Please explain my confused me like I’m 5 (0r 4 or 6).
Years are ordinal numbers, the kind of number that tells you which place you finished in a race, and as such cannot have zeroes or negatives. You’re living in the 2,024th year since the instant that began the Common Era. “0th” and “-1st” are not valid expressions for years for the same reason that you can’t place 0th in the Olympics
Ordinals are largely used for counting and when you’re counting you kind of do start a zero, most people just don’t say it. When you count 1… 2… 3… it would work just as well to start 0… 1… 2… 3… So programmers can rest easy.
It depends which calendar you use! Every calendar picks a basically arbitrary system to uniquely identify each year, and in some of them “year 0” doesn’t refer to any year.
The Gregorian, for example, goes directly from 1 BC to 1 AD, since 1 BC is “the first year before Christ” and 1 AD is “the first in the years of our lord.” This doesn’t make much mathematical sense, but it’s not like there was a year that didn’t happen–they just called one year 1 BC, and the next year 1 AD.
ISO 8601 is based on the Gregorian calendar, but it includes a year 0. 1 BC is the same year as +0000; thus 2 BC is -0001, and all earlier years are likewise offset by 1 between the two calendars.
If ISO says there was a year 0, there was. There’s only one thing better than perfect : standardized !
I need my standardized fixed calendar now dammit
Zero doesn’t even exist so how would year zero.
https://en.wikipedia.org/wiki/Year_zero
The year of Jesus’ supposed birth was counted as year 1 AD/CE. The year before that is considered year 1 BC/BCE. It’s worth noting that the concept of zero didn’t yet exist back then. https://en.wikipedia.org/wiki/0#History
Probably worth noting that the Gregorian Calendar was an invention of the 16th Century. It was invented to deal with the problems of the Julian Calendar and the creators would have had a firm understanding of the concept of zero. The AD/BC split was all about the assumed year of the birth of Jesus of Nazareth (according to Christian mythology). The year of his birth was set as the first year Anno Domini or “The year of the Lord”. Or the first year where Jesus was kicking about. The year prior to that would therefore be the first year before “Before Christ” was alive, and therefore the year 1 BC.
Especially weird considering that Christmas has been set to December for a long time, so 98% of year 1 AD was actually before the ostensible birth of Christ (I know that scholars now think he was born in April or something, but they probably didn’t always)
Ultimately, they had to set the calendar’s dates based on something. Given the vast hold on Europe which Christianity had at the time, it’s not surprising that the starting date was based on such an important event in the mythology. However, trying to deviate too far from the currently understood order (the Julian Calendar) was likely to end in failure. So, they could either fight the tide of history or just accept a logical oddity. Given all the other logical oddities one must accept for supernatural belief, who’s going to complain about having a holy reason to eat, drink and be merry during one of the most terrible parts of the year?
When someone decides to change the way that they keep track of time, the new calendar typically starts at 1, as in “the first year of this new era”. It’s not that there was no existing year before that, just that it doesn’t make sense to start as zero.
It’s not like the Gregorian calendar that we use now existed in -1 and then rolled over to 0 and then 1. They just started the new one at 1, and for a period of time, there was surely some overlap in people using both calendars, until one was phased out entirely.
Korea kinda takes this to the extreme with birthdays.
The year 1AD wasn’t called 1AD in 1AD. The system was invented hundreds of years later.
No, in our calendar system there was year 1 BC followed by year 1 AD. So no zero. It’s just how they set it up, they’re human made ideas anyway. Many countries do not even use this system, for example it is currently year 2567 in Thailand and year 113 in North Korea.
I’m no expert but I assume that the year Christ died would be “year zero” (assuming you’re talking about anno Domini (AD) and before Christ (BC)) since we started counting after that.
EDIT: reading more on the topic I might be completely incorrect with my above statement. If someone else knows, please do correct me
EDIT 2: I found this on Wikipedia which talks about a “year zero”
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like I’m 5 (0r 4 or 6).
Okay then.
Before dawn of technology advancements that we have today, people did stuff in a very different manner, for the sake of this explanation, I will call it “primitive”
As brilliant as human beings are, they often forget little things (little because may not have higher priority at that particular time) and dates is one of them.
Even now, if you happen to forget today’s date, and do not have means for referring that (like looking at your smartphone or watch, some digital billboards and whatnot),
what you would naturally do is refer back/forward, to the closest (recent/upcoming) date and day where a memorable event occurred/will occur. Events like your cousin’s birthday, trump impeachment, the coming football derby or the coming elections date. then you start counting with your fingers towards/backwards to the current day. This is “primitive”
These variations of calendars that currently exist today have their own sort of “memorable event”.
