Ley Lines

are "rivers" of highly dense aether that are used for navigation by spaceships. 
== Properties ==
=== Circular Nature ===
All fully-mapped ley lines form closed loops. Some ethericists speculate that ley lines need to be closed loops in order to persist in the greater aether. No ley lines have been observed to disappear in modern memory, so the validity of this theory cannot be determined. Additionally, no new lines have emerged. Maps from the Mage Imperium show different gates and leylines that no longer seem to be where they were, but it is unknown if drift is the cause of this.
As there are some lines that have not been completely mapped, it is presently unknown if all ley lines are closed loops at all. Speculation exists around some leylines being infinite lines or line segments, or possibly forming wholly different shapes.
=== Relation to Pocket Dimensions ===
All etheric gates open onto a ley line, but it is unknown if the lines help maintain the gates or vice-versa. Sometimes a new planet will be discovered as the result of the natural drift of leylines, so the planets themselves do not need the gates to survive.
=== The Pin-Jump ===
As with all other cosmological phenomena, all known ley lines shift relative to the Pin-Jump.
== Implications for Conquest and Trade ==
The Aeldman colonial enterprise depends on the control of ley lines and the monopoly of the Aeldrum Trade Company or, later, the Aeldman State, on the etheric gates of a colonial world. Whatever happens in the interior of a planet, Aeldman doctrine demands the Gate(s) must hold, for if these are lost then both the lines of supply to the interior are compromised and (perhaps worse) reestablishing control of the planet will most likely require a costly etheric invasion. The next tier of Aeldrum’s “Gate Doctrine” generally prevents the rebellious colony from readily accessing rival trade powers, however: Aeldman control of key strategic worlds allows a similar stranglehold over entire regions of space, either because no navigable route exists except by passing through a world-junction under Aeldman control or because alternative routes are so long or so perilous as to prohibit rival trade powers from profitably engaging with a world. In this respect, the power of Aeldrum is not its navies, but in its careful construction of a multilayered prison of fortified etheric gates. As direct Aeldman control over the colonies recedes (around the mid-5th century A.U.), the heaviest fighting will not be over the vast stretches of worlds that lie within Aeldrum’s “Regions of Transfer Monopoly” but over the critical junctions that prevent foreign powers from accessing the rebellious worlds. In short, a monopoly over transfer between the ley lines is nearly as powerful as a total monopoly over navigation within a single ley line. The exception to this strategy is when an encircled region begins to develop self-sufficiency and no longer depends on Aeldrum for its imports. 
The largest worlds by surface area (see cosmic demographics) have the least to gain, all else equal, from orienting productive land toward cosmic trade and are thus the most likely to develop self-sustaining economies that do not depend on a cosmic supply chain: it is possible that with these different incentives, such worlds could develop the means to resist Aeldman-style mercantile strategies, though they are in turn relatively unlikely to find profit in projecting themselves outward. Such large worlds could form important parts in the development of more localized confederacies, however (shorter overall transit time) and thus may exert themselves to achieve concentrated trade networks at odds with the long-haul and relatively low value shipping strategy favored by mercantile empires under the segment-control strategy.
An etheric segment is useful unit of analysis for the division of the cosmos into spheres of influence among rival powers: an etheric segment is a sequence of worlds on a single lane (with rare exception, etheric lanes will contain only one or two worlds abreast at a given point) in which no worlds except for those as the beginning and end of the segment have gates connecting to a point outside the segment: this connection is most often to another lane, but segments can be disrupted (essentially split into two new segments) by interior worlds with gates that connect to a point on the same lane but outside the segment. It would be theoretically possible for a multi-lane segment with the same essential properties of control to exist, though ultimately such an arrangement (improbable to begin with) would be susceptible to invasion along the ley lines rather than through a critical junction.
An important property in the development of monolithic powers (trade empires) as opposed to heterogeneous minor powers dividing an etheric segment is the degree of "lane monotonicity." If an extent of many worlds lies on a segment with only distant endpoints connecting to other lanes, it is easier to isolate and control than a segment with a density of relatively proximate options for connections to other lanes.
Though Aeldrum is the archetypal trade power, it is of course far from the only one. All engage in jockeying for control of the crucial routes: the development of trans-ley navigation may disrupt this arrangement. 
An interesting geopolitical (etherpolitical?) problem is the eventual breaking of the lane-navigation paradigm. If it becomes possible for fleets to reliably cross the etheric gulf between two lanes without relying on a planetary link using etheric gates, then the strategic value of such a world diminishes significantly and, indeed, the imperial strategy of segment control loses viability. Local force projection at the planetary scale will still rely on gate control, and a sufficiently effective "core force" operating out of a central world could continue to exert a measure of control through proximity (greater than other imperial rivals) and threats to the infrastructure and gate-access of specific worlds. This form of control, however, scales much less effectively than the segment-control strategy, effectively requiring the controlling power to outpace rivals (often by a significant margin depending on the size of the controlling force) who may intervene in the zone of control. In the worst case, a single effective fleet must be able to strike at a world on one extreme end of its zone of influence and return to the other extreme before a rival force can reach that world from its staging zone. The obvious solution is to have more fleets, but the risk of attack anywhere along the zone of control requires a much more involved network of bases and staging areas. The advantage of the defender in etheric conflict thus becomes nullified if the invader is acting in support of local planetary forces. The economics of transportation are still likely to favor a lane-control strategy (at least more-so than lane control as a strategy for suppression), but there will be important exceptions: a sufficiently short jump between lanes (also less risky than a long jaunt between lanes) will likely require less time than a roundabout circuit from a point of origin in Lane A, to the A-B junction, to a point in Lane B, especially depending on the infrastructural development of the A-B junction. Depending on this critical balance, the extreme outcomes may either be a much more infrastructurally developed junction-world (to maintain competitiveness) or the abandonment of the junction world's status altogether.
Category:Cosmological Phenomena