Dimensional Divide
The Dimensional Divide is the "space between spaces" where beings of energy, such as the Benoi live and spend most of their lives. This is a place of "living energy" from which dimensions are born, and in which they live, and eventually die. It is like the amniotic fluid for the entire multiverse and consists of super dense pure energy. From this living energy comes matter, which the Benoi and others call "dead energy" due to the form it's taken. It's also the place where power generation systems such as the coaxial and quantum reactors used by Earthfleet draw their power. Due to the incredible density of the energy in this region of space, only beings of living energy, as well as specially equipped and shielded ships, are capable of passing through its expanses. It is also the space through which one must pass if they are moving between dimensions, be that by inter-dimensional gateway or other means.