Buzz
If you’ve been browsing the internet or engaging on social media lately, you’ve likely encountered debates about when the new decade truly begins: January 1, 2020, or January 1, 2021?
Culturally, it’s widely accepted that decades start with years ending in zero and conclude with years ending in nine. For example, the ’70s ran from 1970 to 1979, the ’80s from 1980 to 1989, and so on. However, an increasing number of people argue that this viewpoint is incorrect. They contend that, because there was no year 0, it’s more accurate to say that decades actually begin in years ending in one and end in years ending with zero.
This argument is based on the Gregorian calendar, which was designed around the birth of Jesus Christ. In the 6th century, an abbot named Dionysius Exiguus attempted to calculate the year of Christ’s birth. Although his calculation was later proven inaccurate, it formed the foundation for both the Julian and Gregorian calendars. According to TimeandDate.com, Dionysius labeled the year of Jesus’s birth with the Roman numeral for one (I). Approximately 200 years later, a monk named St. Bede the Venerable published five books of history that calculated the years preceding Christ’s birth. However, Bede recorded the final year before Jesus’s birth as 1 B.C., leaving no room for a year 0. In fact, the concept of zero didn’t even reach Europe until the 12th century.
So technically, it has only been 2019 years since the year Dionysius determined as 1 A.D.—not 2020. This has led some organizations, like the Farmers' Almanac and the United States Naval Observatory, to favor a decade starting in 2021 and ending in 2030.
However, that’s not the entire picture. Andrew Novick, an electrical engineer at the National Institute of Standards and Technology, explained to NPR that this is mainly a semantic issue.
"A decade is really just 10 years," he said. So, a span from 2020 to 2029 is just as valid as 2021 to 2030. But because people often discuss decades in cultural terms, it can be confusing when, for instance, you decide that 1990 is technically in the same decade as the ’80s, according to Novick. "I would say however someone wants to define something in language is up to them," he told NPR. "But they might have to clarify how they’re defining it so that people know what they’re saying."
TimeandDate.com highlights that this issue only arises with the widely used Gregorian calendar. Other calendars, like the Jewish calendar and the Islamic calendar, assign entirely different numbers to years.
"It’s a man-made system," Konstantin Bikos, the lead editor of TimeandDate.com, told CNN. "It matters when it comes to categorizing time spans and discussing time periods. But the 203rd decade is, in astronomical terms, no different than the decade before or after."
