From OSR

Image:Index 01b.jpg

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• [#trouble The Trouble with StarDrives]
• [#barrier The Light-Speed Barrier]
• [#causality Causality]
• [#limits Establishing Limits]
  • [#mote The Mote in God's Eye]
  • [#starforce StarForce Alpha Centauri]
• [#existing Existing Drives]
• [#stardrives The Canonical List of StarDrives]

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Image:Phantomcruiser2.jpg

The Trouble with StarDrives I wasn't going to put this section in, but I have to. I wanted to keep the website as free from [rocket3a.html#handwavium handwavium] as possible. However, while Faster-Than-Light travel is about as handwavium as you can get, it is unfortunately the [rocket3Notes.html#sinequanon sine qua non] of interstellar space opera. Space opera with no StarDrive is like chocolate cake without the chocolate. In his "Lucky Starr" novels, Isaac Asimov uses the term "Hyperatomic spaceships", presumably since the spacecraft had both a faster-than-light Hyperspace engine and a more conventional atomic engine. Go to The Tough Guide to the Known Galaxy and read the entry "FTL", and the "Faster Than Light" entry in Wikipedia. Fred Kiesche says that a faster than light starship should have a license plate that reads "ME = MC2"

The important point is to keep the fracture under control. Hack writers will assume that "if we have to break a few laws of physics for FTL, why not just throw all the laws out the window?" Don't give in. Omitting physics will degrade your novel to a pathetic lack of accuracy worse than an average Space Ghost cartoon.

What to do? Keep all the physics you can. And when you break the laws for your FTL drive, at least [#limits establish some limitations] and rules. Then stick to them! Internal self-consistency is better than nothing.

An example from the movie Forbidden Planet are the DC stations where the crew members are protected from the deceleration from hyperspace to normal space by stasis beams

The general rule is what physicists call the correspondence principle or the Classical limit. This states that any new theory must give the same answers as the old theory where the old theory has been confirmed by experiment. Newton's laws and Einstein's Relativity give the same answers in ordinary conditions, they only give different answers in extreme conditions such as near the speed of light, refining the accuracy of the GPS system, or calculating the orbit of Mercury (none of which Newton could confirm by experiment).

The point is: you, as a science fiction author inventing a FTL drive, have to explain why current scientific theory didn't discover FTL travel decades ago. Harry Turtledove turned the problem on its head and turned the explaination into the [rocket3ab.html#roadNotTaken plot of the short story].

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Why does FTL violate the laws of physics? Well, that is complicated, but there are two main problems: the Light-speed barrier and Causality. This is explained with some depth at Jason Hinson's authoritative "Relativity and FTL" website, so I'm just going to give a short summary. Refer to Hinson for details.

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Image:Lightspeedbarrier.jpg

The Light-Speed Barrier

No, this is not like the "sound barrier", it is much more fundamental. That old spoil-sport Einstein created his theory of General and Special Relativity. Before that, Newtonian physics predicted that if your spacecraft burnt X amount of fuel, it would be accelerated by a velocity of Y, always. Which makes common sense. Relativity says that may be true at normal velocities, but it doesn't hold at speeds close to the speed of light "c". At those speeds, burning X amount of fuel will accelerate your spacecraft by less than Y, i.e., to accelerate by Y, you need to burn more than X fuel.

Image:Soundbarrier.jpg

Image:Lightwall.gif

And to move at the speed of light, you'd need an infinite amount of fuel. And more than infinity if you want to move faster. Since it is impossible to burn an infinite amount of fuel it is impossible to move at the speed of light, let alone faster. Every single FTL drive you read about in science fiction is some clever way to avoid the light speed barrier.

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Causality However, very few SF novels deal with the second problem. The aphorism at rec.arts.sf.written goes "Causality, Relativity, FTL travel: chose any two." Your average physicist holds Relativity quite strongly. It has been tested again and again with an accuracy of many decimal places. They hold onto Causality even tighter. Without Causality the entire structure of physics crumbles. Causes must preceed effects, or it becomes impossible to make predictions. If it is impossible to make predictions, it would be best to give up physics for a more profitable line of work. Therefore, they chose to jettison FTL travel. Please note that as far as Causality is concerned, FTL communication is every bit as bad as FTL travel.

Why only two? Relativity proves that FTL travel is identical to Time travel (to help your research, the technical term for time travel is "Closed timelike curve"). Time travel makes Causality impossible, since it can be used to create paradoxes. So if you have Relativity and FTL, Causality is impossible. If you do not have Relativity, FTL is not Time travel, so you can have Causality. Or more mundanely you can have Relativity and Causality, but no FTL/Time travel (the latter is the opinion of physicist Stephen Hawking, he calls it the chronology protection conjecture). Clever readers will have already spotted a possible loop-hole. What if there was some law of physics that prevented Time travel from creating paradoxes?

Image:Timetunnel.jpg The Time Tunnel (1966)

Image:Borisb.jpg Image:Wayback.jpg

The classic Time-travel paradox is the so-called "Grandfather paradox" (though it actually should be called the "Grandmother paradox"). Boris Badenov sneaks into Mr. Peabody's Wayback Machine (actually the WABAC machine, but who cares?) and travels back in time to when Boris' grandfather was a baby. Boris then gives his infant grandfather a lit stick of dynamite then cackles evilly as his grandfather is blown to bits. Bah-hah-hah! But wait! Boris' grandfather is now smithereens, he'll never grow up, beget Boris' father, who will beget Boris. In other words, Boris will never exist. But if Boris never exists, then he will never travel back in time to assassinate his grandfather. In which case grandpop will beget Poppa Boris, who will beget Boris. Start back at the beginning and repeat. Does Boris' grandfather get blown up? Both Yes and No! A paradox.

Hinson shows there are four ways of enforcing a "no-paradox" rule for time travel. Parallel Universes, Consistency Protection, Restricted Space-Time Areas, and Special Frames. In some ways Special Frames is the best, though it directly contradicts part of Relativity (the first postulate of special relativity is that there are no special frames, "no privileged inertial frames of reference"). Oh well. For details, you'd best read the Hinson article. The latter three are examples of the Novikov self-consistency principle. In some late-breaking news, physicists Daniel Greenberger and Karl Svozil have shown that the laws of quantum mechanics enforces Consistency Protection. You can read their paper here, but it makes my brain hurt. Translated into English, they maintain that time travellers going back into the past cannot alter the past (i.e., the past is deterministic). This is because quantum objects can act sometimes as a wave. When they go back in time, the various probabilities interfere destructively, thus preventing anything from happening differently from that which has already taken place. As a side note, those interested in the various ways time-travel seems to work in SF novel should run to the Guide To SF CHRONOPHYSICS.

