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"I'm interested in bending the edges of the spectrum to make the abstract and the concrete hit one another more directly." — Peter Galison

EINSTEIN AND POINCARÉ: A Talk with Peter Galison [6.24.03]

I tried to understand how Poincaré and Einstein radically reformulated our ideas of time and space by looking at the way that philosophical abstractions, physical theories, and the technological problems of keeping trains from bashing into each other and coordinating mapmaking across empires might cross in a single story. I began with an extraordinarily simple idea that marked the last century: two events are simultaneous if coordinated clocks at the two events say the same thing. How do I coordinate these clocks? I send a signal from one to the other and take into account the time it takes for the signal to get there. That’s the basic idea, but all of relativity theory, E = mc2, and so much of what Einstein does followed from it. The question is, where did this idea come from? Albert Einstein and Henri Poincaré were the two people who worked out this practical, almost operational idea of simultaneity, and I want to see them as occupying points of intersection—of technological, philosophical, and physical reasoning. They were the two people who stood at those triple cross-sections.



Peter Galison, Professor of the History of Science and of Physics at Harvard, asks how Poincaré and Einstein "could have radically reformulated our ideas of time and space by looking at the way that philosophically abstract concerns, physics concerns, and ... technological problems of keeping trains from bashing into each other and coordinating mapmaking across the empires might fit into a single story."

Regarding Einstein’s and Poincaré’s account of simultaneity, he wonders: "Is it really physics, or fundamentally technology, or does it come down to philosophy?" He calls it "an extraordinary moment when philosophy, physics and technology cross, precisely because of the intersection of three very powerful streams of action and reasoning at the turn of the century."

This moment resonates with many recent discussions on Edge, and to what Galison terms "the collection of sciences that have grown up around computation. Here, ideas about the mind, about how computers function, and about science, codes, and mathematical physics all come together. Von Neumann thinks about the mind and its organs (memory, input-output, processing) as a way of designing a programmed computer. The programmed computer then becomes a model for the mind. The ideas of information, which are encoded into the development of computation, also become ways to understand language and communication more generally, and again feed back into devices. Information, entropy, and computation become metaphors for us at a much broader level."

Convergences such as Einstein’s and Poincaré’s account of simultaneity or new the sciences of computation are "opalescent moments" that "point to science in times and places where we’re starting to think with and through machines at radically different scales—Where we are flipping back and forth between abstraction and concreteness so intensively that they illuminate each other in fundamentally novel ways, in ways not captured by models of simple evaporation or condensation. When we see such opalescence, we should dig into them, and deeply, for they are transformative moments of our cultures."


PETER GALISON is the Mallinckrodt Professor of the History of Science and of Physics at Harvard University and the author of How Experiments End; Image and Logic; and Einstein's Clocks and Poincaré's Maps: Empires of Time.

Two collections of interpretive essays have been published about Image and Logic, which also won the Pfizer Prize for Best Book in the History of Science. For his work on these books he was awarded a MacArthur Fellowship in 1997, and a Max Planck Prize by the Max Planck Gesellschaft and Humboldt Stiftung in 1999.

Peter Galison's Edge Bio page

Peter Galison presents his new book: Einstein's Clocks and Poincaré's Maps: Empires of Time:

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 absolute time that belonged not to our human world, but to the "sensorium of God." Tides, planets, moons—everything changed, Newton believed, against the universal background of a single, constantly flowing river of time. In Einstein's electro-technical 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...Two events simultaneous for a clock-observer at rest are not simultaneous for one in motion. With that shock, the foundation of Newtonian physics cracked; Einstein knew it. Late in life, he interrupted his autobiographical notes to apostrophize Sir Isaac 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; 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 time lay an extraordinary yet easily stated idea that has remained dead-center in physics, philosophy, and technology ever since: To talk about simultaneity, you have to synchronize clocks with a flash from one clock to another, adjusting for the time that the flash takes to arrive. What could be simpler? Yet with this definition of time, the last piece of the relativity puzzle fell into place, changing physics forever.

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