A phenomenological examination of the nature of hyperdrive travel in the STAR WARS films, novels, games and comics. An explanation and synthesis in terms of real-world conjectures in superluminal physics.


This page attempts a synthesis of all phenomena associated with hyperspace known in the STAR WARS universe. I take a phenomenological approach, outlining the observed characteristics of hyperspace as seen in the films and in the more reliable non-canonical sources. I weave these empirical facts and their physical implications into a synthesis with some of the more secure aspects of real-world speculative superluminal physics. Extended Special Relativity as presented in Tachyons, Monopoles and Related Topics is a particularly important basis for this work.

The reader should not attempt to apply my conclusions outside STAR WARS fiction. What you are reading is the best available rationalisation of an important aspect of the most popular science-fiction series. It does not pretend to be a comprehensive or definitive treatise on real physics. Also, please do not send me real-world crackpot theories about miracle cures and home-made theories of the universe; there is enough "pseudo" in my pseudophysics as it is.

Like my other STAR WARS Technical Commentaries, this page will progressively be expanded, corrected and upgraded. New illustrations will be added. I reserve the right to modify my interpretation of STAR WARS hyperspace at any time in order to improve the physical plausibility and create a closer agreement with new and established observations.

Special thanks are due to, in alphabetic order:

Superluminal physics.

Symmetry of the universe requires that there exist one velocity which does not vary according to the observer's point of view. The nature of electromagnetism is such that light in vacuum only travels at this special speed, which therefore is called lightspeed. The numerical value of lightspeed is commonly denoted by the symbol c. (Its approximate value is 2.98 x 10^8 m/s.) No matter how fast a person is moving relative to any other observer, a beam of light is always seen to move at lightspeed by both observers. This basic fact gives rise to all of the time dilation and other effects associated with Special Relativity.

Light is not the only entity which can propagate at lightspeed. Gravitational influences do also. All entities travelling at lightspeed must have zero mass and can never travel at any other speed. They are collectively called luxons.

Particles which bear mass can be either below or above lightspeed. The former are called bradyons and the latter are tachyons. (In the real world, detection of tachyons is practically difficult and has not yet been accomplished. It seems as if most of the matter in the universe is subluminal relative to Earth.) The fundamental particles of the tachyonic realm are the same as those of the bradyonic world, because the only difference is the velocity of an observer's point of view. From the vantage of a tachyon it is the rest of the universe which is moving at superluminal speed in a certain direction. However the interaction of tachyons with bradyons is in many ways unlike the familiar interactions of bradyons with other bradyons. Some of the specific consequences are rather bizarre, and will be outlined later.

For the purpose of superluminal travel in STAR WARS it is sufficient to choose the viewpoint of the galaxy at rest as realspace, and anything which is tachyonic relative to the collective of star systems is considered to be in a realm called hyperspace.

Relativistic variation of the energy of an object according to its velocity relative to the observer. At rest the energy is at the mass-energy minimum. At lightspeed the energy becomes infinite. In the superluminal realm the energy becomes ever smaller for increasing velocity. [Tachyons, Monopoles and Related Topics]

Relativistic variation of the magnitude of an object's momentum according to its velocity relative to the observer. At rest the momentum is zero. At lightspeed the momentum goes becomes infinite. For high hyperspatial velocities the momentum descends to a limiting value which depends on the object's rest-mass. [Tachyons, Monopoles and Related Topics]

The jump.


For common starships, the jump to hyperspace involves a brief but violent acceleration to high relativistic speeds and then a leap beyond the lightspeed threshold by some unknown mechanism. Contrary to popular perception, the high velocity relative to the galactic background cannot be related to the jump process because even the highest subluminal velocity converts to any other subluminal velocity (eg. perfect rest) for an appropriate choice of observational reference frame. Although the velocity at any moment is unimportant, the acceleration seems to be involved in the jump mechanism as either a trigger, a prerequisite or a side-effect.

Inertial dampers linked to the hyperdrive systems must protect the ship, its crew and contents from feeling the effect of this acceleration, otherwise the entire system would be crushed by acceleration stress before significant sublight speeds were attained. Tampering with the inertial dampers of a starship might cause safety systems to prevent the hyperspace jump. It is conjectured that this might have been what Imperial agents did in order to disable the hyperdrive of the Millennium Falcon in its flight from Bespin. When he set the systems right, the droid R2-D2 was propelled forward, opposite the expected direction of the inertial force due to a simple jump acceleration. However the Falcon was also undergoing a rapid spin in order to match the desired jump orientation; the droid's undamped inertia ("centrifugal force" in the ship's accelerated reference frame) is probably the reason for the droid being propelled outwards. It seems most likely that this was due to poor calibration and incorrect compensation by the inertial dampers as they glitched and warmed up to normal operation. Tampering with the safety overrides as well as the inertial dampers would have conveniently killed everyone aboard.

Material objects are able to move at any speed above or below that of light, but never precisely at lightspeed. Accelerating a sublight body becomes harder the faster it goes because high speed is accompanied by a relativistic increase in mass. Acceleration to the point of sitting exactly on the lightspeed barrier would require infinite energy input. On the other hand superluminal objects are difficult to slow. It requires infinite energy to decelerate a superluminal object down to sit on the lightspeed barrier. Tachyons move faster as they lose energy. A body in hyperspace has zero energy when it reaches infinite speed.

A starship can exist comfortably above or below lightspeed but cannot pass through lightspeed via ordinary physical means. However all of ordinary physical existence becomes imprecisely defined below a certain subatomic scale, and we can speculate that this may have something to do with the super-technology that permits hyperdrive in STAR WARS. The leap beyond the lightspeed may be an event which exploits some kind of quantum-mechanical effect in order to slip from subluminal to superluminal speed without ever being at intermediate speeds. As seen by an external observer, the jump must be accomplished within Plank time, a tiny time unit below which time itself becomes meaningless.

In one respect the jump to hyperspace is similar to the passage through a black hole. From an external point of view, an object which falls freely through into a hole is converted into tachyonic matter when it passes through the event horizon. At that point it is no longer observable from realspace outside the hole. This similarity and the spatial twist left in the jump wake (described below) suggest that the action of a hyperdrive may be at least partially gravitational in nature.


Starlines are an effect seen from the internal reference frame of the travelling starship. The background starfield ahead of the vessel undergoes some kind of distortion which is probably chiefly due to relativistic effects and may also be related to the particular phototropic properties of the transparent cockpit materials through which the effect is observed. The stars appear to be stretched radially outwards or inwards around the direction of the jump trajectory. Colours of the stars appear to be shifted into the blue, in accord with the conventional relativistic Doppler effect. At least as far as present observations show, the starline effect always lacks any rotational component, despite the inherently rotational nature of the wake rotation effect outlined below.

* * *
Blue-shifted entry and exit starlines seen from the Millennium Falcon's cockpit on its journey from Tatooine to Alderaan.

Wake rotation.

Ships entering and exiting hyperspace appear to produce a transient distortion of local spacetime. Nearby surveillance equipment of the appropriate type can detect the resulting gravity waves. Looking along the trajectory of the departed vessel, the background starfield appears to rotate for one or two seconds. Similarly the background starfield may seem to rotate upon reentry, as seen from the ship's cockpit1. This is reminiscent of a gravitational lens effect, but it involves a twisting of the space through which the light rays pass rather than so much bending or focussing. It is akin to the behaviour of light passing through the vicinity of a rotating black hole, where the hole's immense gravitation drags neighbouring space into circulation in the same direction as the hole's own spin. It seems possible that a ship jumping the light barrier to hyperspace imparts a large amount of angular momentum to the spacetime near its departure/arrival point, which is quickly dissipated by gravity waves. The fact that the twist takes about a second to vanish completely suggests that the spatial extent of this spatial distortion may be as great as 3 x 10^5 km.

