Favorite type of FTL?

[SirNitram]

Whatever *IS* isn't going to be figured out or guessed at anytime soon.

Are you familiar with Debating Rule 6?

[Catman]

Just acknowledging that if a interstellar drive is possible, none of us will have a clue NOW what it is, and will probably just make shit UP.

This is a mentality I have seen pop up before, but I don't like it at all. Sure, our predictions of the future probably (certainly) aren't going to be 100% accurate, but we can have a pretty good idea of what might happen, what is probable or improbable to happen, and what will certainly not happen. That is what science and engineering are all about.

For a simple example, I don't know exactly what future airplanes will look like, but I can say they will probably still have wings. I don't know exactly what a future spaceship will look like, but it will probably have a rocket and fuel tanks of some sort (which may be very big, depending on the intended use of this ship). These things are simply needed - the field of aerospace engineering and the basic dynamics of motion are pretty well understood today, so it is reasonable to assume these basics will at least hold true.


(Actually, interstellar drives are possible, but FTL drives are not. They are not the same thing; an interstellar drive might be a generation ship, etc, taking its time to get to a new star. But, the laws of physics do give us a pretty good idea of what these things may be, enough that we can speculate designs down to pretty detailed levels.)

And why would it be faster than light? If it's a wormhole, it probably won't involve moving faster than light.

My understanding of a wormhole is it is also problematic. Creating one will in the first place is non trivial, and even so it will be very small (at least for realistic energies), and will collapse almost instantly, certainly before any macroscopic object can get through.

It might also bring up causality problems, since if it goes through space, it can jump through time as well (one side simply needs to move at a different speed, I think). It may also create a preferred reference frame, where one side of the wormhole is more 'right' than the other, which poops on special relativity.

I'm afraid my own knowledge is not good enough to go into more detail here, but unless I am grievously mistaken, a wormhole is no more realistic than a warp drive. Both are impossible in the real world.

But how do YOU know what will be developed in the next thousand years?

It can't just be predicted.

And once again, I disagree with this mentality pretty strongly. We can't know for sure, but we do have a pretty good grasp on the basic laws on the universe, and from these, several things can be extrapolated. Science simply isn't a revolutionary field - the knowledge of 3000 AD will surely be built upon the knowledge of today.

Well, okay. They're both unrealistic. And I was focusing too much on the impossibilities of warp and barely focusing on the wormhole. There's the mistake of my assumptions.

Trying too hard to consider that a bunch of things will pop up in the future isn't going to make it better either.

[Ariphaos]

I'm aware of this, and as Nitram says the fewer steps required to get to the magic makes for 'better' fantasy... but it's still just fantasy. It's still handwaving away huge problems that are apparently insoluble and then claiming it's 'realistic'. As D-13 mentioned, the closer you stay to 'sensible' with your tech the less technological oversights you get that make no sense - many FTL concepts have staggering utility as weapons, but in stories are simply used to get from A to B. :)

Well, your valid points aside (the weaponry angle - FUCK quantum torpedos, ram the warp bubble through the target!), there's another issue here.

Earnshaw's theorem states that magnetic levitation in a static field is impossible. In 1842, the idea of superconductors and computers was beyond the comprehension of the time. These devices are both built, remotely, on 19th century technology, but they're not obvious extensions. They make magnetic levitation possible.

Earnshaw's theorem is still true, we just got around it by creating machines and substances capable of violating the precepts upon which his theory is based. These were -impossible- in 1842. Superconductors wouldn't be seen for 70 years, computers later, and taking advantage of these took a few decades on their own.

So I tend to find running around saying IMPOSSIBLE! IMPOSSIBLE! to be...

Inelegant.

What we -can- comprehend, now, is a few potential means by which, 'if we can do this, FTL may follow'. If you find you -must- explain your fantasy physics in your Sci-fi, thinking it through is certainly better than not.

[montypython]

Damn, I thought that I could edit these.

Well, if you need a further explanation form this, it's that I think that a Wormhole drive is more realistic.

Which is like saying pink magical fairies are more realistic than blue magical fairies.

My personal favorite is the Maeda drive. Ship is converted into pseudomaterial which moves at c to its destination, with time not advancing for the crew during the transition. Yeah, I'm plugging my own piece of handwavium--I'm entitled (though I'm pretty sure others have come up with the same thing before me). Of course, it's not FTL, so it's useless to you.

