About Time

by Adam Frank

  FIGURE 4.5. The triumph of thermodynamics. A giant “Corliss” steam engine on display at the Philadelphia Exposition, 1876. Material engagement in the form of steam power became the basis for both the industrial revolution and the theoretical principles of thermodynamics.

  The second law of thermodynamics told physicists that energy flowed from one form to another in a particular direction. It focused on transformations of energy that produce useful work: a burning fire creates steam, which turns a wheel; an exploding star sets a trillion trillion tonnes of gas into motion. According to the second law, transformations that move energy into a workable form must also create unusable energy. In other words, useful energy transformations always create waste.

  For machines, the consequences of the second law are immediately apparent. A steam engine can never be 100 percent efficient; in burning coal to power it, some of the energy released will go into heating the engine itself rather than turning its gears. The same rules apply for the formation of stars. A cloud of interstellar gas can collapse under its own gravity to form a sun, but the collapse will generate heat, inflating the cloud and slowing the collapse. There will always be waste heat created. Physicists found a way to explicitly calculate this notion of waste heat in a new physical quantity called entropy.

  Entropy can be thought of as the disorder in a system. All energy transformations that do work also create disorder. When you break eggs to make an omelette (the classic example), the tidy system of egg white and yolk gets irreversibly mixed. Thus in making an omelette you produce disorder and entropy. The second law tells us that all energy transformations that do work also create entropy and, most important, that the entropy in a closed system can never decrease.

  This was the principal lesson of the second law: entropy for systems as a whole will always increase and can never decrease. At best, in a closed system, the entropy will reach a maximum value when equilibrium has been reached. At that point all evolution ceases. Place a hot cup of coffee in a box of cold air and heat will flow from the cup to the air until both reach the same temperature. In that final configuration of cup and air in equilibrium, the entropy of the total system will be at its maximum and all further evolution (in temperature at least) is ruled out.

  Time and the second law of thermodynamics seem intimately connected. If you burn a tonne of coal to drive a steam train, the entropy of the system increases. Because you cannot reduce a system’s entropy, you cannot unburn the coal. The transformation can only flow in one direction, and that direction appears to separate the past (low entropy) from the future (high entropy). In the nineteenth century, this so-called arrow of time—moving from past to future—and the entropy increase demanded by the second law appeared to many scientists to be equivalent.69 Nineteenth-century cosmological thinkers quickly incorporated the relationship between entropy and time into new models of the universe’s evolution.

  The second law appeared to have implications for both the beginning and the end of cosmic time. “There is at present in the material world”, wrote British physicist William Thompson, “a universal tendency to the dissipation of mechanical energy”.70 Dissipation meant entropy’s generation of waste heat. Even in 1850 Thompson could see its consequences for the terrestrial future; he proposed that eventually the generation of this “waste” heat in the evolution of the Earth would render the planet “unfit for habitation of man”. In the 1860s Rudolf Clausius took this thinking to cosmological heights, coining the term heat death for the universe. Clausius was sure that thermodynamics demanded a cosmic accumulation of entropy until a maximum was achieved and all further evolution ceased, leading to an eternal and universal stasis.

  The more the universe approaches this limiting condition in which the entropy is a maximum, the more do the occasions of further change diminish; and supposing this condition to be at last completely attained, no further change could evermore take place, and the universe would be in a state of unchanging death.71

  It is noteworthy that these pronouncements were made by physicists rather than geologists or astronomers. What makes thermodynamics so powerful is that regardless of the system—the Earth, a star or the universe itself—the first and second laws will always hold true.

  By the mid-1800s all scientific establishments had come to recognize that evolution was a fundamental principle. Darwin had already shown that life evolved, and geologists such as Charles Lyell had shown that the Earth evolved.72 With its growing focus on dynamics, astronomy had shown that the heavens evolved as well. Could the universe, as a whole, be any different? Clausius and others argued that if cosmic evolution did occur, then its pathways must be no different from those of a steam engine.

  Ready to go further than just predicting the heat death of the universe, Clausius was sure the principles of thermodynamics could be used to rule out some cosmological models as surely as it pointed to the veracity of others. Throughout the nineteenth century, a growing chorus of scientists and philosophers had begun to entertain cyclic, or oscillating, models of cosmic history in which creation was followed by destruction over and over again. According to Clausius, the second law ruled out such models.73 Entropy generated in one cycle could not be disposed of at the beginning of the next. It would persist and eventually drive the whole system to equilibrium. Heat death could not be avoided.

  Just as Clausius used the second law to argue against a cyclic geometry for the cosmic dimension of time, others would use it to argue against an infinite age for the universe. While the entropy of the world must increase towards an equilibrium state, it was easy to see that we have yet to reach that state. Thus, some writers argued, the universe cannot have existed forever and must have originated at some finite time in the past in a low-entropy state. For avowedly Christian scientists such as William Thompson, this apparent “proof” of a beginning held strong appeal. In an address to the British Association of Science, Peter Guthrie Tait, one of Thompson’s Christian colleagues argued,

  The present order of things has not evolved through infinite past time by the agency of laws now at work, but must have had a distinctive beginning, a state beyond which we are totally unable to penetrate, a state, in fact, which must have been produced by other than the now acting causes.74

  This other cause was, for Tait, the God of the Christian faith.

