I want my spaceship to go fast...

You can use pretty much any methodology you like. There may be specific phrases that are trademarked, but beyond that, deciding how it works doesn't have to be some magic new unique thing. You can use warp drive, and just say everybody goes faster than light. Physics-wise, there are implications to that, and you can either handwave that or use it as a plot point, but especially in soft SF readers will mostly let you off the hook.

The phrase you’re looking for is “faster than light travel”, or FTL, and it’s basically space magic (there is no known, or even theoretically likely, way to travel faster than light) so you can make up whatever rules you want.

The three basic systems I’ve seen used are warp/hyperspeed, hyperspace, and wormholes or jump gates. Hyperspeed — actually traveling faster than light — is the most straightforward but also the most scientifically dubious, and if you’re trying to make it scale at all, you run into the fact that space is really, really, REALLY big.

Hyperspace and wormholes both use the same workaround: rather than travel through normal space you move into a different dimension, travel through it, and pop out wherever you want. It is 100% black magic but one of the well-accepted handwaves of SF. The main difference is whether your ships can enter hyperspace on their own, or whether they have to reach a specific point in space to go into hyperspace, but even then there’s wiggle room (the Babylon 5 universe had jumpgates, but some big ships could open their own jump points, for example).

How long it takes to get from place to place, how simple or difficult it is, how far can be travelled in one go, what name you use — that’s entirely up to you. I have one story-universe that uses hugely expensive “weftgates” that only a few races (not humans) know how to build; it takes weeks to get to and from inhabited planets to the gate, weeks or months more to travel the weftspace between gates. In another, “phase jumps” are instantaneous and can be done from any point (though it still takes 6-8 hours to reach the speed you need for a jump), but you can only go about 10 light years in a jump and you have to refuel and refurbish the ship before you can jump again — and there’s an upper limit to the mass of ship you can get into phasespace. This creates very different interstellar societies, but it’s all made up of exactly the same complete and utter hand-waved science.

My advice is to decide what system best fits the universe you want to write about, then slap a name on it and call it yours. Stick to the limitations you’ve created yourself and you’ll be fine.

Call it a warp drive, or do something totally crazy and different . A lot of people use wormholes because, unlike FTL, they're actually feasible, the problem is they always cut down on travel times and you lose that cool 'space is an ocean' vibe a lot of SF goes for. But there is no element of FTL that cannot be handwaved away, I think internal consistency and plausible technobabble are fun in some settings, but even then, the less said the better. I remember when the first Expanse book came out, there was an interview with the author(s) in the back, and when the question was asked 'How does the Epstein Drive work', they said 'It works very well, thank you'.

The only term I would avoid using is 'ultra-light' which is more about weight than speed.

There's a saying about ships "moving at the speed of plot" that applies, too...

As others have said, it can be handwaved, so long as you have at least some form of internal consistency. For instance, if you decide that handwavium crystals create a hole allowing travel between two points, don't suddenly have people jumping around without handwavium crystals for no explained reason. If the trip always takes three days for the people on board no matter how far they go, you'll need a plot-pertinent reason (and not just lazy writing) to explain a week in crystalspace. Why it would take three days, or how handwavium crystals work, is less important to the story than the fact that these are the rules of your universe and the audience will expect these things once you've established them.

My latest refers to "a version of the Alcubierre drive"

If it's soft sci-fi I would not be too concerned - just give it a name and it becomes a thing in your story. Over-explaining will only get you into trouble.

MaryLennox said:

Okay, thank you! This is all very helpful. I definitely want the 'space is an ocean' vibe.

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How about using wormholes but only have fixed entry/exit points, so you could enjoy the majesty of space and then get quickly across to the other side of it? Like using country lanes to get to the motorway (or check out the Oresund link which connects Copenhagen in Denmark to Malmo in Sweden - beautiful bridge that goes to a man-made island where it dips into a tunnel to complete the crossing, leaving the seaway open.)