The wake rotation can be either clockwise or anticlockwise. The chirality of the wake does not seem to be specific to a starship because the Millennium Falcon is known to make both left-handed and right-handed jumps. The reason why hyperdrives produce the distortion is still open to conjecture, but the phenomenon strongly suggests that the jump process is at least partly related to the technology of artificial gravitation.

It is interesting to consider the possible effects of the wake rotation on objects surrounding the jumping ship. If a hyperdrive was activated on the surface of a planet, the spatial twist might harm the world's surface, inflicting seismic damage on a scale determined by the energy of the jump. However small objects which are close to the jump are not noticeably affected, as has happened on several occasions when the Millennium Falcon fled Imperial warships. When the Avenger jump out of Anoat system, its stream of garbage did not seem disturbed. This may mean that debris stream was entirely within the wake region to start with, and that the wake rotation did not vary much across the inner region, like winds in the eye of a storm. (It is the differential of rotation from one side of an object to the other that would have disturbed the debris.) Perhaps a more powerful jump wake is more extensive but has a lower stress or rotation gradient. (A planetary-scale body, comparable to the size of the wake, would probably suffer more.) Alternatively, it may be that the wake region lies only at a great distance from the point where the pre-jump acceleration began.

* *
In the wake of the Millennium Falcon's jump the starfield seen along the jump trajectory appears to be rotated. Over the next second or two the spatial twist relaxes by about 45 degrees.

Exit from hyperspace.

Exit from hyperspace is automatically triggered by the navicomputer or equivalent systems when the ship has travelled in the correct direction for sufficient duration. Reentry is not directly connected with the proximity of any massive celestial body at the destination point (because it remains possible to jump back to realspace in the middle of empty interstellar space); nor with any other external environmental factor. Safety systems, however, may trigger automatic drop back to realspace if sensors have enough time to detect the ship's entry into the margins of a gravity well. (The observed circumstances of the Millennium Falcon's arrival at Alderaan indicate that a field of decimetre-sized rocks is not sufficiently concentrated to trigger early cut-out.) User-friendly starship navigation and hyperdrive systems will issue an audible or visible alarm just prior to reentry, and prudent crew will then raise their shields and power up their sublight engines.

The reentry process looks exactly like the inverse of the jump to lightspeed. The hyperspace tunnel is replaced by indefinitely-long starlines, which shorten and appear to end with the points of the normal realspace starfield. The ship undergoes rapid sublight deceleration to match the rest frame of the destination system. It is not clear whether this deceleration is accomplished by the normal sublight drives or some other system linked to the hyperdrive. In any case a failure to decelerate would have extremely unpleasant effects: the ship would continue onwards at extremely high sublight velocity, subject to great time dilation, and there might be very little time for the crew to react before crashing into something. During and immediately after reentry there may be some wake rotation, light rays from distant objects near the line of travel are twisted so that travellers perceive an illusion of rotation.

The sudden emergence and deceleration of a ship has significant effects on its surroundings, which may be detected by the security sensor systems of wary locals. Reentry is accompanied by a pulse of gravitational radiation and a hyperwave burst, whatever hyperwaves may be. There is also said to be a flash of what is known as Cronau radiation. This is light emitted in a forward-facing cone centred on the ship's trajectory and with its tip at the reentry point. The sharpness of the cone (its internal angle) depends on the characteristics of the jump.

Occupants may hear a noise during the transition between hyperspace and realspace. This "exit growl" is the result of the release of stress in the ship's hull as different parts of the vessel make the transition over a tiny fraction of a second. A properly-tuned hyperdrive accomplishes the transition over the whole ship effectively simultaneously. If a faulty hyperdrive exhibiting the exit growl is not fixed the ship will eventually destroy itself, with some parts of the vessel making the transition while others do not. The growl associated with the Millennium Falcon's hyperdrives is a modest whine, obviously not serious enough to worry Captain Solo.

Temporal effects.

Duration and speed.

It is not clear whether the time experienced by the passengers of a ship in hyperdrive has any relation to the duration of the jump as observed by a typical observer in the outside galaxy. The Galactic Empire is over 120,000 light years in diameter but has only existed under Palpatine's government for a mere quarter-century or so. If news of the establishment of Palpatine's regime was carried outward from the Core Systems in such a way that it only reached the Outer Rim Territories by the time of his death then the starships bearing the news would have average travel velocities of over 5000c. However we know that transgalactic travel is feasible within the early part of an adult lifetime (Han Solo crossed the galaxy before he turned 29), and furthermore the coherence of the Empire as a single political, economic and cultural entity demands trans-galactic travel times of several weeks at the most. According to this propagation timescale the equivalent realspace speed of hyperdrive travel is typically greater than 1,200,000c. This speed scale is supported in several novels references (eg. Dark Force Rising p.212).

Just like travellers at high sublight speeds, hyperspace commuters will be subject to significant time dilation effects. If the journey were to occur at only slightly above lightspeed then the passengers would experience less time than people remaining at rest with the galaxy. However at velocities much greater than lightspeed, let alone the immense speeds of which hyperdrive ships are capable, the time dilation advantage reverses and the passengers experience time more slowly than the outside galaxy. As the duration of the journey becomes shorter as seen by the outside galaxy, it also becomes longer for the travellers. These effects balance each other so that for high-speeds trips, the duration will be arbitrarily short for the outside observers while the passengers' travel experience woudl lengthen to a limit that does not depend on their speed.

If the distance covered is x then the limiting high-speed travel time experienced by the travellers is x/c. In particular for a journey of hundreds of light years the natural ship-time would be hundreds of years, even if only a split second elapses in the galaxy at rest.

This is a problem. Lord Vader obviously does not die of old age while journeying from Coruscant to Vjun, and nor does he travel so slowly that centuries pass in the Empire. Clearly the hyperdrive technology must solve not only the secret of jumping over the light barrier but must also alter shipboard time. The mechanism of this time retardation may be related to to gravitic technologies like the routine generation of artificial gravity, or it might be related to the jump wake rotation effect.

The introduction of a technology for generating a locally-acting time-retardation field appears to be at least as necessary as the use of inertial dampers to avoid crushing a ship's contents during jumps. Fortunately there is some indirect evidence for the existence of these device in the films. In expressing frustration at his farm life on Tatooine, Luke Skywalker wistfully asked C-3PO whether he could arrange for precisely the kind of time alteration required for ultrafast interstellar travel. The droid regretfully admitted that he had little knowledge of such things. In other stories, such as the novels Han Solo at Star's End and Rebel Dawn, these technologies are named stasis fields. Delicate perishable cargoes are kept in containers with built-in devices which artificially retard time. At the technological extreme, a stasis field reduces the passage of time to a complete standstill, but a more general technology could achieve time dilation factors of millions or some other finite value. It seems that the overall contents of a starship are subject to such fields whose strength is attuned to the hyperdrive systems.

