The Outside is an space of nothingness that is outside the Omniverse, and in diameter is equilavent to 1000 Omniverses. Because of The Outside's configuration, it only consists of isolated pure existence-0 objects, which helps stop The Barrel from causing immense amounts of entropy and chaos due to the fact that things would stuff The Barrel and create a mess of sub-structures.
The Outside is here, because nothingness is an opposite parallel to existence, which implies that instead of nothingness forming chaos over time, nothingness forms order over time. These effects magnify as you get closer to edges of existence and nothingness due to stronger "competition". This explains why The Outside is so strict that it resists almost everything and even every nothing.
Despite the strictness of this bubble of nothingness, there is a way to escape. If you manage to turn particles in a great enough radius around the edges of everything and every nothing into clumps of "nothing", then your distance to the edge will be compressed into 0, a point of infinite order and disorder. The order and disorder combines into a "meta-disorder", turning into a structure that is infinitely "ordered" and infinitely "disordered", which covers a wide enough scope that it breaks logic, allowing tunnels of customized laws and disorder that allow travel to The Barrel's outside, or if you are precise enough with the way you break logic barriers, even reaching the outside of The Box is possible. From this point, bigger structures can be traveled.
However, nowadays, reaching the outside of said box is getting harder and harder, and said difficulty accelerates. This is due to the fact that travels to The Outside have left glitchy regions that are corrupting both The Omniverse and The Outside, which deletes the more unstable regions of both by natural selection, leaving the more stable regions that are harder to break through.
Also, some groups have intentionally gone out to stabilize or destabilize the edges between both for various reasons, such as preventing entities from reaching high-level structures, or to trap entities in the edges between both verses. In addition, a common practice, called Entity Fishing, where entities are lured to the edges, only be erased in an infinitely strict world that destroys itself has been done. A material known as Logicium can be obtained through Entity Fishing. This material can override the laws of verses and structures.
Some entities have done this infamous practice so many times that they are able to bypass enough barriers to reach Nigh Ascendent Omni-God status, but nowadays, said title is hard to get due to traps and measures set up by Ascendent Omni-Gods, like Alphasm. In fact, only a group named Alpha managed to pull off the "upgrade" before the measures were put in place, being the discoverers of Entity Fishing themselves. Soon after they were upgraded, Alphasm, named after Alpha, which he ironically was trying to stop, would set up measures so difficult that only entities controlling more than the Nigh Omnipotence Barrier would be able to upgrade themselves to such an outrageous status.