  Infinite time versus finite age—the old debate had arisen again, but for the first time scientists had general scientific principles to use as tools in separating the possible from the improbable. Thermodynamics gave physicists some firmer ground from which to pose their questions and find their answers. When Tait asked, “What happened before?” he was able to set the question in the context of scientific principles of thermodynamics even while reaching to religion to provide an answer. Cosmological thinking was at the edge of a new age in which pure speculation based on purely philosophical reasoning was fading into the past and principles of mathematical physics were rising to the fore. The complete transformation would, however, take time.

  It must be noted that there were also many scientists who rejected the use of thermodynamics for cosmology. Some, including Ernst Mach, claimed that no meaningful statements could be attached to the universe as a whole.75 Others questioned how concepts such as entropy could be used in an infinite universe. It is also noteworthy that the first efforts to use thermodynamics as a cosmological principle remained divorced from detailed contact with astronomical data. So, in spite of thermodynamics, cosmology remained in a foetal stage during the 1800s and was still as much in the province of philosophy as it was in that of science. By the close of the nineteenth century, however, a thermodynamic vocabulary for cosmological debate had already been firmly established, and it would persist into our current era. Even today it shapes our conception of what might lie beyond the Big Bang.

  ENDINGS AND BEGINNINGS: BRAIDING TIME IN COSMOS AND CULTURE

  When considering purely mythological/religious narratives of the universe and time, it was easy to see
how the braiding of cosmos and culture operated. Myths that suited the hunter-gatherer would not serve the farmer, and so they were replaced. But when entering the era dominated by science, the braiding between cosmic and human time becomes more subtle. Technologies don’t simply appear fully formed from cloistered laboratories to do their work changing culture and fostering new cosmological ideas. Instead, the braiding of human time and narratives of cosmic time appear almost fractal—as if every fibre of each strand of the braid separates to form new braids with the fibres of the other strands.

  Broad-brush accounts of cultural needs driving the next breakthrough in technology are too simple to reach the truth. And the truth is so much more interesting than a simple story of humanity simply discovering the objective account of cosmos and time. Cosmologist Edward Harrison, echoing Joseph Campbell in Masks of God, spoke of cultures creating “masks of the universe”. Each mask is a kind of filter for the experience of the universe that cannot be removed cleanly in order to see the “objective” reality that lies behind it. Instead, each mask guides our investigations through the process of material engagement. With the maturation of science, human beings found powerful tools for entering into a new kind of dialogue with nature. The enigmatic entanglement between culture and scientific cosmologies shows us how, in peeling away layers of nature’s behaviour, we also create new masks for what we call the universe.

  As the pace of scientific and cultural change accelerated into the twentieth century, this enigma deepened. In the path to the present and the Big Bang (which now stands on its own precipice), the next step would see the threads of human and cosmic time become even more tightly woven.

  Chapter 5

  THE TELEGRAPH, THE ELECTRIC CLOCK AND THE BLOCK UNIVERSE

  The Imperatives of Simultaneity from Time Zones to Einstein’s Cosmos

  SOMEWHERE BETWEEN NEW YORK AND PHILADELPHIA, USA • 1881, 10:05 A.M. (GIVE OR TAKE)

  He wants to stay calm but it’s not working. Beneath his starched shirt the sweat is rising. So much depends on this interview; how is he supposed to stay calm? Through the train window he watches the landscape rumbling by. Usually travelling by train is exciting, a pleasure. But today he takes no pleasure in the ride. All that matters is that he make it to Philadelphia on time.

  At least the train is moving again. More than an hour was lost as the train sat on the tracks. Oh, God, he thinks, I cannot be late.

  For the twentieth time since he left Newark, New Jersey, he consults the gleaming pocket watch, a present from his new bride. This morning as he scraped stubble from his cheek with his straight razor she stood behind him, her generous smile reflecting in the mirror. “They are going to be so impressed with you,” she said. “How could they pass on such a handsome and intelligent young accountant?” He had tried to smile. Then she showed him the box with the golden watch inside. “A good accountant keeps accurate time,” she said. She threw her arms around him and whispered, “I love you” in his ear.

  FIGURE 5.1. A train on the Pennsylvania Railroad in West Philadelphia (c. 1874).

  He needs this job, needs it badly. All their dreams of starting a family, buying a house—all his dreams for her—depend on his getting this job. But first the train has to arrive on time. He cannot show up late for the interview. He runs through the calculation again in his head. The train left Central Station at 8:25 a.m. and was scheduled to arrive in Philadelphia at 11:55 a.m.1 His appointment was at 1:30 p.m. Now he had lost an hour as the train just sat there on the tracks. It was going to be so close. He looked at his watch again and a chill shot through him as remembered what she had said as he left. It hadn’t mattered then. Now, suddenly, it meant everything.

