Subspace is a mysterious and complex region which offers both great benefits and great perils to those who utilize it. The major benefits are obvious - interstellar civilizations such as the Federation would be all but impossible without the faster than light travel offered by warp drives which utilize subspace. On the other hand, subspace phenomena can be diverse, unpredictable and almost unbelievably destructive. The following is a brief list of some of the major subspace phenomena encountered by the Federation since its formation. Note that this is not an exhaustive list, simply a selection.1
A phenomenon caused when an object is partially encased in a subspace field, thus altering the gravitational constant of the encased portion and giving the different parts different inertial densities. Subspace compression causes stress to be placed on the object, and in extreme cases can cause it to be destroyed on an atomic level. In addition to this danger there is considerable risk of damage to the platform projecting the subspace field, although a modern Starship is capable of withstanding a considerable degree of subspace compression. The Enterprise-D once attempted to correct the orbit of a moon orbiting Bre'el IV by wrapping a subspace field around part of it, thus resulting in subspace compression. The attempt failed, but as a result of non technical factors rather than any problems with the method employed.2
A rare and highly unusual subspace compression phenomenon was discovered in 2374. The anomaly caused an object which passed through it to be greatly reduced in physical size; the Danube class runabout Rubicon was shrunk to a size of approximately a dozen centimetres while investigating the anomaly, although it was eventually able to return to its normal size. It was hoped that study of the anomaly would enable a better understanding of the mechanisms behind transwarp conduits to be gained.3
A phenomenon which indicates the presence of a functioning warp drive system. The Cytherian probe encountered by the Enterprise-D in 2367 did not generate any subspace field distortions even though it was capable of travelling at faster than light speeds. The nature of the probes drive system remains a mystery to Federation science.4
A subspace link between two points in normal space through which, theoretically, matter and energy can pass. Subspace funnels thus bear some superficial similarity to wormholes. Lieutenant LaForge suggested that the mysterious disappearance of the USS Hera may have been a result of the ship being transported to Marijne VII when trionic initiators in the ships warp core created a subspace funnel. Unfortunately no evidence was discovered to support the theory and the ships loss remains a mystery.5
An area in which the fabric of space is weakened, making it especially vulnerable to the damaging effect of certain types of warp drive. The effect is cumulative, and excessive use of warp drive spacecraft in regions containing subspace instabilities can result in the formation of a subspace rift.
The region around the Hekaras corridor is rife with subspace instabilities and it was here that the damaging effect of warp drives was proven when Dr. Serova created a warp core breach in her ship, resulting in a subspace rift. As a result the local inhabitants feared that they would have to abandon warp drive altogether, but in fact a modification to warp engine design has allowed vessels to operate without damaging space in this manner.6
Our universe coexists with a multitude of others which occupy the same physical space but are separated by the phase difference between them. Occasionally our universe overlaps one of these others, creating a region of interphase. Such interphase pockets are highly dangerous; vessels entering them are likely to find themselves marooned in another universe with little chance of returning. Being in close proximity to an interphase pocket has drastic effects on the brain function of Humanoid life forms, while being trapped inside one is generally fatal.
In 2268 the USS Defiant wandered into an interphase pocket. The effect of the pocket induced intensely violent behaviour patterns in the crew, causing them all to kill each other. When the USS Enterprise investigated the phenomenon Captain James Kirk led a team onto the Defiant. The Defiant began to shift into another universe and Kirk became trapped inside the interphase pocket as his team was beamed back to the Enterprise. He survived for several hours in the pocket, having been protected during the transition by the cushioning effect of the transporter beam, and was eventually recovered. Unfortunately the Defiant herself could not be salvaged.
Interphase pockets are highly sensitive to disturbances in space and any use of energy in their vicinity can cause them to shift position and alter the timing of the periods of interphase significantly.7 An interphase pocket can be produced by detonating a tri-cobalt warhead in a sufficiently large gravitational field, such as that found near to a dead star. Under the right conditions, the pocket can act as a gateway which can allow objects to move both between parallel universes and through time.8
An opening in the fabric of normal space through which subspace protrudes. High level exposure of space containing subspace instabilities to warp fields can result in a subspace rift, causing vessels to become trapped. The rifts are extremely sensitive to any use of subspace technology, most especially to warp drive - any use of a warp drive system within a rift causes it to expand greatly.
In 2370 the USS Enterprise was present at the formation of a subspace rift in the Hekaras corridor, and was subsequently trapped within it when the USS Flemming activated its warp drive. The Enterprise managed to escape the rift, but was unable to do anything to repair it. For a time all Starfleet vessels were limited to speeds of no more than Warp 5 in order to prevent the cumulative damage to the fabric of space from creating more rifts, but new models of warp engine are able to operate safely at any speed and the warp 5 limit has been abandoned.6
A large anomaly which acts in a manner similar to a whirlpool, sucking matter into it over a large scale. In 2169 a Vulcan vessel discovered a subspace rupture in the Hanoli system. The Vulcans detonated a pulse wave torpedo in the rupture, setting off a chain reaction which destroyed the entire system.
