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University of Chicago Press
A Tenth of a Second: A History

A Tenth of a Second: A History

by Jimena CanalesJimena Canales


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In the late fifteenth century, clocks acquired minute hands. A century later, second hands appeared. But it wasn’t until the 1850s that instruments could recognize a tenth of a second, and, once they did, the impact on modern science and society was profound. Revealing the history behind this infinitesimal interval, A Tenth of a Second sheds new light on modernity and illuminates the work of important thinkers of the last two centuries.

Tracing debates about the nature of time, causality, and free will, as well as the introduction of modern technologies—telegraphy, photography, cinematography—Jimena Canales locates the reverberations of this “perceptual moment” throughout culture. Once scientists associated the tenth of a second with the speed of thought, they developed reaction time experiments with lasting implications for experimental psychology, physiology, and optics. Astronomers and physicists struggled to control the profound consequences of results that were a tenth of a second off. And references to the interval were part of a general inquiry into time, consciousness, and sensory experience that involved rethinking the contributions of Descartes and Kant.

Considering its impact on much longer time periods and featuring appearances by Henri Bergson, Walter Benjamin, and Albert Einstein, among others, A Tenth of a Second is ultimately an important contribution to history and a novel perspective on modernity.

Product Details

ISBN-13: 9780226093185
Publisher: University of Chicago Press
Publication date: 01/01/2010
Pages: 269
Product dimensions: 6.10(w) x 9.10(h) x 1.00(d)

About the Author

Jimena Canales is associate professor of the history of science at Harvard University.

Read an Excerpt


By Jimena Canales


Copyright © 2009 The University of Chicago
All right reserved.

ISBN: 978-0-226-09319-2

Chapter One


Dwell, for a moment, on a tenth of a second. What do we know about this short period of time? What do we know about its history? Since yesterday, hundreds of thousands of tenths of a second have gone by. A year comprises hundreds of millions of these moments. How can we possibly begin to tell their history? Luckily, traces of it already exist. Many areas of science and culture have been concerned with the tenth of a second, and these accounts offer us a glimpse, albeit an oblique one, into its history.

References to the tenth of a second appeared in two main areas. The first area was predominantly scientific and technological. Starting in the mid-nineteenth century scientists associated this value with the speed of thought. This relation led them to perform reaction time experiments that increasingly defined the field of psychology. Analyzing moments of the order of the tenth of a second was also central to the study of measurement errors and to the development of numerous instruments devised to eliminate them. Entire disciplines, ranging from astronomy to physics, were profoundly affected by errors of this magnitude. Some of the most important measurement practices and techniques in science—from the straight lines used to divide rulers to cinematographic machines—were designed to cope with them. The second area was more broadly philosophical: references to this short period of time were part of a general inquiry into time, temporal development, and sensory experience. By extending these investigations, we can begin to use the tenth of a second as a way to rethink much longer historical periods.

The first concern was practical, and to study its history we must delve into secluded laboratory spaces, technical scientific texts, and into the minute details of one of the most mundane of scientific practices: measuring. The second concern with the tenth of a second was speculative, reflective, and open-ended. Its central purpose was to think about these moments in relation to science, technology, and modern culture. The first was narrow, the second broad. The first (scientific and technological) can be dated with precision: a concern with the tenth of a second in science intensified during the mid-nineteenth century and waned significantly by the beginning decades of the twentieth. The second one (philosophical), less so, since it continues to appear today. Both had repercussions for general culture, affecting areas beyond science and philosophy and encompassing the arts, industry, and media.

By studying the tenth of a second through these two complementary perspectives, this book reveals some of the key characteristics of the modern era and illuminates the work of some of the most important scientists and philosophers of modern times. It also offers a way to productively extend their work in new directions.

The Specificity of This Moment

The tenth of a second is, of course, not the only time interval of interest to scientists, and certainly not the shortest. In fact, since the early nineteenth century scientists had been able to measure, depict, and (later) photograph much shorter periods of time. Lensless microscopic technologies pioneered by Ernst Chladni revealed infinitely small vibrations in the complex patterns left by fine sand on vibrating plates. Similar experiments used moving mirrors to study the even smaller vibrations of tuning forks. Chronoscopes, chronographs, and myographs measured time in much smaller units, well into thousandths of a second. Photographers, first among them Henry Fox Talbot, recorded shorter periods of time by illuminating fast events with electric sparks. Others used multiple cameras, multiple lenses, or naturally intense sources of illumination. Late nineteenth- and early twentieth-century bullet, splash, and solar photography frequently went far beyond tenth-of-a-second limits. When photographic exposure time was further reduced at the end of the nineteenth century, even common subjects, including horses and birds, were captured in much smaller time periods. In 1878 Eadweard Muybridge famously photographed running horses galloping in a manner never seen before, seizing them in a 1/500th of a second by using multiple cameras. In 1882, single-lens photographs made by the French physiologist Étienne Jules Marey surpassed this limit. By 1918, Lucien Bull, the last assistant to Marey, was able to photograph fifty thousand images in one second. In the 1930s, Harold Edgerton's stroboscopic images produced at MIT captured images in the span of a 1/3,000th of a second. Today, millions of frames per second can be recorded.