Image:TimeMachine.jpg

Why have you not read about this in any science fiction novel? It is absent from some because the authors do not know enough relativity theory to spot the FTL equals Time Travel implication. It is absent from the rest because of those who do know enough relativity, practically no author who just wants a quick way to get their hero from star to star wants to deal with the huge squirming can of worms opened by time travel. This is why the time travel connection is the dirty little secret of science fictional FTL travel.

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From Exultant by Stephen Baxter (2004).

Time was slippery. The way Pirius understood it, it was only the speed of light that imposed causal sequences on events.

According to the venerable arguments of relativity there wasn't even a common "now" you could establish across significant distances. All that existed were events, points in space and time. If you had to travel slower than lightspeed from one event to the next, then everything was okay, for the events would be causally connected: you would see everything growing older in an orderly manner.

But with FTL travel, beyond the bounds of lightspeed, the orderly structure of space and time became irrelevant, leaving nothing but events, disconnected incidents floating in the dark. And with an FTL ship you could hop from one event to another arbitrarily, without regard to any putative cause-and-effect sequence.

In this war it wasn't remarkable to have dinged-up ships limping home from an engagement that hadn't happened yet; at Arches Base that occurred every day. And it wasn't unusual to have news from the future. In fact, sending messages to command posts back in the past was a deliberate combat tactic. The flow of information from future to past wasn't perfect; it all depended on complicated geometries of trajectories and FTL leaps. But it was good enough to allow the Commissaries, in their Academies on distant Earth, to compile libraries of possible futures, invaluable precognitive data that shaped strategies -- even if decisions made in the present could wipe away many of those futures before they came to pass.

A war fought with FTL technology had to be like this.

Of course foreknowledge would have been a great advantage -- if not for the fact that the other side had precisely the same capability. In an endless sequence of guesses and counterguesses, as history was tweaked by one side or the other, and then tweaked again in response, the timeline was endlessly redrafted. With both sides foreseeing engagements to come for decades, even centuries ahead, and each side able to counter the other's move even before it had been formulated, it was no wonder that the war had long settled down to a lethal stalemate, stalled in a static front that enveloped the Galaxy's heart.

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Image:WorldShip.jpg Artwork by Ed Emshwiller

From "Beep" by James Blish (1954). She paused and smiled. "I have heard," she said conversationally, "the voice of the President of our Galaxy, in 3480, announcing the federation of the Milky Way and the Magellanic Clouds. I've heard the commander of a world-line cruiser, traveling from 8873 to 8704 along the world line of the planet Hathshepa, which circles a star on the rim of NGC 4725, calling for help across eleven million light-years -- but what kind of help he was calling for, or will be calling for, is beyond my comprehension. And many other things.

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Establishing Limits

Since FTL drives are ruled more or less impossible by current science, you have to invent your own. In such cases, the best way to start is to focus on effects instead of causes. Many novice SF novelists and game designers make the mistake of inventing a cause first and may not even try designing the effects.

An example of an effect is "The star drive can move the ship at ten light-years per hour". An example of a cause is "The Mason Field is generated by the amplification of the interaction of the Alpha and Omega sub-particles contained in the Xanthe crystal when bombarded by pseudo electron valients in a charged hydrogen field."

Effects help you avoid unintended consequences, and define the implications of your drive. Causes are fluffy [rocket3a.html#technobabble technobabble] explanations that a good SF story might avoid all together. As Gene Roddenberry noted, in a police TV show a policeman does not explain to the viewers how the primer of the bullet ignites the main charge propelling the lead slug down the barrel every time he shoots his handgun. Neither should Captain Kirk explain the operating principles of his phaser weapon, the fact that it is some species of sidearm is enough for the viewers.

Causes can also get you into trouble if your explanation implies new effects that you did not intend. They also give more weak points that a scientifically minded reader can use to poke holes in your theory.

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The important things are the effects. Here are a few examples: How big a ship can be moved? How much faster than light is the ship? Does it require large intricate starships, or can you just mount it in a submarine? Does it require huge amounts of energy? Does it require the ship to be outside any planetary or solar gravity wells? Can the ship only enter FTL flight at special locations ? ("jump points") Does each FTL "jump" require days of tedious mathematical calculations? Can a ship in FTL flight be detected by another ship also in FTL flight? Can a ship in FTL flight be detected by another ship not in FTL flight? Does FTL flight make the crew vomit, hallucinate, have epileptic fits? Is the supply of FTL drive units limited due to a tight monopoly on their manufacture, or due to the fact that they can no longer be manufactured at all? Does it require rare and hard to get materials? (the Traveller RPG required Lanthanum, H. Beam Pipers' ships required Gadolinium. Both of these are rare earth elements, emphasis on the "rare")

These are just off the top of my head, you can find more by reading SF novels, or from your imagination.

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The effects have implications in the SF universe you are creating:

If the only ships that can be moved are ones smaller than a Greyhound Bus, one implication is that you will not have titanic ships the size of Star Wars Imperial Star Destroyers, much less any Death Stars.

If your ship is twice as fast as the speed of light, it can go 100 light years in a mere 50 years. Therefore most of the action in your universe will take place close to Sol, if the average interstellar journey is two years. On the other hand if your ship is 36,500,000 times as fast as the speed of light, your ship can cross the Galaxy the long way in about one single day. The action in this universe will therefore be galactic in scope.

If there are only large intricate starships, they will be few in number and crewed by the cream of the crop. If any fool can build an FTL drive from plans downloaded from the internet and convert a septic tank into a starship, there will be zillions of starships crewed by a wide range of eccentric people.

If ships require huge amounts of energy for their FTL drives, you have to decide upon the source of said energy. Antimatter fuel implies antimatter factories or antimatter "mining." There is also the unintended consequences of a given starship containing enough energy to, say, vaporize Greenland. The further implication is that starship captains will be on a very short leash ([rocket3a.html#johnslaw John's Law]). If on the other hand a starship can run on one AAA battery, you start having problems with FTL missiles the size of bullets.

