About Time

by Adam Frank

  Thus we have myth on one side and the Greeks on the other, each defining a set of responses to the cosmos and time that would endure even while they responded to cycles of cultural change. For Gleiser, the impulse behind the earliest creation myths is the same one driving the modern science of cosmology. In one key respect the result of both efforts has been the same. Gleiser distils the range of our responses to the cosmos and time into two distinct forms, two distinct geometries of time: creation myths and no-creation myths.

  A universe born with time constitutes one mythic response to origin questions. These creation-based myths were quite common in civilizations spawned by the Western urban revolution. The universe is created and time begins with that creation. This may occur through the action of a creator or emerge from a timeless background of chaos. In either case, time and the cosmos are joined. “Before” creation there is no time, no duration and no ordered sequence of events.

  By contrast, no-creation myths imagine a universe without a beginning. Some proposed a cosmos with an infinite past and an infinite future that would need no beginning. There was always a cosmos and there was always time. Another possibility explored in myth is a universe of eternal cycles. Time simply forms a loop in these myths, with cosmic history being played out over and again throughout eternity. There is a beginning but there is also a before.

  In the Bible, the origin narrative of Genesis clearly falls into the first category. The creator, Jahweh, wills the universe into being from nonbeing. An undifferentiated whole soon separates into opposite components. It is noteworthy that Genesis differs from other creation myths by its absence of an initial state. The darkness and the waters of Genesis do not exist before God’s decision to initiate the act of creation. In order to emphasize God’s absolute dominion over creation, the later Church would adopt the doctrine of creation ex nihilo (creation from nothing), though it is not mentioned explicitly in the Bible. This has often been taken to mean that time was created with the universe, since God himself must be timeless.

  The Hindu mythologies of the dance of Shiva fall into the second category. In this myth, endless cycles of creation and destruction are manifest through the great god Shiva’s cosmogenic choreography. A remarkable aspect of the Hindu mythic imagination was its attempt to grasp the impossibly large numbers associated with the cycles of cosmic history. One cosmic turn of creation and destruction was called a mahayuga and was reckoned to last 12,000 gods’ years, with each divine year being the equivalent of 360 human years. Thus, each cycle lasted more than four million solar years. A kalpa was a single day in the life of the divine godhead Brahma (a deity below Shiva) and it consisted of two thousand of these mahayugas. There would be many Brahmas, each destined to die and be reborn. The lifetime of a single Brahma lasted one hundred Brahma years, or more than three hundred trillion human years. In these vast stretches of time we can see an early attempt, written in myth, to embrace the intuitive sense that creationless cosmic histories must stretch across vast horizons of time.

  Gleiser’s schema allows us to see how the legacy of our mythologies maps out two basic geometries of cosmic time. Creation myths imagine time as a straight line with a beginning point. No-creation myths imagine time either as a straight line extending infinitely in both directions or as a circle. As we will see in the chapters that follow, the history of cosmology describes our varied explorations of these models. And, as we shall see, the dominance of one model over the other from one era to the next is not random. Rather, it is critically dependent on the way each culture engages with the material world and how the material world pushes back.

  The Greeks first expressed these possibilities in myth, then abstracted them so that their logical possibilities in a fully natural, fully rational universe might be explored. The basic possibilities for the dimensions of time were fleshed out in Greek debates about change versus timelessness and an eternal cosmos versus a created cosmos. Later, the Greeks saw conceptual dilemmas implied by the existence of a true vacuum and the possibilities of other universes. By the end of their era the bedrock of future cosmological debate had been established.

  Thus from the era of myth to the era of the Greeks we can see a finite set of questions emerge that would come to guide nearly all future debate and future cosmological imaginings.

  Question 1: Is there a universe or a multiverse?

  Is what we see, all the stars and galaxies, all there is to the universe? Are there other collections of matter we can’t see? Are there other universes with laws that differ from our own?

  Question 2: Is space infinite or bounded?