The most widely used today is AFTER CHRIST (AD). (Of which, to go back past that, they should have used count backwards tactic, i.e. -1, -2, -3, -4; Eg: -4AD; but instead, -4AD becomes 4BC which is BEFORE CHRIST. That is why counting forwards in BC, number decreases 😏 )
To answer your question;
“Year zero” is the year where that particular memorable event occurred.
But as I demonstrated above, we use that year as a reference to count forward/backwards the following/past years.
Nope. 1 BC/BCE -> 1 AD/CE. That’s just how it was designed.
Almost. The first recorded use of ‘Zero’ was in Mesopotamia in 3BC/BCE. https://www.history.com/news/who-invented-the-zero
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Yes. They skipped right over. It confused many people at the time: a whole year of their lives, gone. Many centuries later when zero was invented, an explanation was finally offered as to why that happened.
😂
Serious answer about what the year would have been in 1 AD, according to 63-year-old Emporer Augustus:
DCCLIV754 Ab Urbe ConditaThat means “from the founding of the city” - they based their calendar on the mythical founding of Rome, as calculated by Verro, who himself was not long dead at that point. Before that, they just counted the years of each person’s reign Japanese-style. Probably other people in the ancient world had older calendars.
They left out 0 from the list. It basically jumps from -1 to 1.
When you consider the time as a number line, years are not points at integers (which would in some way warrant a year 0), but rather periods between them. Year 1 is the period between 0 and 1, and before that was -1 to 0, or year -1. There is no year 0, because there isn’t anything between 0 and 0
This explanation is unclear to me. Why do we choose the later of the two endpoints of the year for (0, 1) but the earlier of the two for (-1, 0)?
Moving from too… not too from
For the same reason why 1.5 is on the right from 1 but -1.5 is on the left from -1
The language is rooted in the same logic as people. Your first year was between the ages of 0 and 1. The first year before you were born is between -1 and 0. There is no 0th year because 0 is a point in time and not a range in time.
Your explanation works equally well for any integer though. You could say the same of 1.
I think you’re saying that it’s a fencepost issue. But even for personal ages this doesn’t check out: for a year after you are born, your age is “0.” A one-year-old baby is in the following year.
I feel you’ve missed the point I was making and assumed I’ve made another. Age number and year number are different. You’re in your first year when your age is not yet 1. You’re in your second year when your age is between 1 and 2.
Years follow numbers as in "this year was the first/second/third year of ", not “this year was the year turned X years old”
Oh I see. Sure, historically it makes sense that years have been ordinal numbers. But in the modern era with all our math and computational knowledge, it is not convenient anymore. It means off-by-one errors are easy to commit when comparing BC and AD years.
This is why programming languages all index from 0 rather than 1 (knuth and lua be damned)
Absolute value. Both systems count time from the same epoch, or zero point.
One year before the epoch is 1 January 1BCE One year after the epoch is 31 December, 1CE.
Half a year before the epoch (-0.5 years) is June 30, 1BCE. Half a year after the epoch (0.5 years) is July 1st, 1CE. These dates occur within the first year before the epoch, and the first year after the epoch, respectively.
Remember originally that -1 was 1 BC, meaning 1 year before the birth of christ. The negative numbers are measuring the distance away from 0.
Edit: in the positive direction, the 1 was 1 AD, meaning the first year of our lord. Just like when talking about the reign of kings/queens, the first year of their reign is 1 and the 14th year that they reigned is 14. I believe the timekeeping for Ages in LOTR may also be similar.
the idea that the year 2000 is the start of the 21st century is hurting my head.
That may be because it is not. The first century was years 1 to 100. The second was 101 to 200. The 21st is therefore 2001 to 2100.
What you’re probably referring to is the “cultural century” which was considered to have started when the lead digit changed from 1 to 2. The same thing happened quite recently when some people argued 2020 was the start of a new decade (again, it wasn’t)
I hate it when people say it wasnt the start of a new decade, it’s a shit argument, why does it matter what the first year was, 2014 - 2024 is also a decade, and 2pm aest September 22nd 2024 will also be the start of a new decade. There is nothing wrong with saying 2020 was the start of a new decade. (again, it was)
There are decades and there are decades. Just like there are weeks (period between Monday and Sunday inclusive) and weeks (any seven consecutive days).
