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.
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.
