The chances are that shortly before you started reading this article you checked the time. Whether you are staring bleary-eyed at an alarm clock, glancing at your wristwatch to see if you are late, or booking appointments into your phone’s calendar app, most of us consult clocks many times a day. It is this familiar and omnipresent tracking of time that forms the starting point for Chad Orzel’s A Brief History of Timekeeping: the Science of Marking Time, from Stonehenge to Atomic Clocks.

In this book, the US physics professor covers the centuries of scientific discoveries, political machinations and societal changes that have led us to current timekeeping methods. Orzel begins in the passage tombs of Neolithic Britain – in which the Sun only shines into the burial chamber at specific times of the year, marking a solstice or equinox – before discussing how the evolution of our modern-day calendar was shaped by religion and politics. As he later remarks, “for everyday purposes, time is not a universal absolute but a social convention”. 

The book cleverly weaves centuries of scientific and technological tales together, taking us from a world of tick-tock to one enabling TikTok. We learn how precision marine chronometers developed in the 18th century led to a boon in reliable long-distance shipping thanks to their ability to correctly track longitude; why 19th-century railway companies were a catalyst for the adoption of global time zones; and how signals distributed via satellites or over the Internet are integral to disseminating today’s international reference time scale. Along the way, we are led through discussions of physics discoveries and phenomena fundamental to the story of timekeeping. These include electromagnetism, simple harmonic motion, celestial mechanics, and special and general relativity, as well as the atomic physics and quantum mechanics behind the atomic clocks that provide national time standards. 

Orzel gives numerous insights into how sophisticated many historic scientific practices were, for their time. Some of the astronomy and mathematics of the Maya civilization sound almost like science fiction. It is incredible, for instance, that Mayan astronomical tables for tracking Venus successfully predicted when the planet will appear and disappear in the sky for several centuries. But we must not get carried away. From 1987 through to the first decade of the 21st century, an extrapolation from the Mayan calendar systems was used to develop mistaken predictions that the world would end on 21 December 2012. Orzel makes a good job of rubbishing the pseudoscience that gave rise to these prophecies of doom. Similarly he skilfully puts scientific results and claims into perspective in later chapters.  

Equally fascinating are the sections highlighted by grey bars down the side of the page, which cover scientific concepts in more detail. Their broad spectrum ranges from describing how fluid mechanics governs the behaviour of water clocks, and delving into thought-experiments to help understand relativity, to explaining how the piezoelectric properties of quartz enable accurate and affordable timepieces, and highlighting why caesium was chosen for the first generation of atomic clocks. 

As well as the science, Orzel includes historical stories, some of which are as amusing as they are engrossing. It made me laugh to learn that outflow water clocks were used to limit the time advocates could speak in Ancient Greek courts, and contemporary records indicate speakers commenting when their time was almost up. Picturing the arrays of several overlapping sand glasses used on board ships when tracking time for navigation was similarly entertaining: this arrangement provided a buffer against lapses in concentration by those delegated to turn over the just-emptied glasses. 

Throughout the book Orzel also highlights how in the past, scientists’ roles could be different to those today. The 16th-century astronomer Tycho Brahe, for instance, cast horoscopes as one of his main duties as court astronomer in Denmark. Orzel also notes how much valuable scientific record can be lost due to invasion, looting and the passage of time; a fact that sadly still resonates today. 

The inclusion of tales of rivalries between scientists, and historic struggles for funding or education, perfectly highlight Orzel’s research process. He also deftly describes how some scientists, like the 17th-century physicist Robert Hooke, had a prodigious talent for self-promotion. Others, though, who were just as important to the development of modern-day timekeeping quietly pressed on with their work – such as 18th century astronomer Tobias Mayer whose meticulous lunar tables later formed the basis for the Royal Observatory’s Nautical Almanac for determining longitude at sea. 

Orzel concludes by looking towards a future in which today’s experimental optical-lattice clocks may eventually enable time measurements so precise that we could track earthquakes via fine-scale monitoring of the Earth’s shape, or possibly even detect particles of dark matter if they interact with the clocks’ atomic tick. 

Throughout A Brief History of Timekeeping, Orzel leads us into some of the topics via events in his own life. This not only helps bring home how much we take the marking of time for granted, but along with his engaging writing style also prevents the physics content from feeling unrelated to our everyday experiences. 

While I mostly feel very positive about this book, it is not without a few flaws. Although the diagrams mainly aid understanding, I found that some would have benefitted from annotations. Equally, Orzel partly based the book on a university course he teaches, and there are sections – such as those on the Michelson interferometer – which seem a bit too obviously derived from that, with some of his explanations requiring a reasonably high level of prior physics understanding. Also, the main text occasionally does not make complete sense if, as Orzel suggests you can opt to do, you have only skimmed over the highlighted sections. Furthermore the book’s title seems a bit of a misnomer in terms of suggesting a quick read. As Orzel himself comments, our personal experiences of time can be subjective, and I don’t consider just over 270 pages “brief”.  

But predominantly A Brief History of Timekeeping is accessible to lay readers, and these are minor quibbles about what is overall an absorbing page-turner.  It never drags, and I’m glad to have invested several hours to learning more about the fascinating history and physics of timekeeping in the hands of this accomplished author.

• 2022 BenBella Books 272pp $16.95pb