Consider this intriguing notion: Time, in the absence of measurement, ceases to exist. Calendars, structured with assigned weeks and months, are human creations synchronized with various earthly and extraterrestrial cycles. Take, for instance, the people of the Trobriand Islands in New Guinea, who traditionally commenced their year with the annual influx of a particular species of sea worms onto their southern coasts.
In the context of our cultural paradigm, we choose dates by considering the motions of the sun and moon, giving precedence to a calendar synchronized with the solar year. The structure of our months is influenced by the phases of the moon, and the commencement of a fresh year corresponds to the conclusion of a full orbit of the Earth around the sun.
Nevertheless, there are occasions when these cycles lose their harmony. If the customary appearance of sea worms fails to occur within the expected lunar cycle, the Trobrianers would interpret it as the "moon going silly," as elucidated by Kevin Birth, a professor of anthropology at Queens College and the Graduate Center at the City University of New York (CUNY). Consequently, the duration of the year would be prolonged. Adherents of conventional calendars confront a comparable, though more foreseeable, dilemma: the Earth's orbit around the sun takes precisely 365.242199 days. Owing to this uneven figure, without any adjustments, the calendar would gradually lag behind by approximately a quarter of a day each year, leading to a gradual misalignment of days with the seasons until completing a full cycle—a protracted span of 1,500 years.
Greek and Egyptian astronomers continually refined their comprehension of the solar year, primarily through the observation of solstices and equinoxes. Transmitting their knowledge to the Romans, by the first century, Roman scientists grasped the discrepancy between the lunar month and the solar year. To address this issue, they eliminated the lunar month, giving rise to the Roman civil calendar, which comprised only 355 days. To compensate for this shortfall, 24-hour time periods needed to be incorporated.
During this period, the Pontifex Maximus, the Roman high priest, held the responsibility of determining the additional days required in the calendar to ensure sufficient time for religious ceremonies. However, this process was susceptible to political influence. The Pontifex Maximus often had vested interests in the election of the consul, the highest position in the Roman Republic. Tonia Sharlach, a professor specializing in ancient history at Oklahoma State University, highlights, "In the event of favoring the individual chosen for a significant office, one could extend their year by incorporating a leap month."
Julius Caesar may not be the most renowned Roman figure for fixing the calendar, but in the annals of Leap Day history, he stands out as a prominent figure. Returning from a post-civil-war cruise with Cleopatra, he found himself confronted with temporal disorder.
"When Julius Caesar returned home, they hadn't added extra months for a long time, resulting in complete chaos," explains Sharlach. Caesar, determined to rectify the situation, sought counsel from philosophers and mathematicians. Implementing several intricate changes, he moved the start of the year from March 1st to January 1st and introduced an extra day every four years. While this addressed the arbitrary leap month problem and established the groundwork for the modern timekeeping system, it also cemented Caesar's perception as a dictator in the view of his political colleagues.
However, the Julian calendar didn't entirely solve the leap day problem. It operated on the assumption that each year is 365.25 days long, slightly less than the actual value of 365.242199 days. This discrepancy caused the seasons to drift in relation to the calendar year, posing significant challenges for Christians celebrating Easter. Sharlach notes that monks and priests wrote to the Pope, expressing their distress over celebrating Easter on a day that might not be the actual Easter day. In 1582, Pope Gregory XIII gathered a group of astronomers, mathematicians, and clergymen to tackle the problem. They chose to uphold the principles of the Julian calendar but introduced minor adjustments. In the Julian calendar, leap days were inserted in years divisible by four. Pope Gregory removed the leap day for three out of every four century years. For example, 1600 and 2000 were leap years, while 1700, 1800, and 1900 were not. Additionally, 2100 will not be a leap year (assuming humanity persists until then).
The rest of the world progressively adopted the more precise Gregorian calendar, as it is recognized today. However, England and its colonies resisted the transition until the mid-1700s, driven by reservations about Catholicism. According to Birth, the introduction of the new calendar even led to confusion for George Washington regarding his birthday when the thirteen colonies switched in 1752, eliminating 11 days from that year, including the day he was born. "So, should he observe his birthday based on the old calendar, or should he adjust it by 11 days? He wasn't certain about what course of action to take," recounts Birth.
The time wars are still ticking
Both calendar reforms encountered controversy in their eras, yet in the contemporary world, the Gregorian calendar enjoys widespread global adoption. Nevertheless, discussions surrounding leap time are ongoing. A fresh challenge has emerged with the prevalent use of atomic clocks. The Earth's orbit is slowly decelerating, leading to intermittent additions of a second to atomic clocks. This adjustment presents a challenge for computer engineers who argue for abandoning reliance on the Earth's orbit altogether and transitioning to exclusive atomic timekeeping.
"I've attended conferences where individuals from both sides of the leap second debate were present, and I was worried it might escalate into violence," comments Birth. He foresees that supporters of atomic timekeeping will emerge victorious when the issue is reevaluated in 2022 (Update: The leap second is indeed scheduled to be eliminated in 2035).
In the United States, our timekeeping systems reflect a tapestry of cultures and the tumultuous course of history. It's essential to recognize the diversity in approaches to measuring time. As pointed out by Sharlach, the ancient Babylonians designated their years with names rather than numerical values. Meanwhile, the Islamic calendar follows lunar cycles, introducing seasonal variations for events such as Ramadan.
Nevertheless, making a transition at this juncture would present a logistical challenge comparable to the Y2K panic, as noted by Sacha Stern, the head of the Department of Hebrew and Jewish Studies at University College London. "The crucial aspect of our calendar is its universality," he emphasizes. "This is a global challenge, and it has wielded a profound cultural influence in bringing the world together under a single time framework."