Ships that can only enter/exit FTL flight at special locations make those locations into military choke points. Ships that can exit FTL flight anywhere coupled with ships that cannot be detected while FTL will open the possibility to [#fiveminute genocidal interstellar wars that last all of five minutes].

In John Maddox Roberts novels Space Angel and Spacer: Window of the Mind, the "Whoopee Drive" makes the crew suffer projectile vomiting, violent diarrhea, and hallucinations. Before each jump they have to attach a barf bag over their mouth, strap themselves on to a toilet, and try to ignore the paisley Peter Max metal termites eating the hull. Naturally this made troop ships a nightmare. In Gordon Dickson's The Genetic General, closely spaced FTL jumps made without a recovery period in between would rapidly incapacitate the crew.

In Frank Herbert's DUNE, mutated Guild Steersmen move starships between stars with their psychic abilities. Thus the spacing guild has a monopoly on starships. In John Brunnner's Interstellar Empire and Frederik Pohl's Heechee novels (Gateway et al) the starships are artifacts from some long lost alien race, humans can fly them but cannot construct them. In SPI's game Freedom in the Galaxy all stardrives are manufactured by the Empire, and contain thermonuclear self-destruct devices to discourage hackers from attempting to engage in reverse-engineering.

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If you want to do the job right, work backwards. Decide what type of universe you want for your book, figure out what implications it must have, then figure what constraints on the FTL will create the desired implications. Finally add a bit of colorful technobabble to describe the cause.

If you want to explore uncharted terrain, work forwards. Create a few unusual constraints, spend some time deducing some implications from the constraints, and see what sort of SF universe flows from the implications. You might stumble over an interesting universe for your next novel and/or game.

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Larry Niven and Jerry Pournelle took the bull by the horns. Before they wrote their award-winning classic The Mote in God's Eye, they went to physicist Dan Alderson. Niven and Pournelle gave Alderson a list of things they wanted the proposed FTL to allow, and things to forbid. Dr. Alderson then custom designed a mostly plausible FTL drive to spec, but with additional limits. Niven and Pournelle kept within those limits, and the novel was improved as a consequence.

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The Mote in God's Eye

From "Building the Mote in God's Eye" by Larry Niven and Jerry Pournelle, collected in N-Space and A Step Farther Out.

(interesting description of the physical basis of the Alderson drive omitted)

Travel by Alderson Drive consists of getting to the proper Alderson Point and turning on the Drive. Energy is used. You vanish, to reappear in an immeasurably short time at the Alderson Point in another star system some several light-years away. If you haven�t done everything right, or aren�t at the Alderson Point, you turn on your drive and a lot of energy vanishes. You don�t move. (In fact you do move, but you instantaneously reappear in the spot where you started.)

That�s all there is to the Drive, but it dictates the structure of an interstellar civilization.

To begin with, the Drive works only from point to point across inter�stellar distances. Once in a star system you must rely on reaction drives to get around. There�s no magic way from, say, Saturn to Earth: you�ve got to slog across.

Thus space battles are possible, and you can�t escape battle by vanishing into hyperspace, as you could in future history series such as Beam Piper�s and Gordon Dickson�s. To reach a given planet you must travel across its stellar system, and you must enter that system at one of the Alderson Points. There won�t be more than five or six possible points of entry, and there may only be one.

Star systems and planets can be thought of as continents and islands, then, and Alderson Points as narrow sea gates such as Suez, Gibraltar, Panama, Malay Straits, etc. To carry the analogy further, there�s tele�graph but no radio: the fastest message between star systems is one car�ried by a ship, but within star systems messages go much faster than the ships.

Hmm. This sounds a bit like the early days of steam. Not sail; the ships require fuel and sophisticated repair facilities. They won�t pull into some deserted star system and rebuild themselves unless they�ve carried the spare parts along. However, if you think of naval actions in the period between the Crimean War and World War One, you�ll have a fair picture of conditions as implied by the Alderson Drive.

If the Drive allowed ships to sneak up on planets, materializing without warning out of hyperspace, then there could be no Empire even with the Field. There'd be no Empire because belonging to the empire wouldn't protect you. Instead there might be populations of planet-bound serfs ruled at random by successive hordes of of space pirates. Upward mobility would consist of getting your own ship and turning pirate.

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The Alderson Drive or "jump point" drive has been used in many SF starship combat games, for the same reason Niven and Pournelle used it: unlike most other FTL, it allows the possibility of interstellar battles. Most other FTL is a "fly anywhere" kind of propulsion, which generally does not allow battles to occur except by mutual consent. Often a planet cannot even detect an enemy invasion fleet until it suddenly pops out of hyperspace. Interstellar wars only last long enough for your hyperspace bombers to fly to the enemy's planets, then a brief emergence to spit out a hellburner, a planet-wrecker nuclear bomb, a planet-sterilizing torch warhead, a planet-cracker antimatter warhead, or a planet-buster neutronium-antimatter warhead. Then they fly home, only to discover that the enemy's bombers were on a similar mission. Go to The Tough Guide to the Known Galaxy and read the entry "SLAG"

(As a side note, SF Author Colin Kapp often had ships armed with "Diffract Meson" warheads, presumably based on an as-yet undiscovered scientific principle. I always thought that there was some room for a warhead type in between the 10% efficient thermonuclear warhead and the 100% efficient antimatter warhead. Say Diffract Meson warheads are 50% efficient. )

Brett Evill put it this way: "These start-anyway go-anywhere drives play merry Hell with concepts like 'distance', 'remoteness', 'proximity', 'adjacency', 'line of communication', 'border', and 'defence', while reinforcing such concepts as 'trade', 'concentration of force', and 'first strike'. Give me a setting in which the map still matters."

With jump points, you have choke points that can be defended. Battles occur because the enemy has no choice but to invade though the jump point. Though it does become difficult and fuel intensive for the defenders, since Alderson points do not orbit their primary star, while planets, orbital fortresses, anti-ship mines and blockading tasks forces have to. The defending forces must constantly be thrusting for the entire tour of duty just to maintain their position. In The Gripping Hand, sequel to The Mote in God's Eye, there is some mention of a constant stream of tanker ships travelling between the defending forces and the gas giant fuel sources. And there are only blockading spacecraft, orbital fortresses and mines are impractical. Well, maybe not totally impractical. For mines a possibility is Dr. Robert Forward's statite concept. This uses a carefully angled solar sail to generate the constant thrust required to keep the mine stationary. I haven't done the math, but my gut feeling is that if the jump point is too far from the primary star the solar flux will be so low that even for low mass miles the sails will have to be huge. However, I am quite proud of making the jump point/statite connection, since this is actually an original idea by me (unlike almost all of the rest of this website).