  Does space extend forever? Does it have a boundary? If so, what lies beyond the boundary?

  Question 3: Does space exist by itself?

  Is a true vacuum possible, or does space exist only relative to the matter that fills it? Would space exist in a universe without matter?

  Question 4: Does time exist by itself?

  Is time a real property of the universe? Or does it exist only relative to changes in matter? Would time exist in a universe without matter?

  Question 5: Does the universe have a beginning and/or an ending in time?

  Did the universe come into being? Will it come to an end? If so, what came before and what will come after? If the universe is eternal, how is such a thing possible?

  These five questions will appear again and again in the braided narrative of cosmic and human time. In each culture’s response—from the age of myth to the digital age—we will see the way lived experience and the seemingly abstract realms of cosmic time are entangled.

  Chapter 3

  THE CLOCK, THE BELL TOWER AND THE SPHERES OF GOD

  From the Medieval Monastery to the Renaissance Cosmos

  MONTE CASSINO, ITALY • 1100 CE

  The Frenchman was in trouble again.

  The abbot looked at the sleeping form slumped forward in the pew and asked God for patience. Outside it was dark. The monastery was still deep in its night-time stillness. The abbot was not usually awake so late but his ongoing tussle with the Vatican, eighty miles to the north, had robbed him of sleep once again.1 Every year was the same but he fretted over it nonetheless. With sleep impossible, the abbot had decided to join the late-night prayers. So it was, with considerable dismay, that the abbot had entered the sacristy to find Brother Jacques—the monk assigned timekeeping—asleep again and missing the call to prayer.

  The abbot bit his lip. He was not one to indulge in anger. Still, the offices of the Church must be maintained. It was St Benedict himself who had established the Rule, breaking the day into horae (hours), the regular rounds of prayer that formed the meter of monastic life. Each day, every day, year in and year out, the Benedictine monks at Monte Cassino moved through their ordered days of prayer. It was the heartbeat of their worship. “Truly are they monks, if they live by the work of their hands,” the abbot would tell his charges, quoting St Benedict.2 The division of the day into periods of work and periods of prayer was a mirror of God’s own divine order. Some of his monks listened and applied themselves in earnest exaltation. But some were burdened by the sin of sloth, none more so than his dear Frenchman.

  Father Jacques had come to him as a refugee from the Cistercians and had begged to join the order at Monte Cassino. His love for the Lord and for monastic life was so apparent that the abbot could not turn him away. But Father Jacques had failed at almost every job the abbot turned him to. In desperation he assigned the Frenchman the role of sacrist—keeper of the horae, ringing the bells that alerted brothers to the change of time and called them to prayer. The position of sacrist was an important one.3 There was, of course, no exact measure of the change. He had heard that some monasteries used sandglasses to mark the hour but he found such practices distasteful. God’s time could not be marked off like an account book. Instead he taught them to watch for the signs, the rising morning stars in the east and the waking of birdsong. “God’s signs from Nature for God’s prayers,” he called i
t. That was enough. But, of course, one had to be awake to read those signs.

  The abbot drew a long breath, let compassion wash over him and said, “Jacques, Jacques. Dormez-vous? Wake up. Wake up!”

  FIGURE 3.1. Monks keeping time in a monastery. The monasteries provided the model for a new form of “time consciousness” as Europe emerged from the Dark Ages. From Heinrich Seuse’s Horologium Saptieniae, c. 1406.

  TURNING OF THE WHEEL: FROM SKY TO CLOCK

  The day we live now, made of hours rigidly fixed like moths pinned in a collector’s display case, began at the intersection of man’s world and God’s cosmos. The first intimation of our modern metered day was born in the insular world of the Dark Ages. Medieval monastics provided the archetype of our time in their ritual of the canonical hours—the divisions of the day into separate rounds of prayer. From sunrise to sunrise, the monks marched through the horae canonicae, the rounds of worship beginning from sunrise (matins) through midday (sext) and sunset (compline) and around through the night to matins again.4 The horae were announced by watchful brothers. Each hora, with its prayers and duties, had its place within the ordered day of work and worship of God.

