Year Zero

C’mon Cecil, I feel certain that you know the details. Why withhold them from your readers?

An argument can certainly be made that decades, centuries, millennia begin in the year ending with “1” (1991, 1901, 2001) just after the odometer rolls over. And an equally compelling argument can be made that they start in the “0” year (1990, 1900, 2000). In fact, due to historical uncertainty, both are true. (Check your article on Schroedinger’s cat if this sort of duality is disturbing.)

It’s absolutely beyond dispute that no one observed a Year 0 in the Gregorian or Julian calendars. But it’s also absolutely beyond dispute that no one observed Year 1, Year 2, or even Year 524 – because, as you point out, the current numbering system was created in 525. Everything else is back-formation (“proleptic” to experts).

The issue of what number to apply to the year before the (back-formed) Year 1 has been plaguing people ever since. One approach, called the “historical system,” considers that year to be -1 (or 1 BCE, if you prefer). Another approach, called the “astronomical system,” considers that year to be 0.

And this is not some new-fangled re-interpretation. It really started to gain currency in the 1700s – but even the Venerable Bede, who died in the Eighth Century, before the mathematical concept of zero was even widely understood in Europe, commented that it made sense to him that there be a “null year” between the years after Christ and the years before Christ. Indeed, because neither system is definitive, scholars who reference precise dates prior to the common era must establish at the outset which of the two systems they are using; otherwise, correlation between sources is impossible.

A lot of people celebrated the start of the current century on January 1, 2001. They were not wrong; they were merely followers of the “historical system.” But I, a follower of the “astronomical system,” celebrated it on January 1, 2000 – and I wasn’t wrong either.

Unfortunately, the opportunity to act like they know something just because they read it somewhere (and frankly, your columns on the subject have been no help in this regard) have emboldened a crowd of people who think a search of Yahoo! Answers is more fact checking than can reasonably be expected of a single human being. They are not concerned with knowing things like “facts” and “details” – they just want to be able to point at others and say, “You’re a dumb-ass.” Surely, surely, this is not the crowd with whom you want to cast your lot.

I invite you to join me when I celebrate the beginning of the next century on January 1, 2100. I’ll be there. Will you? (And because I expect that I’ll still love a party even when I’m 137, I’ll be happy to show up a year later and do it all over again with the “historical system” crowd.)

I’m guessing this is the column in question.

It is indeed. I apologize for the omission.

Considering that:

[li]It appears that Christ might not have been born in the Year 1[/li][li]This numbering system didn’t start until the 6th century[/li][/ul]

That this nitpicking is just plain silly. Does 2001 or 2000 start the new millennium? Well, if you are talking about the second millennium since the birth of Christ, you might have to go with 1996 or 1975 or who knows what. Otherwise, you’re talking about a year numbering system that didn’t start until the sixth century and wasn’t commonly used until the 10th century.

I’d say we look at popular culture and see what it says, and let that be that: It says centuries begin on the zeroth year and the new millennium began in 2000.

I just imagine the scene at the millennium panic back in 1000 AD. People are praying and fasting. Children are crying. Then at midnight, on December 31, 999 passes and it’s now January 1, 1000. People are relieved. Shouts of joy fill the air. The world didn’t end!

Then the jerk next to you says “I told you the new millennium didn’t start until 1001!”


Every Christmas, the same old things get resurrected for discussion.

1 A.D. is numbered that way because it is the first “year of the Lord.” Yes, one could have made it work like age does, in that you don’t say you are “1 year old” until your first anniversary of your birth has been accomplished. But they didn’t, and the fact that they didn’t is integral to the naming convention used, “A.D.”

Much more problematic is the numbering of years prior to the putative birth of Christ. But at least there is a symmetry about the numbering system. And it’s not relevant to the issue of what to do now.

Given that the system numbers the years by starting from the assumed date of Christ’s birth and calls that first year “in the year of our Lord 1”, the completion of the second full millenium from that starting point occurred at midnight between 12/31/2000 and 1/1/2001. The fact that large numbers of people are simply too stupid, or too unlearned, to understand why 1/1/2000 wasn’t the start of the third millenium doesn’t mean anything except that large numbers of people get it wrong, and probably don’t really care.

