The Observable Universe is the finite sphere of the cosmos from which light has had time to reach us since the Big Bang. Its edge marks the maximum distance we can theoretically observe, a cosmic horizon beyond which information simply hasn't arrived. Due to the ongoing expansion of space, the radius of the observable universe is estimated to be around 46.5 billion light-years, even though the universe is approximately 13.8 billion years old. Every observer in the universe has their own observable universe, centered on their location. While vast, it is but a fraction of the entire universe.
History
The concept of the observable universe evolved with our understanding of cosmology. Early astronomers like Edwin Hubble observed that galaxies were moving away from each other, indicating an expanding universe. This led to the development of the Big Bang theory. The discovery of the Cosmic Microwave Background radiation in the 1960s provided strong evidence for the Big Bang and helped establish the age and size of the observable universe. Further advancements in observational astronomy and theoretical physics continue to refine our measurements and understanding of this vast cosmic region.