  Europe’s Dark Ages began sometime around the fifth century CE and did not retreat until after 1100 CE.5 In the long years after the fall of Rome, the baton of learning and inquiry—and a trove of Greek and Latin texts—had passed to the Islamic empires. Ptolemaic astronomy continued its dominance as Muslim scholars charted the skies with increasing accuracy and invention. Then Europe slowly reawakened to its own ingenuity, and time and cosmos were shaped again.

  CALENDARS RULE: POLITICS, RELIGION AND TIME MATERIALIZED

  The European Middle Ages were, for the most part, lived on Roman time (as we are still today).6 Our word calendar derives from the Latin calends, denoting the Roman designation of the months beginning at new moon.7 The earliest Roman calendars were based on counting monthly cycles of the moon rather than marking the sun’s cycle through the sky. According to archaeoastronomer Anthony Aveni, the first Roman calendars were conveniences for farmers and may have been little more than listings of festivals and “rights days” when business could be conducted. While counting the astronomically imposed monthly cycles that formed the basis of the early Roman time reckoning, a purely economic time unit also emerged in the form of an eight-day “market week”. Altogether, the early Roman year was based on a ten-month cycle, and each month contained thirty days.8

  While the Romans were well aware that a solar cycle contained approximately 365¼ days, their shorter 300-day year was not considered a problem. The extra two months occurred during the seasons when fields were not productive. In a sense it was a time of no time; at least, time did not need to be tallied.

  By the last century BCE, the Romans were well on their way to controlling much of the Western world. One of the principal demands of the nascent empire would be a more rationalized time. Our word rationality takes its original meaning from the Latin ratio, and indeed, calendars came to focus on the ratio of two critical numbers.

  Attempts to fit the 29.5306-day lunar cycle into the 365.2422-day solar cycle animate much of the calendar’s story.9 Divide the length of the year by the length of the month (365.2422 ÷ 29.5306) and you end up with the number 12.3683.10 As Roman society became more complex it demanded continuous time reckoning. It was relatively easy to build a socially agreed-upon year with twelve months. But the remaining 0.3683 month could not be ignored. It left approximately eleven days of each solar year consigned to limbo. If unattended, those eleven days could set the year adrift, sending months sliding through the seasons until the winter months begin to appear in midsummer. To overcome this dilemma, the Romans gave most of their months twenty-nine or thirty-one days, leaving only February with twenty-eight days. But this manipulation was still not enough to bring the months into perfect temporal alignment with the year. A fraction of a day still remained unaccounted for. Wait long enough and even that sliver of a day would push the months through the seasons until summer festivals were celebrated in snow.

  By the end of the Roman republic, a special class of calendar “priests”, or pontifices, was created. A pontifex’s job was to periodically manipulate the calendar in order to keep the months and seasons in line by inserting an extra twenty-seven-day month known as Mercedonius.11 In a clear example of material engagement yielding new institutional facts, time and politics were swept together as pontifices purposely manipulated the intercalation, delaying or speeding up the insertion of the bonus month to benefit themselves or their friends. Then, in 63 BCE, an ambitious young politician with dreams of military glory was elected pontifex maximus. His name was Julius Caesar. In 46 BCE, after conquering Gaul and winning Rome’s bloody civil war, Caesar undertook a dramatic temporal reform. The Julian calendar, with its six 31-day months, five 30-day months, and 28-day February, became the standard.12 Every fourth solar cycle became a leap year with an extra day added to February to keep the months and seasons in line.13

  The Julian calendar became the de facto map of time for the next sixteen hundred years, undergoing only minor modifications and adjustments during the long centuries. The most nagging problem facing Caesar’s construction emerged with the advent of Christianity.

