What's your explanation for FTL?

There are several I've heard, reasonable methods -

(Mostly hammered out by James P Hogan a decade or two ago...)

1) Places in space where spacetime is 'warped' and ships must navigate TO these places using conventional drive, then hit the spot in a tight path right under the SOL. (ala Heinlein's Starman Jones)

2) Rotate an object off its 3 physical axes by bombarding it with rads, causing instant transport anywhere in the universe, where it comes out is based on trajectory and speed at point of entering K-space. (ala James P Hogan, Genesis machine?)

3) Set up a rotating black hole (microscopic) toroid into which the ship continually 'falls' (ala Hogan, Gentle Giants of Ganymede)

4) Space is folded like a silk handkerchief stuffed in a thimble. Slide across the folds by breaking through anywhere at all at SOL and you are instantly somewhere far away (ala Heinlein - Have Spacesuit, Will Travel)

5) Ignore the methodology, just say scientists figured it out long ago. (ala most everybody else)

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Well, one method that I recently read about that might be theoretically possible is actually the method they use in Star Trek. The article is here: linky!

The summary version is that while it's impossible to accelerate a vehicle faster than light, we might be able to take a piece of space-time around that vehicle and move that faster than light.

Pretty neat stuff.

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I think that I'll use a sort of jump drive -- the silk handkerchief in a thimble thing. But you can only do it at a considerable distance from a star so it will have the right sort of months-to-years of travel that I'm wanting for the best effect.

I might even have it so that making a jump sets up some kind of interference for a time so that you can't make that jump again for a good while. I want contact with home to be at least as limited as sailing from England to Australia.

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The Swiss Family Robinson in space? Little House on a New Planet? Why not?

Basically, it started with their attempts to make FTL communication possible, which they did using (insert gibberish about tachyons here). After a while refining it, they realized that when it became truly possible, time and space would fold in on themselves, and the problem of FTL drive - as well as limited time travel - would become trivial.

Faster than light communication : Ansible

Travel. Jumpdrive, hyperspace, wormholes, foldspace, and so on.

You have a problem with me? Then spit it out. Or do you only do passive/aggressive. Because nobody has ever accused me of being passive.

You (very specific "you") did not read my post all the way through.

For my story I use the one like in Star Trek but slightly different. I decided to use its real name, the Alcubierre drive. It said that it warped the space around the ship so that it won't be affected by things in normal space time when traveling faster than light like time dilation etc. Look it up.

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My story is also going to have an Alcubierre drive as the main FTL method. (NB: The Planet Express Ship in Futurama used the same kind of drive.) However there won't be any FTL communications, so there will be many couriers, both intrastellar and interstellar.

I'll probably end up naming the drive after the fictional creator (in story universe) of the first working version. Got any naming suggestions?

What did I miss? Coz I just read it again and all I read was some gibberish about tachiyons and space folding in on itself.

You have a problem with me? Then spit it out. Or do you only do passive/aggressive. Because nobody has ever accused me of being passive.

...usually we call things like that a "bad sign."

Look up Bose Einstein condensates, M Theory, and the time dilation equation.

A system of spinning magnetic plates takes plasma from the ship's power plant. When the plates spin up to the right speed, the plasma becomes a bose einstein condensate, where all the particles behave as one big particle. Since that "big particle" can represent a membrane, and since membranes can hold multiple dimensions, the ship's engine creates multiple dimensions. At that point, it creates a field a lot like the Alcubierre field. The Alcubierre field allows the ship to control the shape of space and time flowing around it.

The membrane also adds an effect to the time dilation equation called a "threshold." This threshold represents relative velocity through hyperspace and is always slightly greater than one minus the ship's velocity divided by light speed (v divided by C). The threshold prevents a square root in the equation from being taken on a negative number. The threshold is just enough that the time on board the ship barely dilates.

Studies indicate that a sustained voyage in hyperspace (lasting longer than three weeks) could make you lose a couple of days of time, but since hyperdrives create a lot of heat, the engine would melt down after only a few days.

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There are literally hundreds of methods one can use to travel faster than light. I suggest people find their own rather than rely on someone else's old method. Warp engines, for instance, can damage the fabric of space, as most of you know. Use something else.

