FTL Flavors: Summary

This is the sixth and final installment of my series on the different flavors of FTL. We’ve warped through hyperspace and jumped through wormholes… or something like that. To clear it up, here’s a summary table showing how these various flavors stack up on the criteria I used:


Clearly, that’s a simplification of several simplifications, but in reducing the various drive features to simple yes/no pairs, it highlights a couple of things. First, not all of the options are represented. What if you took something like warp drive and changed the FTL-FTL box to no? What would that look like if FTL ships could no longer interact? Is it that they cannot see each other? Or maybe they only see each other long after they’ve passed? Maybe they have FTL drives but not FTL sensors?

For another example, what if we put a “yes” in the FTL-Navigation box for wormholes? Maybe instead of simple point-to-point tubes, we’re actually cruising through a complex network of junctions and connectors. Maybe our expected Sol-to-Rigel trip is merely the result of taking all the default options at every junction? What if we could alter course at key junction points and end up somewhere entirely different? What if that kind of exploration can only be done by trial and fatal error?

The second thing I notice with such a table reduction is that there are very different ways to expand these choices into the story mechanics of the drive system. Consider that wormholes and jump drives have almost identical table entries, i.e. Rarely or No across most of the table. Yet these two FTL systems have very different feels to their stories.

Similarly, even staying within a single system can give you FTL drives that end up looking quite different in the actual stories. Consider warp drive. We’re all familiar with how it works in Star Trek. We tear across the universe, warping space and manipulating subspace fields and so on. In my space opera universe of the Hudson Confederacy, ships are using tachyon drives, essentially throwing up ephemeral sails to catch the tachyon wind and yank them up to FTL speeds. The mechanism looks completely different, yet functionally, my tachyon sails are just another warp drive. But my navigators don’t worry about subspace interference. Instead, they worry about shifting winds and tachyon storms.

Furthermore, it’s also an over-simplification to think that a story must use only one flavor of FTL. Many combine them. For example, the Honor Harrington series by David Weber uses a mix of hyperspace and wormholes. That is, while most travel occurs via hyperspace, one planetary system hosts the intersection point of several long-distance wormholes, giving them a huge strategic advantage both for shipping and war. Similarly, some of the later Star Trek series (TNG, DS9, and Voyager) added rare wormholes on top of their trusty warp drive fleet.

So, did I skip a flavor? Probably. There’s a lot of SF out there. Some of those FTL systems may indeed be fundamentally different, but I suspect that a lot of them will boil down to being one of these four with different names and different hand-waving for the so-called science.

But the most important thing for all of them is to get your characters from here to there before they grow old and die. And once there, they can try to write a letter home, which brings up the matter of FTL communication, but that’s a subject for some future series of articles. With luck, I’ll get to that before we reach Sirius.

The whole series: Intro, Warp Drive, Hyperspace, Wormholes, Jumping, Summary

FTL Flavors: Wormholes

artsywormholeThis is the fourth in my series on various flavors of Faster Than Light (FTL) travel, and today I’m dropping into wormholes. The basic idea of a wormhole is that it’s a shortcut between two points. Usually they are fixed points, but there’s some variation on that. Sometimes they are done as predefined shortcuts through some alternate parallel space, and other times they are special tunnels through our own space.

In most cases, they are fairly permanent and independent of the ships traversing them. Thus, ships that have only sublight capabilities are now about to cross vast interstellar distances just by popping through these wormholes, just like a pedestrian can cross town quickly by taking the subway.

FTL-to-FTL interactions: These are almost nonexistent. The only interactions you might have are with other ships (or beings) that are in the same wormhole with you. Plus, wormhole trips are usually presented as being fairly short, so the opportunities for interaction would be fleeting.

FTL-to-sublight interactions: There are none. At least, that’s how I typically see it done. The wormhole is completely cut off from the rest of the universe. At best, there might be some communication with stations near either end of the wormhole.

Relativistic effects: Typically, there are none. Sometimes the transits are essentially instant, like walking through a doorway. Other times, they last seconds to hours, but it’s generally presented as time flowing tick by tick along with a stationary timeframe.

