1st Edition
As Time Goes By A Comprehensive Guide to Time and Frequency Measurements
PART I – Clocks and Oscillators
Chapter 1 – Shadow, Flow, and Mechanical Clocks
Chapter 2 – Quartz Clocks
Chapter 3 – Atomic Clocks
PART II – Measurements
Chapter 4 – Time Measurements
Chapter 5 – Frequency Measurements
Chapter 6 – Accuracy
Chapter 7 – Stability
Chapter 8 – Uncertainty
Chapter 9 – Traceability
PART III – Clocks Controlled by Radio and Network Time Signals
Chapter 10 – Clocks Controlled by Radio Time Signals
Chapter 11 – Clocks Controlled by Network Time Signals
Chapter 12 – Clocks Controlled by Satellite Navigation Systems
PART IV – Research Areas
Chapter 13 - Optical Clocks
Chapter 14 – Optical Time Transfer
PART V – Applications
Chapter 15 – Time and Navigation
Chapter 16 – Time and Telecommunications
Chapter 17 – Time and Electricity
Chapter 18 - Time and Money
Biography
Michael A. Lombardi worked in the Time and Frequency division of the National Institute of Standards and Technology (NIST) from 1980 until his retirement in 2023. During his career, Lombardi was engaged in measurement system design, clock and oscillator calibrations, time and frequency distribution via terrestrial radio and satellite signals, and international time scale comparisons. He received the NCSL International William A. Wildhack award for his contributions to measurement science, the Institute of Navigation’s Precise Time and Time Interval (ION-PTTI) Distinguished Service award, and the Dr. Willie E. May Award for a Distinguished Career at NIST. He is also a two-time recipient of the NIST Edgar Uhler Condon award for clarity in scientific writing.
“This book is a labor of love from one who has devoted his life to the timekeeping art. We learn that the history of clockmaking is the history of civilization. The book is particularly insightful in the areas Lombardi has worked on himself, such as time transfer and measurement for practical applications. Readers will learn why financial markets need timing at the millisecond level, as well as why GPS needs time and how it can deliver time a million times more accurately than that. The tools of the trade are described in an understandable manner, from clocks to oscilloscopes and counters, along with specialized statistical measures. It is a pleasure to read this carefully scribed work.”
Dr Demetrios Matsakis
Coauthor of An Introduction to Modern Time Keeping and Time Transfer
“As Time Goes By presents a clear and compelling journey through the science and history of time measurements, revealing how an abstract concept becomes a precise and practical tool. It skillfully traces the evolution of timekeeping—from ancient observations to today’s ultra-precise atomic clocks—while remaining accessible to general readers. It not only informs but also inspires curiosity about the profound role that accurate timekeeping plays in modern life and technological progress.”
Dr Amitava Sen Gupta
CSIR – National Physical Laboratory, India
“As Time Goes By is a masterful and comprehensive account of time and frequency measurements. It traces the journey from early natural observations to the precision of modern atomic clocks. Written by a leading expert, it combines historical insight with technical clarity, illuminating the evolution and significance of timekeeping. Both authoritative and accessible, it highlights the central role of time in science, technology, and our understanding of the universe.”
Dr José Mauricio López Romero
Center for Research and Advanced Studies of the National Polytechnic Institute, Mexico