ETA - also Chesapeake Bay Bridge–Tunnel. Been Googling... and think what fun you could have with customs halls and space-bars on the "man made island" bit...)

The Black Prince said:

My latest refers to "a version of the Alcubierre drive"

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You can never go wrong with an Alcubierre drive. I've named mine the Inheritor Drive, or sometimes use the term Metric Drive which is the same thing. But they're by far my favorite type of drive, even if I tend to stick to the STL variety.

BTW, I tend to point people to Project Rho enough that I sound like some kind of evangelist. Thats where I got that cute meme from, btw. The folks over there are way hardcore about scientific accuracy and tend to favor old school & military SF authors a little too much for my taste, I actually take it all with a grain of salt. But it's a great resource even if you ignore all their 'thou musts'. Check out their FTL section.

IMO, if you don't want to get bogged down with science-y details and argue with people about the plausibility of your magic space science (which is what any FTL boils down to), you're best staying far away from anything that looks like an "explanation" of how it supposedly works. Just figure out what your story needs to happen, dress it up with language that sounds cool, apply a heavy dose of handwavium, and maintain internal consistency.

benbenberi said:

IMO, if you don't want to get bogged down with science-y details and argue with people about the plausibility of your magic space science (which is what any FTL boils down to), you're best staying far away from anything that looks like an "explanation" of how it supposedly works. Just figure out what your story needs to happen, dress it up with language that sounds cool, apply a heavy dose of handwavium, and maintain internal consistency.

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While I agree with the don't explain too much point, I can't agree with the assertion that any FTL must be magic. It may be preternatural for us right now but we don't yet understand all of science and the multiverse - and how to manipulate it. People are fond of using wormholes etc which are at least plausible if far from clearly understood. My own work relies on the idea of superposition - entangled particles behaving in a spooky fashion as Einstein called it. I also invented an alien branch of physics called multiplanar reality which exploits superposition.

Even that though is way more explanation than happens in the book. As one of the characters says: It's a form of transport like any other transport. You don't need to understand it to use it.

The Black Prince said:

While I agree with the don't explain too much point, I can't agree with the assertion that any FTL must be magic.

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No current science supports FTL transport of matter from one place to another. It just doesn't. If you want to posit potential future science, math, & engineering breakthroughs to allow it in a fictional context, that's 100% fine. That's what SF writers do. But it has no basis in *actual current science.* Therefore, it's magic. Magic dressed up in science-y words still isn't science.

benbenberi said:

No current science supports FTL transport of matter from one place to another. It just doesn't.

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Yep. I have a physicist in my family, and as he put it: if you have faster-than-light travel, everything breaks.

It's actually fascinating when you start thinking about it, which I try not to do too much, because it makes my head hurt.

benbenberi said:

No current science supports FTL transport of matter from one place to another. It just doesn't. If you want to posit potential future science, math, & engineering breakthroughs to allow it in a fictional context, that's 100% fine. That's what SF writers do. But it has no basis in *actual current science.* Therefore, it's magic. Magic dressed up in science-y words still isn't science.

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Sure, that's exactly what I said.

It's called science fiction.

The Black Prince said:

Sure, that's exactly what I said.

It may be preternatural for us right now but we don't yet understand all of science and the multiverse - and how to manipulate it.

The difference between magic and not-yet-understood-science is that magic is supernatural and can never be real.

Not-yet-understood-science is preternatural and is potentially real.​

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Preternatural? You really want to hang your whole argument on that? Can you tell, right now, which impossible-according-to-current-science phenomenon is going to be eventually real thanks to some unpredictable theoretical breakthrough in some future century/millenium? FTL? Telepathy? Antigravity? Teleportation? Time travel? Love spells? Communication with the dead? On what basis do you make that determination? How can you possibly *know* that one thing that is currently impossible under any scientific theory will someday be possible, even commonplace, in a future-science context, while this other equally impossible thing will always be impossible, and therefore one is "preternatural and potentially real," while the other is supernatural and magic.

