This accessible reference presents the evolution of concepts of time and methods of time keeping, for historians, scientists, engineers, and educators. The second edition has been updated throughout to describe twentieth- and twenty-first-century advances, progress in devices, time and cosmology, the redefinition of SI units, and the future of UTC.

A unique insight into the measurement of time and its applications, at an introductory level.

Until the 1950s timekeeping was based on the apparent motion of the Sun that in turn reflected the rotation of the Earth on its axis. But the Earth does not turn smoothly. By the 1940s it was clear that the length of the day fluctuated unpredictably and with it the length of the second. Astronomers wanted to redefine the second in terms of the moti

Clear and accessible introduction to the concept of time examines measurement, historic timekeeping methods, uses of time information, role of time in science and technology, and much more. Over 300 illustrations.

This second edition course text introduces the fundamental quantum physics of atoms and molecules. With revised and extended content, this book is the first volume in a series of three aiming to present a broad coverage of atomic, molecular, solid-state and statistical physics. Divided into three parts, the first provides a historical perspective leading to the contemporary view of atomic and molecular physics, outlining the principles of non-relativistic quantum mechanics. The second covers the physical description of atoms and their interaction with radiation, whilst the third deals with molecular physics. The book's pedagogical features include conceptual layout sections that define the goals of each chapter, a simplified but rigorous mathematical apparatus, and a thorough discussion of approximations used to develop the adopted physical models. Key Features Fills a gap for a self-contained undergraduate textbook in atomic and molecular physics Is tailored for a one-semester course Focuses on a selected set of topics, whilst also providing substantial, in-depth coverage of the subject Emphasises phenomenology rather than mathematics/formalism Uses various pedagogical features, including end-of-chapter exercises with solutions

" ... Concise explanations and descriptions - easily read and readily understood - of what we know of the chain of events and processes that connect the Sun to the Earth, with special emphasis on space weather and Sun-Climate."--Dear Reader.

This book is intended for geophysicists, astronomers (especially those with an interest in history), historians and orientalists. The culmination of many years of research, it discusses, in depth, ancient and medieval eclipse observations and their importance in studying Earth's past rotation. This was the first major book on this subject to appear in the last twenty years. The author has specialised in the interpretation of early astronomical records and their application to problems in modern astronomy for many years. The book contains an in-depth discussion of numerous eclipse records from Babylon, China, Europe and the Arab lands. Translations of almost every record studied are given. It is shown that although tides play a dominant long-term role in producing variations in Earth's rate of rotation - causing a gradual increase in the length of the day - there are significant, and variable non-tidal changes in opposition to the main trend.