Bit of Discourse: FTL

[Ahriman238]

Hello all, welcome to what I hope will be the first in a new series of analysis threads. Instead of picking apart a series, I’m going to try looking at a science fiction concept, where and how it gets used. Who does it better, and why. Most of all, I’ll be talking about whatever I find interesting because I’m really only doing this for fun.

Now, despite a long-running interest in Sci-fi, I’m not an expert. I haven’t read everything out there, or a tenth part, or even many popular things. My physics knowledge extends to Newton, the first two laws of Thermodynamics, whatever trivia made its way into my chemistry course, and the crappy American High School Textbook TM explanation of ‘quantum.’ So if you see any gaping holes in what I’m covering, if you have an opinion, especially if I make an ass of myself, stand up and speak out.

First stop on the magical mystery tour is FTL: faster than light travel. In this, I’ll be retreading a lot of ground already covered by smarter and more passionate men and women than myself. Still, they had agendas that I don’t so maybe it’ll be an interesting ride.




Light (well, all electromagnetic radiation) travels at 186,282 miles per second (299,792 km/s if you come from Yurp or some stranger part of the world) in a vacuum, and somewhat slower through a gas or liquid medium. This is one of life’s constants, represented as c, the thing that nobody can travel as fast as or faster, because of relativity. I have a vague and probably monstrously incorrect notion of why that is, gained from Fourth Grade science class. I’ll just leave the details, if anyone’s interested, to someone more capable.

For now, suffice to say you cannot travel faster than light. Which is rather inconvenient, because the universe is incredibly vast. It takes light 4 years and some months to reach the nearest star, Proxima Centauri from Sol, and 100,000 years to cross the Milky Way galaxy. All the universe we can observe when we look up at the night sky, or through advanced telescopes, it takes light approximately 93 billion years to span. So if a science fiction writer can’t invent some way of cheating past the speed of light, he must accept a universe where it takes weeks to get anywhere in the Solar System, there are a handful of stars that can be reached inside a decade, and otherwise interstellar voyages are the work of centuries, millennia, and epochs. There might be some interesting stories there, an impossibly ancient civilization on Earth so far removed from its colonies that they barely share a common mythology, much less any culture or language. But that’s not a story a lot of authors want to tell.

They say sci-fi writers have no sense of scale. I say they ignore it whenever convenient, though yes, there is some genuine ignorance there too.




Well, I couldn’t very well end my first post without tackling the big two. Each is rather personal to me, my earliest memories of watching a film and understanding the plot were ANH and TMP. The Next Generation was the only show for a decent chuck of my childhood, and it was Star Wars that shaped my idea of what a film should be.


In Star Trek ships use warp drive, which encases a ship in a warp field or subspace bubble which distorts space-time. In physics, this theoretical effect is properly know as an Alcubierre Metric, contracting the fabric of space-time before the ship and elongating it behind to cheat around the lightspeed limit.

Warp speeds on the show were measured in warp factors, time-warp factors in a couple of TOS episodes. The thing is, we weren’t told a lot in the old show about what those meant, except that Warp 1 is the speed of light. For the second show, TNG, the scale was redone, Gene Rodeenberry wanted Warp 10 to be an unreachable, absolute limit where the old Enterprise had done Warp 12 or 15 on occasion. The new chart was faithfully printed in a variety of supplementary materials. We still don’t know the old scale, though a number that’s been very popular with fans for TOS was warp factor cubed= multiple of c. In which case…

Warp 1= 1c
Warp 2=8c
Warp 3=27c
Warp 4=64c
Warp 5=125c
Warp 6=216c
Warp 7=343c

If this is true, which I must stress is from the Making of Star Trek of dubious canon, we can see that Kirk’s Enterprise could not quite cover a light year in a day and could conceivably reach the far side of the Milky Way in roughly 300 years. It isn’t precisely clear if these speeds are meant to be reflected in Star Trek Enterprise, but a screen-capture of a warp speed chart in the flashback episode “First Flight” showed Warp 1, 2, and 3 as these lightspeed equivalents. Though, Enterprise was full of small Star Trek EU easter eggs that don’t necessarily mean anything.

It is also know that in Gene Roddenberry’s original draft proposal for the show Star Trek, he defined the top speed of the Enterprise as “0.73% of a light year in one hour.” That is much, much faster than anything suggested by the above scale, in the neighborhood of 6400 c.

