A Closed Universe: de Sitter Cosmic Gate

A new cosmological object in analogy with the concept of a wormhole in general relativity is introduced. As wormholes connect two distant points through a tunnel in spacetime, this new object connects two spacetime through a large mouth which is referred to as a "Cosmic Gate". In this context, two identical copies of the regular part of the de Sitter spacetime are cut through a timelike hyperplane. Then, they are glued at their identical boundaries (the only boundary) to form a complete spacetime. The stability of the cosmic gate against a linear radial perturbation is studied as well. Finally, the radial geodesics of the spacetime for a timelike and a null particle are presented.