THE HIGH-ENERGY UNIVERSE.
This book provides an overview of topics in high energy, particle
and gravitational astrophysics, aimed mainly at interested undergraduates
and other readers with only a modest science background. Mathematics and
equations have been kept to a minimum, emphasizing instead the main concepts
by means of everyday examples where possible. I have tried to cover
and discuss in some detail all the major areas in these topics where significant
advances are being made or are expected in the near future, with discussions
of the main theoretical ideas and descriptions of the principal experimental
techniques and their results.
Cosmology, particle physics, high energy astrophysics and gravitational
physics have, in the last two decades, become increasingly closely meshed,
and it has become clear that thinking and experimenting within the isolated
confines of each of these disciplines is no longer possible. The multi-channel
approach to investigating nature has long been practiced in high energy accelerators
involving the strong, the weak and the electromagnetic interactions,
whereas astrophysics has long been possible only using electromagnetic signals.
This situation, however, is rapidly changing, with the advent of major
cosmic-ray, neutrino and gravitational wave observatories for studying cosmic
sources, and the building of particle physics experiments using beams and signals
of cosmic origin. At the same time, theoretical physics has increasingly
concentrated efforts in attempts to unify gravity with the other three forces
into an ultimate theory involving all four. The intense activity in these fields
is beginning to open new vistas onto the Universe and our understanding of
Nature’s working on the very small and very large scales. In this book I have
sought to convey not only the facts but also the challenges and the excitement
in this quest.