Image:SolarSail.jpg

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Image:SolarSail02.jpg

While I haven't done the math on statites, David Harris did! Here is his analysis: There is actually a very simple method to find the "thrust" on an object due to the solar flux radiating on it. The intensity of light per square meter divided by the speed of light has the same units (after some manipulation) as a pressure. So, very simply, to find this solar pressure, divide the intensity of light (in Watts per meter squared) by c (in meters per second). You get a pressure (in Newtons per meter squared). This pressure equates to light impacting on a surface, but if you have a mirror, the light also bounces off. This actually doubles the pressure on a mirror. At 1 AU from the sun, the solar intensity is 1400W/m2. Dividing by c = 3x108 m/s and multiplying by two, we find that the pressure on a 1 square meter mirror should be 9.3x10-6 Newtons.

Now, if you want your mirror to float stationary at a certain point in space (like a non-orbiting "Jump Point"), the light pressure must counterbalance the gravitational force of the sun at that point. A quick check through a high-school physics book (bring a calculator) will show that the force on a 1 kg object at 1AU from the sun is a mere 0.00590 N. With this, it is easy to show that a 1 kg statite needs a solar sail 632m2 in area, or a square 25m on a side. Now here cones something interesting: Solar intensity falls off as a 1/r2 law (inverse square), meaning if you increase the distance by a factor of three, the intensity falls by a factor of nine. Gravity also follows a 1/r2 law, meaning if you increase the distance by a factor of three, the gravitational force falls by a factor of nine. The math is easy, but it is excruciating to type, so I will leave it as an exercise for the reader to show that, since both forces are governed by a 1/r2 law, the size of the sail does not change as you change your distance from the sun. No matter how far you are from the sun, a 1 kg statite will always need a sail 25m on a side.

[solarSail03.jpg Image:SolarSail03TB.jpg] Artwork by Frank Tinsley. Click for larger image.

Now, what fun things can we go and do with this? Perhaps we can start with a simple minefield. We can arbitrarily assume that each mine is 1 megaton. Adding on detonators, sensors, etc., assume that the whole mine is one tonne. A one tonne mine needs a sail 794 meters on a side, or 632,000m². Since the statite mine field will be located away from a planet, let us also arbitrarily decide that we will be defending a volume of space equal to the volume of the Earth. I really do not know how big the Jump Points or Crazy Eddie Points are, so this is pure guess work.

Assume we set our mines to detonate when a ship is 1km away. If a ship flew straight through the center of our minefield, I would hope that it would get within 1 km of at least one mine. If we assume one mine per 37,680 cubic kilometers, this gives us a 50/50 chance of a ship traveling through the center of our minefield coming within 1 km of a mine. Again, the tedium of algebra manipulation in ASCII prevents me from showing how I came to this figure. At one mine per 37,680 km³, we need 24 million (!) mines. That's 15 million square kilometers of solar sails!

With that many mirrors, you could do more damage with the reflected light than with the nuclear mines themselves! 15 million kilometers of solar sails adds up to 2.1x10¹⁶ watts of reflected light at 1 AU. That's 5 megatons of energy every second. In less than two months, the solar energy delivered by these mirrors would do more than the nuclear mines they are supporting.

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ClaysGhost's points out that the magnitude of the constant thrust problem depends upon how far the jump points are from the primary star. He says "The acceleration due to the Sun's gravity acting on a mass at the orbital distance of Jupiter is about 0.2mm/sec². Even for a 100 tonne vehicle you need a counter-force of only 20N to keep your station." This will make stealth difficult for a minefield. Even such low thrust from a rocket will be readily detectable, and a statite sail will be large enough to be hard to hide.

A very common limit is that the FTL drive can only be entered if the ship is "not too deep in a gravity well", that is, farther than a certain distance from either a planet or the primary star. Again keep in mind that if ships can only enter or leave FTL at about Pluto's orbit, the ships will either require unreasonably powerful normal-space rocket drives that run afoul of [rocket3a.html#johnslaw Jon's Law], or the ships will take years to travel between Earth and the FTL take-off point.

In the boardgame Attack Vector: Tactical, Ken Burnside avoided this problem by specifying that jump points orbit a star at about the orbit of Mercury.

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StarForce Alpha Centauri Another FTL system that was carefully crafted in order to force a specific situation was the one created by Redmond Simonsen for the wargame StarForce: Alpha Centauri. In the game, starships or "TeleShips" are jumped or "shifted" instantaneously from one location to another several light-years away by teams of women with psionic powers. Shifting cannot be done by a machine, it has to be done by a person. The supply of psionic or "telesthetic" women is limited. There is no way to genetically engineer them, they naturally occur at the rate of one First Order Telesthetic per million females. Energy is cheap, any ore or element can be synthesized, any material good can be manufactured. So the only valuable interstellar commodity are telesthetic women. This has several implications. In interstellar warfare, there are no carpet bombings of planetary populations with mass destruction weapons. This would destroy the only valuable item the planet has: a population that can produce more telesthetic women. Obviously, there are no restrictions placed on population growth, and large families are encouraged by the planetary governments. Since the population of telesthetics is so limited, they sort of know each other. They are also all members of the same Telesthetics Guild. Therefore, in ship-to-ship combat, weapons are not designed to kill.

StarForce: Alpha Centauri (1974)

Instead, the anti-ship weapon is sort of a telepathic command to the enemy teleship to make an uncontrolled interstellar shift into a random location. Such a shift can be up to five times the distance of a safe shift, so a teleship will take a while to crawl back to the battle. And in any event, a teleship that can jump between the stars is not going to have any difficulty avoiding something as sluggish as a laser beam.

Against planetary populations, teams of telesthetics can create the so-called Heissen Effect. This sedates the inhabitants, sending them to sleep. The ships then land squads of StarSoldiers in gravity sleds to take control. The inhabitants later wake up with migraine headaches.

