Clocks, Poincaré’s Maps: Empires of Time
Norton & Co., 389 pages, $23.95
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
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.