Wormholes - A Layman's Guide

Wormhole and Grapeship
Image from Steve Bowers

It turns out that there are very simple, exact solutions of the Einstein field equations which describe wormholes that have none of the above problems. If, somehow, an advanced civilization could construct such wormholes, they could be used as a galactic or intergalactic transportation system and they might also be usable for backward time travel.

- Michael Morris and Kip Thorne, 18 A.T.

"A wormhole is any compact region of space-time with a topologically simple boundary, but topologically non-trivial interior."

- Matt Visser, 26 A.T.

First postulated as far back as the early Information Age, wormholes are artifacts of space-time engineering which provide rapid transportation across distances that would normally require decades, centuries, or millennia to cross. The Wormhole Nexus, or simply Nexus, is the foundation of modern galactic commerce.

Wormholes are the product of high transapient intelligence. Indeed, it was not until after the evolution of the Third Singularity that the means to create such devices became available. The first wormhole in the Sephirotic Empires was created at Vega in 2110 A.T.. Since then, each new Singularity level has refined or advanced the technology of wormhole creation, until in the modern era it is theorized that even the very minds of the gods are bound up somehow in structures of wormhole linked space-time.

All but the most basic details of wormhole creation are beyond the comprehension and generally beyond the interest of modosophont minds, but the basics of wormhole operation and usage are readily understandable.

Types of Wormholes

Theoretically there are several different types of wormhole that may be created within the bounds of the laws of physics. While some are believed to be employed by the highest Singularity level minds, to date only two are in common usage by modosophont level intelligence.

Traversable Wormholes

Traversable wormholes (as their name implies) are mostly used to link distant points in space that would otherwise take years, decades, or centuries to travel between even at the speed of light. Traversable wormholes are based on a type of wormhole that might best be described as a modified Morris-Thorne-Kuhfittig metric (after the Information Age theorists who first proposed the basic structure and theory). The basic properties of this class of wormhole are described below:

Spherical and Stable

Although they are generally referred to as "gateways" or "portals" wormholes are in fact nothing like the picture of simple two-dimensional doorways that such terms invoke. Rather they are complex spherical structures that connect widely separated points in space-time. While non-spherical gateways are theoretically possible, the engineering and practical difficulties of such structures are huge. As yet, no credible reports of non-spherical wormholes have been made, although rumors that such structures have been produced by the archai or discovered in some remote region of space continue to persist.

Asymptotic Flatness

Wormholes connect two regions of space that are not normally adjacent to each other. These two regions must be 'asymptotically flat' in order to keep the wormhole stable. In practice what this means is that if a mass greater than that of the wormhole attempts to enter the wormhole mouth, the structure of the hole will become unstable and implode into a black hole.

Multi-Layered Internal Structure:

All known types of wormhole possess a similar internal structure, but this structure is most obvious in a transport gate. Passage through a wormhole from mouth to throat is passage through a series of increasingly smaller spheres; the minimum radius sphere is at the throat.
The structure of a wormhole can be seen in the graphic below. Modern wormholes are consistently 327 Astronomical Units (A.U.s) in radius from the region of flat-space to the wormhole mouth.s

wormhole 3
Image from Adam Getchell

Wormhole Layers

TransitionRegion of the wormhole mouth extending from flat space to a point some 3 Astronomical Units from the wormhole throat.
VortexFrom 3 A.U.s to the throat of the wormhole is the region known as the Vortex. Space-time closes in around the ship exponentially with decreasing distance. Velocities attained in the Transition are high, and acceleration levels may be fatal for unaugmented bionts.
CausticThe thin (less than 1cm) shell of exotic matter-energy surrounding the throat of the wormhole and holding it open.
ThroatThe region of maximum space-time constriction and linkage to the destination space-time.

The size of the Throat dictates the maximum size of any vessel transiting the wormhole. If a vessel is larger than the diameter of the Throat in any dimension (length, height, width) it will come into contact with the walls of the Throat and be destroyed.

Vessels larger than the diameter of the Throat that wish to transit the wormhole must either contract to a smaller size or break up into independently maneuvering sections which transit the gate individually and then reassemble on the other side.