However, I know of one wormhole setup where the wormhole is a tubular region of space where time flows thousands of times faster than normal, thus making the speed of light in that region thousands of times faster. Ships passing through this make up for the time-scale by travelling at relativistic speeds, thus slowing their internal time by a similar factor to the external speed increase. Thus, they make a multi-year journey in a few minutes according to their own clocks and quite possibly a few minutes according to our clocks as well. In that setup, however, there is no guarantee of an absolute matchup between the ship clocks and the stationary clocks, so there would be some variation from one wormhole to another, and sometimes even from one trip to another on the same wormhole.

In-FTL Navigation: Nope, sorry. You don’t get to steer the train. You can’t even pull the emergency brake. And no hopping out the back either. You stay on it until it dumps you out the other end. Do not pass Rigel. Do not collect two hundred quatloos. Your best bet is to hope that there are other wormholes near the end of this one so that you can exercise at least a little choice.

Speed Differential: In all the wormhole systems I’ve seen, the ships within the wormhole all travelled through it at the same speed. Or if there was any speed variation, it was not under the control of the ships themselves. They were merely being swept along by currents of different speed. Of course, there’s no guarantee that all wormholes move you along at the same speed.

Malfunctions: All the breakdowns I’ve seen with wormholes have been with the wormholes themselves. Either they collapsed or became untethered at one end. Typically, the worst that happens to you is that you’re stuck at the wrong end of a wormhole. Then again, I’d hate to be inside one when it collapsed.

Special traits: Wormholes have several interesting traits in the story-telling sense. The first is that they are often pre-existing objects outside the control of the characters using them. Maybe they’re naturally occurring phenomena, or maybe they were built by “the ancients”. Or maybe, like the subways, they were built by the government, and we peons have to live with them as they are. They key here is that it’s no longer a space travel system where we get to pick out our destination and sail on through the night. Instead, there are a handful of destinations to pick from, and if that’s not where we want to go, that’s just too bad.

The second interesting thing about wormholes is what they do to the Euclidean topology of space. I’m not referring to some freaky space warping around the wormhole entrance. Rather, I mean that Rigel is now 500 million kilometers away rather than 900 light years, because there’s a wormhole to take us there. Meanwhile, our next door neighbor Proxima is still 4.24 light years away because it has no wormhole. Yet another nearby star Sirius is now only 2.1 billion kilometers away (rather than 8.6 light years) because we can get to it via a series of wormholes, i.e. first Rigel, then to Polaris, Antares, Deneb, and finally Sirius. (Don’t get lost at Deneb – it’s a bad neighborhood.)

And finally, if the wormholes are not strictly ignorant carriers of traffic, but instead, intelligent agents of control, then those first two factors can make for some very interesting situations. Imagine being able to control all commerce, traffic, even information flow between these distant stellar islands, simply by deciding which ships will complete their journey, which worlds to cut off, or which radio transmissions to shunt aside. Now start thinking about it from the point of view of we peons not realizing that the wormholes are under intelligent control, and let your space-opera paranoia turn all the way up to Eleven.

technicalwormholeBut one last bit on wormholes. Like the warp drive, these might be possible if not actually feasible. What we call a wormhole is remarkably similar to a prediction of General Relativity, known more properly as a Einstein-Rosen Bridge. However, since our best theoretical examples of such wormholes are tied up with black holes, this still has a long way to go to before we can turn it into the green-line express from Sol to Rigel.

Tune in next week when we go Jumping.

The whole series: Intro, Warp Drive, Hyperspace, Wormholes, Jumping, Summary

FTL Flavors: Hyperspace

hyperspaceThis is the third in my series on different flavors of Faster Than Light (FTL) travel, and today I’m taking a look at hyperspace. The general idea here is that there is a separate space, parallel to our own, that allows for shorter travel between two points. It’s no longer four light years to Proxima. Instead, you transition over to hyperspace, travel a hundred thousand kilometers, and drop back into normal space at Proxima.

Generally, hyperspace is considered to be as Euclidean as normal space (which is not always truly Euclidean) and is scaled linearly with normal space. That’s the $5 way of saying that if you go twice as far in hypespace, you’ll go twice as far in normal space and in the direction you would have expected.

gateThe only tricky thing about hyperspace is getting between normal space and hyperspace. In some stories, your ship can contain the necessary equipment to open a transition point. In other tales, it requires a gate in normal space to open that transition point. But once you’re over in hyperspace, it’s just a matter of throttling up or sailing away.