Travel duration depends on performance qualities of the hyperdrive as well as the abundance of local hazards and obstacles along the particular hyperlane. Jumps along well-known routes tend to be quicker in relation to the distances covered, because a more precise knowledge of potential obstacles allows more efficient paths and higher speeds can be used. Within these safety constraints, the hyperdrive efficiencies of starship designs vary. This is expressed in the hyperdrive class rating; a ship with a statistic of "point five" completes most interstellar journeys in half of the standard time.

These hyperdrive ratings are defined in the references of West End Games and subsequently used in most unfilmed STAR WARS fiction. The terminology seems to be based on a single spacer's boast by Han Solo to the effect that his ship can "make point five past lightspeed". The hyperdrive class interpretation is very reasonable, but other theories are possible. The problem is that Solo's slang is very loose and listeners are not privy to the technological and social context. "Point five" sounds like some kind of rating factor, but there is also a chance that it is a statistic with physical units, which Solo neglected to utter. Just as easily as describing travel-time, it might instead relate to energy efficiency, avoidance of time dilation, or some supralight benchmark (which cannot involve typical speeds of less than many hundreds of thousands of times lightspeed). Solo implies that "point five" is a great accomplishment, but does not tell us whether smaller or larger numbers are considered better.

Some readers believe that there is a direct (perhaps linear) relationship between hyperspace speed and Solo's factor. In this case the speed might relate to the standard speed of the route (h) according to something like v=h(1+f) with f the Solo factor; rather than the speed relation implied by West End Games' hyperdrive class (v=h/f). Some references in Timothy Zahn's novels are open to this interpretation, though without excluding other possibilities. Should ever a body of references be found which unequivocally refutes the common "hyperdrive rating" view, we shall then be forced to conclude that there exist two kinds of hyperdrive statistic which sound similar but quantify different things. In any case, this terminology is ultimately rather arbitrary and does not affect the independent and substantive speed estimates made in the above discussions.

It should be noted that the speed estimates presented in this document are typical scales only. Acceleration requires effort, but speed does not. The laws of inertia hold the same for bodies in hyperspace and realspace. An object moving in hyperspace at a certain speed in a certain direction continues to move with the same speed in the same direction unless acted upon by a force (either an external force or a ship's own propulsion systems). This aspect of elemental physics was explicitly confirmed in the expositions of former Imperial hyperphysics researchers in Tyrant's Test. Therefore, if the "point five" performance factor is not merely a comparison of transit times, it is most likely to be a measure of some kind of acceleration or propulsive power in hyperspace, and not a raw speed.

Causality paradoxes.

A naive interpretation of Special Relativity would suggest that under some circumstances superluminal travel results in time reversal. The trouble arises when observers at the starship's destination are moving at some significant velocity relative to the origin. If v is the velocity of the ship in hyperspace, u is the difference of velocity between the origin and destination points, then a kind of reverse time-dilation occurs when v u > c² (where c is lightspeed). This is considered a paradoxical problem for spaceflight and communications because it seemingly allows someone at the destination to send out a superluminal signal to the origin system, affecting the circumstance of the ship's launch. For instance we might suppose that the Grand Moff Tarkin would send a message to Tatooine ordering the impoundment of the Millennium Falcon, preventing the ship from launching in the first place. Thus (on a superficial reading) it would seem as if hyperdrive travel would lead to confusing violations of causality and historical paradoxes.

The galaxy rotates, with star systems and interstellar material orbiting the common centre of mass. The nett rotation and other internal motions give rise to velocity differences of dozens of maybe a hundred kilometres per second between distant regions of the disk. The drift speeds are much smaller between neighbouring systems. For a jump between systems with velocity separation of 50km/s observers at the destination system will witness the time-reversal effect if the vessel travels faster than about 6000c. For jumps of more typical length (only a few hundreds or thousands of light years) the velocity differences will be smaller, but the threshold for time reversal rises to only a few tens of thousands of times lightspeed. The range of velocities involved in hyperdrive travel are very much greater, far into the realm of possible causality violation.

Fortunately it turns out that causality paradoxes actually cannot arise. Although nobody will see starships travelling backwards in time, other exotic effects will be observed. A particle moving backwards in time is equivalent to the motion of some antiparticle forwards in time. In relativistic quantum mechanics that's exactly what antiparticles are: time-reversed versions of ordinary particles. In those situations where naive relativistic considerations would suggest the observation of a starship travelling backwards in time what the bystanders will really witness is an antimatter starship travelling forward in time. This mirror ship will be seen to head in the opposite direction.

When the reentry jump occurs the real ship would emerge from a point in space and the antimatter mirror ship appears simultaneously at the same location and then accelerates off at superluminal velocity in the opposite direction. At the jump point, where both the vessel and the mirage are indistinguishably close to lightspeed, they would each appear to be compressed into zero length. This is due to a length-dilation which is similar to the relativistic time dilation effect. (All objects appear to be shortened along their direction of motion by a factor which depends on speed. This contraction becomes indefinite at lightspeed.)

Thankfully, even this disconcerting sight is unlikely to be witnessed under ordinary circumstances. In preparation for the jump back to realspace the ship must reduce velocity to very near lightspeed, well below the time-reversal / antimatter threshold speed. It will cover great distances while doing so, and even more distance while it decelerates from lightspeed to rest. Even if it is possible to see a ship in hyperdrive, the transition back to realspace will take place far from inhabited space, on the outer reaches of the destination system or even further away. Similarly a ship jumping into hyperspace covers a great distance during the pre-jump acceleration phase.

Tracking and communications

Accurate scanning of a ship as it makes its jump to lightspeed can reveal its destination. The elongated spatial distortion which gives rise to the wake rotation effect should be detectable to CGT (crystal gravfield trap) sensors, as well as any electromagnetic sensors fortuitously aligned with the jump trajectory. The Cronau radiation associated with the jump will also be visible for any scanners within a certain conical region around the jump site. Sensors at Echo Base Hoth detected the emergence of Death Squadron from hyperspace at the edges of the Hoth system, at a range of at least several light-hours.

Because normal hyperdrive travel is essentially a straight-line affair, careful observation of the last known direction of sublight motion reveals the heading of the hyperspace jump also. Of course this track will be useless if the pilot of the departed ship decides to make a second jump immediately after the first, from a point in space where there are no nearby bystanders to make the necessary measurements.

At least some starship propulsion systems are known to leave tenuous trails of particles which gradually diffuse and dissipate into surrounding space. Antimatter particles have been named among these, though it is unclear whether it is associated with the hyperjump process or normal sublight propulsion. "Hyperdust" is another term used, which is obviously connected with supralight travel although its physical nature is unknown. Trails for a ship can be carefully reconstructed through clever use of common sensors if the space has been undisturbed and less than a few weeks have elapsed. Beyond that time limit, the gradual diffusion and decay of the trail is too advanced for useful information to be deduced. However it is not known how useful even a fresh trail is for the purpose of reconstructing a precise hyperjump trajectory. [Refer to Children of the Jedi, p.37.]

Hyperphysics technicians have developed one method for reliably tracking a ship through hyperspace. An Imperial hyperspace tracking device must be directly installed aboard the ship which is to be tracked. The device is similar in nature to a hyperwave transceiver, except that it is dramatically reduced in size and power output. Although its range is far too short to directly signal even the most sensitive hyperwave arrays across interstellar distances, it will disrupt the fixed hyperwave communications beams of the Imperial HoloNet, known as HoloNet S-threads, when the vessel passes very near or through a thread. These interference signals are registered and collated to establish a good estimate of the ship's position and trajectory. Estimates are usually good to within about one parsec. Because the HoloNet is entirely maintained by the galactic government this tracking method is only available to the military and major law-enforcement agencies; and because hyperwave sensors are so rare and expensive it is difficult for unwitting starship crews to discover a hidden homing beacon.