During the past five to ten years, the advances in cosmology, subatomic physics, and metaphysical brainography have been such that new forms of space and time travel can easily be constructed both within and outside of the imagination.

Think how easy it will be after we have mapped out more than three quarters of our own polyverse, and are ready to explore the entire omniaverse, working our way in from the outside, as we move sideways through time (rather than forwards or backwards).

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I like the mysterious "wormhole." Maybe a natural occurence, or maybe placed there.

I don't really bother explaining it beyond vague references to folded geometry (wormholes) and exotic negative energy density in a rather bland "stardrive".

The actual FTL requires solving some very advanced equations to reconcile the imaginary values that crop up with tachyonic trajectories put into the drive - something that humans haven't really figured out how to do, but isn't technically impossible. Otherwise it just jumps the ship or planet or whatever at exactly c.

It craps all over causality, of course, so FTL travel requires you to pay attention or bad things can happen.

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I use a combination of two different drives.

First is the gravitic drive which is based on manipulating the space around the ship, causing a displacement effect. The idea is that for a fairly small amount of energy (from a fusion reactor) the ship can move at near-light speed. But the closer to c you get, you need exponentially more energy from the drive, approaching infinity at c. Also, it's a displacement effect, the ship doesn't gain any kinetic energy, only the potentials change. Also the space around the ship is only affected, not the ship itself and it needs to be a void, if there's any matter, the energies jump to the mc^2 category and on top of that gravity wells mess even more with the drive. And all this is just to make sure nobody drives a million ton spaceship into a planet at 0,8c causing cosmic cataclysm.

But for the FTL part, there's a trapped singularity contained within the ship's core. Not the collapsed star -kind, but one weighing just some tons. I'm not at all sure if it would be even possible, but I decided that as long as the ships systems maintain the effect, it can be done. This black hole is then used to create rather short wormholes but at very high frequency. As a result, the ship uses it's gravitic drive to move very fast and the FTL drive basically shifts the entire local space forward by a small amount, but a few million times per second.

All this is just a load of pseudo-physics, but it's for a space opera setting and I'm not aiming for scientific accuracy, but rather a nice story.

I tentatively subscribe to the belief that explaining FTL is unnecessary ninety percent of the time. All too often SF writers get too bogged down in the shiny trinkets and fail to pay enough attention to what really matters in the end of things, the characters and their problems immediately relating to the plot. People don't connect with the engine room, they connect with Bill, the thorny anti-hero with a penchant for rock collecting and a taste for fine wine who works in the engine room.

The more description you give the less mysterious it becomes. Remember Treknobabble? TNG was especially famous for this. Whole episodes hinged on stuff like "Well, if we can only reverse the anti-matter polarity stream into the subspace widget transponder... we might just be able to alter the gravitational constant of the ship's quadlitium matrix! Yes! Now I'll be able to tie my shoes!" Not only did it sound fake and break the flow of the episode, but it eroded plot integrity. Suddenly everything could be fixed so long as some big, science flavored words were used.

In the absence of detail, thar be dragons.

I agree. My story wouldn't focus on the FTL but to focus on the character. Beside the FTL drive I describe earlier will be used in my story as a faulty prototype ships that overload on activation and explode.

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I don't think that future tech needs to be "mysterious". But in the future, it'll likely be as mundane as driving a car. If your character isn't a mechanic, they probably don't know about and aren't interested in the details anyway.

Personally, I'm just using the good old standby: A handwavium drive that travels at the speed of plot.

As long as the world stays internally coherent. It's really frustrating to see the universe switch rules in the middle of the story just to allow some plot to happen. It's the same thing where plot happens just because someone does something really stupid on purpose to allow the plot to happen. This is the reason why I like to know how my FTL drives and other gadgets work, I'm pretty sure that none of that is gonna be explained in the story, it's just implicitly present in it.

"...and the problem of FTL drive would become trivial."

In other words, the ansible locally twists spacetime into enough of a knot that going faster than light, or even backwards in time, is hardly different from going cross-country. So it's a drive.

Well said.

I only need to know enough to know why my colonists can't readily contact home. My readers may not need that much.

3KBs

2009 -- Onward to New Caanan

The Swiss Family Robinson in space? Little House on a New Planet? Why not?

