Einstein's Clocks, Poincaré's Maps
True time would never be revealed by mere clocks--of this Newton was sure. Even a master clockmaker's finest work would offer only pale reflections of the higher, absolute time that belonged not to our human world, but to the "sensorium of God". Tides, planets, moons--everything in the Universe that moved or changed--did so, Newton believed, against the universal background of a single, constantly flowing river of time. In Einstein's electrotechnical world, there was no place for such a "universally audible tick-tock that we can call time, no way to define time meaningfully except in reference to a definite system of linked clocks. Time flows at different rates for one clock-system in motion with respect to another: two events simultaneous for a clock observer at rest are not simultaneous for one in motion. "Times" replace "time". With that shock, the sure foundation of Newtonian physics cracked; Einstein knew it. Late in life, he interrupted his autobiographical notes to apostrophize Sir Isaac with intense intimacy, as if the intervening centuries had vanished; reflecting on the absolutes of space and time that his theory of relativity had shattered, Einstein wrote: "Newton, forgive me ['Newton, verzeih' mir']; you found the only way which, in your age, was just about possible for a man of highest thought--and creative power."
At the heart of this radical upheaval in the conception of time lay an extraordinary yet easily stated idea that has remained dead-center in physics, philosophy, and technology ever since: To talk about time, about simultaneity at a distance, you have to synchronize your clocks. And if you want to synchronize two clocks, you have to start with one, flash a signal to the other, and adjust for the time that the flash takes to arrive. What could be simpler? Yet with this procedural definition of time, the last piece of the relativity puzzle fell into place, changing physics forever.
This book is about that clock-coordinating procedure. Simple as it seems, our subject, the coordination of clocks, is at once lofty abstraction and industrial concreteness. The materialization of simultaneity suffused a turn-of-the-century world very different from ours. It was a world where the highest reaches of theoretical physics stood hard by a fierce modern ambition to lay time-bearing cables over the whole of the planet to choreograph trains and complete maps. It was a world where engineers, philosophers, and physicists rubbed shoulders; where the mayor of New York City discoursed on the conventionality of time, where the Emperor of Brazil waited by the ocean's edge for the telegraphic arrival of European time; and where two of the century's leading scientists, Albert Einstein and Henri Poincaré, put simultaneity at the crossroads of physics, philosophy, and technology.
Links to items about Einstein's Clocks, Poincaré's Maps:
Einstein's Clocks, Poincaré's Maps: An Interview with Peter Galison
Part I, Historically Speaking, Volume 5, Number 2, November 2003, pp. 5-9
Part II, Historically Speaking, Volume 5, Number 3, January 2004, pp. 7-10.
Science Historian at Work: Peter Galison; The Clocks That Shaped Einstein's Leap in Time, (NY Times.com, June 24, 2003)
“This is how twentieth-century science really began--not just in abstractions but in machines; not just in Einstein’s brain but in coal mines and railway stations. Peter Galison’s book is engaging, original, and absolutely brilliant.” —James Gleick, author of Chaos.
“Peter Galison provides a masterful and exciting account of the revolution in our understanding of time that occurred at the beginning of the twentieth century. Galison places Einstein and Poincaré at the crossroads of physics, philosophy and technology where the problem of coordinating distant clocks played a crucial role in both the new physics and in the new technology.” —David Gross, Frederick W. Gluck Professor of Theoretical Physics
“In what amounts to a stroke of genius, Peter Galison employs his unmatched ability to depict historical events on many levels and from many vantage points, as well as his unique combination of historical, scientific and philosophical sophistication, to shed fresh light on the revolution in physics that we associate with the word ‘Relativity.’ This is simultaneously an indispensable book for the specialist, and a wonderful “read” for anyone.”—Hilary Putnam, Cogan University Professor Emeritus, Harvard University.
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