Trans-System Travel

Trans-System Travel (TST for short) or Sub-Space Travel, was a form of Faster-than-light travel used by space-faring species to journey around the galaxy within average lifetimes. The general principle and equation was developed independently by many species, and marked a peak milestone in technological developement for a species as it allowed them to become multi-stellar (inhabit multiple star systems). While the means of attaining Trans-System-Travel via entering Sub-space was different depending on the method of acceleration and power, every way allowed the user to enter a realm of relatively quick transportation around the galaxy. Trans-System Travel is different than Wormhole Travel, another form of interstellar transportation, and Light-speed and sub-light-speed travel, forms of  inter-planetary transportation.

History and Principle
The Idea of Tran-System Travel, or something similar, arose from the one fundamental problem with space travel: the size of the Star Sea. At more than 150,000 light-years accross from East to West edge (a light-year being the distance a particle of light, or photon, travels in one standard stellar cycle, 365 days), a traveller in a starship could expect his journey to take 150,000 years at light-speed from edge to edge. To attain a craft that accelerates up to just 1% of the speed of light, an almost impossible feat for many species, would stretch the journey out to millions of years. It is a commonly known fact that, under normal conditions, accelerating an object over the speed of light would require an infinite amount of mass and velocity, making faster-than-light travel impossible (in Real-Space). When ancient species began to explore the vast cosmos of the Star Sea in the time before the Dawn Era, light-speed and even sub-light-speed travel would be used in order to cross relatively short distances (under 10 light-years). To combat the short lifespan most species have (120 years being the approximate standard), Sleeper Ships and Generation Ships were developed. Because of this, the galaxy remained unexplored and mysterious. Such "small" journeys could take tens of thousands of years, assuming no collisions occured whilst travelling. The Star Sea was simply too vast to support any multi-stellar civilizations, until the advent of Trans-System Travel.

While records remain fuzzy to modern scholars, it is believed by most that the Eos were the first to invent a faster-than-light form of transportation. The general principle devised in the Dawn Era is still in use today, though some of the specifics vary among different species. By entering the alternate dimension known as Sub-Space (the state of existance above the speed of light), a starship could theoretically travel between two astronomically isolated locations (say between stars, for example) within a reasonable amount of time. Sub-Space is the state that an object is in when it travels above the speed of light: it is simply the dimension at which nothing can exist below the speed of light.

To enter Sub-Space, one must use a Trans-System Drive of some sort. The Process usually involves one achieving 99.999% of the speed of light (The Entrance-velocity), and then jumping into Sub-Space (1% above the Speed-of-light and above). Once in Sub-Space, the starship would have to use additional thrust to get itself moving, as all velocity and kinetic energy in Real-Space is lost upon entry. Because of this, starships often needed to include massive reserves in fuel once in Sub-Space, not to mention the fuel used to attain light-speed in the first place.

Initial Eos Experimentation led to some of the first colonization of alien star-systems, and a starship that journeyed at 99.999% of the speed of light in Real-Space would generally travel at about 300-500% the speed of light in Sub-Space (3 to 5 light-years for every 1 light-year in Real-Space). While this could vastly shorten travel times between star systems, journeys between stars would still on average take years at a time, and cryogenic freezing was often used in the early TST Ships. After thousands of years of refinement and vast energy consumption (in order to jumpstart thrust once Sub-Space was entered), the Eos and other civilizations began to be able to travel at hundreds of thousands and, eventually, millions of times the speed of light, making trips accross the galaxy taking weeks, days, and even hours. A starship travelling from Eos to Jadini could get there in as little as 15 hours at the peak of the Eos' Golden Age in the Dawn Era.

First Era Use
In the First Era, the Eos began to re-colonize the Star Sea once again. The Principle of Trans-System Travel was re-discovered, allowing realistic space travel between star systems. A multitude of younger species followed suit in the three millenia afterward. In the height of the First Era, an average starship could expect to make the trip between Jadini and Yulvi in about a month and a half.