Ah right, sorry. Didn't get that you were talking about the ansible. I read a shortstory "beep" about that years ago. Never realised that ansibles were no longer part of the science fiction arsenal.

Ah well, how about subspace then?

You have a problem with me? Then spit it out. Or do you only do passive/aggressive. Because nobody has ever accused me of being passive.

I'm using two different FTL drives - quantum tunneling and tachyon. (I needed two for an element in my story.)

I'm planning on doing a very light explanation (in part, because I'm no physicist, and part because in my real life, they don't exist, so the details will have to be from imagination. ;-))

I'm not sure what you mean here. Since Le Guin, "ansible" has essentially been a generic word for a device capable of transporting information at faster-than-light speeds without matter, regardless of the "principles" behind it. It's not a theory of any kind, unless you count the idea that information is easier to transport along long distances than matter.

The thrust of my story is that they set out to create this, but find that the way the universe is set up, it isn't actually any harder to send matter.

I guess that's one way to do it. You've still got to deal with the causality issue, though.

All of these posts are amazing. And a crawl on Wikipedia is threatening to keep me up all hours.

I came in here because I borrowed another NaNoer's scientists who had come up with the 'formula' for FTL. I was planning on glossing over it, mostly because my characters are no physicists, but they're geeks and would probably want at least a rudimentary understanding of how things work. From what I've been reading so far, FTL kind of messes up causality a whole lot... though if you take some theories of time travel (like WHH) causality doesn't seem to matter so much.

I just need to figure out why it's only just now that we're intercepting an alien transmission from space, because it's the transmission that matters to my story and I'd like to drop a Chekhov's gun in Act I to point towards it.

So, I think what becomes a better question is, what kinds of causality theories are we ready to accept along with the potential time-traveling of FTL?

Well, I'm of the opinion that if you explain it well enough, any theory on faster than light travel can be at least partially accepted by a reader... if it doesn't sound like a crock of shit it goes into the "I'll suspend my doubt and pretend to believe it for the story" mental box. So I guess it would depend on your target audience. If you're focusing on overly technical stuff for the physicists that love reading Sci Fi who have to understand EVERYTHING it's going to be a little harder to sound convincing. If your target audience is the general public/general sci fi fans/general geeky folks.. it's less complicated as long as you don't obviously go against what people understand of how physics works. In my opinion it's all about guessing the acceptability of the target audience and using an appropriate delivery to describe the theory of how something like FTL works in *your* universe.

Myself... I cheated. I use a theory based around the craft being taken out of "normal" space so the normal physics rules don't apply. The craft (from the point of view of "normal" space) simply disappears out of space into a wormhole and then several hours later appears back into space at it's target location, inside the wormhole the normal rules of physics break down/don't exist because it's technically "outside" of normal space. Easy cheat way of doing it.. least in my opinion XD

Mine's known as a "lightdrive" (simply because it outruns light :P). I don't go into the tech specifics, simply because in my story, everyone's been FTL-capable for something like 5000 years so it's no more remarkable or in need of explanation than a car engine or, for that matter, walking. ;)

However I figured it uses a hyperspace/warp drive principle, warping space to allow a ship to travel FTL while not actually *accelerating* to lightspeed. Hence, easily dispensing with causality effects, time dilation, etc etc. Wormholes exist in my 'universe' but they're so rare and very dangerous to try to travel through that all the major races long since abandoned the idea of creating any kind of wormhole drive.

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I like M. John Harrison's take on this problem in Light: he says explicitly that each starfaring species in the universe utilizes some technology of its own based on some unique theory about the nature of space travel, and all of them Just Kind Of Work Somehow. 'Everything works,' he says repeatedly; the various theories turn out to be nothing more than idiosyncratic motivations for a repeating universal action, which is: Flight. Outreach. Risk.

In any case: as long as you can make it sound convincing, don't sweat it. Think about what it means. Think about what a society would be like that could outrun light. Don't worry about how.

I am a physicist. There is no explanation for something that nature does not allow. Your only option is to find NATURE's folds in spacetime. Not difficult. Finding a humanly-survivable fold is where the difficulty lies and where the fantastic must hold.

All your other arguments and hand-waving amount to nada and make me cry.

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