When Does the New Decade Start?
The division of time into decades, centuries, and millennia has been a subject of debate among scholars, historians, and everyday individuals for centuries. As we approach the end of the 2020s and the start of the 2030s, questions about when exactly the new decade begins are once again at the forefront of our minds.
The Academic and Historical Perspectives
The last decade, known as the 2020s, officially began on January 1, 2020, and ended on December 31, 2029. The next decade, the 2030s, will begin on January 1, 2030, and end on December 31, 2039. However, by convention, the start of the next decade is often marked by a year 1, meaning that 2030 would begin the 2030s on January 1, 2030.
This convention, which is deeply rooted in our common secular calendar (the Gregorian calendar), has historical origins. The Gregorian calendar, introduced in October 1582, was an update of the Julian calendar, which was first introduced by Pope Gregory XIII in 1544. The Julian calendar itself derived from the Roman calendar, and even earlier systems that predated it.
The concept of a year starting in zero is perhaps the most intriguing aspect of time management. No calendar system has ever officially included a year zero, although the idea has been proposed by many. For instance, in the academic world, and particularly in astronomy, the year zero is implied in the BC and AD systems, where the year 1 BC is treated as 0, and 1 AD is treated as 1.
The Mathematical and Astronomical Viewpoints
Astronomers and standards bodies like ISO 8601 follow the practice of treating the year 1 BC as 0, and using negative numbers for earlier years. This system avoids the complex problem of having a gap between 1 BC and 1 AD.
Our current system, which is based on the Gregorian calendar (used worldwide for civil and religious purposes), does not have a year zero. This means that the start of the new decade is conventionally marked by year 1. For example, the 21st century did not begin on January 1, 1999, but on January 1, 2000. Similarly, the 2030s would begin on January 1, 2030, and not on December 31, 2029, under this convention.
On the other hand, some argue that it makes more logical sense to mark the start of the new decade on January 1, 2021. This view is based on the idea that the start of the new decade should align with the calendar date, regardless of conventions.
The Complicated History of Calendar Systems
The history of calendars is a deep and complex subject that has evolved over time. For instance, the Julian calendar, which has a year length of 365.25 days, was intended to approximate the tropical year, the time it takes the Earth to orbit the Sun. However, this calendar introduced inaccuracies over time, necessitating the adoption of the Gregorian calendar in 1582.
Even more intriguing is the origin of our modern AD system, which is based on the traditional celebration of the birth of Jesus Christ. However, the AD system was not widely used for centuries, and the year 1 AD was not the year of His birth. It was created by a monk in the 6th century to align with the specification of an Easter date calculation.
The calendar system, therefore, is more than a simple tool for marking time. It reflects the history, tradition, and conventions of different societies and cultures.
Conclusion
When does the new decade start? While the historical and mathematical answers suggest that the next decade begins in 2030, it ultimately depends on the conventions and preferences of various groups. As long as we acknowledge that these concepts are man-made and can evolve with time, we can appreciate the rich history and complexity behind our modern calendar system.
As we approach the new decade, whether we celebrate it on January 1, 2030, or 2021, the important thing is to celebrate this new cycle of ten years together with newfound knowledge and historical appreciation.