There is a charming novel, Federation, following linked adventures in Kirk, Picard and Zefram Cochrane’s time. Just about everything about Cochrane’s period is contradicted by the later film First Contact, even the name of the first warp-capable ship is changed from the more dignified Bonadventure to Phoenix. But one thing I cannot drop whatever the canon conflicts is the origin of the Starfleet delta that Cochrane uses to explain warp physics.



The idea being that the elongated star represents the speed of light (or infinity) and the upper line is the power curve needed to reach light-speed normally, while the bottom line is the power curve with his warp drive.


The revised scale for The Next Generation and following shows is considered canon. The scale is calculated;


Where wf is warp factor. So in the scale from there on out

Warp 1=1c
Warp 2=10c
Warp 3=39c
Warp 4=102c
Warp 5=214c
Warp 6=392c
Warp 7=656c
Warp 8=1024c
Warp 9=1516c

And from there on out, with Warp 10 being the absolute, limit every speed is a decimal increase on Warp 9. So you realize Warp 9.9 is almost twice Warp 9 at 3,053 c. 9.99 is more than double that with 7,912 c. Five Nines, or 9.9999 is the speed of Federation transmissions (which allow real-time communication some light-years away, but not say, from the Neutral Zone to Earth) is 199,516 c.
I have no idea what’s going on with the Trek reboot, we’ve discussed it a bit in the relevant section and come to no answers. Just a vague idea that they must be far faster than we’ve ever seen before.


Star Wars uses a concept that’s probably the most common idea for FTL, hyperspace. Hyperspace is an alternate or higher dimension that can be traveled to and from, typically a given distance in hyperspace corresponds to a far greater distance in realspace. In Star Wars, we know that ships need to travel along carefully charted routes or spend a considerable time calculating a jump with a navigational computer. Journeys across the galaxy seem to take no more than a few days or weeks.

Hyperdrives and variants appear more-or-less everywhere. In Stargate, there are numerous hyperdrive types used by various races, some with very little speed or endurance like the Goa’uld or Wraith, while the Ancients and Asgard could make major intergalactic trips within hours. Plus we had a near-instant “Wormhole Drive” appear in the last episode of Atlantis, and in SGU a realspace (probably also Alcubierre) FTL drive.

The horror flick Event Horizon and Warhammer 40,000 both ask, “what if hyperspace was a literal hell full of powerful, Lovecraftian alien horrors?” Spoilers, the answer isn’t “good times.”

David Weber has this oft-repeated idea where there are “bands” of hyperspace, other layers stacked over each over like a tiered period allowing faster and faster travel the higher you go. In a similar vein, Animorphs had Zero Space or Z-Space, which described the universe like a cone. At the end of the coin is a mathematically determined zero point equidistant from every point in the universe. Well, that’s the theory, though it takes weeks or months to get anywhere and Z-Space apparently routinely reconfigures to make things harder. And there are places that are strategic junctions and easier and quicker to access than other locations, so it sort of falls apart. Then again, the whole cone thing was never more than a simplified analogy for a couple of high-schoolers.

[Simon_Jester]

One thing that I find interesting is the kind of context you get from science fiction settings where FTL drive is relatively slow, such as Niven's Known Space where the rule of thumb is "three days to the light year" (~100c).

On the one hand, this means that starship travel is relatively slow and deliberate; even a trip to Alpha Centauri takes about two weeks, so you do not go anywhere lightly, and when you do travel you need something well-appointed and well-supplied. Passenger vessels look less like commercial airplanes and more like ocean liners, in other words.

On the other hand, to have an interesting story here requires that "Known Space" be very compact- which may make statements about the density of habitable worlds and alien races inyour setting that you would prefer not to make.

[Ahriman238]

One thing that I find interesting is the kind of context you get from science fiction settings where FTL drive is relatively slow, such as Niven's Known Space where the rule of thumb is "three days to the light year" (~100c).

On the one hand, this means that starship travel is relatively slow and deliberate; even a trip to Alpha Centauri takes about two weeks, so you do not go anywhere lightly, and when you do travel you need something well-appointed and well-supplied. Passenger vessels look less like commercial airplanes and more like ocean liners, in other words.

