Made popular by a number of SF sources, this drive postulates temporarily shunting a starship into a higher dimensional space that also permeates our own universe. This other space has different physical topologies than our own, and distance, even light-years of distance, means something very different there. The ship can traverse the equivalent of quadrillions of kilometers in a relatively short time, so that the stars are easily bypassed when the ship re-enters normal space.
The word "hyperdrive" takes its name from the term hyperspace. Hyperspace is the theoretical realm that exists beyond our three-dimensional world, which permeates our universe and into which our space/time can curve.
Links to much more detailed explanations of hyperspace are given at the bottom of the page. What follows is an extremely simplified discussion.
Take a one dimensional object, a line. Turn the line in on itself at right angles and you get a two dimensional object--a square. Now take the square, turned it on itself at right angles, and we go up a dimension to the third. A cube.
Now take the cube, turn it on itself at right angles and you get...
What?
According to theory, you get an object that projects into a fourth physical dimension (not to be confused with Time, which is also sometimes called the fourth dimension) called a hypercube. Trying to actually visualize this with our analog 3D brains is a bit difficult; however, the mathematics and logic of it work out very neatly, and leads to a number of interesting implications.
Think of a 2D object, like an infinitely thin piece of paper. You can "warp" it into a third dimension by folding or rolling it. We know from Einstein that 3D space can also be warped; observational evidence for this abounds in the form of gravitational lensing effects in astronomical objects. But what does it warp into?
The answer is hyperspace. A fourth physical dimension somewhat beyond our three-dimensional senses to perceive, but which surrounds and permeates our 3D universe much like the 3D universe surrounds and permeates our 2D piece of paper.
But how does this help one travel between the stars?
There is some evidence that our 3D cosmos as a whole may be curved, just as a 2D object as a whole can be curved into a sphere or parabola or such. Instead of travelling the entire distance over the curved surface of the 2D object, one can simply bore a tunnel between two points on the paper through 3D space to arrive at your destination that much sooner.
The hyperdrive uses this principle taken up a dimensional level; it allows a ship to take a more direct 4D "shortcut" to bypass the 3D "surface area" in between two points.
However, it should be pointed out that just because such hyperspaces may exist they may not necessarily allow FTL travel, or indeed allow any kind of travel faster than what’s available to us in normal 3D space. Three-dimensional space may not be curved in the right way to allow any significant shortcuts; hyperspace itself may be curved and complicated in many ways that would make accessing it problematic if not impossible.
For instance, if our 3D space has no macroscopic curve (a "flat" universe in some terminologies) hyperspace access could turn out to be fairly useless as a means of FTL travel.
The best example of this, ironically, comes from a SF universe better known for a very different means of FTL travel: Star Trek. The warp drives of the civilizations in Star Trek double easily as hyperdrives, and, indeed, can be seen on many episodes and movies moving in and out of hyperspace with ease. However, in that universe, no hyperspace or level thereof has apparently been found that allows for travel faster than warp 1. Thus, the Federation and its neighbors still rely exclusively on the warp drive for interstellar travel, and apparently use hyperspace simply to avoid material obstacles such as gravity wells, hydrogen clouds, etc, that they may otherwise run into at translight speeds in normal space.
Hyperspace is also almost certain to be far more complicated than just a void with an extra physical dimension. It may be prone to odd curvatures and anomalies, may be host to different storms, currents, hyperobjects, and perhaps even life. This is the case in Jeffrey Carver’s Star Rigger series of novels, as pilots ("riggers") translate the chaotic dangers of hyperspace into visual metaphors they can more easily grasp, and literally have to "sail" through hyperdimensional storms, whirlpools, tidal waves, and other dangers.
Hyperdrive travel can also be complicated by the fact that more than one level of hyper space can exist. After all, if there’s a fourth dimensional aspect to the cosmos, why not a fifth or sixth or so on? Each level may be subject to physical quirks we can only guess at, and would have its own dangers and advantages. Even if 3D space is flat, the 4D space that permeates it may itself be curved, allowing ships that can access the 5D "level" of hyperspace FTL travel where a lower level 4D hyperdrive would get the pilot nowhere. It is generally assumed that accessing higher levels of hyperspace require more powerful and sophisticated drives that lower levels do.
This can even be further complicated by the possible existence of fractal dimensions. A fractal dimension exists between two "integer" dimensions and contains aspects of both. Often, mathematical and physical constants will vary slightly from one fractal hyperspace to another. For example, it could be possible to define a fractal dimension by its particular value of pi. One level would have a pi value of 3.14159..., one would have a pi value of 4.78, and another would have a value of 3.00 exactly. As with decimals, there would be an infinite number of fractals between integer dimensions, and therefore an infinite number of possible hyperspaces.
Of course, the hyperspace level with a value of pi of 3.14159... not coincidentally corresponds with our own universe’s value of pi, indicating that in this cosmological scheme our universe is just yet another a level of hyperspace. Every other level would also be a universe in and of itself.
In order to a enter higher dimensions, one has to warp 3D space. As natural-occurring gravity sources readily warp space, most hyperdrive schemes envision artificial, concentrated gravity fields to warp or tear or weaken the fabric of space/time in order to insert the ship into higher-dimensional space. These may be enhanced or complimented by other quantum mechanical tricks left conveniently obscure by science fiction creators.
In several versions of the hyperdrive, the drive imparts a higher dimensional "momentum" to the starship, meaning the ship can’t alter course or come out of hyperspace until it comes to the end of its 4D trajectory and ends up precipitating back into normal space. This is the case of the hyperdrives in Asimov’s Foundation series, the world of the Traveller RPG, and the Star Wars Universe.