Teleships have a maximum safe shift limit of five light years. If a friendly teleship does nothing but sit stationary and telesthetically "enhance" its location, another friendly can do a safe shift to that enhanced location from up to ten light years.

Attempting to shift a distance greater than the safe limit is called "over-shifting." There is a small chance that the shift will go as planned. There is a greater chance that the shift will malfunction. A bad shift will be either a "mirror shift" where the teleship moves in the exact opposite vector, or a "randomization" where the teleship appears in a random location within twenty light-years of Sol.

A "Star Gate" is a nine kilometer ring of chanplastic, crammed with telesthetics intimately familiar with the fabric of local space. A teleship starting at a star gate and shifting to an unenhanced location has a safe range of ten light-years, fifteen light-years to an enhanced location. Shifting from one star gate to another has a safe range of twenty light-years.

Since telesthetics are at a premium, there are no warships or orbital fortresses. Instead, merchant ships and star gates are modified for warfare.

You see the basic effect that flows from the FTL drive is that wars are relatively bloodless. The secondary effect is that pressures were created that caused wars. The latter effect is desirable, since a wargame simulation requires wars to simulate.

Image:StarForceTeleship.jpg Artwork by Redmond A. Simonsen

Redmond Simonsen: The Solar Government was to expend several trillion Labor Credits before it discovered that...(a) the discontinuity window could not reliably be produced on or near a planetary mass; (b) only 139 people out of 19 billion could produce the effect; (c) they were all women; (d) they were all powerfully telesthetic (i.e., clairvoyant), and mildly telekinetic; (e) a window could only be created between two positions in space that the Telesthetic was "comfortable" in and felt she "knew"; (f) a Gnostech initiated by the using Telesthetic was required; (g) bionic/electronic techniques could be used to amplify and refine the effect, but no pure-machine system could create it; (h) the range of the effect was theoretically unlimited but its accuracy was subject to degradation with the square of the distance. Psionic linking techniques and the Telesthetics founding of the Telesthetic Guild was the response. It is probably the heavy use of empathetic bridging in these techniques that explains the remarkable fact that no member of the Guild, even while on opposing combat teams, has ever deliberately caused another member's death.) This solidarity of Telesthetics was almost totally responsible for the virtually bloodless conduct of the Intra-Specific Wars of Autonomy in the 25th Century. In a sense the Outleap itself was responsible for the Wars of Autonomy: it dispersed and enlarged the human community into a multi-system race which was heavily dependent upon one socioeconomic factor, one resource that could not be synthesized by technology -- the Telesthetics. The number of Telesthetics available to a given system was almost purely a function of how much population was contained within or controlled by that system.

THE TELESHIP Length: 1048 meters. Ring diameter: 1224 meters. Mass: 50,402 tons. Telesthetic crew: 104. Service crew: 43. Star Soldier lift capacity: 80,000 in stasis. Maximum safe shift: 5.12 light years. Stellar shift cycle rate: 7.31 hours. Tac-Shift cycle rate: 0.15 hours. A. Primary Shift Ring. B. Secondary Shift Ring. C. Bridge. Real Flight Maneuver Center, Crew quarters. D. Gnostech Module, Mapping and Recovery tanks. E. Gravity Sled cluster. F. Energy Modulation Pack, Kinetic Drive. G. Ship systems control, life-support, and recreation garden.

The freedom from birth-controls in the colonized systems did have the desired effects of providing the population basis for "home-grown" Telesthetic crews to operate the Star Gates and the increasing number of Teleship.

It also, however, had several counter-productive side effects: (a) The vastly increased and dispersed human population became ungovernable by the institutions of the Solar Hegemony, (b) the "frontier" societies tended to produce divergent eco-political systems that either wanted independence, or worse, attempted to impose their provincial "solutions" on the rest of humanity.

All these factors conspired to produce a number of essentially pointless wars.

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From Islands In Space by John W. Campbell, jr. (1931).

Fuller still looked puzzled. "See here; with this new space strain drive, why do we have to have the molecular drive at all?"

"To move around near a heavy mass -- in the presence of a strong gravitational field," Arcot said. "A gravitational field tends to warp space in such a way that the velocity of light is lower in its presence. Our drive tries to warp or strain space in the opposite manner. The two would simply cancel each other out and we'd waste a lot of power going nowhere. As a matter of fact, the gravitational field of the sun is so intense that we'll have to go out beyond the orbit of Pluto before we can use the space strain drive effectively."

---

From Starman Jones by Robert A. Heinlein (1953).

But he had not eyes for it. To the west where avenue and buildings ended was the field and on it space ships, stretching away for miles -- fast little military darts, stubby Moon shuttles, winged ships that served the satellite stations, robot freighters, graceless and powerful. But directly in front of the gate hardly half a mile away was a great ship that he knew at once, the starship Asgard. He knew her history, Uncle Chet had served in her. A hundred years earlier she had been built out in space as a space-to-space rocket ship; she was then the Prince of Wales. Years passed, her tubes were ripped out and a mass-conversion torch was kindled in her; she became the Einstein. More years passed, for nearly twenty she swung empty around Luna, a lifeless, outmoded hulk. Now in place of the torch she had Horst-Conrad impellers that clutched at the fabric of space itself; thanks to them she was now able to touch Mother Terra. To commemorate her rebirth she had been dubbed Asgard, heavenly home of the gods.

Her massive, pear-shaped body was poised on its smaller end, steadied by an invisible scaffolding of thrust beams. Max knew where they must be, for there was a ring of barricades spotted around her to keep the careless from wandering into the deadly loci.

---

Image:Warp3.gif

Existing Drives There are a few semi-plausible FTL methods out there. One of the most famous is Dr. Miguel Alcubierre "Warp Drive", along with Chris Van Den Broeck's improvement. There are others at Dr. John Cramer's Alternate View archives, Edward Halerewicz, Jr.'s Warp Physics site, Marcelo B. Ribeiro's Warp Drive Theory site, Lawrence H. Ford and Thomas A. Roman's Scientific American article Negative Energy, Wormholes and Warp Drive, David Waite's Modern Relativity site (if you can understand the math), and NASA's Warp Drive When? More on the fringe is Burkhard Heim and his theory of everything. If the theory describes reality, it could give a form of FTL travel with an artifical gravity propulsion system at no extra charge. You can read a PDF file of the research paper here and the expanded version here

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Image:F-285.jpg

The Canonical List of StarDrives If you want to roll your own, you might find the following useful. Noted physicist and Hugo & Nebula award-winning SF author Geoffrey A. Landis has created a catalog of every kind of StarDrive that has ever existed in science fiction. It appears here with Dr. Landis' permission.

