  Did time begin at a Big Bang? Will the present expansion of the universe last
for a finite or infinite time? These questions sound philosophical but are
becoming, now in the twenty-first century, central to the scientific study of
cosmology. The answers, which should become clarified in the next decade or
two, could have profound implications for how we see our own role in the
universe. Since the original publication of Stephen Hawking's {\it A Brief
History of Time} in 1988, the answers to these questions have progressed as a
result of research by the community of active theoretical physicists including
myself. To present the underlying ideas requires discussion of a wide range of
topics in cosmology, especially the make up of the energy content of the
universe. A brief summary of my conclusions, that of three different
possibilities concerning the history and future of time, the least likely is
the conventional wisdom (time began and will never end) and most likely is a
cyclic model (time never begins or ends), is in the short final Chapter which
could be read first. To understand the reasoning leading to my conclusions
could encourage reading of my entire book. My hope in writing this, my first
popular book, is that it will engender reflection about time. Many a
non-scientist may already hold a philosophical opinion about whether time
begins and ends. This book's aim is to present some recently discovered
scientific facts which can focus the reader's consideration of the two short
questions in my title.

Astrophysics