In other versions, the hyperdrive opens a "portal" or undergoes a phase shift to enter hyperspace, and the ship can maneuver around freely in the higher dimensional realm. The ship has to open another "portal" or phase shift again to exit it. This is similar to the scheme used in Babylon 5 and the "Known Space" stories of Larry Niven.
Exactly how hyperspace would be perceived by our 3-D brains and perceptions is a matter of much wild speculation in SF sources. There’s no way we can know for sure until (and IF) a real hyperdrive is ever made. Still, some authors have come up with some very interesting conjectures. For example...
In Asimov’s Foundation series, there is no hyperspace experience, because the transition to 4D and back again takes place nearly instantaneously.
In the universe of the Fading Suns, the hyperjump temporarily alters human brain chemistry and induces a mystical, near-ecstatic experience on many passengers. The phenomenon became the basis of a popular and influential religion in that universe.
In the universe of the Traveller RPG, many passenger can experience jump sickness--the transition to hyperspace stresses the space/time within the ship, resulting in possible vertigo, nausea, and spasms that can last anywhere from a few minutes to the entire time the ship spends within hyperspace.
In Larry Niven’s "Known Space" stories, hyperspace literally has nothing we can perceive--not time, not space, not even a void. As a result, windows on a starship experience a phenomenon called the Blind Spot, where--with absolute NOTHING beyond the porthole--the brain "stretches" the images of the surrounding bulkhead so that it covers the hole in its perception, just like it does its natural blind spot. The window and every other portal that opens into hyperspace disappears from visual human perception. Passengers have been known to go mad staring at the Blind Spot for too long.
Some versions of hyperspace envision it as having truly bizarre physical laws that sometimes contradict those of our 3D universe, necessitating a protective bubble of "normal" spacetime be wrapped around the ship to protect it. However, as the 4D+ cosmos would just be a natural extension of our own, all natural laws of our universe would still apply, and no special protection would in fact be necessary.
TRANSFER POINT HYPERDRIVE
Tech Level: 16
This is similar to the standard hyperdrive, but in this scheme hyperspace can only be accessed at certain points where hyperspace and normal space overlap. Hyperdrives simply won't work unless they are at these coordinates. The ship will enter one transfer point and come out another. Usually, a transfer point will only lead to a few destinations, and sometimes to only one. Webs of transfer points would cover the galaxy, as the ship would have to go from one transfer point to another to the next and so on to eventually arrive at its destination.
The position and abundance of transfer points depend on how they would form. For example, in the novel The Mote in God's Eye, by Niven and Pournelle, transfer points were formed between two stars at the point where their gravitational fields were most synchronous, forming low energy "channels" through four dimensional space-time. In other universes, the tides and eddies of hyperspace itself may determine when and where transfer points form. In the latter case, transfer points may constantly shift position throughout space, creating all sorts of chaos for interstellar civilizations. Transfer points may only exist in a system for a short time, severely limiting interstellar contact for only a few days or weeks every decade or so. Being able to predict where transfer points will appear and how long they will last would be necessary for any FTL civilization to thrive in such a universe. Passage through transfer points are generally depicted as instantaneous or nearly so. However, travel between transfer points in the same system in normal space may take days or weeks or months, depending on the type of sublight drive available.
STANDARD HYPERDRIVE | The Millennium Falcon enters hyperspace in the movie Star Wars. Image copyright Lucasfilm. |
A standard hyperdrive uses gravity manipulation and/or quantum effects to warp the fabric of the universe around it in order to launch itself into hyperspace. Usually a standard hyperdrive can only access one level of hyperspace per jump. I.e., it enters that level of hyperspace and can’t exit it again until it precipitates back into normal space.
Though a hyperdrive can access hyperspace from theoretically anywhere in space, some conditions and areas may make the feat more dangerous or difficult than others. In the Traveller and Known Space universes, hyperdrives are dangerous to operate too close to significant concentrations of mass, such as a star or planet. In Traveller, a star ship must be at least 100 diameters out from a planet or star to make a safe hyperjump; in Known Space the ship must be on the extreme borderlands of a star system for its hyperdrive to function.
In other schemes, the opposite is true. In Ursula K. LeGuin’s Ekumen stories and Karl Schroeder’s novel Permanence, a ship had to be deep in a gravity well in order to get the extreme space curvature needed to enter hyperspace.
MULTIPLE LEVEL HYPERDRIVE
Tech Level: 19
A ‘standard’ hyperdrive is able to access only one level of hyperspace per jump. This is because its systems are designed to bend, ripple and/or stretch only standard three-dimensional space, and therefore can enter and exit any one level of hyperspace from 3D space only.
A multiple level hyperdrive uses an advanced version of the same gravity/quantum manipulation effects that bend and stretch 3D space to further warp and bend higher dimensional spaces in an analogous way, allowing the ship to "climb" up and down hyperspacial levels at will. In universes where different levels might have differing features, such as one level allowing faster absolute travel or another possessing less turbulence or obstacles, the advantage of being able to switch levels easily should be obvious.
The hyperdrives of the ships in the Starigger and Uplift universes are examples of multiple-level hyperdrives.
In The Media:
Star Wars, et al
Star Trek, et al
Babylon 5, et al
In Print:
The Foundation series, by Isaac AsimovOn The Web:
http://www.lboro.ac.uk/departments/ma/gallery/hyper/
http://www.grc.nasa.gov/WWW/PAO/warp.htm
http://www.itsf.org/resources/factsheet.php?fsID=86
http://exn.ca/starwars/hyperdrive.cfm