  “You have to reset your watch when you arrive,” she’d said. “Remember, Philadelphia is far away. They have their own time.”

  A NEW NOW

  Fifty years was all it took to partition the world’s hours. After covering tens of millennia in our story of human and cosmic time, we now reach the boundaries of our modern life—a world of legalized, compressed and metered time. From the Palaeolithic to the Neolithic, from the first city-states to the Greeks’ rational cosmos, from Newton’s mechanics to the industrial revolution, human time has changed and changed again. Cosmic time, in narratives of mythic creation or scientific evolution, has transformed as well. These changes reflected and refracted off each other as our engagement with the raw stuff of the world shaped the institutional facts of each human life. Our story of these changes has, up until now, run with the rhythm of centuries. For the most part, entire generations could pass with only small differences in their experience.

  There are only forty or so years separating the American Civil War and Albert Einstein’s theory of relativity. In those four decades, human time and cosmic time would undergo profound transformations and influence each other as never before. In 1865 railways, powered by the same steam technology that had driven the industrial revolution, were in the middle of their assault across the continents.2 In that same year telegraph cables threading electrical impulses into instantaneous communication were just beginning to bind far-flung cities to each other.3 As distance shrank, time became problematic in an entirely new way.

  Simultaneity—the balance between your time in your location and my time in my location—suddenly moved from abstract physics into the realms of nation building and economic necessity. In 1865 simultaneity was just beginning to become an issue of contention. In 1905 Albert Einstein would make it a cornerstone of his radical revision of physical law that would lead the way to the first true scientific cosmology. The confluence of real-world and theoretical concerns with simultaneity would prove to be no accident.

  RAILWAYS AND TIME ZONES

  It was a crisp autumn day in Chicago when the modern meaning of “now” was legislated into existence. On October 11, 1883, the first General Time Convention convened in this great hub of the American Midwest. Its mission was to rationalize the patchwork of hours that had spread like vines across a nation newly connected by transcontinental trains. Time reform was the order of the day.

  In the United States and Europe, the growth of railways connecting city and village alike reshaped the human experience of distance and time. One hundred miles lie between New York and Philadelphia. In the 1770s, the fastest time in which that distance could be covered was two days (via carriage).4 By the 1880s, regular train service cut the trip to a mere three and a half hours.5 By linking distant cities in short trips, travellers were forced to confront the new and vexing issue of time standards. Each large city kept its own standard. Whose time was the traveller bound to? The clocks of each city were set according to a regional time standard often provided, remarkably, by astronomers working at the local university observatory. Thus noon in New York was not noon in Philadelphia.6

  Before the advent of trains these local differences in time did not matter. If it takes a day and a half to travel from New York to Philadelphia, you are not likely to care about a five-minute difference in the definition of 2:00 p.m. If, however, you are planning to leave Philadelphia by catching the 5:05 back to New York after a day of business, those five minutes suddenly rise in importance. Thus the public meaning of time and the personal experience of “now” were reshaped in the forge of cultural innovation. As William Allen, secretary of the General Time Convention of Railroad Officials, put it, “Railroad trains are the great educators and monitors of the people in teaching and maintaining exact time.”7

  By 1880 a schizophrenic patchwork of local times had emerged. To deal with the mess, American railways adopted an ungainly convention. Inside the train, clocks were set according to specific major cities on a given railway line.8 That meant it could be 1:00 p.m. inside the train and 12:00 p.m. in the towns the train was passing. By 1883 there were at least 47 lines on New York time, 36 taking time from Chicago and 33 with clocks in sync with Philadelphia. It was a mess of hours.9

  Things were worse in France, as Paris became the standard fo
r all railway lines. A traveller in Nice, almost six hundred miles from the capital, would experience three different times as he approached a railway station. First there would be the local time given by the clock in street; then he would find Paris time given by a clock in the railway waiting lounge; finally, he would encounter train platform time—set a few minutes different than Paris time to give the confused traveller “a margin of error” in catching his trains.10

  The call to rationalize time rose across the world. The United States, with its continent-spanning jurisdiction, led the charge. The problem lay in the difference between the experience of local time—interpreted as it had always been by local celestial rhythms—and the new traveller’s time, which had outpaced the planet.

  The determination of noon, for example, depends on where you are on the rotating, spherical Earth. Define noon to be the moment when the sun reaches its highest point in the sky. Now imagine the meridian that runs along the Earth’s surface from the North Pole to the South Pole and cuts right though where you are standing. Anyone standing anywhere along your median shares your understanding of noon and therefore shares your time. Their astronomically defined “now” will be the same as yours. But if you step just a little to the west or to the east, the astronomically defined time standard (noon, midnight, etc.) shifts. Time reformers at the Chicago meeting were demanding a global convention that would move people away from this local sun-centred interpretation of time.

  Throughout the 1870s various schemes were submitted, some more radical than others. Taking reform to its extreme, Sandford Fleming, a powerful empire-building Canadian railway engineer, proposed a single worldwide system.11 Under Fleming’s plan it would be 3:00 a.m. everywhere on the planet at the same time regardless of local conditions of day or night.