Jump (Alliance-Union Universe) - Mechanics of Jump

Mechanics of Jump

In the Alliance-Union universe faster-than-light (FTL) ships have two major drive systems, slower-than-light (STL) thrusters and FTL jump engines. The jump engines comprise vanes that are attached to the outside of the ship. When the vanes are pulsed, they generate gravity waves which create a field, or "bubble", around the ship that pulls it (and anything else in the field) along the interface between realspace (Einsteinian space) and hyperspace (jumpspace).

Jump takes place between two massive objects, called jump-points, which are generally stars, brown dwarves, or "rogue planets" sufficiently massive to make "pockmarks" in hyperspace. Prior to jumping, the ship's navigators calculate an outbound vector, targeting the destination jump-point with direction and speed. The ship accelerates along this vector with a long STL burn until it is clear of the current jump-point's gravity well and the requisite velocity is reached. The jump engines are then engaged and the ship enters the interface between realspace and hyperspace. In this quasi-state of being half-in and half-out of hyperspace the ship is drawn along the interface to the nearest gravity well on the outbound vector, the destination jump-point. Here it re-enters realspace, travelling at the same speed and direction it entered the interface. Back in normal space the ship dumps velocity by cycling its vanes to graze the interface before the STL thrusters take over. It is possible to pass through several jump-points without slowing down, but this is risky as it can cause the ship's velocity to become uncontrollable.

Calculating the correct outbound vector prior to jumping is crucial, and the mass of the ship and its load have to be factored in. The more momentum the ship has in jumpspace, the closer to the destination jump-point it will re-appear. Too much momentum could result in it dropping into realspace too close to, or even inside, the destination mass. The ship can also "overshoot" the jump-point with too much momentum and will then drift through hyperspace until a sufficiently massive object is encountered which could drop it "anywhere" in realspace. Not enough momentum, or targeting an object not massive enough to pull the ship out of hyperspace will also leave the ship drifting. A ship's power-to-mass is significant, allowing an unloaded ship to travel faster in jumpspace than a loaded ship of similar design, even enabling the former to "over-jump" the latter. Warships have high power-to-mass ratios, making them fast despite their size. If another ship happens to be at your ship's re-entry point, both ships will be destroyed.

In theory it is possible to jump "any" distance, but the practical limit is about ten light-years. Calculating trajectories beyond a certain distance become too unreliable because of the unpredictable nature of n-dimensional hyperspace. Over short distances the calculation discrepancies are negligible, but over longer distances, the errors multiply. In addition, there is the interference of nearby stars that are likely to alter the intended trajectory.

Contrary to other "jump technologies", jump in the Alliance-Union universe is not instantaneous. However, just how long a ship actually spends in jumpspace is difficult to gauge because jump-time (also called "no-time") is not real-time. But sufficient time does elapse for minor injuries on "tranked" (tranquilized) crew's bodies to heal and for "night-walkers" to move about the ship. Typically subjective time aboard a ship in jumpspace can vary from a few days to several weeks.