Objects moving in hyperspace manifest themselves strangely in realspace. Just as a supersonic vehicle in air has a sonic boom, there is an optic flash associated with a ship in hyperspace. From a realspace vantage, the influence of a starship can only be felt when the observer happens to be within a conical region behind the ship called the Cerenkov cone. The cone is centred around the ship's trajectory and its sharpness depends on the ship's speed. For low superluminal speeds the cone is broad. For the high speeds characteristic of STAR WARS vessels in hyperspace the cone is very narrow; its surface is almost at right angles to the ship's trajectory. Until the cone's surface first sweeps across the observer's position there is absolutely no evidence of the ship's presence, unless hyperwaves are employed.

The cone concept is similar to the Cerenkov cone of light emission from a particle moving through a substance faster than the medium's reduced reduced light propagation speed. However Cerenkov radiation is due to the presence of the medium; a tachyonic starship in vacuum does not spontaneously emit light because of its motion any more than a bradyonic object.

The only light received from the ship will be that which it emits and the background starlight reflected off it. Along the hyperlanes in deep interstellar space the illumination is very dim, so ordinary visual detection of a ship will be virtually impossible. In any case superluminal relativistic effects render the vessel's image effectively unrecognisable. In form this peculiar sight is dictated by the boundary of the optic flash cone. A witness looking perpendicularly into the cone's surface sees an amorphous instantaneous flash; yet someone watching from an oblique angle will see twin sources come into existence at a point and then blink off rapidly along what is actually the starship's trajectory.

Communication between realspace and vessels in hyperspace is essentially impossible except via hyperwave. Any luxonic or subluminal signal beamed towards a receding ship will never catch up with it and any similar signal transmitted from an approaching ship will arrive later than the vessel itself. Sideways communications with a passing ship requires foreknowledge or luck to choose an appropriate sitting position near the ship's trajectory, and even then the vessel will flash past before much can be said. Without superluminal signalling, two-way causal connections between realspace and hyperspace are impossible. Thus tachyonic hyperwaves are the only viable option for transmissions.

Hyperwave transceivers capable of beaming across interstellar distances consume a tremendous amount of power. This effectively prohibits the mounting of these devices aboard all but large capital ships. Thus small and ordinary vessels in hyperspace are effectively incommunicado.

Diagram depicting the XX-23 S-thread tracker and its operation, from Cracken's Rebel Field Guide.

Hyperspace environment.

Relative to the realspace galaxy, all objects in hyperspace move faster than lightspeed. It is not possible for a ship in hyperspace to stay at rest relative to a planet or other feature. For some devices it may be possible to travel along a curved path so that it returns to the same point. This is the case for the cyclic hyperspace orbits of Imperial Intelligence Hyperspace Orbiting Scanners.

Tunnel effect.

The sights of hyperspace are related to the objects of realspace along the flight path, but the vista is distorted by the fact that everything is rushing past at superluminal speed. Relativistic effects are be severe. Observers in realspace watching the ship pass would see it through severe and bizarre relativistic distortions, but for the starship occupants the entire galaxy seems to be rushing past with the same sort of distortion.

Kaleidoscopic splotches appear to sweep past the starship as if they were features outside the walls of a tubular tunnel down which the ship travels. This vista is actually due to the galactic starfield. The splotches are related to local astronomical inhomogeneities like star clusters and emptier spaces. They appear to fly past at different visual distances because of the starfield itself is three-dimensional. The fact that they never appear to pass close to the starship is simply because sane pilots always plot courses which avoid obstacles.

Experienced hyperspace scouts may have a limited skill in interpreting the swirls of hyperspace in terms of realspace star clusters and nebulae. Thus with good reflexes and good luck new jump routes can be safely explored. It was in this way that young sibling scouts Gav and Jori Daragon accidentally discovered a fast route between the known worlds of the Old Republic and the isolated Sith Empire. Manual hyperspace scouting is extremely dangerous and is usually performed by inexpensive probe droids rather than crewed vessels.

The Millennium Falcon flies through hyperspace, with passing astronomical features appearing as brilliant amorphous swirls due to extreme superluminal relativistic distortions.

The crew of the Starbreaker 12 scout new hyperlanes manually.

Collisions and mass shadows.

Hyperspace is not simply another realm, disconnected from the real universe. Every point and time in hyperspace is associated with a place and moment in realspace, and vice-versa. Hyperspace is not apart from realspace; instead it is an alternate aspect of the universe which is only experienced by objects moving faster than light.

Objects and energy fields in realspace have effects on bodies in hyperspace. From the viewpoint of hyperspatial travellers the ordinary subluminal phenomena of the galaxy manifest themselves in a different form, just as a ship in hyperspace appears to have peculiar characteristics from the vantage of observers in realspace. The influence of realspace masses in hyperspace is known as the hyperspace mass-shadow effect. Collision with the shadow of a macroscopic object is catastrophic and usually fatal.

Subluminal objects can interact with objects in hyperspace. Therefore the reverse must also be true. The realspace object involved in a superluminal collision will also suffer destructive effects, though the detailed kinematics of superluminal collisions are not as straightforward or amenable to human intuition as interactions between ordinary bodies.

When real, bradyonic bodies lose energy they become slower; it requires effort to approach lightspeed from below. Approaching lightspeed from above also requires effort. As a tachyonic object loses energy it becomes faster. The remnants of ships involved in superluminal collisions will scatter in different directions at higher speed. This leads to further collisions with the mass shadows of nearby background objects and eventually all of the matter is pulverised to individual subatomic particles travelling at indefinitely high speed. This thin superluminal radiation would rapidly diffuse out across the entire universe.

Ships destroyed in hyperspace are never known to return their debris to realspace, and ships which experience accidents while jumping in or out tend to leave very little wreckage. According to Major Sil Sorannan, who once worked for a military research team in experimental hyperphysics, objects released in hyperspace always remain in hyperspace. To return from hyperspace requires the use of a hyperdrive. This makes perfect sense in terms of the tachyonic view of hyperspace and superluminal travel elucidated above.

It is possible that starships in hyperspace will experience a drag force due to tiny collisions with diffuse interstellar gas. If this effect is significant then it will tend to accelerate the vessel. Starships passing through thicker portions of the interstellar medium might suffer ablation as well as being in peril of reaching unnavigably high speeds, overshooting the proper destination and possibly ending in a more serious collision.

Interstellar hyperspace drag effect might be counterbalanced through the judicious use of the sublight drives while in hyperspace. This could account for the fact that the sublight engines of the Millennium Falcon were already glowing when the ship was seen approaching its exit point at Alderaan in A New Hope. (Alternatively, it might simply have been keeping its sublight engines running at lower power to keep them prepared for immediate use upon realspace reversion.)

Interdiction fields.

Like the shadow masses, the gravitational fields of realspace bodies are felt by vessels in hyperspace. Uncontrolled passage through such a field might perturb the trajectory of the starship, potentially onto a hazardous course, and possibly into collision with the celestial body possessing the field. At best the ship would arrive somewhere far away from the expected destination. For these reasons all hyperdrive units are built with safety cut-out systems designed to abruptly yank the ship back to realspace whenever the gradient of a significant gravitational well is detected. Any ship already in hyperspace passing through a region dominated by the shadow of a significant gravity well is automatically returned to realspace by these standard safety systems.

