified to
include recent applications. The previous editions were set in type
using pre-computer technology. No computer file existed of the prior
editions. The publisher scanned the second edition and gave me a disk
with the contents. This scan recorded the words accurately and scrambled
the equations into unintelligible form. So I retyped the equations using
LaTeX. Although tedious, it allowed me to correct the infinite numbers
of typographical errors in the previous edition. The earlier typesetting
methods did not permit such corrections. The entire book was edited
sentence-by- sentence. Most old sections of the book were shortened by
editing sentences and paragraphs.
