observable universe
spherical region of the Universe comprising all matter that can be observed from Earth at the present time
AI overview
The observable universe is the spherical region of space containing all the matter we can see from Earth right now. It matters because it represents the actual limits of what we can study and understand about the cosmos, rather than assuming there's nothing beyond what we can observe.
AI-generated from the Wikipedia summary — may contain errors.
Article
The observable universe is a spherical region of the universe consisting of all matter that can be observed from Earth; the electromagnetic radiation from these astronomical objects has had time to reach the Solar System and Earth since the beginning of the cosmological expansion. The radius of this region is about 14.26 gigaparsecs (46.5 billion light-years or 4.40×10 m).
The word observable in this sense does not refer to the capability of modern technology to detect light or other information from an object, or whether there is anything to be detected. It refers to the physical limit created by the speed of light itself. No signal can travel faster than light and the universe has only existed for about 14 billion years. Objects which emit light but which exist too far away for that light to have reached Earth are beyond the particle horizon, outside the observable universe. Every location in the universe has its own observable universe, which may or may not overlap with the one centered on Earth.