When does the new decade start? (Was there a year zero?)

Is tomorrow the last day of this decade or do we still have 366 days to go? Either way is acceptable, but because I love finding out the reasons for this sort of thing I thought I’d share them with you. 🙂

For anyone that can remember their history the Roman Empire covered much of the globe and advanced civilization greatly with prominent innovations such as roads, aqueducts and other feats of unique architecture such as the Colosseum that have endured time well. They also had minor innovations that exist to this day in some form or another: Foot-powered loom (Weaving), Hypocaust (Central Heating) and Cement. The sheer size of the Empire facilitated widespread incorporation of many ideas from conquered nations including that of a standard calendar.

Julius Caesar reformed the Roman calendar in 46 BC, and the current dating system, the Gregorian Calendar, is an extended version ratified in 1582 by the Pope.

Pope Gregory XIII knew Christ had been born and yet there is not widely accepted use of the year 0. It makes sense, one year JC wasn’t here, the next he was, simple. Having the year 1 BC directly followed by the year 1 AD makes sense. And Caesar, not being a soothsayer (as far as I know), did not know Christ was coming and thus whilst his foundation of the Gregorian calendars Days, Weeks and Months remain the year has not so I doubt that he planned a ‘Year 0’ 44 years after his death.

What this means is starting in 1 AD either the first decade was nine years long (1,2,3,4,5,6,7,8,9) because we start new decades like…2010 on a zero or that the first decade was a full 10 years long and the first day of the new decade is 1st January 2011.

It all comes down to personal preference really because you stick with the popular convention (start on a 1) and the first AD decade is 9 years long, start Mathematically and you’re logically correct but you sound like a loon unless you’re got a few quirky people that wonder the same as you.

Sidenote: Everyone remember the Millennium malarkey over the ’99’ in 1999 breaking computers, the so called Millennium Bug’? The bug was from computers adding 1 to 99 getting 100 and only having 2 digits to store information and essentially making an error that could’ve just corrupted a small bit of data or crashed the entire system. Thus 00 did not follow 99, computers started as 00 counting 1 at a time upto 99. Computers start counting with zero.

5 thoughts on “When does the new decade start? (Was there a year zero?)”

  1. Just seen this…. Mathematically both answers are correct. Zero is a non-number, it both exists and doesn’t in mathematics. It is a value that is used in calculations and so can be used in a decade calculation but it also doesn’t exist.

    When counting you don’t count zero, as there isn’t anything to count. You only really use zero when you are removing things rather that counting. “I had one now I have zero” works better than, “I had zero now I have one”.

    So, although technically the first decade would be 1 to 10 and second decade 11 to 10 etc, it is easier to call the decade at the 10, 20, 30 year mark as visually it is better.

  2. ooops I’ve just spotted a lot of typing errors….

    first: “…removing things rather than counting”

    second: “…second decade 11 to 20 etc,”

    corrections made.

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