The age of the universe, currently estimated at approximately 13.8 billion years, refers to the elapsed time since the Big Bang, which is believed to be the event that marked the beginning of our universe. However, the concept of measuring time as we do today did not exist immediately after the Big Bang.
The universe underwent a rapid expansion phase called cosmic inflation during its early moments, which lasted for a fraction of a second. Following that, the universe continued to evolve and change over billions of years, leading to the formation of galaxies, stars, and planets, including our own Earth.
The concept of calendars and the way we measure time based on the Earth's rotation and orbit around the Sun was developed by human civilizations much later. The modern Gregorian calendar, which is widely used today, was introduced in the 16th century and has its starting point tied to the birth of Jesus Christ.
So, the date December 16, 2022, is based on the Gregorian calendar, which counts years from the traditionally accepted birth year of Jesus. It does not reflect the actual age of the universe, as the concept of measuring time in years as we do now was not in existence for the entire duration of the universe's existence.