DSYoungEsq, I’m worried that you are more interested in telling people they are wrong than you are in understanding the nuances of this subject.

Who is this “they” that you refer to? It’s certainly not the Roman Catholic Church, which established the calendar and maintains it. They are silent on the subject of what year precedes Year 1. And it’s definitely not the scientists of the Eighteenth Century who institutionalized the “astronomical system”; they were on the other side of the argument.

Now, maybe you’re saying that even if there was a Year Zero, it didn’t belong to the first decade, century, and millennium. That is one way to look at it, but I find it a bit disconcerting to think that one decade might have run from 1 to 10, while the decade preceding it ran from -9 to 0. But putting aside my own personal discomfort with such a system, it’s a perfectly valid way to look at the topic; it’s just not the only valid way to look at it.

Seriously? You really want to call me “stupid”?

I disagree with you – but the reason I disagree with you is not that I am “too stupid, or too unlearned.” It is because I have studied this subject and I have been persuaded that the astronomical system (1) is more mathematically convenient for comparing CE dates with BCE dates, (2) does not violate the precepts around which the Julian and Gregorian calendars were established, and (3) jibes better with the socially important transition years (e.g., 1990, 1900, 2000).

But, like a Hindu discussing religion with a Baptist, I don’t reject your preference for the historical system. It, too, is valid. But I will not say that it is the only valid approach. And I think you would be a better person if you didn’t say so either.

This is both wrong and not valid. The decade before year 1 ran from 10 BC to 1 BC. The next decade ran from 1 AD through 10 AD. There was no year zero. Nobody is saying otherwise.

This is the only way that is valid, because it is the only way, period.

The question of when the public thinks that centuries and millennia begin is a different one. By the calendar, which is the calendar everyone in the western world uses, both a century and millennium begin in a year 01. It has to.

In popular culture and public lore centuries and millennia begin in the nice rollover years of 00. That’s fine, too, as long as no one tries to claim it’s what the calendar says. The calendar refutes this.

I have to admit I can’t understand exactly what you’re arguing against. Every educated person does understand this distinction. Most people simply ignore it, but most people simply ignore anything that smacks or math or science or sense.

Including Cecil, of course. The 80s are not the same thing as the eight decade of a century. The 80s run from 80 to 89. The eighth decade runs from 81 to 90. They’re not even called the same thing. But Cecil always gets math and science wrong.

He’s arguing that the ASTORNOMICAL system does have a year zero. And I believe he is right, as most calculations I’ve seen work with a number line (which has a zero), and do not include any calculations to remove that year.

The argument about what people use is only used to bolster the claim that the ASTRONOMICAL system is better, as it indicates that most people find the lack of a year zero to be unintuitive.

The problem with this argument is simple: all historical works presuppose the historical system. Every single historical date before A.D. 1 is going to be off by a year. Astronomers could use the mya system instead. Heck, since exact dates don’t matter as much, they can just keep using their system.

I found his use of the “astronomical system” to be a small part of his overall argument, so I didn’t take it as seriously as you did.

If we have to get into it, we’ll wind up in a tedious definition game. Although you can search hard and come up with a cite for astronomical system, the tile of that page shows the more usual nomenclature of astronomical year numbering.

Lots of sites say that astronomers use this system, although I don’t find it familiar from my reading of astronomy and I found a page on the Julian century that seems to back me up.

But even if we allow him every usage, he’s still wrong. Look at that page on Astronomical year numbering.

Traditional Traditional   "Religiously neutral"       Astronomical
Christian     Christian   "Politically correct"          system
(English)      (German) 

4 B.C.           4 v.Chr.         4 BCE                     -3 CE 
3 B.C.           3 v.Chr.         3 BCE                     -2 CE 
2 B.C.           2 v.Chr.         2 BCE                     -1 CE 
1 B.C.           1 v.Chr.         1 BCE                      0 CE 
1 A.D.           1 n.Chr.         1 CE                       1 CE 
2 A.D.           2 n.Chr.         2 CE                       2 CE 

His year 0 corresponds to the Christian year 1 BC. What does that gain us? Jesus was not born during the year 0 or 1 BC. by either astronomical or religious reckoning so it’s not clear to me why that should be the start of the numbering for the positive years. As a time since the purported birth of Jesus, the calendar needs to start with a 1. Clearly his calendar starts with the first year as 1 CE corresponding to the Christian 1 AD. And that ineluctably leads to the end of second millennium at 12/31/2000 with the third beginning on 1/1/2001.