Hyperdrives do not operate effectively in regions of space affected by strong gravitational distortion. It is not possible to jump to hyperspace within the immediate vicinity of a planet or other large celestial body due to the natural gravity well. A starship must move out to at least several planetary diameters before it is safe to make the jump into hyperspace. The gravitational influence of an average habitable planet makes the jump calculations impossibly imprecise out to distances of about twelve planetary radii. This implies that the threshold gravitational field strength for practical hyperdrive operation is less than 0.7 m / s². However the requirements for hyperspace exit are not as restrictive as those for entry. The Millennium Falcon's planned exit point for the jump from Tatooine to Alderaan should have been only about one diameter from the surface.

Artificial gravity, repulsorlift, tractor beams and related effects have been part of the technological repertoire of the STAR WARS civilisation since forgotten millennia. At least twice in galactic history technologists have been inspired to find new applications of common gravitic technology which thwart the action of hyperdrives.

Some time before the Battle of Yavin, weapons researchers for the Galactic Empire developed the concept of an artificial gravity-well generator. This device is like an enormously powerful gravity generator which distorts local spacetime to simulate the hyperdrive-blocking effect of a planetary or stellar body. Engineers aboard the Death Star had at least one experimental prototype generator but this device was as unstable as it was portable. When activated without elaborate safeguard systems it was prone to catastrophic implosion leading to black hole formation. Study of the unusual properties of the intelligent communal organism known as Golden Sun on the planet Sedri led to the development of safe and practical gravity-well generators in the months following the Death Star's demise.

The Imperial Navy commissioned the design of new classes of capital ships dedicated to the wielding of gravity-well weapons. The Interdictor picket ship from Seinar Fleet Systems was the first production vessel to emerge from the program. These vessels exploit the interdiction effect to prevent nearby enemy ships from jumping to the safety of hyperspace, or to return passing superluminal ships to realspace for ambush or inspection. The great Executor-class command ships were not designed to incorporate gravity-well generators because they were under separate development by the rival Kuat Drive Yards during almost the same period. However the technology spread so that interdiction field generators became standard in the armaments of later flagship designs, including the Sovereign-class vessels and the Emperor's own Eclipse.

The greatest known interdiction field was employed during the Corellian Sector's Starbuster Plot, fourteen years after the Battle of Endor. The entire Corellian system was blanketed under an interdiction field of several light-months' extent, focussed at the ancient and mysterious Centrepoint Station - a monstrous construct of unknown origin, with abilities which would probably impress even Death Star engineering mastermind Bevel Lemelisk. The Corellian interdiction field effectively secured the political and military events taking place within the system against interference from most outside forces, since arriving starships were thrust out of hyperspace at distances well beyond the limits of tolerable sublight travel.

SWCCG card from Decipher depicts a Y-Wing starfighter involved in a hyperspace collision resulting from an encounter with the shadow of a large object's gravity well.


The orbital motion of a planet about its sun or of a sun about the galactic core is fully determined by the laws of physics. However over time properties of a planet's orbit such as the perihelion position and the eccentricity vary slowly due to General Relativity, tidal influences and the cumulative effects of tiny gravitational perturbations by sibling planets. The motion of a star through the galaxy is subject to more complex influences. The nett effect of all this is that the long-term motions of celestial bodies experience some degree of dynamical chaos and other uncertainties. If the object is considered statistically likely to fall within a certain region of space, then this region of uncertainty grows gradually over centuries and millennia. A poorly-charted planet may be considered to reside anywhere in a toroidal zone surrounding its original orbit; a star may be considered to be anywhere within a conical region originating at the last known location and in the direction of its last observed velocity vector.

Hyperspace jump courses must be plotted to avoid passing through these regions, rather than any precisely determined positions. The older and more inaccurate the astrogation data, the larger the avoidance zone around a celestial obstacle. Because it takes hundreds or thousands of years for starlight to propagate useful distances, updating star charts requires an actual scouting visit to the systems in question. Hyperdrive travel is essentially straight-line constant-velocity motion. Linear travel requires that starships avoid the volumes of uncertainty around obstacle locations. For any region of space there will be a typical limiting distance beyond which any useful direction of travel becomes dangerously cluttered or blocked by potential hazards. Thus the quality of hyperspatial travel depends critically on how well and recently the local space has been surveyed.

Even with the best data, a direct jump between distant points may not be possible, due to the presence of intermediate obstacles, such as the large interstellar clouds which occupy much of the space within the galactic disk. This places limits on the maximum jump range in any region. Straight-line travel may be limited to an absolute maximum of hundreds or thousands of light-years per jump, the typical optical viewing depth of the interstellar medium.

During the Palpatine Era it was fashionable for starships to carry navicomputers, astrogation aids which greatly simplify the process of calculating a jump through hyperspace. Navicomputers contain at least a rudimentary database of navigational obstacles and destinations within the galaxy. Their primary value is that they enable ships to choose their own courses through interstellar space, rather than being restricted to common trade routes. For smugglers, rebels and other dubious individuals the independence provided by a navicomputer is extremely valuable. Of course the same is true of the Imperial warships and the bounty hunters who must pursue the renegades.

Desperate for resources and dependent on hit-and-run tactics, the Rebel Alliance installed rudimentary hyperdrive systems into many of its starfighter designs. The jump capabilities of these ships were limited. In most cases there was no onboard navicomputer and the only possible destinations were a small handful of pre-calculated jumps loaded into the memory of an astromech droid mounted behind the pilot. Consumables including air and fuel are extremely limited for these vessels, so only short hyperspace hops are possible in a starfighter without resort to hibernation, Jedi trances or other unorthodox and uncomfortable measures.

At the time of the Great Sith War hyperspace travellers relied on a network of hyperspace jump beacons stationed at the nodes of safe routes. These acted as milestones of the galaxy and contained computers to provide safe jump coordinates to departing vessels. In that age most vessels relied on these fixed facilities for jump calculations, rather than supporting the complex onboard navicomputers which were in fashion during the Palpatine Era. The computers aboard the jump beacons were able to compensate for local hazards and galactic drift in order to provide safe passage to a number of neighbouring beacons and systems. (For the sake of stability, most beacons are located in interstellar space, outside the gravitational wells of nearby star systems.) This system reduced travellers' independence of movement but improved jump reliability, provided that the beacon was in working condition. Only the specially-equipped scout ships of explorers were equipped with navicomputers and capable of jumping into unknown territory. At any given time almost one fifth of beacons might suffer from some malfunction, despite the continual repair efforts of the Republic Spacelane Bureau jump beacon patrols.


Short hyperspace hops are usually employed for the sake of reducing in-system travel times. Sublight travel between planets of a star system would take several hours, even at high relativistic speeds. High sublight speeds are undesirable for crew and sensors because of the time-dilation side-effects involved, and because inertial dampers might not be able to protect the ship's contents at high acceleration for prolonged periods.

Although microjumps of several light-hours are the norm, jumps of as little as several light minutes are possible with extremely careful calculation, as employed by Chewbacca in his assault at N'zoth during the Koornacht Cluster crisis.

Automated devices.