• [1.0] [#1.0 Discontinuous Drives] ("teleport-like")
  • [1.1] [#1.1 Flash gates]
    • [1.1.1] [#1.1.1 Transmitter to receiver]
    • [1.1.2] [#1.1.2 Transmitter to anywhere]
      • [1.1.2.1] [#1.1.2.1 Transmitter to anywhere] /variant
    • [1.1.3] [#1.1.3 Anywhere to receiver]
    • [1.1.4] [#1.1.4 Distant transmitter]
  • [1.2] [#1.2 "Door" gates]
    • [1.2.1] [#1.2.1 Portal to portal]
    • [1.2.2] [#1.2.2 Portal to anywhere]
    • [1.2.3] [#1.2.3 Anywhere to portal]
    • [1.2.4] [#1.2.4 Distant portal]
  • [1.3] [#1.3 "Permanent" gates] (Wormholes)
  • [1.4] [#1.4 Teleportation] (aka "jump")
    • [1.4.1] [#1.4.1 Single jump]
      • [1.4.1.1] [#1.4.1.1 Single jump]/variant
    • [1.4.2] [#1.4.2 Multiple-connection]
    • [1.4.3] [#1.4.3 Multi-jump] (Stutter)
    • [1.4.4] [#1.4.4 Hopscotch drive]
    • [1.4.5] [#1.4.5 FTL by time travel]
  • [1.5] [#1.5 "Fold" drive] ( Telportation/variant )
• [2.0] [#2.0 Continuous Drives]
  • [2.1] [#2.1 "Railroad" drives]
    • [2.1.1] [#2.1.1 Fixed trail]
    • [2.1.2] [#2.1.2 Consumable trail]
  • [2.2] [#2.2 "Non-railroad" drives]
    • [2.2.1] [#2.2.1 Real space drives]
      • [2.2.1.1] [#2.2.1.1 Newtonian space drives]
      • [2.2.1.2] [#2.2.1.2 Post-relativistic space drives]
      • [2.2.1.3] [#2.2.1.3 Tachyonic travel]
      • [2.2.1.4] [#2.2.1.4 Modified local speed of light]
      • [2.2.1.5] [#2.2.1.5 Modified regional speed of light]
      • [2.2.1.6] [#2.2.1.6 Modified universal speed of light]
      • [2.2.1.7] [#2.2.1.7 Tachyonic teleportation]
      • [2.2.1.8] [#2.2.1.8 Other real drives]
      • [2.2.1.9] [#2.2.1.9 "Bubble" drives]
    • [2.2.2] [#2.2.2 Alternative space] (non-real space drives)
      • [2.2.2.1] [#2.2.2.1 Alternative space with fixed nodes]
        • [2.2.2.1.1] [#2.2.2.1.1 Hyperspace with transmitter and receiver]
        • [2.2.2.1.2] [#2.2.2.1.2 Hyperspace with transmitter]
        • [2.2.2.1.3] [#2.2.2.1.3 Hyperspace with receiver]
        • [2.2.2.1.4] [#2.2.2.1.4 Hyperspace with distant transmitter]
      • [2.2.2.2] [#2.2.2.2 Alternative space without fixed nodes]
        • [2.2.2.2.1] [#2.2.2.2.1 "Jump" hyperspace]
        • [2.2.2.2.2] [#2.2.2.2.2 Direction hyperspace]
        • [2.2.2.2.3] [#2.2.2.2.3 Navigable hyperspace]
• [3.0] [#3.0 Modifying the Universe]
  • [3.1] [#3.1 Modify distance in space]
  • [3.2] [#3.2 Modify the speed of light]
  • [3.3] [#3.3 Universal parameter change]

---

• [1.0] Discontinuous Drives ("teleport-like"). Discontinuous drives are ones in which the traveler does not traverse the space between origin and destination.
  
  • [1.1] Flash gates. Devices in which the object transported disappears from point X and reappears at point Y.
    
    • [1.1.1] Transmitter to receiver. Teleport in which a discrete transmitter and a receiver are needed. May require a ship, or may not.
      
    • [1.1.2] Transmitter to anywhere.Teleport in which a transmitter is needed, but a receiver is not; the transporter can select the target location ("Beam me down" is the most well-known example)
      
      • [1.1.2.1] Transmitter to anywhere /variant. Transmitter can be transported with the teleportation. See also [#1.4.1.1 [1.4.1.1] "Single jump/variant"].
        
    • [1.1.3] Anywhere to receiverTeleport in which a receiving unit is needed, but a transmitter is not. ("Beam me up" is an example of this.)
      
    • [1.1.4] Distant transmitterA teleport system in which a fixed unit is needed, but this unit can teleport you from a place to another place. (The "point to point" use of the transporter in Trek is an example.)
      
  • [1.2] "Door" gates. Gates in which an opening is made between point X and point Y which exists for some finite time; the object transported then moves though the gate.
    
    • [1.2.1] Portal to portal. A transmitting device to act as the "out" door and a receiving device to act as the "in" door are both required. (e.g., Poul Anderson, The Enemy Stars.)
      
    • [1.2.2] Portal to anywhere. Here the transmitting door opens a receiving door without requirement for any device at the receiving end. ('Tak Halus' (pseud. of Steven Robinette) did a series of stories in Analog in early 70s with this premise)
      
    • [1.2.3] Anywhere to portal. The same as [#1.2.2 [1.2.2] "Portal to anywhere"], but traveling in the opposite direction.
      
    • [1.2.4] Distant portal. Anywhere to anywhere, device located elsewhere. Here "door" opens from X to Y by use of a device at a third location C. The 'door' equivalent of [#1.1.4 [1.1.4] "Distant transmitter"].
      
