Hyperspace

Hyperspace is a set of lower dimensions existing beneath realspace, made possible through the interactions of gravity wells with Arcanic Energy. The most useful property of hyperspace is the scalar correlation between points in realspace and different layers of hyperspace; namely, distances between two realspace points become exponentially shorter to cross the deeper an object dives into hyperspace. An object crossing through hyperspace technically never breaks relativistic speeds, and avoids time dilation as well.
The best way to visualize hyperspace is to flatten conventional 3D spaces into 2d. Hyperspace then materializes as a shrinking cone made of a continuum of exponentially shrinking layers. Ships can vibrate specially designed Thaumium crystals using Dive Drives to phase into hyperspace. However, the energy needed to pierce through deeper layers increases exponentially, and thus much of hyperspace is out of reach of current technology. With the widespread loss of commonplace fusion power and quantum computing, most vessels only make use of the very top of hyperspace, which yields the smallest speed gains at the lowest precision.
It is also believed that the gateway studied at Outpost X-5 somehow focuses hyperspace in the middle of its ring, effectively punching a wormhole through hyperspace at high energy costs, which would allow ships to travel at speeds far faster than their dive drives would allow.
Hyperspace seems to be the native habitat for Shades, according to the theory that they are more than extremely convincing manifestations of arcane energy and indeed their own entities.

The Singularity Theory

As the hyperspace cone shrinks, it is theorized at all points eventually converge into a single point called the Singularity, which would require infinite energy to reach. Should such a place exist, it would almost certainly resemble nothing known, for if every realspace point eventually leads to it, the very notion of time and distance would break down completely.
There are those who claim to have reached this exotic realm at the end of reality, and describe it as a place ruled by strange creatures and chaotic energies. However, such claims are often dismissed as hogwash.