Hyperdrive technology is used in several applications other than rapid travel for sentient beings. Unmanned devices are able to exploit different aspects of hyperspace which might involve conditions inhospitable to living beings. Machines can be designed to cope with acceleration stress without the need for the extensive inertial dampers which prevent the pulverisation of starship crews. They also need no artificial protection from time dilation effects which might cause living beings to grow old and die during even very short jumps.

Probot hyperspace pods.

Probots are armed disposable self-sufficient military droids deployed to remote systems for on missions of patrol and surveillance. They are expensive in comparison to common droids, but much cheaper than sending trained living beings and life-support systems appropriate to the destination.

The vessels which carry a probot to its target location are tiny craft which go by the generic label of "probot hyperspace pods". Smaller than a standard TIE starfighter, the outer hull is a generally smooth spheroid composed of a high-quality ablation alloys designed to withstand the heat and drag of a rapid atmospheric entry. The symmetry of the ship is bilateral, with three large forward protuberances on each side. It seems likely that these prominent features contain sensor systems at the forward end and manoeuvring thrusters towards the aft section.

Lacking the life-supports and rigorous inertial dampers dampers needed to sustain a human pilot, the hyperspace pods instead mount powerful sublight and hyperdrive engines. These provide extraordinary acceleration and manoeuvrability but at the cost of lasting for only a single journey. Because the droid occupant is unaffected by levels of radiation which would kill a living being, the pod shielding is also minimal.

Systems to compensate for superluminal time dilation effects are also unnecessary because the probe droid is unperishable and infinitely patient. Lacking the need for these compensators also means that the vessel's design and deployment are not limited by the need to accommodate a compensator's capabilities. Thus it should be practical for a probot hyperspace pod to exploit the superluminal realm to maximum potential, making an effectively instantaneous jump if the mission requires it.

* * * *
Stationed among desolate moons in a remote part of the Outer Rim Territories, the star destroyer Stalker releases probot hyperspace pods in search of secret bases of the Rebel Alliance.

* * *
A probot pod in deep space accelerates into its hyperspace jump. In these shots we glimpse several interesting features on the pod's hull. The sublight thruster shines a hot brilliant blue, suggesting great power output in comparison to its size.

* * * *
After hyperspace exit in the Hoth system, a pod speeds towards the habitable sixth planet. It targets a particularly hospitable-looking plain region in the vicinity of what appear to be some temperate or equatorial seas.

* *
A probot pod makes its final atmospheric descent, with its outer hull heated to incandescence by air friction. The outer hull of the pod breaks open on impact, allowing the probot to emerge.

Hyperspace Orbiting Scanners.

Hyperspace Orbiting Scanners were developed and employed by Imperial Intelligence to eavesdrop on communications and information within all of the computer systems of a given planet. The HOS remains in hyperspace where it is virtually undetectable, moving in a hyperspace orbit around the planet's mass shadow. This cannot be an orbit in exactly the same sense as a free realspace orbit because objects in hyperspace are always moving faster than lightspeed. However in the absence of specific information about the characteristics of this kind of motion we cannot tell whether it is a free but curved trajectory or whether active propulsive power is needed to maintain it.

Scanners mounted on the orbitter somehow track the shadows of the elementary particles moving within the computers below. These signals are matched to the patterns of common communications standards and computer languages to yield translated files which are said to be 78% accurate. The nature of the scanning process has not been divulged; all that is known at this time is that realspace particles leave an influence which is potentially detectible over planetary distance scales, and that the information thus obtained is sufficient to reconstruct a three-dimensional time-varying model of the computer system's interior. It is possible that the HOS scanning mechanism involves the emission of hyperwaves from the orbiter, scattering off the target and reabsorption at the scanner.

A HOS is not equipped with a hyperdrive. It remains freely in hyperspace but cannot enter or exit without the assistance of a hyperdrive-capable vessel. A droid-crewed Imperial Intelligence courier ship known as a Plexus Droid Vessel (PDV) enters hyperspace in the known vicinity of the HOS orbit and performs a systematic search, which can take several hours. The tiny size of the HOS and the dominance of the background mass shadows of the nearby planet, its gravity well, starships and other bodies in the region make the calculation of a successful jump to dock with the HOS all but impossible without the high astrogation skills of the PDV droid crew and foreknowledge of the HOS location. Once locked onto the HOS, the PDV returns to realspace in order to download the accumulated data and perform necessary maintenance. The PDV then jumps past lightspeed again and deposits the HOS in its proper superluminal trajectory.

Stasis probes.

Stasis probes are a more conventional military technology. They are space-based reusable probot scouts deployed in advance of naval hostilities. Like the HOS, a stasis probe is a stealthy sensor device, but its scanners are designed for realspace operation rather than for receiving the bizarre superluminal energies which are essential to a HOS. The hyperdrive-capable probe darts around a target region of space, spending less than half a minute in realspace before moving on. During those seconds it gathers sensor data about an assigned target and receives beamed instructions for the next jump and set of observations. Under normal conditions the probe will only employ passive sensors because any ping of scanner energy risks alerting the enemy to the probe's presence.

It is colloquially claimed that the probes return to realspace at "zero space velocity" in order to reduce the reentry Cronau radiation to a narrow wave cone which can be directed away from all likely observers. Although reference to the radiation is clear, the velocity reference is very peculiar, because the jump from hyperspace to realspace is associated with passing through lightspeed, which is not a "zero velocity". Perhaps the writer's correct meaning would be that the probe decelerates to the target rest frame very rapidly (though not instantaneously).

Hypergates of the Gree Enclave.

In a remote corner of the Outer Rim Territories there exists a remnant of an ancient and mysterious civilisation. The cities and technologies of the six-tentacled Gree have been stagnant and falling into ruin for hundreds of millennia. The Gree lack the ability and the will to maintain or reproduce their ancient engineering works, and their cultural focus is set against the understanding of their devices, in favour of blind rote application.

One of the more noteworthy Gree technologies are their "hypergates". A hypergate resembles a large artistically-sculpted archway or door frame on the surface of a Gree world. As the term suggests, hypergates are reputed to hurl objects through hyperspace to a destination gate, where a conversion back to the subluminal realm occurs. Almost all lie in ruin or disrepair, and the Gree gatemasters appear to lack full understanding of how to operate the devices. No hypergate has functioned for centuries or millennia, so it is possible that the ancient accounts of their function are distorted or exaggerated.

Some regard hypergates as a more advanced technology than that of hyperdrive-capable starships. However this is not necessarily so. The foundations of hyperdrive engineering are said to be incomprehensible to all but the galaxy's best hyperphysicists, and the phenomena involved in hypergates and hyperdrives have the same fundamental basis. Hypergates are merely an unusual alternative application of hyperspace technology. They are impractical for many purposes: they lead only to fixed destinations and there exist only a few dozens in the entire Gree Enclave. Hypergates are useless for scouting unknown or hostile territory; and they cannot allow for easy and ambush-safe projection of military power. They appear to be difficult to operate and maintain, even accounting for the apathy and technological stagnation of the Gree.

If hypergates function as they are reputed then they seem to be analogous to a kind of inside-out hyperdrive. Presumably some mechanism or force field seizes the jump subject and imposes upon it the same kind of pre-jump acceleration as witnessed in common hyperdrive jumps. Whatever mechanism is used by a starship to jump the light barrier must also be applied to objects and vessels subjected to a hypergate. The mass affected would be sent on an appropriate trajectory and with sufficient superluminal momentum to reach the destination gate safely.

