FourDrive

The current only known method of true faster-than-light travel, the invention of the FourDrive, replacing the Krasnikov-Hiraski Event technology in the mid 3rd millennium CE, enabled a rapid expansion of human-occupied space over a period of a couple of thousand years, up until the disaster caused by the Amnesiac Virus.

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Technology

At its most simplest explanation, the FourDrive enables a vessel to access the fourth spatial dimension (FourSpace) and plot a route through the complicated, 'crumpled' structure of three-dimensional space. This results in a journey time far faster then in sub-luminal travel, and avoids the causational issues of the old Krasnikov-Hiraski Event technology. The process is not without its side effects however;
Firstly the actual journey time does not seem to be affected by distance, and is not fixed - the complex nature of FourSpace makes every journey variable in duration. Most are in the order of between a few hours and a week, but almost instant transitions have been known to occur, as have travel times measured in decades or even centuries.
Secondly, the calculations required for the jump cannot be done whilst the vessel is in real space, only done once the vessel transits into FourSpace and, for the longest distances, can take weeks to complete. This is a fixed amount of time for a given distance, but scales exponentially above about 1,000 lightyears, with most ships only engaging their FourDrive for distances below that.
Third, once a destination point has been fixed, it emanates gravitational waves until the vessel emerges from FourSpace in a burst of radiation. These waves begin quietly, but increase dramatically in the hours leading up to a vessel's transition into realspace. If a transit time is longer than just a few minutes, these waves are easily detectable, removing any element of surprise. The actual transition is also extremely bright, often brighter than the local star, and can even be seen by the naked eye hundreds of AU distant.
Fourthly, transition into FourSpace is disrupted by strong gravitational fields around it, massively increasing the risk of transit failure and the loss of the vessel. For this reason, vessels will travel high above the plane of the system, typically ten or more astronomical units, before engaging their FourDrive. Despite sub-luminal drives being efficient and powerful, this can still take several days, and adds to the total journey time. Transitions can, and have, been made within strong gravitational field influences, but this is only ever done as an act of last resort.
Finally, FourDrives are large and require large amounts of power. FourDrive enabled vessels are some of the largest human constructions, and capable of carrying entire fleets into FourSpace. The power requirements can only be met either through antimatter consumption or blackhole generators, charging vast capacitors to provide the boost of energy required to break out of real space and into FourSpace. A substantial part of the waiting time between FourDrive jumps is waiting for the capacitors to recharge.

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History

Scientists first uncovered evidence in the latter years of the 2nd millennium of not only the existence of 'upper' dimensions, but that they could be accessed using technology. The required technologies did not exist, and despite the availability of advanced supercomputers, the work to develop such things was a long, drawn out process.
In the early 3300s, scientists and engineers finally developed mechanisms for enabling a vessel to enter FourSpace, and the first successful transition between star systems took place one year later. Although the demonstration had mixed results (the unmanned vessel took almost eight months to travel only 1.5 lightyears and was first considered lost), it was shown in subsequent tests that the journey duration appeared to fluctuate considerably; the second test transitioned almost instantly, and the third took less than an hour. Further studies could not create any way of predicting journey times, as it appeared that the complexities in FourSpace made any real world attempts of explanations pointless.
Despite this inconsistency in travel times, the FourDrive had no upper limit on range, although the time taken to calculate a transit route increases exponentially after around one thousand light years, but it took years of testing to allow for official transits to systems beyond the Keyhole network. That the first three attempts to jump to unconnected systems resulted in perceived failures did not help. (Note: the second attempt worked, but the vessel was in FourSpace for over 200 years, eventually emerging at its target with a crew long-dead).

The Great Expansion

The technology resulted in an outward explosion of human settlement into the wider galaxy in an event known as The Great Expansion. Human settlement spread out over the following centuries with a subsequent boom in population and technology. A survey conducted in 4610 counted over five thousand inhabited human systems, a second survey in 8320 counted close to four hundred thousand. The last survey, at some point in the decades prior to the Amnesiac Virus, had well over 25 million star systems with at least some permenant human habitation within a thousand lightyears of Sol.
In the long, dark years after the disaster of the Amnesiac Virus, FourDrive technology was all but lost. Worlds that had retained technical expertise knew the concepts, and FourDrive vessels existed, but without the complex computers to navigate, they were all but useless. The worlds that would one day become the Northup Alliance managed to resurrect some of the old Krasnikov-Hiraski Event network, and kept in touch with each other, but for most systems, they remained isolated.
It was the Federation of Xah that first came up with a work-around to the lack of computing power for the FourDrive jumps. Using their practical, yet horrific Ninyo Networks, they finally had the ability to make FourDrive jumps, and quickly made the most of it, beginning the The Xahian Crusade. After the Invasion of Beta Canum Venaticorum, the newly formed Northup Alliance, whilst disavowing the horrors of the Ninyo Network, managed to recreate their effects using electro-mechanical computers, enabling their expansion to counter that of the Xahians.

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Uses

With the power requirements for the FourDrive precluding its installation into anything less than large vessels, with the two most ubiquitous human craft with FourDrive capability being the Xahian 'Kurir' class, and the Northup 'Phase' class. Ghalimi vessels have also been observed translating into and out of FourSpace, so are assumed to have similar technologies, although their craft do not display the spires that are necessary on human craft for generating the field that protects the ship from four dimensional space.
The Kurir and Phase class ships display similar capability in FourSpace travel; with the randomised nature of the journey time, although Xahian ships employ brain-linked ninyo networks, as opposed to the electro-mechanical computers of the Northup Alliance, which gives a slight speed advantage in FourSpace calculations. How the Ghalimi perform their jumps is not known to human science as yet.

 FourDrive ships - (from left to right) Ghalimi vessel, Xahain Kurir class, Northup Phase class

Access & Availability

Limited to large vessels due to immense power requirements. The smallest FourDrive enabled vessels are tens of kilometers long, with a mass of millions of tonnes.

Discovery

Approx. 3200 CE

Related Materials

• Hydrogen

Related Vehicles

• Kurir class carrier