When does the new decade start?

(7) On January 6, 2011 at 12:59 am ElanVital [0] said:

(I posted this in an alternate WikiAnswers thread on the same subject. I hope that's okay.)

January 1, 2010, was the first day of a new decade.

There are 3650 days in a decade.

Imagine a tall and skinny glass cylinder marked with 20 notches moving up the cylinder in 1-inch increments, with the first notch starting 1 inch up from the bottom.

Now imagine pouring grains of sand into the cylinder with each grain of sand representing 1 day.

It takes 365 grains of sand to reach each ascending notch, representing a year.

So then, from the bottom of the empty cylinder (0 days), adding 365 grains of sand up to the first notch would be the completion of year number 1.

The first day of year number 2 would be the first grain of sand (grain # 366) leading up to the second notch.

Extending this upward, the first grain of sand just past the ninth notch (year 9 just completed = 3285 days) would be the first day of the tenth year.

Thus, the 365 grains of sand above the ninth notch would be the completion of the tenth year, or one full decade (3650 days).

Therefore, the very next grain of sand past the tenth notch would represent the first day of the beginning of year 1 of a new decade, or 1/1/10 (1/1/2010 in this discussion).

Extrapolating this backwards in our human "contrived" earthly timeline, the first split second beginning the first day of year 1 CE, would basically be "0".

ElanVital

Read more: http://wiki.answers.com/Q/Discuss:Does 2010 or 2011 start the new decade#ixzz1ADCrJ0l0

(6) On January 5, 2011 at 3:49 pm Drzaza [0] said:

There's a technical/mathematical, calendar-related answer that the decades start at the start of years 1, 11, ... 2011, etc.

But surely that's only in order for those with indivisibly ordered brains to compute exactly the number of decades since the infinitely small "year zero"?

Culturally, and commonly, it makes more sense for us to use the start of years *0 to the end of years *9 as the decades of our time.

It all depends upon our reference point.

If we insist on going right back to the start of the calendar, then can we not agree that, just as there is not really a "year zero", then the "first decade" (and that before it) of our calendar was only nine years long!

;-)

(5) On January 4, 2011 at 3:53 pm Rjsiekman [357] said:

Previous Answer:

Quote:

2011.

The first decade was 1 AD through 10 AD.

This is not to say that 1990 was in the decade of the 80s, because that's a different thing entirely. A decade is any 10 year period.

But if you are asking about when a new decade starts, per the calendar, it always begins in a year that ends with 1.

Unquote.

The first decade of the AD ("Anno Domini" or "Year of the Lord", but not that silly reference as "After Death") era started the 1st of january of the year 1, right after the end of the last day of the BC era (31st of december of the year -1, being zero (0) that moment in between the year -1 and the year +1, just like in math), and ended the 31st of december of the year 10. So, by following this logical order, the decade (and new century) that will end started the 1st of january of the year 2001, and will end tomorrow night.

And yes, 1990 is part of the 80's decade. Although as a popular (which isn't always right) thing, especially with music, the 80's is defined as starting in 1980 and ending in 1989.

Edit

1990 was not part of the 80s, naming decades such as 70s 80s 90s means just the years with that number in. This is not incorrect, it is just a different type of decade, a decade is any 10 year period. 1991 was the first year of the 200th decade since 1ad and the second year of the 90s decade

(4) On January 19, 2010 at 12:35 am Sk8kidamh [0] said:

The problem with your logic Richard is that the new millennium actually began Jan. 1, 2001, not, as you explained, on Jan. 1, 2000

(3) On January 4, 2010 at 5:23 am Patternbuilder [0] said:

I'd like to add the following clarification, which I hope is helpful.

The differing opinions are rooted in what is known as a "fencepost error". Say, for example, a single, straight run of fence is 100' long and comprised of posts spaced at regular 10' intervals. How many posts are in the fence? The answer appears to be 10, but in fact , the correct answer is 11, because of the need for a post at each end. There are, however, exactly 10 intervals of fencing.

Calendar years represent the intervals, not the posts. Birthdays represent the posts, not the intervals. Therein lies the confusion. That's why, when a man celebrates his 100th birthday, he is, in fact, 100. He has lived through 100 complete annual intervals, and enters his 101st interval on his 100th birthday. Whereas in calendar years, the year 1 AD represents the calendar equivalent of the mathematical interval between zero and 1. For comparison's sake, the year 1 AD was only 6 months old on June 1, in 1 AD.

It is, therefore, technically incorrect to say that the reason a decade does not start until the end of 2010, for example, "is because there was no year zero." While it is true that a year zero would allow us to celebrate the end of a decade in every year wholly divisible by 10, it would, nonetheless, be mathematically incorrect for there to have been a year zero, and would actually makes things even more confusing if you can believe that.

The zero position exists, in its proper mathematical place, exactly between 1 BC and 1 AD. And what a party that would have been.

-patternbuilder

(2) On January 4, 2010 at 1:13 am RichardDavies [0] said:

I can see how this is confusing. If there is no year "0" on the calendar (as you agree) then there can't be a year between 0 and 1 (what year would that be??) Our calendar goes 2 BC, 1 BC, 1 AD, then 2 AD etc. There was no year 0. The year you're referring to "from 0 to 1" was actually 1 BC.

You talk about birthdays, which is different than the calendar, because we have a year 0. We're 0 years old from our birth to our first birthday. So a human's first decade is from 0 to the end of their 9th year. Their second decade begins with their 10th birthday.

But as we've established, our calendar doesn't have a year "0". It began at year 1. The first year was from January 1st, 1 to December 31st, 1. Therefore the tenth, and final year of the first decade was January 1st, 10 through December 31st, 10.

A decade is any set of 10 years, so any arbitrary set is technically a decade. 1993 through 2002 was a decade. But if we're referring to decades of our calendar, they go from years 1 through 10 (not 0 through 9).

Now I'm not suggesting that the 80s was 1981 through 1990, as that obviously doesn't make sense. The 80s, by definition, must be 1980 through 1989. And yes, those ten years are a decade of years, but they're not a "calendar" decade. 1990 did not mark the start of the following calendar decade. That actually began in 1991.

(1) On January 4, 2010 at 12:37 am RichardDavies [0] said:

Anonymous103 wrote:

I completely disagree with this, because although there is no year "0" - a whole year takes place from 0 to 1. The last decade was all of 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 and 2009. Ten years = one decade. You can't ignore the first year - just like birthdays. You are celebrating how many years have past on each birthday and you exist during that first year.

I think it's just confusing to people when it's a single digit year (ie, "00" and "01") compared to when it was the 80s or 90s, because it was easier to see that 80-89 was the 80s, etc.

Sign in to add your own comment. (This only takes a few seconds.)