  Ever since the calendar’s invention in ancient Mesopotamia and Egypt, its mythoreligious role in marking festival days had been paramount. The emergence of Christianity as the dominant power in Europe would be no exception to this rule. The great failing of the Julian calendar for the Christian cosmos was its inability to fix the all-important holy day of Easter. With a cycle of 365 days and six hours, the Julian calendar’s year was still eleven minutes too long.14 That may not seem like much, but over centuries those extra minutes add up. After 138 years, the Julian calendar ends up a day ahead of itself. Easter, intended to occur on the spring equinox (March 25 in the Julian calendar), slowly drifted to earlier dates. In the third century CE, the Church in Alexandria reset the date to March 21 using new calendar calculations that were intended to solve the problem. But as the centuries clicked by, the slide of Easter away from the equinox became ever more apparent. It was not until the famous papal bull of Pope Gregory XIII in 1578 that a new calendar reform process was set in motion.15

  The maintenance of the Julian calendar throughout the long centuries after the fall of the western Roman Empire was one of the few examples of astronomy-based thinking left in Europe during this period. This narrow focus is indicative of the European state of mind during the Dark Ages. Astronomical learning and the cosmological imagination stalled. In the life of the mind, time had regressed.

  ATHENS AND JERUSALEM: THE MEDIEVAL COSMOS

  The Middle Ages are rightly called “dark” when compared with the triumph of Greek culture. Many European Christian thinkers during the first millennium CE had abandoned the Greek tradition and no longer considered reason to be a sufficient form of investigation. Nowhere is this “closing of the Western mind” more apparent than in cosmology and astronomy.16 Many in the newly ascendant Christian Church were hostile towards natural philosophy and the Greeks who championed it. As the early Christian writer Tertullian put it, “We want no further curious disputation after possessing Christ Jesus.”17 The old era of inquiry was gone and the achievements of the Greeks were dismissed as irrelevant. “What indeed has Athens to do with Jerusalem?” Tertullian asked mockingly.18

  So intellectually apathetic had the Western world become that the Earth was made flat again. Lactantius, a fourth-century bishop, dismissed ideas of a spherical Earth as heretical and absurd: “Is there anyone stupid enough to believe that there are men whose footprints are higher than their heads?”19 While many of the early Church fathers were content to simply dismiss Greek cosmology without offering anything in response, the sixth-century Byzantine merchant Cosmas Indicopleustes did propose such a map of the cosmos in his work entitled Christian Topography. In this early work Cosmas claimed the universe was built like a vaulted te
nt or a tabernacle and heavenly bodies were moved by the will of angels, with the sun and moon disappearing each night behind a huge mountain located at the centre of the cosmic box.20 After the intricacies of Ptolemy’s astronomy, with its finely tuned epicycles, a vaulted tent with a mountain in the middle was certainly a step into the dark. But while the Greek emphasis on reason was abandoned, material engagement was still present and still shaping the human worlds of mind and matter.

  FIGURE 3.2. As Europe fell into its Dark Ages, cosmological models stepped backwards. Early Christian cosmology held that that the universe was a vaulted tent with a mountain at the centre.

  When the Roman Empire collapsed in the western domains of Europe, the capacity to engineer culture on a massive scale was lost as well. At the same time, Christianity became the new cosmological material of everyday life. The structure of the previous society had been dismantled, and order and stability disappeared with it. The vaulted roads crumbled, enduring institutions failed and power devolved locally to whoever was strongest.21 The world had become dangerous in entirely new ways. Thus the Church, with its promise of eternal salvation beyond the chaos of life in the here and now, did not just augment life, but came to utterly define it.

  Just as agrarian myths were the very stuff of life in the Neolithic, the cosmic religious vision offered by the Church was not simply a shackle that had to be thrown off before an intellectual life could be lived again. The time after the collapse of Rome may have been a retreat from the Greeks’ “first scientific revolution”, but people did not stop thinking or learning or picturing the universe. They may not have approached the world in the same way as the natural philosophers, but they were not stupid and they certainly were not all as ham-fisted in their cosmological thinking as Cosmas and Lactantius.