  • [1.3] "Permanent" gates (Wormholes). "Permanent" here means that these stay open without the requirement of a device, that is, they are a path from X to Y without being energized. There are a wide variety of subsets of this. Recently the most talked-about are Lorentzian wormholes, which are apparently allowed by the general theory of relativity if the presence of negative matter is permitted. General relativity variants include Morris-Thorne spherical wormholes, Visser portals, Kerr ring-wormholes, Einstein-Rosen bridges (nb: which actually collapse before allowing you to traverse them), Tippler rotating cylinders (nb: which don't actually serve as bridges, but at least one SF writer, Poul Anderson, wrote a book which assumed that they did). A non-relativity version is the "mirrors" used in Wolfe's New Sun series of books.
    
  • [1.4] Teleportation (aka "jump"). Here I use "teleportation" to imply something that can transport itself without a fixed transmitter or receiver. Reference to quantum "tunneling" is often made. Some books imply that humans can do this unassisted (Tyger, Tyger/The Stars My Destination). Many more use ships which can "jump" with some device. Here I use 'jump' or 'teleportation' only for the case that physical travel is not required in some alternate version of space, in distinction to some SF writers who use the term or a variant for cases where a ship 'jumps' to some 'hyperspace' (jumpspace, subspace, etc) where it can travel FTL.
    
    • [1.4.1] Single jump. A ship (or person) who can jump from place to destination in a single step, and can select the target.
      
      • [1.4.1.1] Single jump/variant. In the variant, this only works at selected places, and takes you only to selected spaces (The Mote in God's Eye). This type of variant in general can be considered a version of the [#1.1 [1.1] "Flash-gate"] discussed above.
        
    • [1.4.2] Multiple-connection. The ship can engage a "jump" drive, which will connect your location in space-time with another location in space-time that is fixed by the universe (may depend on your state of motion in some variants). The connection will vary from place to place, so to go to a given destination you need a "map" of where to go in space to find the place that jumps to the right spot. The analogy is of the universe to a crumpled sheet of paper. An ant can cross from one place on the paper to another where the paper touches itself. (Heinlein, Starman Jones). For some locations, a long trip moving from one place to another to take multiple jumps may be necessary.
      
    • [1.4.3] Multi-jump (Stutter). A ship can jump from place to place, but not far enough to travel in a single jump. Thus, the ship travels by a series of short jumps. In the limit of very short jumps, the ship "appears" to be traveling through space at a "pseudo" velocity without actually having any momentum. (This shades into [#1.4.1 [1.4.1] "Single jump"] as the length of jump gets longer).
      
    • [1.4.4] Hopscotch drive. Use of any version of a gate or portal to accomplish self-motivated teleportation by having a transmitter transmit a transmitter, so that a ship "bootstraps" across space by continuously beaming itself incremental distances. (Such a drive is somewhere in the fuzzy region between a [#2.0 [2.0] "Continuous"] and a [#1.0 [1.0] "Discontinuous drive"]).
      
    • [1.4.5] FTL by time travel. In FTL by time travel, faster than light travel is achieved by traveling to the destination at ordinary slower-than-light speed, then teleporting backward in time to arrive at the same time you started (e.g., Roger MacBride Allen, The Depths of Time).
      
  • [1.5] "Fold" drive ( Telportation/variant ). A "fold" drive appeals to the "folded space" concept of [1.4.2] "Multiple-connection", but now assumes that the ship can intentionally "fold" space to produce the direct connection between point X and point Y required. Since this categorization is by how the drive appears, and not how it functions, "fold" variants are identical to actual teleport (or "portal") variants, cf. [#1.2 [1.2] "Door gates"])
    
• [2.0] Continuous Drives. Continuous drives are ones in which the traveler does traverse the space between start and finish. A ship gets from point X to point Y by traveling rather than by an instant "jump", although the travel is not necessarily in "real" space. The word "ship-like" is a little fuzzy, since many SF writers use 'ships' to accomplish what is actually teleportation-like travel. This is, I think, because ships are such a great story device
  
  • [2.1] "Railroad" drives
    
    • [2.1.1] Fixed trail. A "railroad" drive is one in which it is assumed that some physical structure connects two points, and that FTL travel is possible, but only traveling along this structure (as railroad travel is only possible along a railroad). One might appeal to the concept of a cosmic string, or some other astrophysical object. The railroad is in some ways a conceptual link between wormhole-like drives and ship-like drives. If the travel is actually instantaneous, with an object leaving one end appearing at the same time at the other end, the railroad drive becomes a variant of [#1.3 [1.3] "Permanent gate]". (e.g., Glen Cook, The Dragon Never Sleeps.)
      
    • [2.1.2] Consumable trail. In a consumable trail, some structure must be put in place between a and b, and the drive consumes this material as it travels in order to produce FTL. Some versions of the Alcubierre drive, for example, require that a structure of negative energy be put in place along the path from x to y, and the ship can then travel between the two points, but destroys the structure as it travels.
      
  • [2.2] "Non-railroad" drives. This section covers continuous drives (that is, drives where the ship traverses space to get to the place desired) which do not require a structure in place in space.
    
    • [2.2.1] Real space drives. Real space drives assume that faster than light travel is possible in physical space. In terms of appearance, all of these drives apparently operate the same way (you go faster than light), and so if I were to keep to my strict classification, these would all be in the same category. The main difference between the drives is how they talk around relativity.
      
      • [2.2.1.1] Newtonian space drives (EMF classification: [#fakedrive fakedrive]). This version of a FTL drive simply ignores relativity. The ship goes faster than light merely by speeding up to a velocity which is faster than light. (e.g., E.E."Doc" Smith, The Skylark of Space.)
        
      • [2.2.1.2] Post-relativistic space drives (EMF classification: [#fakedrive fakedrive]). This is a minor variant [2.2.1.1] "Newtonian space drive"; the drive assumes that there is some (yet unknown) "correction" to relativity such that the speed of light is not, in fact, a barrier. Often this correction will be some added term which applies only very close to the speed of light.
        
      • [2.2.1.3] Tachyonic travel. Tachyonic travel notes that faster than light speeds are in fact permitted by relativity for bodies of imaginary rest mass, and assumes that there is some way to reach the faster than light state (often invoking "tunneling") from slower than light states without leaving "real" spacetime. (nb: tachyonic FTL travel still has causality paradoxes in special relativity).
        
      • [2.2.1.4] Modified local speed of light. Drive assumes that the speed of light in the vicinity of the ship can be modified by the drive system in some way, so that although the ship does not exceed the speed of light, it nevertheless can travel faster than 300,000 kilometers per second.
        
