Peter L. Galison Home

Peter L. Galison

June 24, 2003, Tuesday

SCIENCE HISTORIAN AT WORK: PETER GALISON; The Clocks That Shaped Einstein's Leap in Time

By DENNIS OVERBYE (NYT) 3837 words

CAMBRIDGE, Mass. -- What does it mean, Albert Einstein asked in 1905, to say that a train arrives someplace -- in Paris, say -- at 7 o'clock?

You might not think you need to know something as deep as relativity to answer such a question. But Einstein needed to answer the question to invent his theory of relativity, the breakthrough that wrenched science into a new century and enshrined the equivalence of matter and energy.

In his last step, after a decade of pondering the mysteries of light and motion, Einstein concluded that there was no such thing as absolute time, envisioned by scientists since Newton, ticking uniformly through the cosmos. Rather there were only the times measured by individual clocks. To talk about times and measurements at different places, the clocks have to be synchronized, he said. And the way to do that is to flash light signals between them, correcting for the time it takes for the signal to travel from one clock to another.

A simple prescription. Yet when Einstein followed it, he found that clocks moving with respect to one another would not run at the same speed. The modern age was born.

Einstein's relativity has long been regarded by scholars as a monument to the power of abstract thought. But if Dr. Peter Galison, 48 -- a Harvard professor of the history of science and of physics, a pilot, art lover and nascent filmmaker -- is right, physics and Einstein have flourished more in their connections to the world than in any ivory tower aloofness. And one clue to the origin of relativity can be found in something as mundane and practical as a 19th-century train schedule. ''It's in as plain sight as it could possibly be,'' he said.

As Dr. Galison relates, before the advent of factories began to standardize life, and railroad systems with crisscrossing tracks made it imperative to know which train was where and when, there were too many times, one for every village.

In the last part of the 19th century, the coordination of clocks and the standardization of time had engaged the passions of nations, business leaders, astronomers and philosophers. The patent office in Bern, Switzerland, where Einstein worked, was a clearinghouse for patents on the synchronization of clocks.

In New England, the Harvard and Yale observatories were competing to sell time signals to the public, and in Paris pneumatic tubes snaked under the streets to synchronize the city's clocks with blasts of air. Far from being a bit of abstraction by a loner genius, the clocks that Einstein used as examples in his papers were as familiar then as computers are today.

That is one of the messages of Dr. Galison's new book, ''Einstein's Clocks, Poincaré's Maps: Empires of Time,'' due out in August from W. W. Norton. Part history, part science, part adventure, part biography, part meditation on the meaning of modernity, Dr. Galison's story takes readers from the patent office to lonely telegraphers sitting in the rain in the Andes, from the coal mines of France to town councils in New England as it circles around the exploits of Einstein and his rival, the French physicist, philosopher and mathematician Henri Poincaré.

It offers gritty descriptions of how undersea cables are made and issues cosmic-sounding pronouncements just this side of metaphysics.

Although the book sheds fresh light on the context in which Einstein made his great leap forward, it is not a history of relativity, Dr. Galison said. Rather it is an attempt to capture a rare moment when the very abstract and the very concrete collided, when physics, philosophy and technology all converged around one question, the meaning of simultaneity.

At such moments, as he writes in ''Einstein's Clocks,'' ''We find metaphysics in machines and machines in metaphysics.''

Dr. Galison has made his mark exploring such moments of collision, both in modern science and out of it. ''He is now recognized as one of the premier science historians in the world,'' said Dr. Michael Riordan, a physicist and historian at Stanford.

''Einstein's Clocks'' is the third in a series of books, beginning with ''How Experiments End,'' in 1987, and ''Image and Logic: A Material Culture of Microphysics,'' published in 1997, in which he has reimagined 20th-century physics, in all its complexity and messy interdisciplinary overlaps ''from the shop floor,'' as Dr. Daniel Kevles, a science historian at Yale, once put it.

In Dr. Galison's telling of science, the meters and wires and epoxy and solder come alive as characters, along with physicists, engineers, technicians and others in the armies of modern science.

''You seldom read a page without some concrete object being depicted in its particularity,'' said Dr. Lorraine Daston, of the Max Planck Institute for the History of Science. ''Clocks and maps come to embody ways of understanding the cosmos.''

Dr. Galison has written and edited books on subjects as diverse as the architecture of scientific laboratories and museums, photography, intellectual property and the history of aviation. He and a Harvard colleague, Pamela Hogan, a documentary filmmaker, produced ''Ultimate Weapon: The H-Bomb Dilemma,'' about the decision to build the hydrogen bomb, which was shown on the History Channel. He teaches a course on filming science.

''I'm interested in what counts as a scientist,'' he said. ''How do we track the history of what it means to be a scientist at different times?'' Dr. Galison is working on a book about theory in physics, to complete the trilogy with experiments and instruments, and another with Dr. Daston on the history of objectivity.

He is also a pilot, with instrument and commercial ratings. And he is a husband -- his wife, Dr. Caroline A. Jones, is an art historian at M.I.T. -- and a father of two.

Fortunately, he does not need much sleep. ''You can do a lot reading between 3 and 5 a.m.,'' he said.