Let’s see how the details break out.

FTL-to-FTL interactions: This varies. In some stories, hyperspace is a chaotic or void space that is completely incomprehensible, so you cannot interact with other ships even if they were supposed to be flying formation with you. In other tales, hyperspace is pretty much just like normal space but with better graphics. In those cases, you can fly around, talk to other ships, and even shoot at them. Of course, there’s room to play around between those two extremes such as limiting communication range due to “hyperspace flux” or the likes.

FTL-to-sublight interactions: Usually there are no interactions here. You are in a truly separate space. At best there is a level of communication, but that is typically done via fixed points like gates. However, I have seen a couple of odd exceptions to this rule, typically where something unusual in normal space (such as a supernova or black hole) will cause a disturbance in hyperspace.

Relativistic effects: Generally there are none. The ships aren’t typically travelling very fast in hyperspace. It’s just that the distance there is shorter. Either that, or there is simply no special relativity in hyperspace. However, I have seen an odd time variation in some of C.J. Cherryh’s stories where mental processes continue on at a normal pace while other biological processes slow down. This allows frequent travelers to have a mental age of 40 while still appearing to be only 30.

In-FTL Navigation: This can vary, but there is almost always some. At the very least, ships travelling through hyperspace have the option of dropping back to normal space early, short of their destination. Course changes might require such a transition back to normal space, but there is that option. However, in most cases, hyperspace seems to allow as much navigational flexibility as the warp drive, complete with screeching turns and barrel rolls. Still, one limitation on this is the fixed points of gates. If you can only transition via the gates, then all the zigs and zags of your pilot won’t change the fact that you really only have a handful of destinations.

Speed Differential: Again, there typically is speed differential in hyperspace, typically achieved simply by travelling faster or slower within hyperspace. Sometimes, though, I have seen it done with multiple parallel spaces with different speed limits with them, e.g. hyperspace-A allows an effective 10-to-1 speed boost, while hyperspace-B gives 1000-to-1. However, I have seen a few cases (notably most of Jack McDevitt’s Omega Cloud series) where all ships travel through hyperspace at the same rate, since that is believed to be a fundamental property of hyperspace.

Malfunctions: These can suck. The most common malfunction is with your ability to transition to and from hyperspace. If you end up stuck in normal space, you’re just like the folks with the busted warp-drive, sticking your thumbs out in hopes of rescue. Except, of course, if you’re out in the middle of interstellar space, there won’t be any warp-drive ships careening past to see you. Instead, they’ll all be passing by unseen in hyperspace. Even worse is when you get stuck in hyperspace. Unless you can get to a gate to transition back, you’re left to the mercy of whatever monsters the author has left lurking in the dark corners of this alternate reality. Most often, those ships will simply disappear like the sailing ships of old, leaving only grieving widows and frustrated insurance adjusters.

Special traits: This is a nice dodge around relativity’s limits that doesn’t require much hand-waving with dubious physics. About the only big decision to make is whether or not ships can generate their own transition points or if some or all of them require a system of gates.

Tune in next week for a look at wormholes.

The whole series: Intro, Warp Drive, Hyperspace, Wormholes, Jumping, Summary

FTL Flavors: Warp Drive

This is the second in my series on the different flavors of Faster Than Light (FTL) travel, and today I’ll be looking at the warp drive. The ideas for warp drive predate Star Trek, and they weren’t always called by that name, but Captain Kirk and the Enterprise are the iconic example of the warp drive. With a few words of technobabble, the universal speed limit is suddenly gone.

Yes, they paid lip service with the distinction between impulse drives and the warp drive, and over the years, they’ve filled our heads with all the technical details of subspace fields, warp bubbles, and such, but the basic result is that we are no longer bound by the upper limit of lightspeed. Let’s look at how some of the details shake out.

FTL-to-FTL interactions: Two ships travelling at warp speed can interact. That seems pretty universal. They can travel together, see each other coming, even take pot shots as they fly past. Sometimes there are a few restrictions, but they’re usually more of the nature of “that’s never been attempted at this speed!” In other words, they’re dramatic challenges for the engineer, not fundamental limitations on the physics.

