A subspace inversion is an event that takes place in the Bajoran wormhole every fifty years. It can also be created artificially. It has been theorized that the subspace inversions that occur every fifty years have been visible from Dahkur Province on Bajor for at least three and half thousand years. (DS9 reference: Star Trek: Deep Space Nine Technical Manual) In 2371, a carrier wave being sent through the wormhole created a subspace inversion which increased the wormhole's gravity well by a factor of three. (DS9 episode: "Destiny")