Gadgets and art are in Dr. Galison's blood. His great-grandfather Frank Alexander was an inventor who maintained an electrical laboratory in his house and once worked for Thomas Edison. ''The whole place stank of ozone,'' Dr. Galison recalled.

The oldest of three children, Dr. Galison grew up in Manhattan. As a high school student at Riverdale Country School in the Bronx, he developed a love of French literature, and after graduating a year early he arranged to work for a year in a physics laboratory at the École Polytechnique in Paris. On the side, he studied philosophy and took a math course. A year later he entered Harvard as a sophomore.

Looking for a major, he stumbled into the history of science department. ''And that seemed like a wonderful place for me to be because they were happy for me to do as much math and physics as I wanted.''

Creoles and Clocks
In Science, Strength in Disunity

Peter Galison's first book grew out of his Harvard Ph.D. dissertation. In it he examined how scientists decide to stop looking for errors and conclude that they have an argument that will stand up.

The book also led Dr. Galison, with the encouragement of two Harvard physics colleagues, Dr. Steven Weinberg and Dr. Howard Georgi, to pursue a second doctorate, in particle physics, during a three-year postdoctoral fellowship at Harvard.

Dr. Galison's second book traced two different ways of doing particle physics -- studying images like the tracks of cosmic rays recorded in devices like cloud chambers, and counting statistics, like the clicks on a Geiger counter. It showed, said Dr. Weinberg, now at the University of Texas, that ''they are not only different techniques but become whole different ways of life.''

The book's publication coincided with a ''genius'' grant from the MacArthur Foundation. Dr. Galison used it to buy a small house on Cape Cod and as a psychological boost to take risks and be innovative.

He likes to emphasize what he calls ''the disunity of science,'' arguing that the border skirmishes and ''shootouts'' between overlapping subcultures and disciplines inside and outside the laboratory give science its strength and coherence.

"My question is not how different scientific communities pass like ships in the night,'' he wrote in ''Image and Logic.'' ''It is rather how, given the extraordinary diversity of the participants in physics -- cryogenic engineers, radio chemists, algebraic topologists, prototype tinkerers, computer wizards, quantum field theorists -- they speak to each other at all."

To understand this, Dr. Galison has borrowed from anthropology the idea of a trading zone -- languages like creoles or pidgins, for example, where people from different backgrounds can find common ground.

Such trading zones or creoles are the lubricant of large projects. For example, Dr. Julian Schwinger, a Harvard theorist who had worked on the radar project at M.I.T. during World War II, used calculational tricks he learned working with engineers in that work in his Nobel Prize-winning reformulation of quantum mechanics.

''Schwinger takes the techniques that he helped develop during the war to communicate with the radio engineers and brings them back into the heart of physics,'' said Dr. Galison. It's the kind of ''man-bites-dog story'' that he loves.

Clock synchronization functioned as kind of a trading zone in Einstein's day, Dr. Galison said, occupying as it did the domains of physics, philosophy and technology.

''Einstein's Clocks'' began, as Dr. Galison tells it, one spring day in 1997 when he found himself staring at a line of clocks in a Northern European train station.

''There's a whole line of these beautiful clocks,'' he recalled, sitting on the couch in his Cambridge study. He noticed first that the minute hands were aligned, then that the second hands were all ticking in unison: the clocks were synchronized.

''And then I thought, well, wait a second, maybe Einstein saw clocks in stations that were synchronized.''

That was the beginning of an odyssey into a nearly forgotten chapter of history. ''What was amazing was the prominence of synchronized clocks, not the difficulty of finding out about them,'' Dr. Galison recalled. ''They were everywhere.''

At the beginning of the 19th century, he said, many clocks didn't even have minute hands, but by the end of the century the drive for precision and coordination was on, spurred by the demands of trade and national pride and even metaphysics.

''There was a struggle over whose time would dominate, and at every scale.'' Dr. Galison said. ''From trying to synchronize the clocks within an observatory or within a school or within a factory, to counties, states, regions, railroad lines, the country, and eventually there were people who were advocating a single time for the whole world, what they call cosmopolitan time.''

A Step From Relativity
A Frenchman For All Seasons

One of the men in whom physics, philosophy and technology merged was the Frenchman Poincaré. Einstein is a household name today. But at the end of the 19th century, it was Poincaré, a mathematician, physicist, philosopher and member of national academies, who was the famous one -- as consummate an insider as Einstein, toiling in obscurity at the patent office, was an outsider.

As a mathematician and astronomer, Poincaré helped invent chaos theory, Dr. Galison said, and as a philosopher and follower of the French Enlightenment he championed a scheme of decimalizing time.

Among his noteworthy feats now is what he did not do: he did not invent relativity, even though he had some of the same ideas as Einstein, often in advance, and arrived, with the Dutch physicist Hendrik Lorentz at a theory that was mathematically identical.

The difference was that Poincaré refused to abandon the idea of the ether, the substance in which light waves supposedly vibrated and which presumably filled all space. The ether provided a definition of absolute rest, and of ''true'' time -- the time measured by a clock not moving relative to the ether. ''He was truly a universal man; he was one step away from relativity,'' said Dr. Arthur Miller, a relativity historian at the University College London.

