The Calendar (40 page)
What this means is that we humans have fulfilled the dream of Caesar, Aryabhata, al-Khwarizmi, Bacon, Clavius and so many others: by creating a device at last that can measure a true and accurate year.
But alas, this is not the end of our story.
As we know, the earth wobbles and wiggles, causing random fluctuations in the earth’s rotation. Which is why the master clock is
too
accurate, and must be periodically recalibrated. This is done by adding or subtracting leap seconds to compensate for the actual motion of the earth. Otherwise the master clock would gradually fall out of step with earth time, eventually rendering the atomic time-grid as erroneous for the nanosecond crowd as the Julian calendar became for those who could not tolerate drifts of minutes a year. Since 1972, leap seconds have been added almost every year. So far, none have been subtracted.
Think of the irony. After millennia of struggle to come up with a true and accurate year, we have actually overshot the mark. For in the end the earth itself is not entirely accurate--a fact that would have astonished Roger Bacon and many an astronomer and time reckoner who fought to objectify time by using nature as their standard, as represented by the motions of the earth, planets and stars. It seemed--well, more natural to them than a year devised by a church, emperor, parliament, or even a newfangled mechanical clock, which had to be rewound and reset and often ran fast or slow.
So we are left with yet another gap, one between atomic time and earth time, which fluctuates according to the whims of nature, if ever so slightly. Even with sophisticated modern instruments, time reckoners today can only watch and record the earth’s bobs and dips as it drops a nanosecond here and gains two or three there. But they remain as helpless to predict the size of this gap at any moment as Bede was in the eighth century with
his
gap: between what he observed was the length of the year according to his sundial, and what the Church’s calendar said the year should be. Indeed in his day the same problem existed with sacred time being too perfect compared to earth time, inasmuch as people believed it was perfect: though in this case the perfection came from God, not of caesium.
Which leaves anyone living by the clock or the calendar trapped in a conundrum of our own making, between our seemingly genetic compulsion for order and perfection, and the plain reality that nothing is perfect, particularly nature--something we relearn every hurricane season, and whenever the latest Theory of Everything falls short.
Further complicating matters is the fact that our little planet offers not one or two but several ‘years’ to measure, each slightly different. I have several times mentioned the Sidereal Year: the year as measured by the time it takes for the earth to orbit the sun. And of course the Tropical Year, defined as a year measured from one March equinox to the next, though this is not entirely accurate in modem astronomy, if one gets picky. Officially, a Tropical Year is the time interval it takes for the earth to make a full orbit of the sun, using as the starting and stopping point the vernal equinox. This is slightly different than the value for the equinoctial year, since the earth’s rotation is slowing ever so slightly over time. This means that the point where the equinox started in a given year in relation to the sun is not going to be exactly the same point a year later due to the slowing, and to other planetary fluctuations.
If this is not numbing enough, we also have the year as measured from one June solstice to the next, from one September equinox to the next, and so forth--all of which offer up minutely varying values for the length of the year that would have left the heads spinning of Sosigenes, Bede, Roger Bacon and all the rest.
In the spirit of full disclosure, for those who are interested, I list below the various ‘years’ and their values for the year 2000.*
*These values were determined by astronomer Jean Meeus in 1992, except for the sidereal year.
Year Type Mean Time Interval, Year 2000 (in days)
Sidereal 365.2564 days
Tropical 365.24219 days
Between two March equinoxes 365.24237 days
Between two June solstices 365.24162 days
Between two September equinoxes 365.24201 days
Between two December solstices 365.24274 days
Our calendar year is linked to the year as measured between two March equinoxes, as originally established by Caesar and Sosigenes. Pope Gregory’s correction in 1582 brought our calendar year within 26 seconds of the equinoctial year, where it remains today.
At the moment, I can see from my desk a clock, my watch, a wall-calendar, a planning calendar and a small icon on my computer with the date and time. In my briefcase is an electronic organizer and a schedule of baseball games for the Baltimore Orioles. And at home we have at least a half-dozen more calendars and Lord knows how many clocks; schedules for my son’s and daughter’s soccer games, school schedules, schedules for paying bills and dates everywhere.
This begs the question: Why do we need to measure a picosecond when I cannot even keep track of what I am doing day to day?
I posed this to historian Steve Dick at the US Naval Observatory. An affable, quiet man with short brown hair and a well-kept moustache, he laughed and said that
everyone
asks this. ‘You would be surprised at how many uses there are,’ he said, starting with navigation--which was the original impetus to start a national time synchronization system here at the Naval Observatory in the nineteenth century.
According to him a billionth of a second translates into the space of about one foot for navigation, which can be significant if you are a pilot at night in the fog trying to land a Boeing 747 on a runway or an F-14 Tomcat onto an aircraft carrier. These sorts of minute measurements are critical for synchronizing television feeds, bouncing signals off satellites, calculating bank transfers, transmitting everything from e-mail to sonar signals in a submarine, and keeping ‘smart’ missiles on course so they slam into an enemy’s chemical weapon’s complex instead of the middle of a populated neighbourhood. Hikers in the wilderness are using the master clock to find trails down to a foot or two in accuracy by using handheld GPS (Global Positioning System) locators. These locators cost as little as $250, and work by simply holding the device up to the sky and waiting for it to link up with three or more satellites. Once contact is made, the locator flashes an exact location in degrees, minutes and seconds.