I say you can't. No one can. That's the nature of unforeseeable theoretical breakthroughs -- no one can foresee them. Until they happen, when they become inevitable.

You seem to be hung up on the definition of magic = supernatural. Sorry. From the position of the present-day observer, Clarkean "sufficiently advanced science looks like magic" is indistinguishable from magic. And without a valid theoretical underpinning, it can't be explained or understood. From the present-day perspective, it's not possible. In the absence of a future scientist who can fill in our knowledge gap, it is magic.

And since we're not dealing with real phenomena in any case, but a writer's invented made-up valid-only-in-a-fictional-context totally-not-real imaginary spaceships and stuff, I say: they're not real. They're not science. They are fantasy dressed up in future-science-y fancy dress that is under no requirement to conform to currently understood science BECAUSE they are invented, made up, and useful in their fictional context.

Someday, our understanding of the universe may change to permit one or more of these things to exist. It's entirely possible that our whole current scientific framework is flawed in some fundamental way and that the current struggles of physicists to reconcile relativity and quantum mechanics will seem as quaint and futile as the late Ptolemaists' epicycles. And that FTL will be as straightforward as a jet engine. But right now, it's not.

(And it's called "science fiction" because the genre has grandfathered certain foundational tropes, including FTL, largely because they can be gussied up with science-type jargon and hardware. The folks who are really rigorous about the hardness of their science fiction don't allow it. Because it's not real, and there's no way around that until the above-mentioned unforeseeable breakthrough breaks things.)

Come up with anything you want, so long as it sounds convincing and you use it consistently. It should be something that fits in with your world and does what you need it to do. FTL travel in sci-fi isn't even an exception anymore, it's expected in space epics.

The Black Prince said:

It's called science fiction.

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Yes it is, it isn't fantasy. It's got to be at least somewhat believable within the context of the world you've created. Otherwise, you're writing magic.

benbenberi said:

Someday, our understanding of the universe may change to permit one or more of these things to exist. It's entirely possible that our whole current scientific framework is flawed in some fundamental way and that the current struggles of physicists to reconcile relativity and quantum mechanics will seem as quaint and futile as the late Ptolemaists' epicycles. And that FTL will be as straightforward as a jet engine. But right now, it's not.

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Absolutely, that's exactly the point I was making. Thank you.

It's not quite the case that there is no "known" method of FTL. There's a sizable literature on traversable wormholes (vide. Matt Visser, Lorentzian Wormholes from Einstein to Hawking, American Institute of Physics Press (1996);QC173.6.V57 1995. Visser actually built an academic career on wormhole physics!

They require unobtainium in the form of exotic matter, so it is correct to say that not only do we not know how to realize the concept practically, we don't even know if is possible to pull off.

A problem with traversable wormholes is that it is almost impossible to prevent them from turning into time machines: If you have one wormhole mouth out somewhere in intergalactic space, and another orbiting a massive star, the gravitational redshift caused by the massive star will cause a clock just outside the stellar-bound wormhole mouth to run slower than one just outside the deep space mouth. Wait long enough, and by travelling from intergalactic space to the stellar system you will travel into the past according to an observer in intergalactic space. Time machines are fun to play with, but they open up multiple cans of worms. Starting in about 1988 and continuing till the early noughts, theoretical physicists had a lot of fun with both wormhole physics and time machine; there's quite a literature on both.

An additional problem with traversable wormholes is it's not immediately obvious that they can be manipulated.

Maybe I missed it - this thread is pretty dense reading (as in it's tough to keep track of the different arguments), but another one I haven't seen much used is that of phase drives. Kinda like wormholes, or other dimensions of space, but operating on different principles entirely. Remember in TNG when Wesley and that time traveler were phasing in and out of the current reality, and his mom Beverly was in another reality? Something like that...so what if you had a phase drive that could put you in another reality, and that allowed for easier transport because of...whatever?