The concept of mass is one of the most fundamental notions in
physics, comparable in importance only to those of space and
time. But in contrast to the latter, which are the subject of
innumerable physical and philosophical studies, the concept of
mass has been but rarely investigated. Here Max Jammer, a
leading philosopher and historian of physics, provides a concise
but comprehensive, coherent, and self-contained study of the
concept of mass as it is defined, interpreted, and applied in
contemporary physics and as it is critically examined in the
modern philosophy of science. With its focus on theories
proposed after the mid-1950s, the book is the first of its kind,
covering the most recent experimental and theoretical
investigations into the nature of mass and its role in modern
physics, from the realm of elementary particles to the cosmology
of galaxies. The book begins with an analysis of the persistent
difficulties of defining inertial mass in a noncircular manner
and discusses the related question of w