As long as something is not truly ruled out by science (like the ether theory), its not really handwavium.

[SirNitram]

Damn, I thought that I could edit these.

Well, if you need a further explanation form this, it's that I think that a Wormhole drive is more realistic.

Which is like saying pink magical fairies are more realistic than blue magical fairies.

My personal favorite is the Maeda drive. Ship is converted into pseudomaterial which moves at c to its destination, with time not advancing for the crew during the transition. Yeah, I'm plugging my own piece of handwavium--I'm entitled (though I'm pretty sure others have come up with the same thing before me). Of course, it's not FTL, so it's useless to you.

As long as something is not truly ruled out by science (like the ether theory), its not really handwavium.

It actually is, especially if it uses materials that don't exist(Which is what handwavium means). Wormholes require large amounts of a specific, quantifiable handwavium: Negative energy. Two other options for FTL become possible if you assume casualty will allow it and you have negative energy, and at much, much, much lower costs.

[Catman]

Probably good to separate the two.

[rhoenix]

SF author Geoffrey Landis has catagorized almost forty different types of FTL drives found in various SF novels here:

http://www.projectrho.com/rocket/rocket ... stardrives

Ah, Nyrath - thank you for your comments. However, I was and am using your site rather often for many, many aspects of my writing.

So, thank you for creating and maintaining your site the way you have. I picked my favorite three in the OP based purely on selfish desire.

[OmegaGuy]

I like time/space travel combination drives, like in Doctor Who.

[Luzifer's right hand]

Which is like saying pink magical fairies are more realistic than blue magical fairies.

My personal favorite is the Maeda drive. Ship is converted into pseudomaterial which moves at c to its destination, with time not advancing for the crew during the transition. Yeah, I'm plugging my own piece of handwavium--I'm entitled (though I'm pretty sure others have come up with the same thing before me). Of course, it's not FTL, so it's useless to you.

Indeed.
The Engines of Light trilogy by Ken MacLeod has such a drive.

[Dooey Jo]

As long as something is not truly ruled out by science (like the ether theory), its not really handwavium.

Very few things are truly ruled out by science, though, so that's not a very good definition. If some new discovery is made that match predictions from ether theory, it might have to be brought back in one form or another. So science won't say this and that is absolutely impossible, because it only describes the universe, it doesn't tell it what to do.

Actually, the math works for Alucubierre, and it doesn't fuck Casuality up the ass, so it's not 'impossible', it just requires a material we don't see.

It can fuck up causality, just like wormholes.

[Nyrath]

Ah, Nyrath - thank you for your comments. However, I was and am using your site rather often for many, many aspects of my writing.

I figured that might be the case. But I like to mention things for the benefit of any other readers who are new. In any event, I'm glad you found it useful.

[Nyrath]

I personally draw a line between handwavium and unobtanium: ...snip...
I think most people use the terms interchangably, so my personal usage is irrelevant in reality (though, I am pretty sure I picked this up from somewhere else myself - maybe Atomic Rockets or maybe sfconsim-l, I don't remember), but I just thought I'd throw it out there.

I'm pretty sure it was Atomic Rockets.
http://www.projectrho.com/rocket/rocket ... handwavium

[kinnison]

Just thought of another one; the physics extension proposed in "Moving Mars" by Greg Bear. Basically, the thesis is that all particles and objects are mathematical structures with a hidden matrix of descriptors; which include ones for which particle it is, terrene sign, charge, and most especially location and momentum.

Essentially, it's a "disappear and reappear anywhere" drive with a problem; that problem being that the smallest mass it will move is about that of a small moon, There are other problems too; describing them would be even more of a spoiler.

[kinnison]

Just had a look at Atomic Rockets. There is a good point here, not original with me; it's not a good idea to throw around relativistic kinetic-kills in a solar system you want to have some use for afterwards. Numbers in the double-digit teraton range are typical when discussing stuff like this.

I have seen a bombardment weapon concept which is out and out nasty. The only problem is that it would take years to reach target. Simple really; a Bussard ramjet with terminal guidance. With enough runup this could smash a planet, easy.

[Nyrath]

I have seen a bombardment weapon concept which is out and out nasty. The only problem is that it would take years to reach target. Simple really; a Bussard ramjet with terminal guidance. With enough runup this could smash a planet, easy.

