Metroland Online

Einstein’s Clocks, Poincaré’s Maps certainly has a winning title. Einstein is so famous that even dead he has the most recognizable face on our planet. And everyone knows that Einstein’s theories of relativity have something to do with time and space—something about, like, clocks losing time if they zoom through space fast enough. And Poincaré? Though his fame has faded almost to invisibility, he was one of the greatest mathematicians of his age. And in addition to being brilliant, he was a public figure famous across the French Empire and known throughout the educated Western world.

Peter Galison has written a book to show a connection between these two thinkers. Alas, he presents them not as flesh-and-blood people but as minds, which removes much drama from this story. Both minds were intrigued by the nature of time. Before these two arrived on the scene, we put our faith in Isaac Newton, who believed in absolute time. In that view, time flows evenly everywhere and all the clocks in the universe could stop ticking, but time would stream on. For Poincaré and Einstein it was the other way around. It’s only because we have something moving that we have time; the tick-tock doesn’t merely measure time, it makes it.

Henri Poincaré played a multitude of roles on the stage of imperial France, and one of the most important was as president of the French Bureau of Longitude. In that position he helped to map the globe and to locate precisely distant colonial cities of the French Empire. This was during the era of great railroad expansion, and it happens that mapmaking and railroading require a special knowledge of time.

As Galison points out, to know your longitude on a map—your distance east or west of home—you have to know precisely what time it is back home, as well as what time it is where you are. The sun circles the globe every 24 hours, so every hour of difference between you and home is equal to 15 degrees of latitude east or west. As for railroading, prior to the locomotive, every town and village set its clock to noon when the sun was overhead. That made excellent sense locally, but it made railroad timetables a confusing mess. So the clocks at railroad stations need to be synchronized, too.

The author provides a wealth of material (perhaps too much) on the spread of time signals through railway telegraphs and undersea cables. Poincaré, in addition to being a mathematician and physicist, was a bureaucrat. Much of the work of synchronizing time signals and setting standards involved committees, conferences, and reports; perhaps that’s why passages in this book have the stagnant air of a committee report. It’s true that Poincaré lived at a time when the French and the British were battling for supremacy in the race to establish technical conventions, and it’s nice to understand the strategies they employed. But frankly, we don’t need such exhaustive detail about the French maneuvers that resulted in the acceptance of the standard meter and kilogram.

The elder Poincaré, like the younger Einstein, saw space and time as relative, not absolute. Poincaré, who was also a popular writer on science, expressed his views on relativism throughout his career. But the older man had been educated to believe in the ether, an insubstantial medium said to permeate the universe. After all, if there are light waves there must be something in which to have those waves. Right?

Wrong. No experiment had ever detected the ether. Poincaré knew that, of course, but he continued to believe the ether was a valuable tool when thinking about time and light. Experiments unbelievably showed that light always came flying past you at the same speed, no matter how fast the light source was coming or going, no matter how fast you were coming or going. Einstein, born 25 years after Poincaré, found it easy to junk the idea of the ether. And—going further than anyone before him—he scrapped Newtonian theory and created a new one based on those inexplicable experimental results.

The title, Einstein’s Clocks, Poincaré’s Maps, suggests that Galison will deal equally with both figures. But the author gives Poincaré more than twice as many pages as he gives Einstein. Poincaré and Einstein met for the first and only time at a conference in 1911. Poincaré, ever open to new ideas and alternative ways of looking at the world, later spoke with admiration of Einstein and even wrote a letter to support the younger man’s appointment to the Swiss Federal Institute of Technology. But despite Poincaré’s numerous publications on the problems of light and time, Einstein never alluded to the older man’s achievements. It was as if he had never existed.

Einstein’s Clocks, Poincaré’s Maps contains a lot about clocks and maps or, to be precise, the synchronization of clocks, the transmission of time signals, and the role of railroads in establishing uniform time zones. Yet it’s still hard to figure out the point of this book. It has remarkably little of the man Poincaré or the young man Einstein. Yes, we know what Einstein looked like, so we don’t miss seeing his photograph again. But it’s symptomatic of this book’s bloodless nature that it has a photo of the standard meter and kilogram, and not even a snapshot of Poincaré.

	Send A Letter to Our Editor
	Back Home