FTL-to-sublight interactions: Yes, you can see the planet coming, and it can see you. You can steer around it and come back in for a strafing run. Stories with warp drive usually ignore the fact that you can’t literally see something coming at you faster than light with vague talk of “long-range sensors”.

Relativistic effects: Warp drives almost never deal with relativity. I think a lot of this is that once having dispensed with Einstein’s limits, they would rather not bring up real physics again. However, I have seen one or two instances of mild relativistic effects with warp drives. Kube-McDowell’s Trigon Disunity trilogy had a drive that ultimately moved the ship faster than light via some tricks of warped space, but the occupants were also travelling at relativistic speeds within that warped space. Thus, they experienced less than half the elapsed time as their Earthbound friends.

In-FTL Navigation: Warp-drive ships generally have no problem turning to starboard at faster than light speeds. Since we’re now pretending there’s nothing special about the speed of light and imagining ourselves in space-going navy vessels, there is no reason to suspect otherwise.

Speed Differential: Yes, the Joneses have a faster warp drive than you do. After all, if there is no longer an upper limit on speed, someone is always going to be at least little faster than you. Of course, since speed variation is possible, this also means you don’t have to be traveling at your maximum speed all the time. You can save warp 9 for the really dramatic moments.

Malfunctions: Whether it’s something as minor as a crack in the dilithium crystals or an ejected warp core, you’re not necessarily dead when things go wrong with your warp drive. Most of the time, you’re simply restricted to sublight travel again as Einstein takes a brief rest from spinning in his grave. Of course, many faults can be repaired, and you can get moving again. Failing that, you just have to stick out your warp thumb and wait for rescue.

Special traits: For storytelling, this is probably the easiest and to write and the simplest to grasp. It essentially ignores relativity and removes the problem of interstellar distances from the story. Rigel-4 is no longer hundreds of light-years away. It’s merely on the other side of the pond, so climb aboard the newest ship from the White Star Lines and have a safe… er… at least a short voyage.

alb-warp-driveBut ironically, this flagrant slap in the face to physics is starting to look like it just might, maybe, theoretically be almost possible. In 1994, Miguel Alcubierre proposed a way of changing the shape of space around us, shrinking it in the direction we wanted to travel and expanding it in the direction behind us. It requires some pretty crazy technology, the science for which is still pure speculation, but after about twenty years, it has a few people seriously considering it as a matter for research. How seriously? Apparently NASA is spending some of its precious half-pennies on it. It might not be much more than a publicity stunt, but there’s always that outside chance that it might be something huge.

So, tune in next week when we take a tour of hyperspace…

The whole series: Intro, Warp Drive, Hyperspace, Wormholes, Jumping, Summary

Exploring the Final Frontier on a Schedule

In the first two installments of this series, I looked at exploring a new star system and examining a planet from orbit. Depending on the level of detail you want, this could take a few days to a few years… for each planet. With 15,000 star systems to explore within 100 light years from Earth, how are we going to do this in a reasonable amount of time, even with our nifty FTL survey ships?

I think the best solution is to parallelize as much as possible. That is, throw more manpower at it, or in this case, more ship-power. Since it takes some number of orbits around a planet to map it with the desired detail, the best way to speed that up is to do multiple orbits at once by employing satellites rather than simply orbit in the ship.

Such satellites would not need independent launch systems. The ship could assume the desired orbit, lower the satellite out of a cargo bay, and gently move off towards the next desired orbit. That way, something that would have taken a few days could be done in one.

Alternatively, if a particular system has more than one planet (or moon) in need of such mapping, a portion of the satellites could be deployed at one world, left to do their survey, while the ship goes to another world to deploy more of the satellites. In our solar system, this would be the equivalent of populating Earth’s orbit with observation satellites, popping over to Mars in mere moments using your nifty FTL drive to seed it with satellites. You might even dash out to Jupiter to set one around Europa. By the time you had set all that up, it would be time to swing back to Earth to collect your satellites and their data.

In fact, if one world in particular deserved a longer, high-resolution look, then one or more satellites could be left in place while the ship moves on to another star system entirely. It could then come back after a few months and collect a wealth of information. This would be useful if you saw signs of life or hints of artificial constructs on the ground and wanted to get that 1-meter resolution scan, or perhaps even zoom in further on the really interesting spots. I would not propose to attempt reading the New Rigel Times over someone’s shoulder, but you might discover that he did, in fact, have a shoulder to begin with.