In 2369 the crew of Deep Space Nine believed that a subspace rupture had formed near the station, but the anomaly proved to be a manifestation of their imaginations created by an alien species investigating Humanoid mental processes.9
A phenomenon which prevents the use of warp drive, effectively tying a spacecraft in place. Essentially, a region with a Cochrane factor of zero. In 2375 USS Voyager was marooned on a subspace sandbar which was created when a species of Photonic beings from another universe created gateways into our dimension. Voyagers crew was able to convince the beings to return to their own space and close the gateways, after which the sandbar dissipated and the ship was able to continue on its way.10
A shock wave produced by certain types of explosion, most notably those involving dilithium ore. Subspace shock waves tend to propagate across an almost flat plane rather than in the three dimensional manner of a normal explosion. The shock wave propagates through normal space and can interact with objects within our universe, but its subspace nature allows it to travel at high multiples of the speed of light. The near destruction of the Klingon moon Praxis in 2293 produced a large subspace shock wave with a double wave front which extended out of Klingon territory altogether and hit the USS Excelsior, which was patrolling in the area at the time.11
A subspace tear can be created by an isolytic subspace weapon. It allows a portion of subspace to intrude upon normal space, presenting a threat to Starships in the vicinity. The tear can be attracted to a Starships warp core, which drags it across space like a zipper. Detonating such a warp core within the tear can cause it to close up again, although this is not guaranteed. Such a tactic was successfully employed by the Starship Enterprise-E when a Son'a vessel used a subspace weapon against it during the Ba'ku crisis.12
A phenomenon associated with the dimensional shift transport technology employed by the Ansata terrorists on Rutia IV. Virtually undetectable by conventional sensor systems, the effect can be scanned with accuracy by an adaptive subspace echogram. In 2366 the USS Enterprise used such a scan to locate the Ansata headquarters and score a major victory over the Ansata.13
A natural subspace phenomenon which links two points in space time and causes matter and energy located at each point to switch places with its counterpart. The two points can be separated by virtually any distance, or for that matter could even exist within other dimensions. Subspace vacuoles are attracted to the warp cores of a Federation Starship.
In 2371 USS Voyager encountered a planet whose rings were riddled with subspace vacuoles which linked it to the Vhnori home world. The Vhnori had been sending their corpses through the vacuoles for a long time, believing that the phenomena were conveying their dead to the afterlife. When Ensign Kim was accidentally transported through a vacuole to their world he revealed the true destination of the vacuoles and revealed that he had seen the bodies of the Vhnori dead before being transported to their world, confirming that this aspect of their religion was in fact false. This prompting something of a religious crisis on the planet. When he - eventually - realized that such revelations were a prime directive violation Kim effected an escape through another vacuole back to Voyager.
Captain Janeway subsequently noted that the Vhnori beliefs may in fact have had some slight basis in reality, since the planet the dead were being transported to was surrounded by a very complex energy field which might contain the neural patterns of the dead Vhnori. Whilst it may be true that the Vhnori experience an afterlife of sorts, existence as disembodied energy remains fundamentally at odds with Vhnori beliefs as revealed to Ensign Kim.14
A phenomena encountered by Voyager in 2375; the sinkhole produced considerable gravimetric shear, which prevented a warp drive from functioning in the vicinity of the entrance. It was also strong enough to pull small vessels inside, though venting plasma and reversing shield polarity could counter this effect. The entrance to the sinkhole was some 600 metres across, but since it was out of phase with normal space it was extremely difficult to detect. Inside the distortion was much larger - the one Voyager encountered contained an entire solar system comprising a star and three planets. Time passed more slowly inside the sinkhole than outside - more than 126 times slower. Much of the theory regarding subspace sinkholes indicated that they were mono-directional, but Voyager was able to beam out crewmembers who were trapped inside the phenomenon by using a probe as a relay. Sinkholes can collapse naturally, destroying everything inside them, but the one encountered by Voyager was sealed by an alien vessel using anti-graviton beams before this could happen.15
A naturally occurring bubble of curved space-time, subspace nodes can be huge in size - there is one near Earth which is over a hundred light years across. They prevent star formation, and appear as an empty region of space. The lack of matter and energy phenomena allows certain experiments to be performed in these regions. In 2139 an attempt at a sub-quantum transport left the transporter pattern of a man stranded in the bubble. Fluctuations in the node caused the signal to partially re-appear on occasion, though an attempt to recapture and rematerialise the pattern was unsuccessful and resulted in the death of the man.16
A phenomenon encountered by the Starship Voyager in 2373, astral eddys form at the confluence of space and subspace. They are highly charged with plasma, which causes them to leave an easily detectable particle wake behind them. The plasma makes them a good source of energy for Starships which are otherwise short on such resources. Astral eddys throw off graviton waves which cause considerable turbulence in their vicinity. Within the eddy massive discharges of plasmatic energy are found, and temperature gradients can exceed nine million kelvins. However the centre of an eddy has a perfectly calm region akin to the eye of a hurricane.17
Astral eddys are only partially subspace phenomenon. Matter within the eddy is exchanged between normal space and subspace, and an unstable interfold layer which is not in space or subspace exists between the two. This region is the source of the eddys, which form when subspace is ruptured within the anomaly. Approaching an eddy is dangerous both because of the extreme turbulence and because of the considerable radiation they emit. Vessels in the wake of an eddy can be drawn into the interfold region, as happened to one of Voyager's shuttlecraft. Escape is possible by passing through one of the subspace ruptures which spawns a new eddy, though this is somewhat dangerous because of the turbulence eddys cause.17
A phenomena encountered by Voyager in 2377, these Voids are capable of emitting a graviton surge which could drag ships off course. The void itself is a closed structure encased in an inert layer of subspace which neither matter nor energy can penetrate - only funnels which form periodically for a brief duration pull matter into the void. The funnels appeared at irregular intervals, though Borg sensors used with fractal algorithms allowed a ship to predict when and where they would form. There was little in the way of matter or energy in the void, and no deuterium which ships could use for fuel. Worse, the same graviton surge which dragged ships inside drained energy from their power systems, resulting in at least a tenfold increase in fuel useage. The void Voyager encountered was nine light years in circumference.18