Well, there is a problem with that. In 1989 two spoil-sports named Dana Andrews and Robert Zubrin figured out that Bussard ramjets have a terminal velocity, due to the drag caused by their ramscoops. With a proton-proton fusion drive, the speed limit was on the order of a mere 12% lightspeed. This isn't quite enough to create relativistic effects.

At 12% c, each metric ton of mass will impact with about 156 megatons of energy. This is large, but is still a far cry from planet-smashing.

A Ram-Augmented Interstellar Rocket has a terminal velocity that is higher than a Bussard ramjet, but without unlimited fuel. Unfortunately I do not have figures on just how much higher the velocity is.

[RedImperator]

My personal favorite is the Maeda drive. Ship is converted into pseudomaterial which moves at c to its destination, with time not advancing for the crew during the transition. Yeah, I'm plugging my own piece of handwavium--I'm entitled (though I'm pretty sure others have come up with the same thing before me). Of course, it's not FTL, so it's useless to you.

As long as something is not truly ruled out by science (like the ether theory), its not really handwavium.

Um, no. If it's truly ruled out by science, it's just plain wrong. If it's "not technically totally ruled out by science but don't hold your breath waiting for it at Best Buy", it's handwavium. I wrote the damn story, so I'm pretty well qualified to say when I was waving my hands and shouting "please don't ask me how this works".

[Nyrath]

Just had a look at Atomic Rockets. There is a good point here, not original with me; it's not a good idea to throw around relativistic kinetic-kills in a solar system you want to have some use for afterwards. Numbers in the double-digit teraton range are typical when discussing stuff like this.

You do bring up an important point. Since SF authors are reduced to inventing their own imaginary physics in order to allow FTL starflight, there is a danger of unintended consequences.

The reasons that the Alderson Drive from Larry Niven and Jerry Pournelle's THE MOTE IN GODS EYE was so successful (and so widely copied by game designers) is because [1] the desired effects and limits were defined and generated by the new imaginary physics and [2] the unintended consequence were deduced and incorporated into the final design.

The main desired effect was to allow interstellar attack and defense. The drive created military choke points which made defending a possibility.

In other FTL systems they postulate long-range FTL detection and combat while traveling FTL. No choke points but it still allows the defender to intercept the attackers.

Without something like this, you have no defense, no empires, and no story. The single interstellar bomber from the Blortch empire materializes over Terra, spits out one planet-cracker bomb, and jumps back into FTL flight as Terra vaporizes in a Industrial Light And Magic special effect. It arrives back at Blortch Prime just in time to see the expanding smoke ring that marks the former location of the planet, courtesy of the single Terran interstellar bomber. The End. The reader throws your book across the room and resolves to avoid your novels in the future.

[Lord of the Abyss]

One of my favorites due to it's sheer weirdness and implausibility is the mechanical ( yes, mechanical; driveshafts and gears and rotors ) stardrive from A. Bertram Chandler's Commodore Grimes books. It worked primarily by sending the ship backwards in time and forward in space, so that one problem was not arriving before you left. That's fast.

It has parts that spin or otherwise move in higher dimensions/through time, and it moves the ship as a reactionless drive by being an unbalanced engine; the net kinetic energy of all the moving parts doesn't cancel out, but moves the drive and ship. Yes, I know that violates physical laws; I don't recall the name, but it should have been called the "Screw Physics ! Drive"

Runner up would by the hyperspace drive from Redshift Rendezvous, because of all it's cool side effects. The ship exists in a hyperspace whre the spped of light is much slower, but where space itself is smaller by even a larger degree; it travels FTL relative to normal space by travelling verrrry slowly in hyperspace. It has the cool advantage that being in a hyperspace it can literally move through planets or intersect with things like buildings, and you can just step out into them.

Plus, the speed of light is slowed down inside the ship; you can approach lightspeed by running. Relativistic effects are easily experienced just walking around. The crew and passengers wear belts that keep their personal lightspeed in a normal, survivable range; tha author admits to the likely logical problems involved, but without them he wouldn't have the story.

In other FTL systems they postulate long-range FTL detection and combat while traveling FTL. No choke points but it still allows the defender to intercept the attackers.