This hints at an additional peril and difficulty in hypergate operation. When hyperdrive coordinates are slightly inaccurate the ship may return to realspace off-course but intact. If the alignment of a hypergate is incorrect then the hapless traveller will miss the destination and never be brought back to realspace. This would inevitably lead to collisions with mass-shadows and eventual pulverisation to individual zero-energy transcendent particles.

Since the hypergates are fixed on planetary surfaces, their alignment must take account of both regular orbital motion and the gradual orbital variations that planets and star systems experience over the millennia. Without precise astrometric calibration, the hypergates will fail. This is probably one of the most severe impediments to the revival of the gatemasters' profession.

The positioning of hypergates on the ground and in atmosphere also has important implications for their functioning. Passing through the air at supralight speeds would probably be fatal. Perhaps each hypergate has a secondary mechanism to expel the atmospheric gases from a shielded channel in a direction facing the other end of the jump. Alternatively, the air in the atmospheres between the two gates may be transported just like the travellers who step into the gate aperture.

A derelict hypergate of the Gree Enclave.

The head and face of representative of the Gree, the enigmatic species which is heir to an unusual lost hyperspace technology.

Summary of conclusions.

Hyperspace is an aspect of the universe which is experienced by objects which move superluminally relative to the galactic background. Objects in hyperspace only move superluminally relative to realspace.

The act of jumping in or out of hyperspace is accomplished by a device known as a hyperdrive. The action of a hyperdrive seems to be at least partly gravitational and partly quantum mechanical in nature. A hyperjump results in a burst of gravity waves and some weak electromagnetic radiation, and leaves a transient twist in a volume of space elongated in the jump trajectory.

Once in hyperspace, and object remains free in hyperspace. Collisions or anything else which causes it to lose energy will simply cause it to move faster. The action of a hyperdrive is required to make the jump back to realspace.

The peculiar vista of hyperspace as seen from inside the superluminal vessel is mainly the result of relativistic distortion of the ordinary galactic starfield background. From realspace a ship in hyperspace is extremely difficult to detect and track, and impossible to hold two-way communications with, unless hyperwave signals are employed.

The duration of a hyperspace journey depends on several factors. The primary determinant is the presence of obstacles along the route, and the quality of relevant astrogation data. Hyperspace performance of different vessels and their hyperdrives vary, but the typical speed of a STAR WARS starship is over a million times lightspeed. In order to compress the undesirable effects of superluminal time dilation (which would otherwise cause passengers to grow old on even the shortest trips) a time alteration technology is needed. The limitations of this technology are not well known but it seems to be applied only aboard starships, coupled to hyperdrive systems and can only retard the flow of time in the region immediately surrounding the vessel.


Tatooine to Alderaan.

As seen from the cockpit of the Millennium Falcon the starlines were straight. The starfield rotation seen in the hyperjump wake was anticlockwise. Shadows in the hyperspace tunnel effect appeared to move past without any rotation.

Towards the end of the journey, Han Solo remarked that his passengers could "forget about those Imperial slug" because he'd outrun them. This might mean that one or more Imperial ships made a hyperspace pursuit (but ultimately proved too slow), or it might merely be reference to having left the enemy behind at Tatooine.

Blue-shifted starlines visible from the cockpit of the Millennium Falcon.

* *
In the wake of the Millennium Falcon's jump the starfield seen along the jump trajectory appears to be rotated. Over the next second or two the spatial twist relaxes by about 45 degrees.

Arrival at Alderaan

Starlines seen from Millennium Falcon cockpit appear out of hyperspace swirl and shorten to discrete stars without any apparent rotation.

The reversion to realspace took place at the expected time and position, as indicated by the fact that Solo and Chewbacca were prepared and present in their cockpit. Upon discovering the absence of the destination planet, Solo deliberately confirmed their correct position. From this we can conclude that the diffuse field of gravel and rocks near the exit point was not sufficiently massive or concentrated to trigger the safety systems which implement early reentry to avoid collision. This indicates a limit to the sensitivity of any such systems built into the Millennium Falcon.

The Millennium Falcon flies through hyperspace, with passing astronomical features appearing as brilliant amorphous swirls due to extreme superluminal relativistic distortions.

Reentry starlines seen from the Millennium Falcon's cockpit.

Alderaan to Yavin

No direct observations of this hyperjump exist but we do know that the Death Star arrived within a day from the death of Obi-Wan Kenobi and the Millennium Falcon arrived at least several hours earlier..

Hoth to Dagobah

We have no direct observations of Luke Skywalker's jump from Hoth to Dagobah although there are suggestions that he accomplished the trip by somehow plotting a course manually. Skywalker acknowledged to R2-D2 that Dagobah was not on any of their charts. Whether the X-Wing carries extensive charts to enable hyperjumps to many different locations is not clear. In any case, Dagobah was not on any of the charts available to Skywalker. It seems likely that this small starfighter could have only a limited range and hyperjump computational capacity. The books of West End Games suggest that rebel astromech droids are preprogrammed with a handful of preset jumps to enable escape. In Skywalker's case, this probably included a few jumps to emergency rendezvous points, but he used none of those routes. It seems as if he applied the Jedi instinctive astrogation power to plot a safe course.

Avenger departs Anoat.

Sudden acceleration was seen, accompanied by a flash from the main thrust nozzles. No wake rotation was seen, but this is unsurprising because the view was not along the jump trajectory either.

Dagobah to Bespin

We do not see Skywalker's entry or exit from hyperspace on this journey. Presumably he took this trip manually, relying on Jedi instinctive astrogation as he did to reach Dagobah.

Escape from Bespin.

During the moments of jump accelerations the image of the receding ship was seen to be somewhat reddened due to Doppler redshift. Starlines seen from the Millennium Falcon's cockpit were straight and radially centred around the apparent direction of motion. The starfield rotation in the hyperjump wake was clockwise. The ship underwent a rapid change in orientation prior to the initial jump failure. It appeared to make another orientation adjustment for the later successful jump, (after manoeuvring past the Executor) and the ships' crew and contents experienced an uncompensated backwards acceleration during the jump process.

* *
Blue-shifted starlines visible from the cockpit of the Millennium Falcon as it jumps to freedom after a close encounter with Lord Vader's flagship.

The hull of the Millennium Falcon shows obvious relativistic redshift as it leaps through the scale of subluminal speeds at crosses the transition to hyperspace.

The starfield relaxes from the optical rotation caused by the dissipating spatial distortion left in the freighter's wake.

Tatooine to Dagobah and Sullust

Skywalker's X-Wing and the Millennium Falcon departed Tatooine in very different directions, suggesting that Dagobah and Sullust are probably nowhere near each other. Unfortunately the actual jumps were not seen.

Dagobah to Sullust

Skywalker's return to the fleet of the Rebel Alliance was not seen on film. The trip was sufficiently short from the vantage of an external viewer for him to arrive barely late for the main briefing about the Endor attack.

Sullust to Endor

The departure of the stolen shuttle did not produce a detectable wake rotation effect. This may be due to a difference between the hyperdrive quality of this mundane passenger vessel and the illegally-modified systems of the Millennium Falcon. Perhaps the shuttle's wake effect was less pronounced or less visible because the pre-jump sublight acceleration was less abrupt and/or the hyperdrive is less powerful.

