In the binary times in which we live, it might not surprise anyone that people can't even agree on when one period of time ends and another begins. The question many are now asking is: When we ring in the new year and welcome 2020, should we also celebrate a new decade?
Confusion over the answer is similar to the uncertainty that hung over watershed events from the millennium to the 2009-2010 changeover.
As Jan. 1, 2020, approaches, it turns out there is a Team Zero and a Team 1 – those who believe the new decade will begin after midnight on the upcoming New Year's Eve and those who believe the burgeoning celebrations of a new decade (and all the "last decade" retrospectives) are in fact a year early.
In a recent YouGov survey, 64% of Americans said the next decade will begin on Jan. 1, 2020, and end on Dec. 31, 2029. But nearly 20% said they weren't sure – and slightly fewer people said the next decade won't start until Jan. 1, 2021.
On this question, many voices of authority are with the minority. They say that because there was no Year Zero when the current era began more than 2,000 years ago, all decades, centuries and millenia begin with Year 1.
But others say that because people use the term "decades" to discuss culture and chunks of history, it should run from 0 to 9. And besides, they add, the definition of a decade is just any 10-year span. Where it begins is fairly arbitrary, in their view.
"It's one of these mathematical conundrums that people can argue about until they're blue in the face," Duncan said.
When asked about the dispute, Rick Fienberg of the American Astronomical Society says he doesn't think his group has adopted an official position on the matter — but he adds, "History is clear: Because there was no Year Zero, the first decade of the common era (CE or AD) was years 1 to 10, the second decade was years 11 to 20, and the next decade will be years 2021 to 2030."
Part of the issue, he and others say, is our use of "decade" as a frame of cultural reference.
"The reason people get confused is because we tend to think of decades as 'the 20s' or 'the 30s,' Fienberg says. "It's true that 'the 20s' — that is, the period 2020 to 2029 — is a decade, i.e., 10 years, but in terms of keeping track of decades from a calendrical (rather than cultural) perspective, the decades are counted as noted above."
Team Zero has an ally at the federal agency that helps to keep time on track. Andrew Novick of the National Institute of Standards and Technology says he sees it as a matter of semantics — and an interesting discussion. Like Fienberg, he adds that his organization hasn't issued a formal opinion on the public debate.
"It's kind of fun to talk about," Novick says. "It's a friendly debate because we can kind of decide what's interesting, what's important and how we want to define it."
Novick is an electrical engineer in NIST's time and frequency division in Boulder, Colo., where he and his colleagues spend their days thinking about time intervals and the standard definition of a second. He says he has "been in the time business for a long time."
In Novick's view, the answer to the decade question comes down to clarity and simplicity. And anyone on Team Zero may want to use his arguments as their own.
"The definition of a decade really is just 10 years" at any point in time, Novick says. But he acknowledges that people argue over semantics — and that they think about decades in very subjective ways.
The problem with the strict numerical or calendrical reading, Novick says, is that it could lead to even more confusion.
"If you wanted to say something that happened in 1990 was really in the decade of the '80s, you know, just date-wise, it's kind of confusing," he says. Novick suggests we keep it simple by calling a decade a period of 10 years — starting with the zero year.
Of the folks who insist on defining decades on a purely calendrical basis rather than as a cultural marker, Novick says he doesn't necessarily disagree with them.
"I would say however somebody wants to define something in language is up to them," he says. "But they might have to clarify how they're defining it so that people know what they're saying."
As is often the case, other federal opinions are available. The U.S. Naval Observatory's Geoff Chester says his personal views put him on Team 1.
"I count from 1 to 10, not 0 to 9," Chester recently told The Philadelphia Inquirer. As an example, he said, "When I turned 50, I told people that I was in the last year of my 40s."
As for the disputes over defining decades — and where they often break out — Chester said, "this is one of those situations where no matter what side you're on, you're probably going to get into a bar fight."
Dilemmas over marking time have been going on for years. In the late 1990s, the Library of Congress's estimable Ruth S. Freitag famously compiled a 57-page research document titled The Battle of the Centuries, in which she called out people who celebrate any era before its time.
"When the encyclopedia of human folly comes to be written, a page must be reserved for the minor imbecility of the battle of the centuries — the clamorous dispute as to when a century ends," Freitag wrote. Noting that there was no "year 0" in history, she said, "In fact, there has never been a system of recording reigns, dynasties, or eras that did not designate its first year as the year 1."
To bolster her argument, Freitag, who was then a senior science specialist in the library's Science and Technology Division, cited historical records that showed similar disputes had erupted when calendars were turned to 1900.
But even Freitag acknowledged that she was swimming against the tide of popular opinion.
People's beliefs that milestone years begin in zero, she wrote, "have become so widespread that anyone who tries to call attention to the error is disparaged as a pedant and ignored."
As Freitag suggested, the debate has often turned fractious. And that could be because there's something personal at stake. After all, part of the definition of a decade is its cultural significance — the meaning it has for all of us who lived through it.
At the start of 2010, President Barack Obama had just completed his first full year in office. The years since then have been loaded with news and events. Could it be that some people simply want to welcome a new decade's arrival so they can say farewell to the current one?
To test that idea, I asked Novick if perhaps the current decade is full enough, and doesn't need another year tacked on.
"That's a good point," he said.