Causeway

A Causeway is an advanced Iserial structure used to connect worlds across the River of Dreams. Though often described as bridges across the River of Dreams, they are actually more akin to tunnels since the River of Dreams still surrounds a Causeway on all sides. It is only possible to construct a Causeway from and to either an Open World or a Linked World. An Open World that becomes connected to another world by means of a Causeway is turns into a Linked World over the course of roughly one Standard Year.

A Causeway can be thought of as a self-sustaining stabilized corridor within the River of Dreams that acts as a thoroughfare for people and goods. Though requiring considerable amounts of especially Tertiary Iserial Energy to construct, a Causeway usually generates several orders of magnitude more Tertiary Iserial Energy than it consumes.

The physical appearance of a Causeway is entirely up to its builders, the absolute minimum being a stable channel through the River of Dreams that is either filled with air or water, and must be flown or swum through. However, the vast majority of Causeways feature at least a solid surface and the application of gravity to allow land-bound creatures to walk across it.

Connecting two worlds also by a Causeway also time-links them, meaning that an Absolute Year for one Linked World will also equal an Absolute Year for the other linked world. This stands in contrast to Open Worlds and Sealed Worlds, in which time may flow differently. Also, the Causeway itself will also be time-linked to the worlds it is connected to.

Causeways can connect worlds into networks that are theoretically unlimited in size. However, and important factor to consider when linking worlds by causeways is that the amount of Tertiary Iserial Energy generated within a network is directly proportional to the number and size of worlds it contains, while the distribution of that Tertiary Iserial Energy is dependent on the structure of the network. In essence, directly connecting two worlds within a network that are already indirectly connected does not increase the amount of Tertiary Iserial Energy available within the network, but will instead redirect some of the Tertiary Iserial Energy generated within the network to the two worlds that are now directly connected. Though the exact mechanics of this are subject to many factors, two measures of thumbs to visualize this are:

* In a network where every world is directly connected to every other world within the network, all worlds get roughly the same amount of Tertiary Iserial Energy
* In a network where all worlds are only connected to a central hub world, the central hub world gets about 50% of the Tertiary Iserial Energy, while the other worlds share the remaining 50% equally between them

A Causeway can be destroyed by force, and especially smaller or more primitive Causeways can processional fall victim to attacks by sufficiently powerful Nightmares. Such attacks usually demolish only a particular portion of a Causeway that can still be fixed. However, it is important to note that due to the volatile nature of the River of Dreams, any such reconstruction has to be completed sooner rather than later before the worlds "drift apart". Much like he process of linking, it takes two fully linked worlds roughly one Standard Year to unlink.

A notable Causeway in the world of Ceal is the Ceal-Meviek Causeway.