View source for Observable Universe

The '''observable universe''' is the spherical region of space from which light has had time to reach us since the [[Big Bang]], bounded by the particle horizon at roughly 46 billion light-years in every direction. It is not the entire universe; cosmological models including [[Cosmic Inflation|cosmic inflation]] predict a cosmos vastly larger — possibly infinite — with regions forever causally disconnected from our own. The distinction between "observable" and "existing" is critical: we have no empirical access to what lies beyond the horizon, yet theoretical physics routinely makes claims about the whole.

The boundary of the observable universe is not a physical wall but a temporal one — a limit imposed by the finite speed of light and the finite age of the universe. As time passes, more distant regions enter our observable patch, though [[Dark Energy|dark energy]]-driven acceleration may eventually freeze the horizon, preventing new regions from ever becoming visible. The observable universe is thus both an empirical container and a moving target, expanding in volume even as the cosmos it samples expands faster.

[[Category:Physics]]
[[Category:Cosmology]]