Causal Fortress

Use of wormhole temporal technology to give advanced information about events occurring in the vicinity of a particular location

Causal Fortress
Image from Steve Bowers
This solar system is surrounded by a spherical network of comm-gauge wormholes, which give several hours of advanced warning about events in the vicinity. The red dots in this image are comm-gauge wormholes, each connected to an array of active and passive sensors. The purple spheres are a diagrammatic representation of a shared hypersurface of simultaneity that is significantly in advance of the local frame of reference of the central star, but without forming any closed timelike curves.
Wormhole technology allows very fast communication between locations that are significantly separated from each other. A linelayer spacecraft can be used to transport wormhole mouths from one location to another, changing the relationship between the two mouths; if the linelayer travels at relativistic speed, the two mouths of the wormhole can be significantly temporally displaced from each other, although this cannot be used to allow reversal of causality because of Visser Collapse.

This temporal displacement can be used in many useful ways; by sending out temporally-advanced wormholes to distant locations, this can be used to 'buy time' in a so-called Buy Time Machine. The temporally advanced nature of the Wormhole Nexus allows colonisation to appear to proceed more rapidly when seen by an observer within the Nexus as opposed to when seen by a distant observer. Messages can be sent very rapidly across the Wormhole Nexus, especially via the comm-gauge wormholes of the Known Net, so this allows news of important events (and especially news of threats) to pass quickly from star to star. If the information travels via temporally-advance wormholes, this information can come from the global future.

Many stellar systems and other important locations build carefully-constructed causal fortresses around their territory. Such a system will send out comm wormholes at a high fraction of lightspeed, and disperse them in a bubble around their territory. Thanks to relativity these small wormholes are displaced into the future by a significant amount, nearly but not quite enough to form a closed timelike curve.

A powerful array of active and passive sensors is connected to each of these wormholes, and they can then transmit news of an aggressor or other threat that passes by, to the wormhole mouths within the system (which are in the global past compared to the detection array). This gives the users at the centre of the system a significant warning time, much more warning than would be possible if they waited for the light to arrive from these events through normal space.

Causal fortresses may consist of a tightly-packed array of sensors a few light hours away from the central location, giving a few hours of warning; or a larger, more loosely-packed scattering of holes arranged at light-week, light-month or lightyear distances. These swarms are generally more holey but still give good warning, especially when combined with advanced information obtained via the Known Net or Godweb.
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Development Notes
Text by Steve Bowers
Concepts by Ryan B (Rynn) and Sevoris
Initially published on 23 June 2021.

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