Black Light tunnel
The term "Black Light" comes from a direct translation of a German term "Schwarzlicht". It has nothing to do with UV light or "Blacklight" bulbs[1] but a method of translight travel discovered by Dr. Samuel Schwarzlicht.
It is a condition created by a special trans spatial short cut akin to a wormhole. The Schwarzlicht technology utilized by Space Trains is highly classified and exclusively used by the Space Train Company (fully owned by SII ). A so-called "Scharzlicht Tunnel" is established between two points in real space. The "Tunnel" is exactly ten meters in diameter and for some reason can not be bigger in diameter, which limits the size of objects that can be sent through. (Space Trains have a diameter of 950 cm - length has no limitations)
The energy investment is enormous on both ends of the tunnel.
Tunnels can be up to 100,000 lightyears long (in terms of Prime Dimension) and can be "boosted" too much longer distances.
Inside that tunnel, all limitations of Speed of light travel do not exist as the “Universe inside the tunnel” has no light. While Space trains travel much faster than any known conventional space ship ( up to 5 million times the speed of light)
[1]A blacklight (or often black light), also referred to as a UV-A light, Wood's lamp, or ultraviolet light, is a lamp that emits long-wave (UV-A) ultraviolet light and very little visible light.