In September 1846, Henry David Thoreau climbed Katahdin, and from atop the highest mountain in Maine produced one of the great existential freak-outs in American literature. “The solid earth!” he wrote, “the actual world! the common sense! Contact! Contact! Who are we? where are we?” Not to disparage the dislocating power of the sublime, but to modern ears Thoreau sounds like a man badly in need of a cellphone with location services enabled.

As Hiawatha Bray, a technology reporter and longtime staff writer at the Boston Globe, points out in “You Are Here,” his interesting if somewhat skimmed account of how we came to know so precisely where we are, “We now have free run of a planet we have thoroughly mapped and photographed and where even the farthest traveler can count on arriving at his intended destination.”

For most of human history, it was remarkably easy to get lost, especially if you were crossing oceans. Columbus had the compass, which came to Europe by way of China in the 12th century, but the maps of his time were still largely based on calculations of Claudius Ptolemy, the great 2nd-century cartographer who grossly underestimated the circumference of the Earth. When the captain of the Mayflower put ashore 220 miles northeast of his intended anchorage in the mouth of the Hudson River, his navigation methods were not much different from what Phoenician sailors were using in the Mediterranean before the rise of the Roman Empire. For centuries perhaps the greatest obstacle preventing sailors from knowing precisely where they were was the inability to accurately establish longitude, a problem that was not solved until John Harrison devised a precise and seaworthy pocket chronometer in 1761.

It’s a sad comment on the savagery of human nature that many of the technologies that have helped us refine our bearings in the world were initially devised to hasten our departure from it by improving the accuracy of shells and missiles, bombs and bombers. As Bray notes, in the 20th century the “new insights of physics and the demands of war and commerce set loose a torrent of navigational innovation.” Radio beacons and radar made it possible not only for captains and pilots to find their way home at night or in blinding weather, but for airplanes to be shot out of the sky by ingenious, radio-based proximity fuses so effective that the U.S. military would use them only in sea battles lest the secret of the mechanism fall into enemy hands. Gyroscopes and the emerging science of inertial navigation freed sailors from the ancient practice of consulting the sun and the stars — and enhanced the lethality of submarines, as the USS Nautilus demonstrated when it deftly groped its way under the ice of the North Pole in 1958.

The most dramatic technical advances came with the development of global positioning satellites and the increasing computer power of the digital age. Bray traces the idea of satellite navigation to, of all things, a short story called “The Brick Moon,” written in 1869 by U.S. Senate Chaplain Edward Everett Hale. Ninety years later, in the wake of Russia’s success with Sputnik, scientists at the Applied Physics Laboratory at Johns Hopkins University began working on what became the Navy’s Transit satellites. The polar-orbiting satellite navigation system began operating in 1964 and was opened to commercial use three years later; the British and Argentine navies relied on it during the 1982 Falklands War. The limitations of the Transit satellites — spotty coverage, no super-accurate cesium clocks to measure tiny variations in time caused by distance, and a two-dimensional data stream that provided longitude and latitude but not altitude — influenced the engineers of the Aerospace Corporation in El Segundo, Calif., who in 1962 began working Project 621B, a space-based navigation system for the Air Force. Project 621B, Bray writes, “was the beginning of the beginning” of what eventually became the Global Positioning System, the network of satellites that made its devastating military debut in the 1991 Persian Gulf War and without which today we would be unable to find Starbucks in strange neighborhoods.

‘You Are Here: From the Compass to GPS, the History and Future of How We Find Ourselves’ by Hiawatha Bray (Basic)

Thanks to GPS-equipped cellphones, Wi-Fi triangulation, Radio Frequency Identification and various other features of the digital age, we now stand on the threshold of what Bray calls “the last frontier of navigation — inner space,” where it seems we may not want so many maps or such precise location data.

The jacket copy of “You Are Here” asks, “What does it mean never to get lost?,” but alas, this is a question Bray never takes up. He expresses some ambivalence about the new age of eroded privacy in which our daily patterns and behaviors can be predicted by our digital footprints. (Researchers have found that if you track three months of someone’s cellphone data, you can predict where she will be with 93 percent accuracy.) And he is leery of the surveillance state emerging from an unholy alliance of corporate marketers corralling potential consumers in “geo fences” and intrusive government authorities keeping tabs on citizens.

One of the more shocking statistics in “You Are Here” is that in 2012, American federal, state and local police requested cellphone records at a rate of 3,600 times a day. “They know where to find us, and they always will,” Bray concludes. Maybe the paranoia is warranted, but I can’t help but think Thoreau would know how to get lost. The wilderness of who and where we are in the cosmos, and why were here at all, is much closer than the phone in your hand.

Chip Brown , a former Washington Post staff writer, is a contributing editor at National Geographic and the New York Times Magazine.


From the Compass to GPS, the History and Future of How We Find Ourselves

By Hiawatha Bray

Basic. 258 pp. $27.99