The Cosmic Stream was a focal point in a higher plane of existence. (Avalon Universe: "Cosmic Stream: A Star Trek Fan Production")
The scientist Mikaela Allenby postulated that all of multiversal space-time flowed through this focal point, whose name was attributed to her. (Avalon Universe: "Agent of New Worlds") After the apparent deaths of Derek Mason and Jamie Archer, entities occupying this space judged the two Starfleet officers for their part in the death of an energy-based lifeform. Ultimately, Mason and Archer were returned to the Avalon Universe four years after they were thought to have died. ("Cosmic Stream")