No nett wake rotation was observed when the rebel fleet jumped out of the Sullust system, but this may be due to mutual cancellation of roughly equal numbers of left and right-handed wake effects of the dozens of rebel starships. The starfighters jumped first, which may be important if the side-effects of capital ships' jumps are in any way harmful to nearby objects (eg. due to the Cronau radiation or wake rotation).

From the cockpit of the Millennium Falcon the grey/blue hyperspace tunnel lights rotated in a clockwise fashion, a right-handed rotation relative to the ship's motion. Upon return to realspace the usual starlines were seen, and then a very slight right-handed rotation of the celestial surroundings was seen, following on from the spin of the hyperspace swirls seen moments earlier. This rotation shortly after all of the rebel warships had reached their positions in attack formation.

* * * * * *
The rebel fleet makes the jump into hyperspace from the Sullust system towards Endor.

* *
The features of hyperspace near the Endor exit point rotate in a clockwise direction as seen from the cockpit of the Millennium Falcon.

* * * *
Starlines shorten and the rebels decelerate towards Endor in realspace. The rapid increase in the moon's angular size indicates that the rebels are covering distances comparable to the moon's diameter in a matter of seconds.


The rate at which the velocity of an object changes, from the point of view of a particular observer.
angular momentum
A property akin to momentum which expresses the rotational tendency of an object; related to distribution of mass and spin.
artificial gravity
One of the basic technologies of the STAR WARS universe involves the artificial generation of gravitational fields without the need for the corresponding amount of mass needed for an equivalent natural gravity field.
The practices and studies related to travel through and mapping of the galaxy. The space analogue of maritime "navigation".
black hole
A region of space where gravity is so intense that no subluminal object can escape. Black holes are occasionally formed when a remnant of a very massive star implodes under self-gravity. Almost none of the properties of the progenitor object affect the characteristics of the final hole; the few exceptions are the total mass, spin and electric charge.
Anything which travels slower than lightspeed relative to a particular observational frame.
The postulate that causes precede their effects in time. Where superluminal travel is concerned events which one observer witnesses as causes may sometimes appear as effects to someone else.
Cerenkov radiation
Light emitted by a particle when it enters a medium with a light speed lower than its initial velocity. This is nothing to do with true lightspeed, which is universal. The lower light speed in a material is due to the nett effect of electric and magnetic properties of the substance. The light is emitted in a forward-pointing cone centred around the particle's trajectory. Cerenkov radiation is not emitted by tachyons in empty space; a material medium is required.
Cerenkov cone
Backward-pointing cone around a superluminal object's trajectory. The internal angle of the cone depends on the object's speed. Greater velocity gives a wider cone; lower velocity gives a sharper cone.
Crystal gravfield trap; a type of sensor system which detects gravitational waves and measures gravity field effects. These are expensive systems which are generally only available to government military vessels and installations.
Cronau radiation
A burst of radiation emitted in a cone upon exit from hyperspace. Whether this is related to the Cerenkov cone is unclear.
Doppler effect
The frequency of light received from a moving source is not the same as what would be seen by an observer at rest relative to the source. The visible colour of the source will be shifted into either the red or blue ends of the spectrum, depending on whether the source is receding or approaching, and the amount of shift depends on the speed.
event horizon
The surface of a black hole within which only a superluminal object can escape. Ordinary subluminal bodies falling into a hole become tachyonic when they pass inside the horizon.
exit growl
Sound heard inside a starship with poorly-maintained hyperdrive when the jump is made. The sound is due to the release of stresses caused by different sections of the ship making the jump at different instants to other parts.
gravity waves
Disturbances of space-time which propagate through space at lightspeed.
gravity-well generator
An exceptionally powerful artificial gravity device which projects a field into nearby space to simulate the effect of the gravitational well of a planet or other large celestial body. Alternately known as an interdiction field because it is commonly used to trigger the safety systems of passing starships which prevent hyperspatial travel.
The device which achieves the jump to hyperspace, converting a starship from a bradyonic to tachyonic state within a mere moment. A hyperdrive is also needed to produce a return jump from hyperspace to realspace.
A tenuous trail which can be detected in the space surrounding the point where a hyperjump has taken place. Presumably this is a rarefied and invisible material which is a characteristic by-product of the jump mechanism. For all practical purposes the trails dissipate within a few weeks.
That aspect of the universe experienced by travellers who move faster than lightspeed relative to the background galaxy. All objects travelling superluminally relative to the galaxy are in hyperspace; all objects in hyperspace are travelling superluminally. The vista of nearby celestial bodies is distorted by peculiar relativistic effects into a bizarre swirling tunnel-like scene. Tracking and communications between realspace and ships in hyperspace is extremely difficult.
hyperspace orbit
A curved path through hyperspace designed to keep an object within the vicinity of some celestial feature. For example an Imperial Intelligence Hyperspace Orbiting Scanner maintains a hyperspace orbit around an inhabited planet.
An extraordinarily power-consuming and extremely expensive form of superluminal communication which relies on signals sent through hyperspace. With few exception, hyperwave transceivers are massive facilities fixed to only the largest capital ships and ground facilities on civilised planets.
inertial dampers
Devices which nullify the stresses experienced by a starship engaged in high acceleration. Inertial dampers are directly related to artificial gravity technology.
interdiction field
See gravity-well generator.
The discrete transition of an object from a subluminal to superluminal state, or vice-versa. The jump must involve more than merely classical physical processes because of the infinite energy lightspeed barrier.
The speed at which light and other luxons move. Anything moving at lightspeed relative to one observer is seen to move at lightspeed relative to all other observers.
The distance travelled by luxons in one year. Equal to 9.46x10^15 m. In many parts of the galaxy neighbouring star systems are separated by roughly a light-year.
Anything that moves at lightspeed. Only massless particles can be luxons. Photons and gravitons are luxons.
mass shadow
The influence of a realspace object felt in hyperspace, or a hyperspace object felt in realspace. The shadows are difficult to detect because of their extreme speed relative to the observer, but collision with one has disastrous results.
A device aboard a starship which plots safe trajectories for a journey through hyperspace. A navicomputer contains astrogation data about the regions of space which can be probabilistically expected to contain obstacles and hazards to travel.
A unit of distance equal to 3.08x10^16 m. Approximately three light-years.
Plank time
A tiny timescale at which quantum-mechanical effects dominate the structure of spacetime. Time intervals comparable to or smaller than Plank time are fundamentally unmeasurable and time itself becomes meaningless.
The universe as experienced by objects travelling at less than lightspeed relative to the features of the galaxy.
Distortion of the background starfield as seen from a starship jumping into hyperspace. An optical and relativistic effect.
stasis field
An artificial energy field used to retard the passage of time. Perishable cargoes or bored farmboys can be placed in stasis fields so that they experience less time than the outside universe. Stasis fields appear to be necessary for counteracting severe time-dilation effects associated with travel at millions of times lightspeed.
Concerned with things existing moving at velocities below lightspeed.
Concerned with things existing moving at velocities beyond lightspeed.
Anything that travels faster than lightspeed from a particular observational vantage.
time dilation
Time passes differently for different observers depending on their relative velocity. For travellers at hyperspatial velocities and high subluminal velocities the duration of a journey may be very different to that witnessed by observers who stay at home.
The rate at which the position of an object changes, as witnessed from a particular observational reference.
wake rotation
Twisting of the background starfield as seen along the trajectory of a vessel which has recently jumped into or out of hyperspace. The rotational distortion of local spacetime is narrow and elongated in the jump direction, and it dissipates via gravity-wave radiation within about a second.


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