On the other hand, to have an interesting story here requires that "Known Space" be very compact- which may make statements about the density of habitable worlds and alien races in your setting that you would prefer not to make.

An excellent point, we've seen similar in real life. Once upon a time it took a ship a month to cross the Atlanic, and a man an equal time to walk from Boston to the Capitol, so no one undertook those trips without a clear purpose or a good reason. Now such trips can be made in hours, and relatively cheaply so it is far less of a burden to go just to see the world.

And other matters are impacted by travel times. When you're living on a colony, or even planning the original colonization, it makes a HUGE difference when you could expect relief or fresh supplies if something were to go wrong, say an attack by hostile parties, an unknown disease, a famine. Can ships arrive within a matter of hours? Days? Months? Years? Centuries? In the latter 2, likely 3 cases you are effectively on your own and should plan accordingly.

[Simon_Jester]

Other trivial examples come up in detective stories; Niven wrote several in Known Space. Before I go into that more, I also want to point out another very basic issue with FTL: is there the FTL equivalent of a radio, or do messages travel at the speed of courier? Both types of assumptions are credible.

Suppose a man gets on a starship. The detective pursuing him has various leads about where he is going.

If starship travel is slow relative to the scale of civilization (say, habitable worlds are ~100 light years apart and travel speeds are <50c, as suggested by the probably-crackpot theories of Burkhard Heim) and there is no FTL communication, the man has escaped for all practical purposes. No one would chase him.

If starship travel is slow and FTL comm exists, you can 'phone ahead' to alert the destination (or the fugitive's ship). On the other hand, they may not care- what does it matter what someone did in a jurisdiction years of travel time away? At most, that puts the fugitive on a watch list.


Suppose starship travel is of moderate speed (~100c, with habitable worlds only a few light years apart as in Known Space), but there is no FTL comm. Then it may actually be possible for the detective to pursue the fugitive in a reasonable span of time, assuming it's worth months of the detective's time. It might well be. On the other hand, if the fugitive lays a false trail, by the time the detective can figure out what's happened the trail is cold, and has been for months- which has interesting story consequences.

In Niven's actual setting, FTL comm exists- which means that "phone ahead" is possible, and that worlds are close enough together that they might care and cooperate on law enforcement. Our fugitive has a serious problem on his hands- he spends months cooped up in a traveling can, with well alerted people waiting to snag him on the other end, unless he has some other kind of arrangement with the prospective host planet/country/whatever.


If starship travel is as fast, relative to the scale of the "known world," as airline travel is today, then the detective can easily follow the fugitive- IF he's reacting quickly enough. If no FTL communication exists aside from couriers, though, the detective will have to take point in pursuing the fugitive himself- he will arrive at the destination quickly, without much prior preparation. And he may find that the new environment is potentially hostile to him if the fugitive knows the lay of the social or physical terrain.

But what if, again, there IS FTL communication, faster than ships? At this point, travel is so fast that the fugitive might be able to move "faster than the speed of bureaucracy" and reach his destination before said his point of origin figures out what is happening, and/or before his destination has time to clamp down. It requires very complex police organization to prevent this- we have it today, but have not had it at all times in the past.

[chornedsnorkack]

Other trivial examples come up in detective stories; Niven wrote several in Known Space. Before I go into that more, I also want to point out another very basic issue with FTL: is there the FTL equivalent of a radio, or do messages travel at the speed of courier? Both types of assumptions are credible.

Suppose a man gets on a starship. The detective pursuing him has various leads about where he is going.

If starship travel is slow relative to the scale of civilization (say, habitable worlds are ~100 light years apart and travel speeds are <50c, as suggested by the probably-crackpot theories of Burkhard Heim) and there is no FTL communication, the man has escaped for all practical purposes. No one would chase him.

If starship travel is slow and FTL comm exists, you can 'phone ahead' to alert the destination (or the fugitive's ship). On the other hand, they may not care- what does it matter what someone did in a jurisdiction years of travel time away? At most, that puts the fugitive on a watch list.

This means one way trip of >2 years.
Manila Galleon was 4-5 month Acapulco to Philippines, couple of months there, then 7 months back - standard was out of Manila in June, average return to Acapulco in January. Something like 12 months return trip.
If a criminal is awaiting a punishment of 12 months in jail, and all his escape gets him is 12 months aboard ship (because he is not welcome at destination) then the prospect of escape still has its deterrent value.
If, however, a runaway crook knows he will be presumed honest for 12 months - till the next year´s galleon arrives at Philippines - then he has his schedule to pack up his loot and run on.

