Double vision

I still remember the smell of the tobacco smoke. Bans on indoor smoking had recently gone into effect, but there had been no provision to fumigate, and a haze lingered throughout Professor Joseph Harris's office. Still, as a student at Dartmouth College, I found myself racing up three flights of creaking wooden stairs to visit him in the Department of Physics and Astronomy nearly every day. From the moment I arrived on campus as an overeager undergraduate, Harris's musty, book-choked enclave held me in a special kind of thrall.

A professor of both physics and thehistory of science, David Kaiser recently collaborated on a simulation of the "reheating" phase followingcosmic inflation, which could have laid the groundwork for the Big Bang. His latest book explores the history of quantum physics.

I couldn't know it then, but those many hours I spent talking with Harris set me on an unusual path, ultimately helping me build a career as a physicist and historian of science. After 20 years on the faculty at MIT, I still find myself grappling with some of the questions that Harris opened up for me all those years ago in his cramped, pungent office.

Back in the late 1950s, Harris had been a postdoc, advised by the legendary quantum physicist Werner Heisenberg in Munich. His scientific passion centered on Albert Einstein's general theory of relativity, that elegant description of gravitation as a mere side effect of the warping of space and time. By the time I met him, Harris had long since settled into the classic habits of a liberal arts professor, letting his interests wander broadly. He typically had a few recent textbooks on general relativity open on his desk or stacked, haphazard and dog-eared, on a nearby table, inter-leaved with books on everything from the history of an astronomical observatory in 13^th-century Persia to the letters of the novelist Thomas Mann (in the original German, nati1/4rlich).

I had found my way to Harris's office even before classes began for my first semester of college. During one of my initial visits, he listened with a kindly smile as I breathlessly recounted stories he surely knew about Einstein and Heisenberg-things I'd read in the popular books I'd devoured as a high school student about the grand mysteries of modern physics. Then he leaned back in his chair and told me that there was a whole field of study known as the history of science. People specialized in the field, he said, and their rich, empirical studies of science, culture, institutions, and politics were often much more interesting-and far more revealing of what it meant to study nature-than the well-worn tales of genius I had absorbed as a kid.

Harris directed me to two historians of science on campus. Under their guidance I began to explore books and articles by other historians, ranging from studies of Copernicus and the slow-grinding transition to heliocentrism to the early stirrings of quantum theory amid the swirling uncertainties of the Weimar era, right after Germany's shocking defeat in the First World War. These studies were animated by intriguing questions: What does it take to convince a broad scientific community to adopt new ideas or approaches? How do new techniques-so often rooted in specific times and places-percolate to new researchers or become second nature to the next generation?

These questions tugged at me as I dived into my problem sets and laboratory courses in the physics department. Soon the example of Naomi Oreskes-one of the two historians of science I studied with-became as inspiring to me as her classes. She had recently completed PhDs in both geology and the history of science. Her own history advisor in graduate school, Peter Galison, had pursued a similar course not long before, completing PhDs in physics and the history of science. Naomi and Peter became a kind of existence proof for me: it was possible to pursue these paired interests in a serious way.

We are immersed in the particulars, moment by moment, even as so many of us dream of contributing insights that might endure beyond the horizon of our historical circumstances.

I applied to PhD programs in physics and in the history of science, sending off six applications to three institutions. I wound up at Harvard, where I worked closely with Galison and became especially fascinated by the impact-both on the world of ideas and on specific institutions-of massive wartime ventures like radar and the Manhattan Project. Graduate students who studied physics soon after the Second World War-Joe Harris's generation-encountered a discipline that had been utterly transformed. Budgets and enrollments for physics were skyrocketing; cultural shifts were afoot as well. "Physicists are in vogue these days," declared one observer in Harper's magazine in 1946. "No dinner party is a success without at least one physicist." (Oh, how the times have changed.)

For my physics research, I explored a different era of high drama: the earliest moments of cosmic history, around the time of the Big Bang. Beginning in the early 1980s, MIT physicist Alan Guth '68, PhD '72, had upended conventional ideas about the early universe with his theory of cosmic inflation. During inflation the wobbly trampoline of spacetime, as described by Einstein's relativity, should have stretched at a mind-boggling rate, doubling in size every trillion-trillion-trillionth of a second. Tiny quantum fluctuations-an unavoidable consequence of Heisenberg's uncertainty principle-would have been stretched too, ultimately seeding the lumpiness we see throughout the universe today, with huge clusters of galaxies separated by enormous voids. Joe Harris and others had introduced me to these ideas during my undergraduate studies, which only left me hungry to learn more. Alan kindly agreed to advise my physics dissertation, and I got in the habit of riding the Red Line between Harvard and Kendall Square.

Thanks to a joint MIT faculty appointment in both the Program in Science, Technology, and Society and the Department of Physics, I have continued to wrestle, in my research and teaching, with questions that were first sparked for me in Joe Harris's smoky office: questions

revolving around a kind of doubleness of scientific research. So often, scientists have aimed to transcend their limited view and to craft some lasting bit of knowledge about the world. Yet each of us-Einstein and Heisenberg no less than today's researchers-encounters the world from a very particular vantage point. We are immersed in the particulars, moment by moment, even as so many of us dream of contributing insights that might endure beyond the horizon of our historical circumstances.

In one sense, the smoke has cleared; my office smells nothing like Joe's. But the questions remain. What a remarkable privilege it is to puzzle through them with new students of my own.