Wormhole Travel

Passage through a wormhole begins with docking at the transport station orbiting one of the mouths of the wormhole. The mouth is the region where the wormhole metric becomes asymptotically flat. This station is traditionally called Exit Station, as the travelers are exiting this region of space-time. Exit stations are located at the standard distance of 327 A.U.

From the mouth of the wormhole, the transiting vessel travels inward through the Transition where the wormhole metric has been engineered to minimize the final mass of the wormhole mouth. Space-time curvature effects and tidal stresses are relatively mild, and most vessels have already accelerated to maximum velocity, executed turnaround, and are decelerating for final approach. Particular care must be taken at all times to minimize radial motion around the wormhole. Such motion within the volume of the wormhole results in the production of shear stresses on the vessel which, left unchecked, can result in its destruction.

At 3 A.U. from the wormhole mouth the ship enters the Vortex. Space-time closes in around the ship exponentially with decreasing distance, and velocities attained in the Transition can be fatal due to the generation of massive tidal forces. The diverging lens effects from the Throat can be seen in the forward view, and the ship continues to decelerate toward rest.

Finally, the ship crosses the Caustic and enters the Throat. The Caustic is a thin shell of exotic matter/energy that has been engineered to violate the Averaged Null Energy Condition (ANEC) to avoid the creation of an event horizon leading to the collapse of the wormhole into a black hole. Passage through the Caustic disrupts computation and communication and the distortion of space can cause light to wind around the region again and again, creating an infinite set of relativistic images. Travelers will notice two disruptions as the vessel passes through the Caustic to the Throat and back out again.

Passage through the Throat of the wormhole is the most critical phase of the journey. Tidal and shear stresses are maximal, and contact with the boundaries of the Throat leads to exposure to immense gravitational tides. Ships making actual contact with the Throat are shredded by gravitational strains, and even small energy releases turn into violent sprays of energetic radiation which can disrupt or destroy computational or hibernation substrates.

Since neither computation nor communication can occur in the Caustic, transiting vessels shut down and follow ballistic paths during the transition. The size, g-tolerance, and acceleration of the vessel and its passengers determine the length of time required to traverse the Netherworld — the traditional name of this transition. For a typical sophont capable of sustaining moderate tidal stress, the transit time from Exit Station to the Throat to the Entrance Station at the destination takes approximately 103 days. In practice, most sophonts undergo hibernation during transit; this reduces the transit time by increasing allowable acceleration, and adds an additional safety margin for maneuvering.

Modern Wormhole Ferries are capable of crossing from Exit Station to Entrance Station in only 32 days. They typically provide lavish virtual-reality environments and the best vessels provide Known Net access during most of the journey. Of course, all communications and virtual realities shut down during passage through the Netherworld with system restart and acceleration back towards Entrance station commencing as soon as the wormhole transition is complete.

For more on travel through wormholes, see Wormhole Termini.

Wormhole Sizes

The size of a wormhole is primarily determined by the space-time engineering capability of the creating transapient. Wormholes are manufactured using a very extensive array of ultratechnology known collectively as a weylforge. While other factors such as energy and mass availability, anticipated traffic flow, and even the desires of the local modosophont population can all play a role in determining a gateway's dimensions, it is the Singularity level of the portal's creator that is the ultimate arbiter of wormhole size. While First and Second Singularity minds are incapable of wormhole creation, each S-level beyond these is characterized by the ability to both synthesize wormhole gateways and to manufacture them in a manner that makes ever more efficient use of the available mass-energy required to create a gate and expand it up to the desired size in minimal time. The table below provides information on representative wormhole properties versus the S-level creating them.

As of this writing, the largest wormholes ever observed have been no more than 100 km in radius. While observations of the apparent abilities of the archai in the field of wormhole engineering, as well as information gained from rare interviews, have led some researchers to speculate that even larger gates are possible, no such portals have ever been observed. This has led other observers to speculate that some upper limit of stability or practicality prevents the archai from creating such. Others have hypothesized the existence of vast, deep space portals thousands or tens of thousands of kilometers across, used exclusively by the archai for their own mysterious purposes. Perhaps the only real certainty that can be gleaned from these various positions is that all are equally nebulous and lacking in any definite evidence of any description.

