Anti-de Sitter space

Anti-de Sitter (AdS) space is a theoretical model in physics describing a universe with constant negative curvature, meaning it curves inward like a saddle. Unlike our universe, which appears flat or slightly positively curved, AdS space has a boundary at infinity, where signals can reach and return in finite time. This structure makes it useful in studying quantum gravity and string theory, especially in the AdS/CFT correspondence, which suggests a deep connection between gravity in AdS space and a lower-dimensional quantum field theory without gravity. It provides a valuable framework for exploring fundamental physics.