But wait--trying to determine a true year gets much more mind-boggling than this. For when we get down to the world of nanoseconds time begins to change in other ways that must be compensated for. Time in fact begins to
warp
or
bend
noticeably at this level of precision under certain situations, as Albert Einstein noted. He theorized that time is relative to the speed one is travelling through space. That time for someone moving at the speed of light (186,282 miles per second) would move much more slowly than someone moving, say, on the earth as it hurtles through space around the sun at about 20 miles a second.
This was proved in 1971 when two scientists borrowed four atomic clocks from the Naval Observatory and flew them east and west around the globe in jet airliners. Comparing the nanoseconds of these voyages off the earth to atomic clocks on the ground showed that people flying in the jets at less than one-millionth the speed of light experienced a slowing of time equal to 59 nanoseconds going east and 273 nanoseconds going west--the difference caused by the fact that the earth is rotating to the east.
What does this mean for measuring the year? For one thing, it means that every time someone flies their ‘year’ grows by a few billionths of a second: which is entirely meaningless, since the earth’s fluctuations affect the length of the year in the range of a thousandth of a second. But who knows? It may matter a great deal if humans learn to travel at great speeds through space, where a ‘year’ in a space ship moving at 186,000 miles per second would last far longer than 365.242199 earth days.
Lost in this expanding universe of caesium, nanoseconds, warps, and recalibrations is the lowly calendar, with its twelve months and 365 little boxes (366 in a leap year): a device for measuring time that does not oscillate, bend time or have anything to do with the electromagnetic spectrum. Invented in its present form over two thousand years ago and corrected only once four centuries ago, it is old enough to be an artefact in a museum.
Except that it remains vital to everyone.
Not that it is even close to perfect. There are a host of minor flaws that annoy people, and are for ever keeping a small, but vibrant group of would-be reformers hoping to get a new and improved calendar named after them. These flaws include:
· The divisions of the year--the month, the quarter, the half year--are of unequal length. This is most unpleasant for anyone trying to run a business, pay taxes or gather statistics.
· The days of the week drift each year, with each new year starting the day after the previous year, or two days after when following a leap year. Because of the leap year, this drift runs a cycle that repeats itself only after 28 years. This makes it difficult to fix annual dates, since they keep moving in the week. The position of the weeks also move each year within months and quarters.
· The Gregorian calendar remains in error, running fast against the true year by about 25.96 seconds a year. Since 1582, this has accumulated to about 2 hours, 59 minutes and 12 seconds and will equal an entire day about 72 generations from now--in 4909--assuming humans are still here, and are still using the calendar named for a pope who died 3,330 years earlier.
· The ‘era’ we use to number our years--initially called the ‘Christian Era’ and now the ‘Common Era’--remains confused because there is no year zero. This means that technically century-years come in the --01 slot, not --00, and millennium years happen in --001, not --000. But people prefer to celebrate the beginning of, say, the twentieth century as 1900, and the coming millennium in the year 2000, not 2001. Others complain about the awkwardness of an AD and BC timeline with ‘positive’ and ‘negative’ dates.
Over the years, attempts have been made to fix these pesky little problems. One of the most intriguing of these was the French Revolutionary Calendar--the ‘Calendar of Reason’. It did nothing to correct the 25.96 second error, which the revolutionaries were probably unaware of. But they did fix other calendric conundrums in their zeal to expunge the old order in the same way Caesar, Constantine and so many others did.
In this case the French Jacobins simply threw out the Gregorian calendar and replaced it with their own--which happened to be far more uniform and convenient. Launched in 1792--the revolutionary Year One--this new calendar had uniform months of 30 days each, tacking on the extra 5 (or 6) days at the end.* These were reserved for holidays called
Virtue, Genius, Labour, Opinion
and
Recompense.
*The Maya and Aztecs used a similar arrangement; so did the Egyptians.
Instead of gods and emperors it used names for the months:
Nivose
for snowing months,
Pluviose
for Rainy Month,
Thermidor
for Heat Month and
Brumaire
for Foggy Month.* Weeks were 10 days long, with three weeks per month. Days were likewise divided in a decimal arrangement into 10 hours each of 100 minutes, with every minute containing 100 seconds.
*Wags in Britain made fun of these French months, calling them: wheezy, sneezy, freezy, slippy, drippy, nippy and so forth.
The Calendar of Reason was a great improvement, but it lasted only until 1806, when Napoleon quietly reinstated the Gregorian system. The experiment did produce a number of curious watches and clocks with ten hours, and minutes divided up into decimals; and numerous books published with single-digit years.
More recently, reform efforts have centred on trying to tinker with the Gregorian calendar, the most popular being the proposed World Calendar, sometimes known as the Universal Calendar. This would restore Caesar’s original distribution of the 12 months as alternating between 30 and 31 days: which Augustus and the Roman Senate altered in AD 8 to give Augustus the same number of days in August as Caesar had in July. The World Calendar would start each year and each quarter on a Sunday. And each month would always start on the same day. Leap days would simply be an extra day, not attached to a month. One plan was to declare this special day ‘World’s Day’.
Supporters of the World Calendar have several times tried to get the United Nations to endorse this reform--coming close in 1961, which started on a Sunday. In 1954 the Vatican endorsed the World Calendar; it was even introduced in the US Congress. But it never caught on.
Other proposals continue to come and go, including a calendar of 13 months with 28 days each, with an extra day (or two) tacked on as special days. This was the favourite choice of the 1929 National Committee on Calendar Simplification for the United States, chaired by George Eastman of Eastman Kodak.* One of the many more recent ideas is something I saw on the Internet. Called ‘The Goddess Lunar Calendar’, its proponents advocate a 25-month calendar of alternating 29 and 30 days; with each of the months named after a female deity: Artemis, Bast, Cybele and Gaia, to name a few.