How many satellites should the ship carry? All I have is a gut feeling for bringing about a dozen. It would be great to have hundreds, but when you start thinking about the big optical lenses, these satellites are bulky. A dozen should not take up an unreasonable amount of room, and it gives the survey crew enough to check out multiple planets at once as well as a few to leave behind without impairing the rest of the survey mission.

I would also want to carry along a number of communication satellites to be left in key locations. If my FTL communication system requires boosters or relays, it would make sense to leave them near interesting worlds, technology willing. And if the FTL communication is via courier ships, then these message queue satellites should be left at predictable locations, i.e. around promising stars near planets in the habitable zones. Hopefully, these could be of a reasonable size. It would be nice to leave one in every star system visited, but failing that, it would be nice to leave behind five or ten.

So how long will this take? I think with the extra satellites, a star system could get a decent exploration in about five days. For convenience, I’m going to assume an FTL speed of about one light year per day, and say that we can get from one system to the next in an average of five days. Yes, the distance varies from 10 light years for solitary stars to less than one for places like the Pleiades, but we’re into hand-waving territory here. This might take even longer when you considering the problems of efficient routing (i.e. the travelling salesman problem) and the inevitable backtracking to pick up any satellites we left behind, slowing us down just a little more. Then again, there’s nothing to stop me from waving my hands again and saying two light years per day. So let’s stick with five days travel between stars.

So, put those together, and you can explore a new star system every 10 days, and I think that’s pretty optimistic.

But how long will you explore? I’m going to use the U.S. Navy as a guide, and while ship deployment lengths vary, few are longer than six months at a time. Some of this is supplies. Some of it is wear and tear on the equipment (being as sea is kind of rough on things). But I think a lot of it is simply the limits of the human psyche. While visiting Alexandria, Hong Kong, or Rio de Janeiro can ease the stress, the real test would be those guys riding it out alone on the nuclear subs, and I believe their tours are no more than six months.

So is that six months of survey? Well, sure, as long as we’re only exploring the neighborhood right nearby, but as time goes by, we’ll be exploring further and further afield. Even at a light-year per day, we could spend three months getting out to those worlds in the 90-100ly range only to have to turn around and come back home.

So I’m going to assume that as the project progresses, we build up some forward bases. In fact, one of jobs of this survey would be to find good locations for those forward bases. Some of those more interesting worlds could be candidates for terraforming and eventual colonization. Building a meeting place for crews to get a little rest, repairs, and crew rotation would be a decent place to start with such an effort. Welcome to Deepspace-84.

So, I’ll assume that for the duration of the project, the survey area for a particular six month tour is roughly 30 days from a forward base. Furthermore, I’m going to give them two months of downtime back at that base. Ships will need maintenance, resupply, upgrades, and so on. Plus, it gives them some leeway in their schedule if they run a little behind.

After setting aside 60 days to get to and from the survey area, that leaves us with about 120 days to survey, and at ten days per star system, that’s only twelve new star systems. Add in the two months of downtime between survey missions, and that’s twelve new star systems per eight months. Since we’ll certainly be having more than one ship doing this, let’s average it out to only eighteen star systems per ship-year.

Now, how many stars were we talking about? Oh yeah, 15,000 stars within 100 light years. At the survey rate I’ve given, that’s about 830 ship-years worth of survey. If we want to do this in as little as twenty years, that means about 42 survey ships. Maybe even bump that up to fifty for some inevitable problems that we’ll run into along the way.

Considering that the U.S. Navy has varied from 250-600 ocean-going ships over the last century, fifty ships does not seem an unreasonable number of ships to dedicate to such an effort. I’ve been imagining these ships as being fairly lightly crewed by naval standards, requiring probably only forty to one hundred crew each, but that’s still a few thousand crew.

But even 5000 is not that many people, especially considering the number of Earthbound explorers who would be dying for a chance at it. I know I would be eager to put in my resume. Even if I don’t get in on this one, I might still have a shot at the next phase of scoping out the 100,000 stars in the next 100 light years out from there.

Wouldn’t you want to spend a few years of your life on something like this?