When creating a new setting that departs from the normal conventions of reality, it’s always a good idea to define the new rules that are different. Of course, countless writers have always just made stuff up as they went, going with whatever seemed convenient at that point, but that’s just asking to run into contradictions and thing that just don’t make any sense later on. And these are pretty easily avoidable if you just take a bit of time to define the parameters by which the setting works at an early point of the process. In fantasy worlds, the major subjects are the magic system, the categories of supernatural beings, and the nature of other worlds where those beings come from. For settings set in space, I think the number one thing by a wide margin is the rules by which space travel works. This really was pretty much the first thing I was thinking about when I decided to work on this setting. It’s the one biggest change from normal life that really affects everything about economy, politics, and societies throughout the setting.
Something that always bothers me a lot in science fiction is that writers constantly use the latest new terms that have come out of physics to give their works an appearance of scientific backing and legitimacy, but then straight up doing things that have nothing to do with the concepts they are referencing. Personally, I feel highly certain that faster than light travel is physically impossible. Alcubierre drives are the one tiny sliver of hope that the true believers have, but that seems like a really long shot, and even if it might be theoretically possible, there are several complications that make possible applications much less convenient and practical than what you see in sci-fi. In order to not mangle any actual physics, I knew immediately that I want to go with the most purely make believe solution that doesn’t connect to reality at all: Hyperspace.
With Hyperspace, all the existing laws of physics remain completely untouched. It doesn’t violate reality by simply supposing that ships can, somehow, enter another dimension complete separate from our own, in which faster than light speeds are not just possible but easy. There is absolutely no evidence that such a dimension exists, but if there were, then all the problems with faster than light travel just magically disappear. So that’s what I am going for. In this setting, Hyperspace is a thing.
I think this is a pretty good example of Iceberg worldbuilding. Pretty much everything in this post is meant to be stuff that remains under the water. Players don’t need to understand or know any of this to play a campaign. The purpose of this whole system is to be able to answer questions if players ask about how these things work, and to avoid situations where players realize that two things that have been established through the course of the campaign make no sense and contradict each other. Players don’t need any of this to play adventures, but I need to understand this to set up adventures that will hold up to scrutiny.
The Nature of Hyperspace
Hyperspace is a separate dimension from normal space that has very different laws and properties. It takes very little energy to cover incredible distances many times faster than the speed of light, and the engines required to enter and exit hyperspace are simple enough to be very widespread and accessible. In this setting, Hyperspace jump capable space ships are as common as planes and similarly expensive to operate.
Every point in normal space has a corresponding point in Hyperspace. To move between any two places in normal space faster than the speed of light, a ship simply jumps into Hyperspace, flies to the point that corresponds to its destination, and then jumps back out of Hyperspace again. However, things get greatly complicated by the fact that Hyperspace is extremely warped and twisted. In real physics term, the geometry of normal spacetime is flat, but the geometry of Hyperspace is very much not, and there are no indication of any repeating patterns in the curvature of Hyperspace. This means that even when you know the exact position of two or more stars in normal space, you have no way to tell the positions of their corresponding points in Hyperspace. And even if you have the Hyperspace coordinates of two stars, you can’t just draw a straight line between them to know how to get from one star to the other. Even knowing how to get from star A to star B, and from star B to star C, does not really tell you anything useful about getting from star C to star A.
Hyperspace Charts
Determining the corresponding points of stars in Hyperspace and the paths to move between them is part of the field of astrometry. And while moving a ship through Hyperspace is really quite uncomplicated in practice, finding the Hyperspace routes that connect stars is extremely difficult and requires the expense of huge resources. Since the warping of Hyperspace is effectively random, every route between any two stars has to be measured and calculated separately. Accordingly, most star system in the core of known space have only two or three known routes leading to and from them, and many frontier systems are dead ends as Hyperspace travel is concerned. The only place to go from them is back to the system from which you came. In practice it is much cheaper to simply make multiple Hyperspace jumps between systems to get to the one that is your destination than trying to calculate direct routes between all the possible stars people might want to get to. Accordingly, Hyperspace charts look like subway train system maps with many stations that the routes are just passing through, and several stations where two lines cross and you can switch from one line to another.
Since calculating Hyperspace routes takes a long time and is expensive, astrometric services pick new systems to connect to the network not at random. Instead they rely on data from astronomic observations of newly discovered planets around unexplored stars. (Something scientists have learned how to do in the last 20 year, and as such you don’t see in older science-fiction.) There are many exploration companies that commission routes to be calculated to systems which they think have great potential for exploration. But often astrometric services just take a gamble calculating new routes to previously unexplored systems and hoping to make their investment back with sales of licenses for the new routes. But more often than not, these new routes turn out to lead to systems that don’t have anything anyone is interested in, and as such these routes simply expire after 10 years without getting any new updates.
