Telekinesis

Telekinesis is one of the most common types of enchantment in the Locus, and accounts for many of its most economically vital devices including the overwhelming majority of magic-technology hybrids. However, its potential versatility is hampered by the fact that only a handful of mass-produced enchantments account for nearly all telekinetic magic in the Locus.

Telekinetic devices are subject to three major restrictions. The first two are basic physical constraints, namely conservation of energy and conservation of momentum. Telekinesis cannot be used to create a perpetual motion machine, and it cannot violate Newton's third law; if a force field pushes on one object, it must push the other way on something else. The third restriction is conservation of strength. This means that the total power of a telekinetic enchantment is related to the strength and amount of material used to make the magic item itself. Exactly what is defined as the "power" of an enchantment depends on the specific type of enchantment, but in all cases it limits what uses of a particular magic item are economical. Spells are able to circumvent this limitation by drawing strength from materials that were not originally part of the enchantment, but is usually not important as spells are rarely cheap enough or powerful enough to compete with the more common forms of telekinetic devices.

Most telekinetic devices are one of seven types:

Levitation devices come in two distinct types: relative and absolute. Relative levitation devices maintain a fixed distance to ground, absolute levitation devices maintain a fixed altitude. Relative levitation is thus useful for hover vehicles, allowing them to maneuver over complex topography, whereas absolute levitation is more useful for aircraft, as it permits them to ignore said topography. While this distinction is important in that a given device can only perform one of the two functions, the two are otherwise subject to the same limitations.

Energy is conserved by a ratcheting mechanism; in order for the hoverpod (modular levitation device) to change altitude, mechanical work has to be introduced through a crank or related mechanism. Momentum is conserved because the hoverpod has to push against something, either the ground in the case of relative levitation or the planet in the case of absolute levitation. Conservation of strength relates the size of a hoverpod's active elements to the force it can generate. In the case of relative levitation hoverpods, this limitation is doubly enforced as the hoverpod's active elements not only repel the ground, but the hoverpod's own passive elements which normally shield the vehicle from its repulsive force field. If the hoverpod generates too much force, it may cause the active and passive elements to detach, or may cause the active elements to be damaged by crushing at the contact points between the two.

Lateral force devices are similar to levitation devices in packaging, except that they exert a force perpendicular rather than parallel to the displacement between the force generator and the object it acts on. When mounted on a vehicle, it is commonly known as a hoverkeel. These devices allow hover vehicles to steer, and are especially important for sail-powered hoverships as they permit it to extract power from crosswinds.

Conservation of energy is automatic in a lateral force device, as the force they exert is perpendicular to the motion of the vehicle they are attached to. However, conservation of strength creates a particularly problematic limitation. Unlike levitation devices, which are limited in force, lateral force devices are limited in the torque they can exert. This means that they get weaker the further they are from the ground. As a result, high-altitude aircraft are unable to take advantage of these devices in any efficient manner, and must rely on aerodynamics for steering in much the same manner as a blimp or dirigible.

Force bubbles are force fields that cover some area, usually in order to control the motion of a fluid or granular medium (i.e. sand or dirt). More powerful force bubbles can be used as a form of armor against projectiles or physical weapons, i.e. a force shield. However, the weaker force required to confine a soft material requires a much less expensive force bubble, and is thus often preferred even when the goal is protection. This results in an unusual form of armor and fortification known as field stabilized earthworks.

Force bubbles are subject to limitation of virial. Virial is the product of force times displacement, and has the same units as torque (the limitation on lateral force devices). As a result, force bubbles typically do not stray far from their generator. Also, since their limitation is on force and not energy, a hard impact has a good chance of penetrating them.

Force lines are force fields that hold three or more enchanted objects so as to ensure that they occupy the same line. Theoretically any number of devices can participate in a single force line, but two or fewer has no effect for obvious reasons. Force lines have no effect on objects other than the ones originally enchanted to generate it. Thus, object linked with force lines behave as a single object even though other objects can pass without interference through the intervening space. Force lines do not fix the distance between participating objects, but it is relatively simple to combine several force lines to form a system of levers that hold relative distances fixed.

Force lines are an essential component in extensible weapons such as the swordpike and swordlance. However, its most common use is in anti-buckling fields. Anti-buckling fields allow buildings to support a heavier load with less structural material. This is because most of the materials required to support a load under compression are needed not to withstand the physical stress of the load itself, but to stabilize the structure against buckling failure. Replacing those materials with a force line is usually a more economical solution. Force lines are also commonly used to support the outriggers on hoverships, as this reduces both drag and collision risk compared to supporting the outrigger with a cantilevered strut.

Force lines are limited in the force they can generate. However, when used in a stabilizing role, the total force required is usually very small as long as the structure is close to equilibrium.

Force bolts are "projectiles" made of telekinetic energy. Force bolts remain collimated better than the diffuse force exerted by relative levitation hoverpods. However, the main advantage of force bolts is that their generators are limited in energy, not force. This means that a force bolt can generate hard impacts, much like a real projectile. Unlike a real projectile, a force bolt is not affected by wind or gravity, and can have a theoretically unlimited range. Force bolts form the basis for the ray crossbow and related weapons.

While force bolts have theoretically unlimited range, their limitation in energy can lead indirectly to a limitation in rate of fire. If a force bolt generator launches a second bolt before the first either strikes a target or dissipates spontaneously at extreme range, the energies of the two bolts are added for purposes of determining energy limits. A force bolt generator can of course be designed with enough excess capacity that this is not a problem, but this makes it heavier and more expensive. A force bolt generator that is overloaded due to high rates of fire may skip a bolt, or it may crack or shatter from stress.

Force couplers are small utility devices that form an essential component in most magic-technology hybrids. Force coupler transmit force between nearby moving parts. In this sense they work like gears, but their performance can be much more complex. For instance, a clutch, transmission, and differential gear can be replaced by a single force coupler.

Force couplers are an essential component in spinorbs. This is because a spinorb's axis of rotation can change arbitrarily due to gyroscopic forces. Extracting power from such a device would otherwise require a complex system of differentials and gimbals to route power to the fixed housing along a circuitous route. This in addition to then needing a continuously variable transmission to output power at a fixed rotation speed despite the continuously changing speed of the levitated flywheel itself. A force coupler combines all of these operations into a single device, making the spinorb a practical device for energy storage.

Because of their small size and limited range, conservation of strength on force couplers is usually not a significant factor.

Chains of small force couplers can be used to create force conduits, which act like flexible axles for routing power between two machines. These cables superficially resemble electrical power cords both in form and purpose, but should not be confused with them as they transmit mechanical work, and thus do not require the technology to use electricity.