[biostem]

I know it's a bit of a tangent, but here's something I thought about regarding FTL:

1. Let's assume you can *at least* travel faster than 1C.

2. Let's assume this setting possesses very well developed telescope technology.

3. Now let's say that this setting is very intensive when it comes to surveillance and monitoring practices.

What is the feasibility of being able to fly off to some set distance, (assume computers were sophisticated enough to calculate the necessary trajectory), and use these advanced telescopes to essentially observe past activities for purposes of investigating crimes or so forth?

[Simon_Jester]

It would be very difficult to investigate anything by observing it from light-hours away.

[biostem]

It would be very difficult to investigate anything by observing it from light-hours away.

Yes, it would be difficult, but not impossible. And if the setting was one where this type of surveillance was important, this would essentially provide a way of seeing back in time...

[Eternal_Freedom]

You would have to have improbably good optics to see any useful details at a distance of several light-hours. THat's equivalent to saying we can spy on Earth with a satellite in orbit around Saturn (for instance). Plus, if the weather is inclement at the time you are stuffed, just as you are stuffed if whatever crime you are investigating happens indoors, on the far side of the planet, at an awkward angle and so on.

Really, the only crimes you'd likely be able to detect at such a range are crimes so massive in scope that you have plenty of evidence after the fact.

[biostem]

You would have to have improbably good optics to see any useful details at a distance of several light-hours. THat's equivalent to saying we can spy on Earth with a satellite in orbit around Saturn (for instance). Plus, if the weather is inclement at the time you are stuffed, just as you are stuffed if whatever crime you are investigating happens indoors, on the far side of the planet, at an awkward angle and so on.

Really, the only crimes you'd likely be able to detect at such a range are crimes so massive in scope that you have plenty of evidence after the fact.

What about in the scope of, say, a space battle? Let's say side A claims side B attacked them, and side B claims the opposite... if you knew where the attack took place, you could fly away from that location at FTL, then observe the light to see what actually happened.

Yes, the kind of optics you'd need to discern anything useful would be extraordinary, but this is Sci-Fi we're talking about...

[Simon_Jester]

Ah. Yes.

For a sufficiently energetic event, IF there is time, you would be able to do this. I've seen it described as "light-coning," at least twice on this forum alone, referenced in both Eleventh Century Remnant's Hull 721 stories and RedImperator's rewrite of the Voyager pilot episode.

[biostem]

This could make for an interesting piece of fanfic - imagine if someone in the ST verse traveled some 100 or so light years away from Earth, pointed a very powerful telescope of some sort back, and noticed Cochran's Phoenix being fired at by a Borg cube...

[Simon_Jester]

At that point you're probably beyond the limits of resolution even for starships. Any useful tactical data gained by light-coning would have to be gathered within a day or two of the event in question at least. Radio broadcasts and so on might be picked up further out (though not across interstellar distances unless they were MEANT to be that long-ranged).

[Ahriman238]

I know it's a bit of a tangent, but here's something I thought about regarding FTL:

1. Let's assume you can *at least* travel faster than 1C.

2. Let's assume this setting possesses very well developed telescope technology.

3. Now let's say that this setting is very intensive when it comes to surveillance and monitoring practices.

What is the feasibility of being able to fly off to some set distance, (assume computers were sophisticated enough to calculate the necessary trajectory), and use these advanced telescopes to essentially observe past activities for purposes of investigating crimes or so forth?

Not the first time it's been brought up on this board. Questions of resolution aside (and they are a considerable obstacle) space travel would have to get really cheap before this became a viable option.

There may be some uses for historical purposes, examining the first space flights for instance or grabbing a picture of Earth as it appeared from space in the Precambrian.

Debatable, there could be use for information gathering, say between two hostile star empires. But any information thus obtained would be old information and if the other side can also travel faster than light... Well, that's more like an obstacle a scout ship skulking in the outer system would have to overcome than an aid.