A further complication is that all objects in space are always in motion. Stars move around their galaxies at very considerable speeds and even the galaxies themselves are constantly moving around in space themselves. This means that the Hyperspace coordinates for any stars are constantly changing. In theory, you could calculate a route for a Hyperspace jump between two stars at a single moment in time, but even just seconds after that calculated moment the route would leave you somewhere in empty interstellar space with no way to find your way back to a known system. Since this isn’t any useful for almost all space travel, a single Hyperspace route is actually a big catalog of data that lists the correct path for travel between two stars for any moment throughout a longer time span. For smaller routes, this time span is usually 10 years, while for the routes in the home systems it is 100 years. Nobody would go and explore a new system or set up a mine or colony if that system might become unreachable in a few weeks or month, after the route expires and nobody bothered to have an update commissioned. The government owned astrometric services of the home systems are constantly releasing new updated catalogs for the main trade routes, each time extending the expiration date back to 100 years. But in small frontier systems, things can get quite tense if the last updates are reaching their expiration and there is no news of new updates being announced. Often small colonies have to commission a new route update to connect their system to the rest of known space with their own money, which can be a huge financial burden. Colonies that can’t afford the huge costs often have to be abandoned, but there are countless stories of stubborn colonists who supposedly held out and accepted being cut of from the rest of the galaxy forever.
Starship owners have to buy expensive licenses from the astrometric services to get access to their catalogs of Hyperspace charts, which is a substantial part of the cost of space travel. Of course, there are countless unlicensed charts making their rounds on the black markets of the frontier. But since a ship that gets lost in interstellar space for all eternity can’t come back to complain, the accuracy of these black market charts is always extremely dubious. Few captains are desperate enough to gamble their lives on these.
Hyperspace Jumps
While ships in Hyperspace are effectively blind and have no way to tell where they are going, the gravity of massive objects in normal space still has effects on Hyperspace and cause it to warp even more than usual. Accordingly, the routes of Hyperspace charts really only show how to get to the general vicinity of a star. Making a ship arrive at a specific point inside a star system is for all intents and purposes impossible. While stars themselves are actually really small compared to the scale of a system, the warping of Hyperspace near them becomes stronger the closer you get, which makes it actually pretty easy to accidentally get much closer than expected or even come out inside the star itself. Usually navigators keep things safe and jump out of Hyperspace somewhere in the outer part of the star system where the risk of randomly appearing inside a planet are negligible. Similarly, jumping into hyperspace too close to a star could lead to navigational errors that lead to a ship getting lost in interstellar space.
In practice, this means that between arriving at or leaving from a planet, and jumping in or out of hyperspace, ships have to travel considerable distances at sublight speed. While the Hyperspace jumps themselves often take only a few hours, flying between planets and jump points can take from many hours to several days. Small stars with low masses have much weaker gravity and all their planets close to them, so transit times in such systems are on the low end, while large stars with great masses have very strong gravity and their habitable planets much further out, resulting in the very long transit times.
Another quirk of the warping of Hyperspace is that even with the best navigation computers, both the exact point at which a ship jumps out of Hyperspace in another system and also the precise time at which it arrives are somewhat random. Fleets leaving a system together always arrive at their destination scattered over great areas and arriving over the span of several minutes and sometimes even hours. Fleets always require several hours to regroup after a jump, followed by several hours of transit time to reach the planet they are headed for. This leaves people on the planets many hours to notice them and prepare for their arrival, which makes surprise attacks with space ships impossible.
Hyperspace jumps require fuel. Licenses for Hyperspace charts are included in the regular upkeep and maintenance costs for spaceships, but fuel for the Hyperspace engines is a resource that has to be tracked at all time. Players making journeys to other systems have to check if their fuel will last them to make the journey and return trip, or plan to make stop at fuel depots along the way. I think fuel stops can be a great way to introduce randomized encounters into the campaign. Aside from the PCs running into interesting people during these fuel stops and getting into trouble while waiting for their ship to be ready to continue their journey, you could also have various complications like the fuel station turning out to be inoperable, causing long delays, or being destroyed, causing potentially serious problems with keeping the engines running. Fuel costs also seem like a great way to put financial pressure on the players. Without fuel they get stuck and so are forced to make money, or can’t afford to be charitable to people who would really benefit from their cargo. Or they might be driven to try to steal fuel somewhere. I think there’s great potential in this that could lead to wonderful organically developing side adventures.
Hyperspace Travel for Players
Even with all the theoretical background stuff, the things that players need to understand is really simple:
Ships can only go to star systems that are on the map. And every journey has to be taken along the marked lines. Every jump requires a unit of fuel. (Or two or three units, depending on the size of their ship.) After leaving a planet, they need to survive for a couple of hours before they can make the jump. Even if pursuers decide to follow them through Hyperspace, they will arrive far enough apart on the other side to reach a planet before the pursuers catch up to them, and if they manage to make another jump before the pursuers arrive they will have lost them for good.
That’s really all the players need to know. Anything else is just for curious players that enjoy these things, but I find it important as the foundation that explains why these few player facing rules are the way they are and to make them consistent even at closer observation.