Traversable Wormhole Masses in kg and Expansion Rates
Wormhole  table 1
Image from Adam Getchell

Communication Wormholes
(AKA Hayward Wormholes, Comm-gauge Wormholes, Microgauge Wormholes)

comm-gauge wormhole
Image from Steve Bowers
Comm-gauge wormholes are much smaller than traversable wormholes, and only allow the passage of information (usually in the form of modulated electromagnetic radiation).

A simpler class of wormhole to construct is a Communication or Comm-gauge Wormhole. In this case tidal forces and proper transit time are not a consideration since only null geodesics (light beams) traverse the throat. However, this is compensated for by the difficulty entailed in attempting stabilization of wormholes with small masses. Because destabilization can result from the close passage of as little as 1% of the wormhole rest-mass, exotic gravitational artifacts are enough to convert microscopic wormholes into microscopic black holes. This has a number of other space-time engineering uses, but for the purpose of wormhole construction, microscopic, so-call comm-gauge wormholes require transapient stabilization.

Comm-gauge wormholes are generally of the class of wormhole known as Hayward wormholes, which are attractive for communication purposes because asymptotic flatness requirements are reduced to only ten thousand times the wormhole radius. This allows decreased distances between communication routers centered on the communicable wormhole gateway.

Although they have several traits which make them useful communication tools, Hayward class wormholes are not without their disadvantages. Due to the nature of their structure, Hayward holes are vastly more massive compared to their size than a modified MTK wormhole of equivalent dimensions. A 100 meter Hayward wormhole, if one were ever built, would mass some 6.73E30 kilograms or nearly three and a half solar masses. In practice comm-gauge wormhole links are measured in dimensions ranging from nanometers to millimeters and have correspondingly more manageable masses. A link of 1-nanometer radius would only mass some 6.73E19 kilograms or approximately 7% of the mass of the Sol System asteroid Ceres (prior to its reengineering during the Interplanetary Age).

Wormhole Bandwidth

Comm-gauge wormholes play a vital yet curious role in the life of Terragens Civilization and the transapient intelligences which rule it. In one instance these devices are the source of one of modern civilization's greatest strengths: the ability to transmit information across vast distances in almost zero time. In the other, they are a great limitation, channeling and restricting the thoughts and communications of all levels of civilization to a fraction of their full potential. The issue is one of bandwidth.

Modern civilization employs massive data flows to operate and maintain itself, ranging from the statistical modeling simulations of traffic control and planetary weather systems to the uploaded minds of trillions of sophonts to the vast and mysterious thoughts of the AI Gods themselves. To be most effective across the distances encompassed by Terragens culture, these data streams must be routed to their destinations as quickly as possible, which should mean being sent via wormhole. Yet wormholes have a limitation. Due to the nature of their structure, they are severely limited in the amount of information that can pass through them at any given moment. By the standards of past cultures this quantity of data might have seemed so great as to be able to meet any conceivable demand. But by the standards of our modern age, even the most capable wormhole link is woefully inadequate to match the data output of a modest star system.

This situation lends itself to no easy solution, although various methods are employed to at least alleviate the problem. Data compression techniques have been raised to a high art to compact a maximum amount of information into the smallest possible data burst. High energy data lasers in the petawatt range are a standard part of wormhole data networks in nearly all of the most developed systems while gigawatt links are the norm practically everywhere else. On occasion great "data freighters" will be employed to record and transit especially important data across the Nexus. And for the lowest priority or (conversely) largest data packages conventional communications lasers operating across "normal space' volumes are used. This is because the communications shared by the archai may become so large and complex that it literally takes a fraction of the time to send them "conventionally" across interstellar space as it would take to transmit them using the limited bandwidth of a wormhole.

Despite these limitations, the importance of wormhole links and the near instant communication they provide among millions of worlds cannot be underestimated. Without the wormholes, civilization as we know it could not exist.