Poincaré argued that the laws and principles used to describe reality and do science are simply those that are most convenient -- the notion that parallel lines never meet, for example.

We are free to choose another way to organize experience, Poincaré said, but we don't have to if it would make life more complicated. One such convention, he said, was the notion of simultaneity, what it means to say that two events in separate places happen at the same time.

''There is no absolute time,'' Poincaré said in his book ''Science and Hypothesis.'' ''To say that two durations are equal is an assertion that has by itself no meaning at all and which can only acquire one by convention.''

In 1898, in a philosophical paper, ''The Measure of Time,'' he had set forth such a convention, a method of defining simultaneity -- synchronizing distant clocks -- that was identical to Einstein's scheme. It consisted of telegraph operators sending signals back and forth.

Two years later he pointed out that if his telegraphic procedure was used to synchronize clocks that were moving with respect to the ether, then those clocks would not agree with clocks at rest about which events were simultaneous. Neither he nor Lorentz, however, ascribed equal validity to the times kept by the different sets of clocks. That was the step that Einstein alone took.

When Dr. Galison dug deeper into Poincaré's life, however, he discovered that all this telegraphy was no metaphor.

In addition to all his high-flown academic activities, Poincaré was immersed in practical work. He was a mining inspector, for example. Most important, he was deeply involved with the French Board of Longitude, even serving as president, sending teams of soldiers and surveyors across the oceans to map the far-flung empire.

Coordinated clocks were central to this enterprise. To measure the longitude of some mountain or port or gold mine in the New World, it was necessary to measure the difference between the time some star crossed the meridian there and the time it did back in Paris. The leaders and rivals in filling in this ''electric world map,'' as Dr. Galison calls it, were England and France, even though for several years they were embarrassingly unable to agree on the distance between their own principal observatories, Greenwich and Paris. Paris lost out to Greenwich as the locus of zero longitude, but in 1909 Poincaré used the Eiffel Tower to broadcast time signals to the world.

A Sense of the World
Two Versions Of the Modern

With relativity, Einstein threw out the ether, along with absolute space and time.

Poincaré couldn't do that, Dr. Galison said, because of his conventionalist philosophy. Any intuition that helped make sense of the world was all right to use. The ether was one of those. Giving it up would be like a carpenter giving up a hammer. ''You could, but why would you do that?'' said Dr. Galison.

Ultimate truth was not a reason, he explained. As a good rationalist Poincaré didn't think that scientists should make reference to ''pseudo-religious'' notions like the Order of Nature.

To Einstein the ether was a fifth wheel, Dr. Galison pointed out. Einstein sought simplicity as a clue to underlying truth, often referred to the ''old one.''

''Poincaré never spoke that way,'' said Dr. Galison. For the Frenchman, what you saw in the world was what you got.

Poincaré and Einstein represented two different visions of what modern physics should be like, Dr. Galison said, noting that although he wasn't willing to give up the ether, Poincaré often spoke about a crisis in physics.

Einstein, he said, has been called ''the last 19th-century physicist and the first 20th-century physicist. In a way you could say that of Poincaré too.''

Experts on relativity history agree that Dr. Galison has unearthed fascinating material and built a strong if circumstantial case that Einstein's eureka moment about time could have been influenced by his patent office clock work. Einstein's patent reports were destroyed as part of standard procedure. But the scholars caution that there is much more to relativity than synchronizing clocks. The main thread, they agree, lies in the idea that the laws of physics are the same no matter how fast you are moving and that the speed of light is always the same.

Dr. Miller of London, who discussed the time unification campaign in his own book, ''Einstein, Picasso, Space, Time and the Beauty That Causes Havoc'' (2001), said he was glad that Dr. Galison had dug out Poincaré's connection with the longitude bureau.

So why has this aspect of the origin of relativity lain hidden in plain sight for so long? Although Poincaré was a public figure at the time, he never wrote about his engineering activities, Dr. Galison said.

To some extent, the two men tended to portray themselves as lone thinkers in their later years. In a speech in 1933, Einstein said that being a lighthouse keeper would be a good occupation for a physicist.

''Certainly, from the early 30's to his death in 1955 everything about him and the way he presented himself and the way he was understood by others made him a kind of almost mascot to the idea of isolated thought,'' Dr. Galison said.

''But that is not how he lived his younger life, when he was a sociable guy, passionately involved with Mileva,'' Dr. Galison said, referring to Einstein's first wife, Mileva Maric. He loved to argue, tinkered with machines and spoke out against World War I. ''This is somebody very much in the world.''

In his papers Einstein was always using modern machines to illustrate his ideas, Dr. Galison noted. ''There is something wonderful about Einstein invoking trains and telegraphs to get a transformation of space-time, Poincaré turning the Eiffel Tower into a radio,'' Dr. Galison said.

''In the long run I think what's happened to them is that we, partly through our own doing and partly through our doing to them, removed these physicists from the concrete situations that they were involved in. And I think in a way lose some of the fascination that these ideas had for them and still could have for us in a way.''

It's our loss, he said.


Peter's Work