In the midst of these ever-finer slices of time, the tenth of a second retained a particular salience. Tie a piece of coal to one end of a string and twirl it rapidly. If the coal makes a complete turn in less than a tenth of a second, it will seem to form a closed circle. Slow down its speed and the closed circle disappears. Try this experiment with a cinematographic projector. If successive frames pass at a speed exceeding the tenth of a second, the illusion of movement appears smoothly. Reduce its speed, and the illusion disappears. Look closely at a rapidly moving target and try to time the precise moment when it crosses a specific point. Compare the moment with somebody else's and you will see that each of your determinations will probably differ by a few tenths of a second. Step on the brake of your car when an obstacle appears in front of you, and despite your best efforts, a lag time, close to a tenth of a second, will haunt your reactions. Try to read as many words as you can in ten seconds, and you will notice that the number is about a hundred: one word every tenth of a second. Time yourself while talking, and you will see that the time needed to pronounce each syllable will never be less than a tenth of a second. Analyze the electrical rhythm of your brain, which, when at rest, will average ten cycles per second. Study a "perceptual moment" and find that it lasts about this same amount.

These mundane effects, some known since antiquity and others discovered more recently, brought with them a host of philosophical riddles, paradoxes, and questions. Were they due to limitations in the processing speed of the brain, and if so, was this speed measurable? Could it be increased or decreased? Did they point to particular physiological qualities of the human body beyond the brain, such as the speed of nerve transmission or visual persistence? How and when did these effects stray from the tenth of a second? What evolutionary function, if any, did they serve? Were they related to fundamental aspects of the universe and the cosmos? How did they veil our access to reality? Could scientists, engineers, or inventors devise technologies to overcome or alter these effects or defects? How did they transform basic beliefs about causality, movement, and history? How were they incorporated into theories of knowledge?

Answers to these questions were frequently volunteered by scientists, some of whom were influential in crafting new technologies and improving on existing ones (such as telegraphy, photography, and cinematography) to investigate these short moments of time. Yet other answers had to do with understanding the tenth of a second in relation to the much longer period known as modernity. The development of science and technology was seen as an essential characteristic of modernity, and attempts to demystify these short periods of time were considered essential to the survival of the modern project. At stake in the exceptionalism of this instant lay the exceptionalism of modernity itself. The category of modernity itself was, in a sense, parasitic on this moment.

As scientists introduced the language of modern communication theory, employing terms such as "message" and "transmission," they increasingly referred to the tenth of a second. The mid-nineteenth-century descriptions by the influential scientist Hermann von Helmholtz are characteristic: "When the message has reached the brain, it takes about one tenth of a second, even under conditions of most concentrated attention, before volitional transmission of the message to the motor nerves enables the muscles to execute a specific movement." "Self-consciousness," he noted, lagged "behind the present" by an amount equal to "the tenth part of a second." By the 1880s it was common knowledge on both sides of the Atlantic that "the time required by an intelligent person to perceive and to will is about 1/10 of a second.... After allowing for the time required to traverse all of the nerves and for the latent period of the muscles, there still remains about 1/10 second for the cerebral operations."

Almost a century after Helmholtz's investigations, Thomas Edison's chief laboratory engineer was amazed at how "modern communication has greatly increased the interchange of methods and ideas between the nations through the telegraph, the telephone and radio," bringing the world closer together. Yet, even then, the project had not been entirely completed. Communications were still colored by transmission delays of this same magnitude. "We all live," he concluded, "on a tenth of a second world."

Why did the tenth of a second gain such importance in modernity? A psychologist would likely respond: "because of reaction time." William James, for example, referenced this value in his classic Principles of Psychology: "The time usually elapsing between stimulus and movement lies between one and three tenths of a second." Another psychologist could then continue to explain the value of such research, ranging from the speed of thought, to improving industrial production, to simple survival in the modern world. Hugo Münsterberg, the head of the first laboratory of experimental psychology at Harvard University, described the immediate relevance of this value: "If a playing child suddenly runs across the track of the electric railway, a difference of a tenth of a second in the reaction-time may decide his fate." If the speed of reaction could be increased by a tenth of a second, another researcher explained, we could find a way to "preempt death itself."

An astronomer might say "because of the personal equation," referring to the worrisome fact that different individuals differed in their timing of star transits. 0 Referring to two well-known astronomers, the famous historian of psychology Edwin G. Boring explained the meaning of the term: "The equation, 'A - S = 0.202 sec.,' means that on average [the astronomer] Argelander observed transits 0.202 sec. later than [the astronomer] Struve." While the relative personal equation compared two observers against each other, the absolute personal equation compared one observer's timing of an event against the time as determined by a machine. It again took the shape of an equation, where a single number was assigned to a particular person. A personal equation is rarely exactly a tenth of a second; its value tends to oscillate between one to a few tenths of a second. It is often also sometimes much more than simply an equation, since the intriguing term is often used in literary ways.