[Eternal_Freedom]

You would have to have improbably good optics to see any useful details at a distance of several light-hours. THat's equivalent to saying we can spy on Earth with a satellite in orbit around Saturn (for instance). Plus, if the weather is inclement at the time you are stuffed, just as you are stuffed if whatever crime you are investigating happens indoors, on the far side of the planet, at an awkward angle and so on.

Really, the only crimes you'd likely be able to detect at such a range are crimes so massive in scope that you have plenty of evidence after the fact.

What about in the scope of, say, a space battle? Let's say side A claims side B attacked them, and side B claims the opposite... if you knew where the attack took place, you could fly away from that location at FTL, then observe the light to see what actually happened.

Yes, the kind of optics you'd need to discern anything useful would be extraordinary, but this is Sci-Fi we're talking about...

Again, it's a situation where there is bound to be evidence aside from the "fly away and look through a telescope" option. If the battle is over a planet/asteroid/space colony, then there will be witnesses closer to the scene. If there are survivors, odds on they'd have sensor records showing who fired first. If their are no survivors, odds on you'll be able to find black boxes/log buoys with similar data in them.

And if it's the first battle in a war, who fired first won't really matter until it's all over, by which time it will probably be too late and/or unnecessary to ind out who shot first.

[Simon_Jester]

Eh, it's a relevant hypothetical.

Basically, the point is that we can't say for sure what kinds of information might usefully be gathered this way. It depends on the precision of EM sensors, and how energetic the event was. It is almost certainly not useful, even immediately after the fact, for petty crime- but it might be useful either for a tactician to know what happened a few hours ago, or for an investigator in a position to quickly round up information on a major event.

[Ahriman238]

Moving on a little.

Not technically, or really all that close to FTL there are ships we call "lighthuggers." I think it's a Known Space thing, haven't actually read the books so don't hold me to it. If a ship lacking an FTL drive can get close enough to light speed they can make nearby stars in a matter of decades, maybe years. And relativity means time will pass slower for the passengers than here on Earth, plus you still have the usual STL options, generations ships or cyro/suspended animation. There's some debate on where close enough is, I hear 0.7 c a lot but I honestly don't know.

Lighthuggers come up a lot in the really hard sci-fi. Off the top of my head there's Orion's Arm (which has void ships doing 0.999 c) and Ender's Game. It's how ships got to and from Pandora in Avatar, plus the probable Known Space source of the name. Animorphs ships have enough sublight speed they have to worry about relativistic effects.

I've also seen ships that lack FTL but normally are carried or have a damaged or insufficient FTL drive do this as a backup in Heirs to Empire, Stargate Atlantis, and the Three Galaxies setting.

[Simon_Jester]

Relativistic effects start to at least matter significantly (time dilation of 1.4 to 1) at around 0.7c. At 0.86c, it's more like 2 to 1. Between 0.9c and 0.99c it starts to take off sharply and makes it possible to travel 10-100 light year distances in a reasonably short span of subjective time (i.e. only a few years, plus however long it took you to accelerate).

Lord only knows how you develop a engine capable of accelerating a ship until its kinetic energy is equal to several times its own "mc2" rest energy, though. Because note that "gamma," the Lorentz factor, is by definition the ratio of kinetic energy to rest energy.

Niven's Known Space contains such ships, but is far from the only one- however, Niven was one of the first generation of SF writers to write after knowledge of special relativity became widespread and after the theorization of the Bussard ramjet gave people a theoretical explanation for how "light-hugging" STL propulsion might work.

[Ahriman238]

You would need a considerable power source or for much of the motive power to come from outside the starship. Such as having a powerful laser hitting a solar sail-type arrangement, which is, I believe, how it's done in Avatar. This is also the basis of the Beamrider Network in OA. Now if only I could remember what that's properly called.



Wormholes are a theoretical warping of space, the existence of which is predicted by general relativity, which could possibly allow transit between two points faster than a light-beam could travel between them. In fact, I believe the theory these days is that sub-microscopic wormholes are everywhere. Macro-wormholes have never been observed in nature but that may not mean anything. Wormholes in general are sometimes called Einstein-Rosen Bridges for the two scientists whose theories predict wormholes, but that can also refer to a specific unstable non-traversable wormhole that would pinch shut before anything could travel between it's two mouths. Schwarzchild Wormholes would be one-way effects of extreme gravitational distortion, effectively manifesting as a black hole at one end and a white hole on the other, provided I understand correctly. Lorentzian Wormholes are probably what you're thinking of in sci-fi, two-way traversable wormholes.



