The Double "0" Decade (001, 002, etc.), 21st Century, and 3rd Millennium do not begin until January 1, 2001. Here's Why:
Most of the modern world now uses the Gregorian Calendar, which was established by Pope Gregory XIII around 1582 AD. He devised this calendar to replace the flawed Julian Calendar, instituted by Julius Caesar in 46 BC. Caesar developed the first calendar that had 12 months (January-December). His calendar was actually 11 minutes and 14 seconds longer than the solar year, thus requiring the reforms of the Gregorian Calendar.
Our system of counting the years, though, dates back to the early 6th Century AD. Around 532, a Scythian monk named Dionysius Exiguus wanted to establish a Christian method of recording history, based on the birth of Jesus Christ. He estimated Christ's birth to be 753 in the Year of Rome. Modern Historians now believe that Christ was born in 750 A.U.C. which is now 4 BC (Before Christ; a.k.a. BCE - before Christian era), but it is Dionysius' estimate that is still used to determine the year number.
All years following Christ's birth would be referred to as anno Domini, which means year of our Lord, in Latin. Also during this time period, Roman Numerals were still being used (Our current Numerology uses Arabic Numerals, which wasn't used in Europe until 976 AD), and there is no Roman Numeral Zero. The concept of zero and negative numbers is a more modern convention. So, when the AD system began, that year became the First Year of our Lord; it is impossible to have a zero year AD. Since we consider decades, centuries, and millennia to be 10 years, 100 years, and 1000 years long, respectively, each of these divisions MUST end in a "0" year (10 AD, 400 AD, 1000 AD, 2000 AD etc.) That means the (technical) decade of the 90's BEGAN on January 1, 1991, the 20th Century BEGAN on January 1, 1901, and the 2nd Millennium BEGAN on January 1, 1001. And this means that the new divisions can't begin until January 1, 2001!! |