Without something like this, you have no defense, no empires, and no story. The single interstellar bomber from the Blortch empire materializes over Terra, spits out one planet-cracker bomb, and jumps back into FTL flight as Terra vaporizes in a Industrial Light And Magic special effect. It arrives back at Blortch Prime just in time to see the expanding smoke ring that marks the former location of the planet, courtesy of the single Terran interstellar bomber. The End.

Actually you can have have a story; it was a plot point in Acts of Conscience by William Barton. It answers the Fermi Paradox, "Where are they ?" Answer : They invented a drive like that, and killed each other off in a war with unstoppable FTL weapons. A war that literally lasted a few seconds at most, and left exactly one technological species in the universe.

[Admiral Valdemar]

You do bring up an important point. Since SF authors are reduced to inventing their own imaginary physics in order to allow FTL starflight, there is a danger of unintended consequences.

The reasons that the Alderson Drive from Larry Niven and Jerry Pournelle's THE MOTE IN GODS EYE was so successful (and so widely copied by game designers) is because [1] the desired effects and limits were defined and generated by the new imaginary physics and [2] the unintended consequence were deduced and incorporated into the final design.

The main desired effect was to allow interstellar attack and defense. The drive created military choke points which made defending a possibility.

In other FTL systems they postulate long-range FTL detection and combat while traveling FTL. No choke points but it still allows the defender to intercept the attackers.

Without something like this, you have no defense, no empires, and no story. The single interstellar bomber from the Blortch empire materializes over Terra, spits out one planet-cracker bomb, and jumps back into FTL flight as Terra vaporizes in a Industrial Light And Magic special effect. It arrives back at Blortch Prime just in time to see the expanding smoke ring that marks the former location of the planet, courtesy of the single Terran interstellar bomber. The End. The reader throws your book across the room and resolves to avoid your novels in the future.

That is very much like the jump drive in the I-War games. Only, you have to be at a Lagrange point to use the drive, since any gravity well nearby can really screw things up. The transit time can vary given distance, but it is more or less minutes for light years. This permits the guarding of known jump points, but that can be mitigated by the Linear Displacement System (LDS drive) which can be used instead of standard fusion torch drives for interplanetary travel. This involves a inertialess drive that moves the ship using quantum scale tunnelling just a tiny distance every fraction of a second. You gain the flight characteristics of an aeroplane and can go to just under c near instantly, but is energy intensive and the physics can be blocked by inhibiting missiles so as to stop the delicate physics from working and so stop any potential hit and run attacks at relativistic velocities.

Myself, I'm okay with FTL in most things, but personally, I'd rather not have it. The idea of the RAIR using a magnetic monopole, or the Conjoiner drives of the Revelation Space novels (miniature wormholes near the start of te Big Bang using the soup of subatomic particles of the past to act as an infinite source of propellant and energy to an extent) is far more appealing. What can I say, I love my hard, or at least harder, sci-fi.

[Teleros]

Lensman-style inertialess drive (ie top speed is limited only when thrust = "air resistance" of space). Useable in atmosphere, gravity wells, heck if the engine's powerful enough water too, and it doubles up as a great defence mechanism. Problem is when you turn it off - you revert to your pre-inertialess velocity, so be careful .

After that, well I think the SW hyperdrive is pretty good - nice and fast for one thing - as is the ST warp drive providing you don't mind the slow speeds. I wouldn't touch the 40K Warp with a barge pole if I could help it though .

[Admiral Valdemar]

A Lagrange point is a gravity well. Much smaller than a planet or star, but it still takes a little thrust to get out of one (L1, L2, and L3 are hard to stay in, but L4 and L5, when in the stable orbits around them, you will stay there unless you expend some delta-v).

They seem to be among the most poorly understood concepts in science fiction. I've heard them referred to as 'gravitionally null areas', which is absurd; if there was no gravity in that point, how would you be orbiting the planet still? All it means to be at a Lagragian point is the gravitional acceleration on you from the primary is equal to the secondary: thus at an Earth-Moon lagrange point, your orbital period is equal to the moon, so you remain stationary relative to the moon. It by no means you are out of a gravity well.

As to your other point, how does one get "infinitely" far from an object in finite space-time?
Also, the most significant gravity well for interstellar trips is the that of the sun anyway. To get from 1 AU to infinite distance from the sun you have to pay about 900 MJ per kilogram of your ship (this is ignoring rocketry, assuming a magical drive of some sort that doesn't require fuel - the real situation is worse) just to pay the sun for your gravitional potential energy. That is the real gravity well problem.