Correction past the editing limit.

My last paragraph is wrong, because this scheme does put the birth of Jesus in its year 0 CE.

I see this as similar to discussions we’ve had in other threads where the axiom system changes, as in this thread where the introduction of the hyperreals would change the definitions of terms like the limit. Mostly though, consistently demands that the same set of axioms apply throughout. In this case, the disagreement over start dates can be containing in a single argument because all agree that no year 0 is included. Allowing one in changes the entire argument.

I still wonder how many working astronomers go this route. I wonder if the OP could comment on that.

Having a year “0” is only necessary if you want to work with year dating as integers, allowing you to add and subtract them without having to make allowance for the lack of a one unit long piece of the number line. So, as I noted, it’s problematic to have the years run (in essence) -2, -1, 1, 2, … . Apparently, the OP when he excoriated me failed to notice that I mentioned this difficulty. I simply fail to see what bearing it has upon the issue of whether or not the first full year immediately after the putative birth of Christ has to be numbered as “1” or “0”. The assertion isn’t that it must be, but rather, that it is so numbered, and that there is a reason for choosing that method of numbering that goes beyond simply making a 50/50 choice. The system numbers the “years of our Lord.” The first such year is, of course, the first year after the supposed birth of the Lord.

Once we accept that that is what is true, and understand why it is true, to assert that the third millenium after the birth of Christ began on 1/1/2000 is simply stupid, as I asserted. It is refusing to accept fact, or it is failing to calculate properly. It matters not what you call the first year from Jan. through Dec. after Christ’s birth. Either way, the same DAY would be the first of the new millenium. If we called the first year “0”, all that would happen is that the same day would have been numbered 1/1/2000, but it still would have occurred the same exact number of days after 12/31/whateveryouwanttocallthelastyearoftheBCera. Since we number the years starting with 1, you simply cannot call 1/1/2000 as we number things the beginning of the third millenium since Christ’s birth, no matter what system you think should be used.

The fact that JoeDeRose can’t see that this is true, indeed, that a putative “astronomical system” wouldn’t change the DAY upon which the new millenium began, only the name for it, nor that such a system does not require that the year we currently number 1 A.D. (this whole CE and BCE styling is pure nonsense, politically correct crap for those uncomfortable with the idea of accepting that the supposed birth of the Christian saviour should be used as the basis for a world-wide system of dating; get over it, the Christian societies of the world won the world domination game at precisely the right time to get their way of counting institutionalized, too bad, so sad) be numbered anything else (it is totally arbitrary from a mathematical standpoint whether you number it 0 or 1, or any other number, for that matter) shows that, in my opinion, Mr. DeRose is more hung up on the result he’s attempting to obtain than he is on the true value of the numbering systems in question.
Yikes, Doug, didn’t anyone ever teach you how to write short sentences??? :eek:

Good points, all. I just thought his main point was being overlooked.

As I’ve always understood it, the system works perfectly if you consider time to be points on a time line, and a year being defined as the distance from t=0, rounded up. In other words, 1 AD means “within one year after (the point in time when Jesus was supposedly born)” and 1 BC means “within one year prior.” (As the numbers increase, it means within t-1 and t years of said point in time. e.g. 2009 AD means within 2,008 and 2,009 years after.)

It’s this way for all units of time. If we say something happened at 3:32, we mean it happened between 3:32:00 and 3:33:00.

I hope that made some level of sense. It’s pretty late here.

This is one of the silliest arguments I’ve ever seen play out. A decade/century/millenium is a period of 10/100/1000 years starting at any particular time and day one chooses. There doesn’t have to be anything significant about the starting point. “The” millenium is whatever particular 1000 year period the speaker wishes to regard as significant. To most people, this millenium is the one where the dates all start with 2. Those who want to speak about “the” millenium as something different are simply being different for the sake of being different. There was no year one or year zero for the simple reason that the calender we use today was not in use then, so arguments about what people called the first year are nonsense. Same goes for every other argument I’ve heard put.

