Faster Than Light Travel

Faster Than Light Travel commonly known as FTL is a transportation method which allows for an object, most often a spaceship, to move at speeds exceeding the speed of light. There are now multiple known ways of achieving this, most notably the common warp drive and the Terran graviton Henry-Chevalier Drive, commonly known as the gravdrive. 
==History==
Warp drives were the first means of reliable FTL travel discovered in known space. The earliest forms of warp drives were developed by the Mirdesh Confederacy in the early 1800s of the Terran calendar. Most other species also discovered warp drives as their first FTL, with the only two exceptions being Humans and the Komuggal. The discovery of warp was made independently throughout the Galaxy. Whilst warp drives did not evolve much in peace time, they were drastically improved with each large-scale war. In the Great War, the much lower speeds of warp relative to HCDs forced many nations to massively invest in their development. The Terran Federation is considered to be the nation that discovered warp technology the latest in its own history. However by the 2320s, warp drives had all but completely replaced HCDs in civilian sectors. 
Terran beliefs that FTL was impossible were swept away in 2156 when Nicolas Henry-Chevalier discovered gravitons. These allowed for graviton drives, which would completely negate or increase an objects mass by several orders of magnitude. In turn, this opened up the possibility for anti-gravity, artificial gravity and most importantly FTL drives. The Terran Federation invested massively into this technology (8% of GDP in 2188), and what began as an extremely expensive and inefficient means of travel quickly became safer, faster, more efficient and cheaper. This allowed for massive colonisation of the Solar system and eventually Alpha Centauri. To this day, the Federation allocates nearly 0.5% of its GDP every year to improving HCDs, but progress is slow as efficiency limits are reached.
==Differences between Warp and HCD technology==
Whilst both HCDs and warp drives allow for FTL, the two have large differences both in how they operate and their limitations. HCDs function by nullifying a ship's mass allowing for extreme acceleration without overwhelming G force, whilst Warp drives create a distorted area of space around the ship, known as a warp bubble, which moves faster than light, moving the ship with it. This allows for warp drives of large ships to move smaller ships located in the bubble, which HCDs are incapable of. HCDs are however largely faster, as they can easily reach speeds of 6500c on standard models, and up to 9800c on prototypes currently in the making. Warp drives can only reach at around 5200c. HCDs are also not susceptible to FTL inhibition and are more stealthy when in use, but are equally susceptible to detection upon entering real-space. 
Another major difference is the unit which determines the amount of power required to move a ship at a certain speed. HCDs' power consumption is determined by mass, whilst for warp drives it is determined by the volume of the ship, and by extension the warp bubble. 
Both HCDs and warp drives require travel on hyperlanes. Quickly after the discovery of FTL technology it was discovered that travelling could be extremely hazardous. Rogue planets and even small objects could cause immense damage to a ship at such speeds. Whilst at first it was considered that drives could simply automatically stop if the ship was about to collide with an object, this quickly proved unfeasible as the sensors required would eat more power than the drive itself, and that emergency stops permanently damage the ship. Later it was also discovered that dark matter could also have a tremendous impact on FTL ships and could completely disable the FTLs. It was therefore decided that ships would travel only on predetermined routes, called hyperlanes. These hyperlanes could be discovered by launching a ship through an area of space and performing scans, or alternatively and more often sending a drone at slow speeds (up to 10c) which would perform scans. This is a lengthy process and the principal reason why a lot of time is necessary to explore systems with no known hyperlanes.
On an economical and technical level, there are also many differences. Whilst the warp drive has seen widespread adoption throughout known space, HCDs have largely remained confined to the Terran military. Whilst HCDs can reach higher speeds more easily, the very low amount of research dedicated to them (only relative to warp research) has made them extremely expensive and generally unaffordable. The facilities required to build them are highly specialised, and Clarktech is the only one to have such factories. This virtual monopoly has artificially increased prices further for any potential buyers not affiliated with the Terran military-industrial complex.
==Standard FTL Classification==
Standard Faster Than Light Classification (Ψ) often abbreviated to SFC is the main way of classifying FTL drives. It is calculated as follows:
\Psi = \frac dt
The distance in light years divided by the time (measured in days) it takes to cross that distance with and FTL Drive gives the SFC of that FTL Drive. The default time unit for this calculation is Terran days (24h), but sometimes other units are used, most notably Surben (16h) or Mirdesh (22h) days. With the Terran days measurement the Ψ is equal to the number of light years that can be crossed in a day. Minimum requirements for an FTL drive to be sold is for its classification to be at least Ψ5 to the corresponding ship size and mass. Most ships are equipped with Ψ15 drives and larger ships often have a backup Ψ12. The very best drives today can reach as high as Ψ21.74. Most of often, the SFC specification is given alongside the maximum celerity. For example: Ψ15(5475c).