Of course, science fiction can handwave that away, but it pretty much has nothing to do with Lagrange points.

I'm telling you how they rationalise it, which is only the same as an Alderson Point, which I don't even know the definition of. The Lagrange points are the only places these jump drives work, other than deep space, and the often cited argument is to do with the cancelling out of gravity interference from celestial bodies of any magnitude. I don't know how such physics would work for such an impossible drive, but in universe, that's their rule. I recall the mention of null gravity, but this is from years ago with a manual I can't find. It may well have stated it's simply easier to form such wormholes because of the stability of a Lagrange point instead, though I often hear the cancelling of all gravity claims, much like people think orbiting Earth means zero gravity too.

[Batman]

Only, you have to be at a Lagrange point to use the drive, since any gravity well nearby can really screw things up.

A Lagrange point is a gravity well.

It is most emphatically not. A LaGrange point is a point within a gravity well. Given that a Lagrange point is a set of coordinates in empty space how would it generate a gravity well, given it has no mass to begin with?

Much smaller than a planet or star, but it still takes a little thrust to get out of one (L1, L2, and L3 are hard to stay in, but L4 and L5, when in the stable orbits around them, you will stay there unless you expend some delta-v).

You will stay wherever you are OUTSIDE a gravity well a lot more than inside it.

They seem to be among the most poorly understood concepts in science fiction. I've heard them referred to as 'gravitionally null areas', which is absurd; if there was no gravity in that point, how would you be orbiting the planet still? All it means to be at a Lagragian point is the gravitional acceleration on you from the primary is equal to the secondary: thus at an Earth-Moon lagrange point, your orbital period is equal to the moon, so you remain stationary relative to the moon. It by no means you are out of a gravity well.

Completely correct. However, the gravitational effects DO cancel each other out (by and large). Net effect: zero (or close). Who cares if you're theoretically deep inside a gravity well if the effects of being there don't manifest thanks to all of them negating each other?

[Admiral Valdemar]

That's the point to these drives. It's not just the Capsule Drive of I-War, but I believe many books, games and TV shows/movies have drives that can only be used with very little gravitational interaction, hence Lagrange points being used. It makes sense if the wormhole, or whatever physical phenomenon, is easily disrupted, say, by a planet's gravity field tugging a wormhole out of line with a spacecraft ready to jump, causing all sorts of hilarity.

[Nyrath]

It has parts that spin or otherwise move in higher dimensions/through time, and it moves the ship as a reactionless drive by being an unbalanced engine; the net kinetic energy of all the moving parts doesn't cancel out, but moves the drive and ship. Yes, I know that violates physical laws; I don't recall the name, but it should have been called the "Screw Physics ! Drive"

Yes, we know it as the infamous Dean Drive, which was the original "net kinetic energy of all the moving parts doesn't balance out." drive. I'm sure A. Bertram Chandler read about the Dean Drive in John W. Campbell's promotional article in Astounding magazine.

[Nyrath]

That's the point to these drives. It's not just the Capsule Drive of I-War, but I believe many books, games and TV shows/movies have drives that can only be used with very little gravitational interaction, hence Lagrange points being used.

Heh. Well, not to put too fine a point on it (sorry), the point to the points used in these drives is to put some limitations on the stardrives.

Back in the old days (pre-1970s), the popular limitation was the ship could only enter FTL flight when it was sufficiently far away from the gravity of a planet or sun. I dunno who invented it, but all the authors copied it.

John W. Campbell jr. used it in his novel ISLANDS IN SPACE (1931). He used technobabble about the artificial space warpage of the stardrive being interfered with by the natural space warpage of a planet's gravity. This is total hogwash, but it almost sounds reasonable.

Niven and Pournelle popularized (if not invented) the idea of limiting FTL entry to specific points in space. MOTE IN GOD'S EYE has their points determined by "lines of equipotential thermonuclear flux" between two stars, which is more hogwash. The game INDEPENDENCE WAR uses Lagrange points, which is clever.

But the whole purpose is to introduce some limit on the stardrive. You could just as well limit FTL entry to the time of proper phase of the moon or when the proper planetary conjunction occurs, or if enough four-leaf clovers with pixie dust are burnt in the ship's engines, or something.

It's just that a gravity based limit sounds all real and scientific.