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Walking Zero, by Chet Raymo

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Walking Zero, Discovering Cosmic Space and Time along the Prime Meridian by Chet Raymo

Walking Zero, Discovering Cosmic Space and Time along the Prime Meridian by Chet Raymo

Walker Books

The Bottom Line

A deft and astute examination of science as a process that has led humanity from the ancient comfort of a self-centered cosmos to humbling but truer awareness of an immense universe. Told through a focus on the Prime Meridian of zero longitude, a crucial artifact of that historical and intellectual progression. The author's cross-country ramble along this line in England visits a lucky cluster of important sites in scientific history, many of them geological.
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  • A true essay, ably melding personal and factual
  • A deft writing style
  • Breathes life into ancient history and modern technology alike
  • At under 200 pages it's meaty travel reading


  • Overlooks the analogous examples from mapping other worlds
  • A few unfortunate tiny errors like "Adrienne's thread"


  • A history of ideas about the universe and our place in it
  • A survey of some remarkable people in the history of Earth science and astronomy
  • A visit to intriguing and offbeat destinations near longitude zero in southeast England

Guide Review - Walking Zero, by Chet Raymo

I like to say, with respect to geology, that on a round Earth every place is the center of the world. And in ancient times that was literally true in all respects. Claudius Ptolemy's map of the world, made in the second century, was centered on his own city of Alexandria in northern Egypt. Other maps were centered on Rome, or on Jerusalem or some other point of origin. The United States system of land measurement originates at a stone post in front of the White House, and most of the states have their boundaries set in degrees and minutes east or west of that Washington Meridian. Even late in the 19th century, most large cities set their own clocks from local astronomical observations. In Walking Zero: Discovering Cosmic Space and Time along the Prime Meridian, Chet Raymo describes how we have progressed from that heterogeny of local centers to a single universal framework of space and time.

But Raymo's is not a dry tale. He has managed to string a solid and entertaining essay on the thinnest gossamer: the invisible zero line of longitude, set by international agreement at the Royal Observatory in Greenwich, England once upon a time. Commerce and government and science all drove the need for a world standard zero point from which all maps, time zones, dates and measurements could be derived. They required a zero of latitude and longitude. The zero of latitude is straightforward, because anyone with a bit of technical knowledge can accurately find the equator. It is a purely natural fact. But the zero of longitude is arbitrary. Longitude zero is the result of a slow, fitful scientific and political process, and Raymo recognizes that the Prime Meridian is not just a line but part of a story leading from here to the stars.

As it happens, many important localities in this story happen to lie quite near the Greenwich line, and Raymo set out to walk the line and pay these sites a visit. The Jurassic Coast, Darwin's estate, Newton's study and other worthy places for the scientific tourist are on Raymo's route as well as the Greenwich observatory itself. I was charmed by his stop at the village of Piltdown, where he photographed the Piltdown Man pub with a smirking skull on its sign. The famous fossil fraud, Raymo explains, is not only a notorious incident of scientists' human failings but also a shining example of their ability to overcome error.

Raymo is a retired professor of physics and astronomy, the two fields that gave us absolute time and infinite space. A special ingredient in Walking Zero is his knowledgeable citations from theologists and psychologists, with their respective emphases on ancient worldviews and the development of personality. His theme also leans heavily on geology, whose great contribution to the de-centralization of humanity is the discovery of deep, nearly infinite time. Here too he acquits himself well, and readers of any degree of learning will find new things to learn on heaven and earth.

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