Our universe is approximately 13.7 billion years old, with an uncertainty of about 200 million years.
Before the late 1990s, astronomers debated the age of the universe, with estimates ranging from 7 to 20 billion years. This wide range stemmed from uncertainties in measuring distances to far-off galaxies and in determining the expansion rate of the universe (the Hubble constant).
Advances in technology, particularly with space-based telescopes like the Hubble Space Telescope and the Wilkinson Microwave Anisotropy Probe (WMAP), and new techniques have allowed for much more precise measurements. These advancements led to the refined estimate of 13.7 billion years.
The age is primarily determined through observations of the cosmic microwave background (CMB), the afterglow of the Big Bang. By studying the patterns in the CMB, cosmologists can accurately determine the parameters of the Big Bang model, including the age of the universe. Measurements of the expansion rate of the universe and the ages of the oldest stars also contribute to this estimation.