Hayward(Comm-gauge)Wormholes: Sizes, Masses, and Bandwidths
wormhole table 2
Image from Adam Getchell

Failure Modes

Under certain circumstances wormholes can become unstable. While the wormhole solution is reasonably stable, under some conditions it is subject to instabilities that can cause either explosion to an inflationary universe, or collapse to a black hole. For collapse, some 70% of the wormhole mass-energy is radiated away; the rest becomes the mass of the black hole. For explosion, radiated energy self-reinforces leading to inflation into a new space-time.

Instabilities can arise in three forms:

1) In practice, transapient stabilization technologies are able to compensate for such small instabilities with relative ease. However, as the energy or mass involved increases, the ability of stabilizer systems to compensate becomes ever smaller until a point of uncontrollable instability is reached when the perturbing mass-energy exceeds the rest mass of the wormhole and asymptotic flatness constraints are violated.

2) Linear instabilities: Wormholes are typically subjected to linear instabilities during the deployment phase, right after the wormhole has been inflated from the quantum regime, but before it is inflated to traversable size. These instabilities come from Lorentz contraction during the transport of the wormhole mouths to their final destinations and are typically limited to perturbations of less than 50% of the wormhole rest mass. For this reason, wormhole transport velocities are constrained to less than .74c.

It should be noted that this constraint on wormhole transport velocities does not apply when the wormhole mouths are being transported within a Void bubble. Within such bubbles space-time is asymptotically flat and time-dilation and Lorentz contraction effects do not occur. Wormhole mouths transported by Void drive can travel at any velocity below c without harmful effects.

3) Chronodynamic instability: Under certain circumstances a wormhole can become a time machine, resulting in its immediate destruction through the so-called Visser Effect. Whenever a Closed Timelike Curve is formed, a Cauchy horizon will also appear which destabilises the wormhole and causes a collapse. The procedure for creating a CTC is:

· Create a wormhole

· Induce a time shift between the mouths

· Bring the mouths close enough together so that the distance through the simply-connected region ("normal space") is less than the time shift.

The simplest way to induce a time shift is to move one mouth at relativistic velocity. This is the usual course of events in deployment of a wormhole gate between systems. However, once brought to the target system, the wormhole is inflated and remains in far orbit around the star, so a normal wormhole will not create a time machine.

General relativistic means for inducing time shift exist (e.g. orbit around massive objects), but they are of no engineering concern.

Of far greater concern is the possibility of a "Roman" configuration (named for an Information Age physicist who first considered the idea) involving multiple wormholes. Such a configuration results when a set of wormholes by themselves are not time machines, but form a network that does produce a time machine.

For the simplest two-wormhole configuration, there are essentially 3 requirements:

  • Net distance traversed through the wormhole as measured in asymptotically flat space exceeds distance traversed in flat space to the mouths (trivially satisfied)
  • The wormhole time shift is anti-parallel
  • The distance between mouths is shorter than the overall time shift.
To avoid Roman time machines, one of two criteria are sufficient:

  • The wormhole network consists only of directed, acyclic graphs
  • Wormhole linelayers carry wormhole mouths from core systems to exterior systems only; no "backtracking" networks allowed.
As a concrete example, a linelayer with 1g of acceleration will achieve .7c in 10 months. Neglecting acceleration and turnaround (which is a small fraction of the total trip), the travel time as measured by the home system will be ~14 years; the linelayer will measure ~10 years. Upon arrival, if a second linelayer is sent back to the original system, it will generate a CTC when ~5 ly distant. The Chronodynamics significantly restricts wormhole placement and the overall structure of the Wormhole Nexus and Known Net.

In sum, wormholes must be stabilized by transapient systems. Larger wormholes are more stable, but the results of disaster are correspondingly greater. Chronology Protection mandates careful arrangement of wormhole networks.

Image from Steve Bowers
Hidden by the optical distortion around the wormhole is the godtech layer, which controls and maintains the exotic energy required to keep the hole open. The controlling Gate Archailect dwells inside this structure.

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Additional Information
Isaac Arthur's YouTube video on wormholes here Wormholes

An excellent simulation of a journey through a wormhole