Observable universe

The observable universe is a spherical region that encompasses all matter observable from Earth. This region includes the electromagnetic radiation from astronomical objects that have reached Earth since the universe's expansion began. The radius of this region is approximately 14.26 gigaparsecs, equivalent to 46.5 billion light-years.

The term "observable" refers to the physical limit set by the speed of light, not the capability of modern technology. No signal can travel faster than light, and the universe has only existed for about 14 billion years. Therefore, objects beyond the particle horizon, which emit light but are too far away for that light to have reached Earth, are outside the observable universe. Every location in the universe has its own observable universe, which may or may not overlap with Earth's observable universe.

The observable universe's diameter is approximately 93 billion light-years, which is derived from the radius of 46.5 billion light-years. This vast distance highlights the immense scale of the universe and the limitations of human observation. Understanding this concept helps us grasp the scope of the cosmos and the boundaries of our observational capabilities.