      • [2.2.1.5] Modified regional speed of light. Assumes that the speed of light is greater than 300,000 kilometers per second in some places in the universe. Faster speeds can be achieved in other places in the universe .
        
      • [2.2.1.6] Modified universal speed of light. A scientist discovers a way to change the speed of light in the entire universe, and does so. Now any ship can go faster than (what used to be) the speed of light.
        
      • [2.2.1.7] Tachyonic teleportation. The ship and/or person is converted into a stream of tachyons and beamed across space, then reconstituted at the receiver. Actually a variant of [#2.2.1.2 [2.2.1.2] "Tachyonic travel"] and/or [#2.2.2.1.1 [2.2.2.1.1] "Hyperspace with transmitter and receiver"]; listed separately because it is significant that the ship does not travel as a cohesive unit. Other variant names can be used for the particles, which can travel either through real space or some alternative space.
        
      • [2.2.1.8] Other real drives. This covers other ways of dealing with relativity problems without leaving real space. (Usually this involves employing doubletalk and bafflegab.)
        
      • [2.2.1.9] "Bubble" drives (EMF classification: [#fakedrive warpdrive]). "A bubble of different space is projected around the ship so that the ship can travel faster-than-light while still in realspace." This is listed last, since it is an intermediate step between "real space" drives and alternative space drives, with some nature of both. (This seems to be the FTL system used on Star Trek.)
        
    • [2.2.2] Alternative space (non-real space drives). In SF parlance, often called hyperspace, hyper, jumpspace, FTL space, and other such words. EMF classification: "[#hyperdrive Type I; hyperdrive]: The ships enters some different space during the trip, whether or not time passes for the crew while in this space."
      
      • [2.2.2.1] Alternative space with fixed nodes. Like teleport systems, a alternative space drive may require a fixed station.
        
        • [2.2.2.1.1] Hyperspace with transmitter and receiver. A fixed station boosts the ship into hyperspace; another station is needed to retrieve the ship out of hyperspace. In some variants, only specific locations are nodes which can be used to access hyperspace.
          
        • [2.2.2.1.2] Hyperspace with transmitter. A fixed station boosts the ship into hyperspace. (Babylon-5?)
          
        • [2.2.2.1.3] Hyperspace with receiver. A ship can enter hyperspace on its own, but needs a receiver to get back into real space. Another one I've never seen in SF.
          
        • [2.2.2.1.4] Hyperspace with distant transmitter. In this variant, a fixed machine is needed to access hyperspace, but the machine need not be at either the original location or the destination. I've never seen this in SF; included for completeness.
          
      • [2.2.2.2] Alternative space without fixed nodes.These are the variants of the classic SF hyperdrive. There are probably more examples of this in SF than all other of the drive types combined, and hence it is possible to make very fine divisions within the type. EMF classification: "[#hyperdrive Type I; hyperdrive]: The ships enters some different space during the trip, whether or not time passes for the crew while in this space." The space is often explained away as being a dimension different from the four dimensions we currently can perceive (this explanation typically advanced by people who seem to have only a foggy idea what a "dimension" is). There are many variants based on the supposed "theory" of how the drive works, including entering a space where the speed of light is faster, entering a space which maps onto real space with a mapping such that points far apart in real space are closer in the alternative space, entering a space where the ship expands and then contracts to a different place, entering a space where everything moves at the same FTL speed, etc. Likewise, there are a long list of "conditions" which hyperspace drives are imagined to require. A common one is that the FTL space cannot be entered when "in the gravitational well of a massive body," (Niven, Ringworld series) or that your ship must have a high velocity in real space before you can enter FTL space (Niven, World of Ptavvs, O'Donnell, Fire on the Border) These two are convenient for sf writers, because they explain why spaceships are required. Important questions for hyperspace concepts are whether ships can see and/or dock with each other in hyperspace, whether all ships travel the same speed, and whether a ship can navigate while in hyperspace. These questions can also be asked of [#2.2.2.1 [2.2.2.1] "Hyperspace with fixed nodes"]. I will take this last to be the question used for subdivisions.
        
        • [2.2.2.2.1] "Jump" hyperspace. The destination is fixed when the ship enters the alternative space, either as a function of its position and velocity entering, or else by some settings in the drive. After a ship enters the alternative space, there is no way for it to change the destination. (e.g., GDW's "Traveller" RPG)
          
        • [2.2.2.2.2] Direction hyperspace. A ship's direction is fixed when the ship enters hyperspace (often, but not always, fixed by the direction the ship was traveling when it entered). How far it travels, however, is a variable that can be changed. Usually the distance is proportional to time spent in hyperspace, but may be a more complicated function. The ship may or may not be able to calculate its position in real space while in hyperspace.
          
        • [2.2.2.2.3] Navigable hyperspace. The ship is able to completely navigate in hyperspace. It may or may not be able to calculate its position in real space while in hyperspace. Sometimes the hyperspace may have geography or dangers which must be navigated around.
          
• [3.0] Modifying the Universe. A final category of FTL, not precisely fitting in elsewhere, requires modifying the universe. Some items in this category also could be made to fit other categories.
  
  • [3.1] Modify distance in space. Remove or shrink the space between two points.
    
  • [3.2] Modify the speed of light. Change the value of the speed of light in the region where travel is desired (see [#2.2.1.6 [2.2.1.6] "Modified universal speed of light"])
    
  • [3.3] Universal parameter change. Gain access to the parameters that describe the universe, possibly by hacking into the operating system that the universe runs. Find the parameters which describe your location. Rewrite these parameters to put you in the place you want to be. (e.g., Greg Bear, Moving Mars)
    

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The EMF (Erik Max Francis) classification

• Type 0; realdrive: A drive which uses tricks of spacetime geometry (a la general relativity) to travel faster than light.
  
• Type I; hyperdrive: The ships enters some different space during the trip, whether or not time passes for the crew while in this space.
  
• Type II; warpdrive: A bubble of different space is projected around the ship so that the ship can travel faster-than-light while still in realspace.
  
• Type III; jumpdrive: The ship travels from one point to another, possibly in multiple jumps, without occupying the intervening space and without the use of a different space to assist the travel.
  
• Type X; fakedrive: Assume that special relativity or general relativity are incorrect in part or in whole, or just ignore them. Now you can just accelerate at constant gravity until you go faster than light.