Millennium

A millennium (pl. millennia) is a period of time equal to one thousand years (from Latin mille, thousand, and annum, year). The term may implicitly refer to calendar millennia; periods tied numerically to a particular dating system, specifically ones that begin at the starting (initial reference) point of the calendar in question (typically the year 1) or in later years which are whole number multiples of a thousand years after it.

The term can also refer to an interval of time beginning on any date. Frequently in the latter case (and sometimes also in the former) it may have religious or theological implications (see Millenarianism). Especially in religious usage such an interval may be interpreted less precisely, not being, exactly, 1,000 years long.

Ordinal

The original method of counting years was ordinal, whether 1st year A.D. or regnal 10th year of King Henry VIII. This ordinal numbering is still present in the names of the millennia and centuries, for example 1st Millennium or the 20th century, and sometimes in the names of decades, e.g. 1st decade of the 21st century.

[edit] Cardinal

In recent years, most people have moved to expressing individual years as cardinal numbers, for example 1945 or 1998. The usage 1999th year A.D. is no longer found. This follows scientific usage, for example astronomical year numbering. As a result, some other calendar names have also moved to cardinals, e.g. 1980s is an acceptable name for a particular decade. However, 1600s could be understood as either a decade or a century.

[edit] Ranges

A change from ordinals to cardinals is incomplete and might not ever be completed; the main issues arise from the content of the various year ranges. Similar issues affect the contents of decades and centuries.

Those following ordinal year names naturally choose

• 2001–2010 as the current decade
• 2001–2100 as the current century
• 2001–3000 as the current millennium

Those following cardinal year names equally naturally choose

• 2000–2009 as the current decade
• 2000–2099 as the current century
• 2000–2999 as the current millennium

[edit] Debate over millennium celebrations

The common Western calendar, i.e. the Gregorian calendar, has been defined with counting origin 1. Thus each period of 1,000 years concludes with a year number with three zeroes, e.g. the first thousand years in the Western calendar included the year 1000. However, there are two viewpoints about how millennia should be thought of in practice, one which relies on the formal operation of the calendar and one which appeals to other notions that attract popular sentiment.

There was a popular debate leading up to the celebrations of the year 2000 as to whether the beginning of that year should be understood (and celebrated) as the beginning of a new millennium. Historically, there has been debate around the turn of previous decades, centuries, and millennia.

[edit] Arbitrarity

As a side-note to the debate on timing of the turn of the millennium, the arbitrariness of the era itself can be raised. The Gregorian calendar is a secularized, de facto standard, based on a significant Christian event, the purported date of Jesus' birth; thus the foundation of the calendar may not be as relevant to non-Christians. The calendar is one among many still in use and those used historically. Adjustments and errors in the calendar (such as Dionysius Exiguus's incorrect calculation of A.D. 1) make the particular dates we use today arbitrary.

However, given that the Gregorian calendar is a widely used standard, it is valid to discuss the significant dates within it, be it the timing of religious festivals (such as the moving date of Easter which Dionysius Exiguus was involved in calculating) or the delineation of significant periods of time, such as the end of a millennium.

[edit] Viewpoint 1: x001–y000

Those holding that the arrival of new millennium should be celebrated in the transition from 2000 to 2001 (i.e. December 31, 2000), argued that since the Gregorian Calendar has no year zero, the millennia should be counted from A.D. 1. Thus the first period of one thousand complete years runs from the beginning of A.D. 1 to the end of A.D. 1000, and the beginning of the second millennium took place at the beginning of 1001. The second millennium thus ends at the end of the year 2000. Then again, those who defend the opposite idea state that the new millennium started with the year 2000 (because of the changes made to the Gregorian calendar in 1582, or because the first millennium started in 1 A.D. and ended in 999 A.D., being the only millennium (along with the last millennium b.c.) not with 1000 years, but with 999 years).

Illustration of years with a 00-01 demarcation

2 BC	1 BC	AD 1	AD 2	3	4	5	...	998	999	1000	1001	1002	...	1998	1999	2000	2001	2002	...	2998	2999	3000	3001	3002
		First one thousand years (millennium)									Second millennium						Third millennium

Arthur C. Clarke gave this analogy (from a statement received by Reuters): "If the scale on your grocer's weighing machine began at 1 instead of 0, would you be happy when he claimed he'd sold you 10 kg of tea?" This statement illustrates the common confusion about the calendar.

If one counts from the beginning of A.D. 1 to the ending of A.D. 1000, one would have counted 1000 years. The next 1000 years (millennium) would begin on the first day of 1001. So the calendar has not 'cheated' anyone out of a year.

In other words, the argument is based on the fact that the last year of the first two thousand years in the Gregorian Calendar was 2000, not 1999.

[edit] Popular culture: x000–x999

The "year 2000" has also been a popular phrase referring to an often utopian future, or a year when stories in such a future were set, adding to its cultural significance. There was also media and public interest in the Y2K bug. Thus, the populist argument was that the new millennium should begin when the zeroes of 2000 "rolled over," i.e. December 31, 1999. People felt that the change of hundred digit in the year number, and the zeros rolling over, created a sense that a new century had begun. This is similar to the common demarcation of decades by their most significant digits, e.g. naming the period 1980 to 1989 as the 1980s or "the eighties." Similarly, it would be valid to celebrate the year 2000 as a cultural event in its own right, and name the period 2000 to 2999 as "the 2000s."

Most historians agree that Dionysius nominated Christ's birth as 25th December of the year before AD 1 (ref History Today June 1999 p60 Letters, Darian Hiles: "Of Dates and Decimals"). This corresponded with the belief that the birth year itself was considered too holy to mention^{[citation needed]}. It also corresponds to the notion that AD 1 was "the first year of his life," as distinguished from being the year after his first birthday.

Similarly in AD 1000 the church actively discouraged any mention of that year and in modern times it labelled AD 2000 as the "Jubilee Year 2000" marking the 2000th anniversary of the birth of Christ. The AD system counts years with origin 1. Some assume a preceding Year 0 for the start of the first Christian millennium in order to start the millennia in year numbers multiple of 1000. This results in such first millennium containing only 999 Gregorian years.

Illustration of years with a 99-00 demarcation using Year zero (ISO 8601 and astronomical numbering system)

−1 AD	0	1	2	3	4	5	...	998	999	1000	1001	1002	...	1998	1999	2000	2001	2002	...	2998	2999	3000	3001	3002
	First millennium (1000 years)									Second millennium						Third millennium

Illustration of years with a 99-00 demarcation (starting AD 1)

1 BC	1 AD	2	3	4	5	...	998	999	1000	1001	1002	...	1998	1999	2000	2001	2002	...	2998	2999	3000	3001	3002
	First millennium (999 years only)								Second millennium						Third millennium

[edit] Popular approach

The majority popular approach was to treat the end of 1999 as the end of a millennium, and to hold millennium celebrations at midnight between December 31, 1999 and January 1, 2000, as per viewpoint 2. The cultural and psychological significance of the events listed above combined to cause celebrations to be observed one year earlier than the formal Gregorian date. This does not, of course, establish that insistence on the formal Gregorian date is "incorrect", though some view it as pedantic (as in the comment of Douglas Adams mentioned below).

Some event organisers hedged their bets by calling their 1999 celebrations things like "Click" referring to the odometer-like rolling over of the nines to zeros.