Wormholes may allow faster-than-light travel, they may not. A wormhole trip would likely involve tremendous gravitational stresses, radiation sufficient to burn you to a cinder, and a trip taking an indeterminate amount of time (you could grow old and die without seeing the other end) to an uncertain destination. Then there is the potential for wormholes to connect not just two points in space, but in time or even lead to a distinct region of space-time (alternate universe) the latter of which could actually resolve a lot of stability issues in Einstein's and Rosen's original math.

In fiction, wormholes are almost always instantaneous or close enough, certainly far faster than normal FTL if it's present. Mostly, they're safe too, but there are many variations in many stories with distinct rules for how they work.

It's probably futile to try for even a partial list of wormholes in sci-fi. I will note the wormhole in the 2009 Star Trek reboot sure looks like a textbook Schwarzchild wormhole. DS9 centered around a last federation waystation/outpost over a wormhole reaching to the far end of the galaxy. The Vorkosigan Saga has all FTL through an elaborate wormhole network linking each inhabited system, as does Orion's Arm. Wormholes are central to the plot of Farscape. The titular Stargates create wormholes between each other, actually making it much easier to walk to another world than send a ship. The Xelee Sequence, the Forever War, Portal, Contact, the Final Countdown, EVE online, Crysis, Sins of a Solar Empire, Tunnel in the Sky, half a dozen William Sleator books and the Honorverse all have wormholes with varying amounts of plot-relevance.

[Ultonius]

Curtis Saxton talks about the 'light-coning' idea here, calling it 'observational history'. It also occurs here and in subsequent strips in Schlock Mercenary. A similar concept appears in the Babylon 5 episode 'By Any Means Necessary', where, after G'Kar has been prevented from performing a religious ceremony that must be performed on a particular day of the year when the light of Narn's sun strikes a holy mountain, Sinclair points out that Babylon 5 is just over ten Narn light-years from Narn, and that G'Kar can perform the ceremony using light that struck the mountain ten Narn years ago.

[Sleck]

This and this may be useful.

[Ahriman238]

First, let me say thanks Sleck. Atomic Rocket and I are old friends by now, but I'd never encountered Faster than Sight before.


Let's talk a bit about intergalactic travel. In most sci-fi settings, even those with fairly convenient travel across galaxies, going to other galaxies is rare. Which can be assumed to make a certain degree of sense, there is a vast space between the majority of galaxies orders of magnitude greater than the distance between stars. And yet, most of Canis Major is closer to Earth than the far side of our own Milky Way. Within the Local Group there are two more Galaxies roughly twice the distance to the MW's far end. Why should it be possible to cross the one in a matter of weeks, and the latter not at all?

Some of the larger Sci-fi settings have invented their own explanations for this arbitrary limit, which makes it all the more interesting that they'd cling so tightly to the idea. In Star Wars and 40K, hyperspace/the Warp is calm in the between-spaces, absent the forces ships normally rely on to drive them forward. In Star Trek, both the core and the limits of the galaxy are marked by vast energy barriers. Contrast with Stargate, which towards the end develops relatively free intergalactic travel without the story exploding. Though much of Atlantis' plot revolves around keeping the Wraith from developing similar capabilities.

[Eternal_Freedom]

Well, I think you have to draw a distinction between "local" and "true" intergalactic travel. For instance, reaching any of the MW's satellite galaxies should be moderately feasible with a typical FTL drive in SW, ST etc (and indeed in SW people regularly travel to at least one satellite galaxy), a few hundred thousand LY's at most IIRC. Traveling to another big galaxy, for instance Andromeda or Triangulum involves covering millions of light years. The distance to Andromeda is an order of magnitude greater than the Magellanic Clouds.

[Ahriman238]

Sure, and that is a distinction more Sci-fi stories could stand to make.

[Eternal_Freedom]

Offhand, the only sci-fi TV series where true intergalactic travel is routine is Andromeda (not counting Doctor Who) with Stargate following (it's "routine" in the sense it's regularly done in later seasons but it's still rare). Aside from that, very few sci-fi series show even "local" intergalactic travel, SW being the only other I can think of (and that's only based on one single image of the galaxy in the films (if you ignore the EU)).