When you say “I’ll do this next week”, then you mean the next period between Monday and Sunday. When you say you’ll do it in a week, it means you’ll do it after exactly 7 days from now, regardless of what day is it today. Same for decades.
??? You know very well what I meant, be more forgiving to second-language speakers
It should all be zero indexed. Positional number systems like we write with are (600=0600) but our language isn’t, which causes this problem. Basically, if 2004 is the 20th century the gospels took place in the 0th.
Ohh, nice one!
The first convention is common in English-speaking countries, but the latter is favoured in, for example, Sweden (tvåtusentalet, which translates literally as the two thousands period).
I’m not sure that’s entirely true, most people in English speaking countries (and the world over) celebrated the millenium at the beginning of the year 2000.
The enumeration on the losing side of that debate is probably correct. But as a person who was in my early 20s in 2000, I’d like to offer what I will characterize as The Historical Context and Definitive Conclusion to This Debate.
No one actually gave a shit about that debate. Sure, it came up, but it did not alter anyone’s party planning. We weren’t actually celebrating the changing of the millennium, we were celebrating because we had a permission slip to do so. Any attempt to withdraw that permission was unwelcome.
In Paris on December 31st, 1999, at around 11pm local time, someone threw themselves in front of a metro. The trains were free that night (because it was the 100 year anniversary of their opening iirc), but because of that suicide, at least one of the train lines was substantially delayed. The streets from the center of the city to the north side were crowded well toward dawn as everyone chose to walk home instead of wait indefinitely in a stinky train station.
That person, who chose to end their life on the tracks that night, holds the core truth of the debate within his death: it’s a ridiculous debate and those who would fight for it should just stay the hell home and let the rest of us drink a lot and dance.
If we were starting from scratch, it would probably be better to go with two year zeroes, so it would fit normally into positional number systems, and then you could even talk about 0.5AD for the relevant summer.
Unfortunately, positional numbering wouldn’t be invented in the old world until hundreds of years after the Christian calendar.
The only positional numbering system I use daily (base 10) has only one zero. What system are you talking about?
Oh really? What do -0.25 and 0.25 both start with, and round to?
A reminder to read the original reply that started this thread. There’s two “zero-areas” between the one points and the zero point.
Ah, I see. You’re advocating for naming the intervals (0, 1) and (-1,0) by rounding toward zero rather than away from zero. I would advocate for rounding toward the lesser value: (-1, 0) -> “-1” and (0,1) -> “0”
That could work. Calculating across eras would still end up sort of funny (the putative nativity would be a year closer to 233BC than 233AD, for example), but unless you’re an archeologist that doesn’t come up that often.
I had another conversation about this not that long ago, and it really does boil down to treating intervals as numbers. Unix epoch doesn’t officially extend to pre-1970 years, but it’s defined as “the number of seconds that have elapsed [past perfect] since” for that reason, and does have a second 0. It fair to guess Bede himself didn’t properly distinguish between the two, because that leads directly to an argument 0 is a number, which AFAIK doesn’t appear in European mathematics until much later.
I think the only reason that the nativity would be a year closer to 233 ad than 233 bc is because Jesus was born in late December. Had he been born a week later on the 1st of January, it would work out, with 1 ad starting a year after his birth and 1 bc starting a year before (year 0 being that of his birth)
The year was built around it, not the other way. It’s all derived from the Christian calendar. I’m not sure off the top of my head how Christmas ended up a few days before New Years, but they’re deliberately very close. It has been argued that the real life birth might not have been in winter at all (or even Bethlehem).
I digress, though. It would inevitably be lopsided somehow, because you’ve centered the numbering system around six months off of the New Years points.
So in your idea there would be year +0 and year -0 before it, right?
floating point arithmetic on computers does suffer the existence of a negative zero. But it’s generally considered an unfortunate consequence of IEEE754.
Well, AD and BC(E) are the usual notation in this case, but yes. This is distinct from -0 and +0 in computation, because as OP says these are intervals rather than points.
They switched when years are counted. BC years are counted at the beginning of the year. AD years are counted at the end of the year.
The halfway mark in the first inch of a ruler is 0.5". The first inch ends at 1.00. 1.25" falls in the second inch of the ruler.
We recently completed the 3rd month in the 2024th year AD. We have not completed the full, 2024th year yet; but we are in it. This most recent April 1st was 2023.25.
1-Jan-1 BC was almost a year before 31-Dec-1 BC. 31-Dec-1 AD was a year after 31-Dec-1 BC.
