The Extraverse is a term used by humans of the twenty-second century and later to refer to universes that contain matter or antmatter, and the medium that separates the two.
Humans began to organize parts of the Extraverse during the twenty-eighth century, when they had developed the technology to be able to enter it. They categorized it into three main branches, the Multiverse, the Antiverse, and the Separativerse. The Multiverse contains universes that are mainly composed of matter, and the Antiverse includes all universes that are composed mainly of antimatter. The Separativerse consists of neither matter nor antimatter, but a medium that keeps the Multiverse and Antiverse from annihilating each other.
All universes that contain matter are created in an event known as a Big Bang. There is no limit to how many Big Bangs can occur, and, since they have existed before time, have always been occurring. There is no way to measure how long the Extraverse lasts, but it is known that it dies and is reborn again in a series of Big Bangs and Big Crunches.
Big Bangs occur when the Separativerse contracts into a singularity, leaving the Multirverse and Antiverse to annihilate each other. As the Multiverse and Antiverse annihilate each other, there is no space in existence to allow the energy produced by this to travel through, causing numerous shockwaves within the Extraverse, and manipulating the membranes that make up it. The membranes collapse, making the energy produced contract into a singularity. At this point, numerous dimensions are destroyed, making the singularity unable to expand. After unimaginably long periods of time, more dimension are created, and a Big Bang occurs. Then, the whole cycle starts over again.