[LINK] "A little decadence"

[rfmcdonald]

It seems appropriate for my first post here this year and this decade to be a link to Phil Plait's discussion at Bad Astronomy about the terminologies of calendrical time.

My claim is that December 31, 2009 — today, as this is posted — is not just the last day of the year, but the last day of a decade. Now, I don’t mean that in the trivial sense that any moment is the last moment of the past ten year period — you can always talk about the last ten years that end at any time.

I meant, and still mean, specifically the first decade of the 2000s. That does in deed and in fact end today.

What people were arguing over were things like centuries and millennia, and how there was no year 0, and therefore the last day of the decade is actually December 31, 2010. But that’s not relevant because we don’t measure decades the same way we do centuries.

Certainly, the last day of the 20th century was December 31, 2000. In that case, there was no year 0, so the first year of the 1st century ended on December 31, 1 A.D. Doing the math, it’s easy to see that 1999 more years needed to elapse to end the 20th century, and so its demise was on that last calendar day of 2000. January 1, 2001 marked the first day of the 21st century.

But we don’t reckon decades like that. We refer to them by the tens place in the year’s numerals: the 70s, the 80s, the 90s. And since we do, clearly, today is the last day of the decade we will call the aughts or zeroes or whatever.

Actually, looking at this now, it seems to me that centuries are more formal, with an actual method of naming them, whereas decades are more of a nickname, /a handy handle to use when referring to a time period.

Also, you wouldn’t say that 1990 was part of the 80s, would you? I think it’s clear that December 31, 1989 was the last day of the 80s, just as December 31, 2009 is the last day of whatever term we’ll wind up using to refer to the first 10 years of the 2000s.

Confusing this a bit is that we might refer to something happening in the 1900s versus saying it happened in the 20th century. Those terms are synonymous, barring the year of 1900, which was in the 19th century, and 2000, which was in the 20th century but not in the 1900s.

That's not the case I'd make, not least since it's one o'clock in the morning here in Toronto and I'm not that coherent. Still, sharing's good, right?