A striking aspect of 22nd century Xindi technology. The subspace vortex was a mode of faster-than-light transport involving actual penetration of subspace. Generated from a Xindi vessel, the vortex opened into a network of subspace tunnels; this allowed travel between points in normal space considerably faster than warp speed. Even at higher factors, conventional warp engines couldn’t compare.
A vortex was opened with a phase deflector pulse. The visual effect was slight and easily missed, with the ship appearing to vanish or appear without warning. A wave of visible light was present, but rarely pronounced.
While most ships could only travel a few light years, Xindi-Aquatic vessels (namely Cruiser-type ships) were witnessed using vortices to travel great distances, such as the 50 light-year journey from the Delphic Expanse to Earth, achieved in a matter of hours where it would normally take six weeks. The larger a vortex, the more unstable it was. Degra said he’d have great difficulty creating a vortex large enough to carry the Xindi superweapon and four other vessels; he warned one or two of the ships might be destroyed.
While most technologies of the five Xindi species were developed naturally through centuries of refinement and progress, the vortex transit was different. It both accelerated the Xindi’s evolution into a space-faring people, and marked the first time the Guardians significantly aided the progression of the culture. Though the Guardians didn’t simply hand the technology to the Xindi, they nonetheless spoon-fed them the fundamental principles of subspace theory, and let them build the basic machinery on their own. Following nearly a century of experiments, the Xindi finally succeeded in penetrating subspace and made their first FTL flight at the beginning of 1890. Over the next three hundred years, the technology advanced, but one key component would stay the same: Subspace manipulation.
In the Expanse, though not known to the Xindi at the time, the “Guardians”, in fact the Sphere Builders, were at work modifying the very fabric of space, attempting to make it habitable for their kind to colonize. While not existing in any one realm, they were nonetheless able to manipulate the laws of physics in varying dimensions, and managed to create a network of tunnels throughout subspace. These spanned even beyond the barriers of the Expanse. While the Xindi had developed the technology to enter subspace, it was only through these tunnels that they were able to actually travel vast distances beneath normal space. As mentioned, the Aquatics were the Xindi race who utilized the tunnels most effectively.
Over time, though, the deception of the Sphere Builders became known. With the help of the Human starship Enterprise NX-01, the Xindi defeated their “Guardians”, preventing them from further altering the fabric of reality. The resulting effect of the Sphere Builders’ withdrawal was the collapse of the Delphic Expanse. The thermobaric cloud perimeter isolating the region dissipated, the vast fields of spatial anomalies receded and, unfortunately for the Xindi, the network of subspace tunnels soon began to collapse. Without further contact from the Sphere Builders or access to their subspace manipulation technology, the Xindi were forced into more than a decade of exile. During this time, they adapted existing technology from various other “Expanse” races to create their own version of warp drive.