Exapno Mapcase commented:

I am not an astronomer. I think I know the answer, but please don’t take me as an authority. I believe the “astonomical system” was no named in the 1700s because it was a group of astronomers at that time who sought to establish a nomenclature for the system they were using. But in our century (whenever it began), I think astronomers use the Julian Day for their observations – a simple enumeration of days from an arbitrary starting point, independent of any references to years.

Back to DSYoungEsq:

I know that you want this to be true. You want it to be true so much that you’ve attached a fundamentalist-like devotion to the belief that it is true. Unfortunately, like many fundamentalists, you’ve closed your mind to any other possibility.

But the fact that I wish you could face is that your religious devotion to this this belief is not held even by the religion that invented the calendar. Dionysius Exiguus knew from the outset that his calculations of the birth year of Jesus were likely inaccurate, because he was forced to compare historical records which provided an unreconcilable discrepancy.

So let me make it clear, in bold-face type: I understand your argument. You have not failed to explain your views, and I have not failed to understand them. Even so, your certainty does not guarantee accuracy, and it remains just as reasonable to say that the common era started on January 1, 0 as it is to say that it started on January 1, 1. (And keep in mind, of course, that Jesus wasn’t ever believed to have been born on January 1 – of any year – anyway. So that adds another layer of complexity to what we’re even talking about.)

But, at the end of the day, I’m not going to keep fighting to get you to recognize a fact – that there are two valid systems for establishing the start-point of the calendar – that has been established for hundreds of years. I find it frustrating when people call me “stupid” because they don’t understand a complex argument. But I’ve done as much as I can to share my knowledge with you. And I’m not going to get dragged down by your insults.

They do in some countries:

Now that I’m somewhat more awake than when I made that last post (although you wouldn’t know it if you saw my original typing of this), let me try to make my point more coherently.

The argument in the general culture is whether the third millennium began on January 1, 2000 or January 1, 2001 given the calendar that everybody in the argument uses.

That answer is straightforward. By the calendar, the answer is January 1, 2001.

Can you define a totally different calendar that would give a different answer? Yes, you certainly can.

And so what? Did anyone in the culture on either January 1, 2000 or January 1, 2001 use that differently defined calendar? Apparently not.

So why even bring it up? It is irrelevant to this discussion.

In this discussion, the people who argue for a January 1, 2000 date are indeed wrong, and most of them are stupid, because they simply don’t understand the calendar that everyone has already agreed is the base we have defined. They have to resort to contorted tricks, like saying that the first century ran from 1-99, or simply that having zeroes at the end of a year changes the definition of how their calendar system works.

Like idioms, cultural tropes don’t have to make literal sense. People prefer to start in rollover years. Everybody is aware of that. Some people dislike it. But it’s the argument we’re in and changing definitions to make it a different argument that nobody uses or is interested in drives a pointless argument into the negative.

Actually, that is not the arguement most are making here. If you say when does the third millennium begin, the answer is clearly January 1, 2001.

But the arguement that is being made is that the culturally significant millennium, referred to usually as just the new millennium is referring to the 1000 year period whose first digit is 2. It isn’t a redefining of the question or the calendar. It is an understanding that there are new millennia starting at any point one wants to count. To be completely accurate, those on both sides of the arguement need to be a little more explicit when they use a definite article with the word for a time-period.

Ninth, actually.

No, it is stark unreason, because there is no such year except in the professional jargon of astronomers when they are doing astronomy. Ovid wrote The Art of Love in 1 B.C., not A.D. 0.

It is theoretically possible that the calendar could be reformed along other and more computationally convenient lines, just as it is possible that the USA will convert to the metric system. But it hasn’t happened yet.

Pope Gregory XIII declared our current system in 1582. I assume he did this on behalf of God. Good luck arguing with Him about it. Most everybody uses this system, even astronomers. Yes, even astronomers; primarily because their banks use the Gregorian Calender, and you know astronomers, they’ll use the system that makes them the most money.

So, WHY is there no year zero?

– Russ, rainy rainy Western Oregon