A cinematographer, on the other hand, would explain its importance in terms of the visual threshold needed for images to fuse and appear to move. Philosophers, historians, and sociologists of science would give additional answers, some of which would be central to their explanations of how we gain knowledge of the natural world.

Here lies one of the most intriguing aspects of the tenth of a second. While it appeared as a problem in the most detailed and minutely technical accounts of precision science, it was also representative of larger questions about the role of science and technology in modern culture. It was a problem that was simultaneously "of" science and "about" science—scientific and technological as well as epistemological, philosophical, and cultural.

By investigating this moment of time this book seeks to answer three questions. First, how was modernity marked by a distinctive conception of the tenth of a second? Second, how did the tenth of a second affect knowledge practices across scientific disciplines? Third, what fundamental changes in our approach to history can help us better understand the development of modern science? Allow me to elaborate.

The tenth of a second was a distinctly modern and post-Cartesian concept. When Descartes described the reaction of a person to a stimulus in his Treatise on Man, reaction and stimulus occurred "at the same time."

Trust in the instantaneity of nerve transmission continued into the first half of the nineteenth century. But as the century progressed, scientists started to question whether this velocity was indeed infinite. What preoccupied thinkers after 1850 was the existence of a lag time—of the order of a tenth of a second—between stimulus and response. Scientists became increasingly uncomfortable with the mind-body dualisms of Cartesian philosophy and instead focused on interfaces (such as nerves) between these two, increasingly problematic, terms.

This change was also distinctly post-Kantian. A longstanding Enlightenment and Kantian tradition treated free action as unquantifiable. But from the 1850s onward, scientists increasingly turned to tenth-of-a-second measurements to explore the mechanisms of thought and of the will. By the first decades of the twentieth century Edward Bradford Titchener, founder of the first laboratory of psychology in the United States, could claim that reaction time measurements were a "crucial experiment" demonstrating that mental phenomena were measurable. A focus on reaction time would reach its apogee with behaviorism. John Watson, the movement's founder, explained that the purpose of psychology was "to predict, given the stimulus, what reaction will take place; or, given the reaction, state what the situation or stimulus is that has caused the reaction."

Traditional Kantian divisions distinguishing quantifiable from unquantifiable phenomena proved to be, if not totally incorrect, certainly overstated. Research on reaction time was used to extend quantification to the analysis of voluntary action. Quantitative sciences were no longer limited to the realm of inaction. Post-Enlightenment scientists embarked instead on the Faustian quest of extending the reach of measurement-based science to new spaces and exposing the most remote corners of the human psyche to its searching light. As a result, scientists increasingly described perceptual and communication processes in terms of stimulus, message, transmission, reception, and response—essential categories that would dominate numerous discourses well into the twentieth century.

A Proliferation of Hybrids

The process of discovering what lay within tenth-of-a-second moments was fraught with social, philosophical, and even theological controversy. The issues at stake become particularly clear in comparison to the famous seventeenth-century confrontation between Thomas Hobbes and Robert Boyle on the existence of the vacuum. Readers of the debate remind us that their disagreement strengthened the modern divide between the "politics of man" and the "science of things." As a consequence of their confrontation, it became commonplace to think in terms of either politics or science, but rarely in terms of both. The "two cultures" organization of experience was arguably one of the most important legacies of the Scientific Revolution.

The consequences of later debates about tenth-of-a-second moments are quite different. These controversies marked a new era, commonly called the Second Industrial Revolution or the Second Enlightenment. This revolution was neither one of great men nor of great machines. It was characterized by science-based industrial systems based on new connections between hardware (mainly telegraphy, steam, and rail) and wetware (mainly eyes, nerves, and brains). During this period the neat division between "science" and "politics" started to be haunted by numerous problems that did not fit into these exclusive categories. Let me give one example. The relevant problem for philosophy of science was no longer principally based on longstanding questions of objectivity (or matters of fact) and subjectivity (or matters of concern). Instead of struggling with the classic question of how universal, objective knowledge was different from subjective knowledge, scientists and philosophers confronted the problem of observations that varied among and within individuals. The problem was not solely of humans and nature. It was also of humans against humans. It was not only about what was true, but about who was right.


Excerpted from A TENTH OF A SECOND by Jimena Canales Copyright © 2009 by The University of Chicago. Excerpted by permission of THE UNIVERSITY OF CHICAGO PRESS. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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Table of Contents



1. Introduction

2. Reaction Time and the Personal Equation

3. The Measure of All Thoughts

4. Moments of Contact

5. Captured by Cinematography

6. Stabilizing Physics

7. Reacting to Relativity

8. Conclusion




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