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GGG

Space travel: the Gravitic Gradient Gearbox

https://www.youtube.com/watch?v=DJfy2AaTGmY

The GGG is a simple mechanism that allows for extremely quick space travel. Almost entirely unlike gearboxes, they amplify a spaceship's thruster power in a nonlinear way depending on gravity fields nearby. GGG sets are installed so that the "hub" sits as close as possible to the ship's center of mass, and the "teeth" at right angles to each other in 3D spaces. The system can be run on relatively clean DC power, which in a few well-known self-rescue incidents has been provided by lead acid batteries and a particularly robust bicycling or rowing team. To deal with debris and combat damage, most ships have redundant sets of teeth.

Speed naturally increases, presumably to infinity, the further away one is from a gravitational field; the effects are cumulative, so high speeds can only be attained outside of solar systems, making intersystem "blockades" difficult (but not impossible). Interestingly, this breaks down in intergalactic space; there, the gravity gradients become slightly negative, which results in the GGG increasing the effective mass of a spacecraft rather than decreasing it. Theories about a layer of "dark matter" circumveloping the galaxy abound and are varied.

Craft moving faster than light speed should carry magnetic shielding to avoid random destruction at the hand of small debris; larger debris fields have enough of a gravity field that they will force a slowdown at least most of the time.

GGG setups in use nearby each other will tend to lockstep and synchronize, unless very specialized desynching hardware is employed (for a Newtonian example, see https://youtu.be/suxu1bmPm2g ). This interaction between fields is why space battles tend to look like big localized furballs to fighter pilots, and naval engagements to fleet officers - the GGGs in close proximity settle on a gravity gradient to follow, and keep the center of gravit of the fight within the same orbit. It's also why it's practically impossible to run away from an engagement without consuming vast amounts of fuel. This technique is also used to facilitate space docking.

Given the fuel expense that would be necessary to operate a GGG-less ship (the amount of fuel necessary for a mid-size cruiser to cross the Galaxy with a GGG would be barely sufficient to take a three-man lander on a class E moon and back without) and the relative ease of construction of the device, all spacecraft larger than a MOOSE pod are equipped with at least a hub and six teeth.

Careful tuning of the device (mostly involving pulse width modulation cutting power to sets of teeth alternately) allows for daring stunts such as near-lightspeed landing for a minority of gifted pilots and remarkably leathal firework displays for the rest of us. The "reverse slingshot" maneuver, in which one retreats from the gravity well, goes around to the far side of a system, and then approaches back in for interplanetary travel, means that the shortest distance isn't necessarily the fastest and, most interestingly, some routes that are fast in theory can actually have a higher variance in travel time because there may be a trojan asteroid that hadn't been counted. In general, people doing speed runs do a lot of astronomy survey beforehand, and then a lot of very quick turns and quick thinking during the attempt. Or just get lucky. For example, one particular trade route may have an optimal travel distance of 13 parsecs for shortest travel time, whereby 13.1 or 12.9 would give you a big slowdown because there's a blackhole nearby and you got either too far or too close to do a good reverse-slingshot.

At its core, the GGG is a simple but extremely counterintuitive electric circuit; with a design, a skilled goldsmith and glassblower can build a basic system (one hub, six teeth, and some sort of voltaic cell) in a standard year. Nowadays the most common cause of races and cultures elevating to spaceflights is, in fact, castaways. Both the hub and spokes are fairly simple voltaic circuits, the simplest examples only requiring a pair of thermionic valves on the hub and only passive components on the spoke, however the traces and wiring between hub and spokes must carry as little resistance as possible - this necessitates solid gold construction. Modern high performance GGGs use mercury supercooled with liquid helium, but the cooling apparatus increases mass and power usage greatly; this is an ongoing debate between racing enthusiasts. Of course, being able to switch to liquid nitrogen would drastically change the picture. It is said that the Scourge Lord's personal ship used such a system, but the wiring material was never recovered.

Note that while a GGG system permits superluminal travel, it does nothing for communication: courier ships routinely travel between planets with memory cards or even, when appropriate, their own radio and TV transmitters.

In crowded space such as around highly populated worlds, you may be assigned a GGG frequency by the control tower; this is simply to ensure that your pulse width modulation doesn't accidentally sync up with, say, an ambulance or a docking tug, which would be inconvenient for you and potentially catastrophic for them. Modern spacecraft and high-integration space stations use a Gravitic Gradient Gearbox Governor to take in the control tower signal and avoid accidental synchronization; craft and space stations with this feature are sometimes said to be 4G compatible. Unsurprisingly, there are a few competing and not-quite-compatible 4G standards; since it's possible to send spurious signals to the governor in a hostile situation to remotely unbalance someone else's ship, the governor usually has a very visible off switch that physically disconnects it from the hub.

GGGs will assist planetary takeoffs and landings by dealing with gravity, but do absolutely nothing to help against atmospheric density: if you are planning to relive the early days of space exploration, be sure to pack wings and a propeller or, in the right sort of atmosphere, a hydrogen balloon.

Asteroid or planetoid bases (or in very rare cases, completely artificial structures) large enough to have significant natural gravity can be equipped with an untuned GGG set of large gears in order to force other units to slow down in their vicinity, creating blockade points. This requires a significant amount of power and circuitry that can handle this power; purpose-built interdictor rafts have been built in the past, but they are extremely expensive to build and operate. In general, they are built out of separate ships that combine in order to achieve enough mass in one spot to make the interdiction effect meaningful. Old Imperial interdictor rafts, some of which are still active, are generally made out of a minimum of seven elements, each carrying a hub or a tooth for the interdictor as well as its own complete drive.

GGG systems are generally classed (and sold) by reliability, tunability, maximum mass size, and number of teeth. Power requirements increase with mass, a little faster than linearly. You can expect to see pedal generators on starfighters and tramp freighters, heat sails and steam turbines on cargo ships, and internal combustion engines on military ships. Large warships and interdiction bases generally use radiosity heat engines and steam turbines.

Standard thrusters are used normally, for maneuvering and accelerating (deceleration tends to be more easily performed with a GGG burst) and can be run from anything ranging from compressed air or steam, to liquid oxygen and various propellants (kerosene, hydrogen and so on), to gunpowder pellets if there's nothing better available.

Since the GGG is constantly interacting with other gravitational fields, nearly any movement will require some amount of fuel, although it's often possible to "coast" in a Newtonian manner to save fuel at low speeds or even to to avoid detection. Common propellants are solid fuel cartridges, superheated steam, liquid oxygen combined with a variety of liquid fuel, or even firing one's weapons backwards. Since space rockets are simple machines, roughly on par with an internal combustion engine, and efficiency usually isn't a concern, most commercial pumps and nozzles will be able to run on a variety of non-spec fuels if one doesn't mind loss of efficiency and constant maintenance.

If one is in possession of an accurate way to calculate low-gradient paths between planets, they can achieve high-efficiency interplanetary transfer with a GGG that isn't optimized for it. A similar effect exists between stars, although it's less marked. ( https://en.wikipedia.org/wiki/Interplanetary_Transport_Network )

Semi theory: The GGG allows for a bigger multiplier the least gravitational influence is felt by the object (This breaks down intergalactically though, a bit like the catodic effect). This can be achieved by being away from celestial bodies, or being in just the right spot where things cancel out.