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Reactionless Drives

Propulsion without reaction mass; some technical details

halo drive 4
Image from Juan Ochoa
A Halo drive vessel, a reactionless craft which can only be built by Fifth Toposophic Archailects and above

Overview

The use of warp bubbles and manipulation of the space-time metric apparently allows reactionless propulsion in spacecraft designed and built by Archailects. Although the exact details of this technology has never been revealed to lesser sophonts, observation of the characteristics of these kinds of craft has allowed a working theory to be developed which seeks to explain how these vessels work.

A warp bubble is a region of space time enclosed in a fold, or bubble, of highly curved space. By expanding the space time metric behind the bubble and contracting the metric in front, the bubble can be made to move without the use of propellant mass. The vessel can apparently be coupled to the warp bubble(s) in various ways; by containing the bubbles wholly within the ship, as in the Displacement Drive; in front of the ship, coupled by gravitomagnetism, as in the Halo Drive; or entirely enclosing the ship, as in the Void Drive.

Note that no warp bubble has ever been observed travelling at super-luminal speeds. It is thought that such faster-than-light travel is impossible with void bubbles, because of dynamical instability of the warp metric at speeds greater than light and a suspected high flux of Hawking radiation that would turn anything inside a faster-than-light void bubble into a plasma of fundamental particles.

Access to Reactionless Drives

Reactionless drives can only be created by beings with a toposophic level greater than S4, and must be controlled by a high transapient mind. Whenever a reactionless drive is gifted to beings of a lower toosophic level the drive itself will be controlled by a dedicated hyperturing entity of very advanced type.

Technical Details



—beginitem: Editors Note
author: Verified, NodeE4568/EGEB DateTime7.2356E3/10499

Although extensive hypotheses and theoretical explanations regarding the operating principles of transapient 'reactionless' drives have appeared on and off ever since the drives were first observed in action (the oldest known attempt itself has not as yet been conclusively dated, but probably originating on the Known Net (DateTimenull/10000), in recent times a particularly strident hive or group of researchers of unknown clade uploaded to the Known Net (DateTime2.345E6/10499) a lengthy series of reports written in archaic scientific notation from the Martian Genobiology and Mining University access point.

This series of reports contains purported research calculations, experimental evidence, and sensoria of thought-exchanges with a number of archai spanning a substantial stretch of modern history; nearly 5 millennia or so if internal consistency correlated with known events is accepted.

Of particular note in recent times is the generation of a new meme directly traceable from these publications, the Void Bubble. Current experts on retainer to the Encyclopaedia demur as to the accuracy of some of the scientific postulates referenced in the paper explicating this concept, but no specific objections have been delineated to the Review Board, and none of the independent researchers involved in the appropriate disciplines accessible to the Review finds fault in the basic physical principles as explained. Therefore, as an interesting insight into recent memetic propagation, as well as a point of reference to current conspiracy memesets (not articulated here, but the Board duly notes the existence of these alternative viewpoints) this material has been approved for inclusion, although it must be considered to be more speculative than the normative Encyclopaedia Galactica article.

enditem
beginitem: Article
author: Unknown, but attributed to Node45E21/MGMU
DateTime2.345E6/10499, spatiotemporal format of data
suspect/unverified




The concept of a warp drive has a long, illustrious history — longer even than that of wormholes. Unlike wormholes, however, the existence and engineering practicality of warp drives has never been demonstrated — until now.
filterengaged: transapient craft sightings && newmeme:Void Bubble
Whatever the case, the observance of transapient reactionless drive vessels provides empirical confirmation that such technologies exist, and are being withheld from general use.
filterengaged: memeset:ConspiracyTheory
The theory behind a warp drive was first explained in the Interplanetary Era by M. Alcubierre, with refinements by J. Natario and others, to the extent that the historical literature of the times generally refers to warp devices as Alcubierre or Natario drives. I will continue this tradition in the interest of historical continuity and to reduce the memetic shock of the interested audience in the references of the ancient papers.

The basic concept of the warp drive is, as expected, congruent with basic space-time engineering principles. A metric is engineered so as to provide continual contraction in front of the warp bubble and expansion behind it, with the result that the asymptotically flat space-time contained by the bubble is propelled at an effective velocity given by the constraints of the metric.

The Natario version adds the crucial distinction of contracting space-time in the radial direction while expanding it in the axial direction, with the important difference that there is no perceptible warp.

The metric engineering difficulties in this technique are more pronounced than in wormholes, because they are by nature dynamical, with an inherently unstable metric, in contrast to the saddle-point nature of wormhole space-times, which are statically and dynamically stable. This simple difference, along with memetic manipulation by the archai, has held back baseline progress in the understanding of reactionless drives.

Like wormholes, warp drives require negative stress energy tensor fields to maintain the warp drive. For both examples above, the amount of negative stress energy required is given by a simple semi classical General Relativistic calculation to be:

E = -1/12*v^2*(R/delta + delta/12)

where v = warp bubble velocity, R = warp bubble radius, and delta = warp bubble thickness.

Normally, quantum inequality restrictions on warp bubble thickness alone generate unrealistically large amounts of negative stress-energy needed for construction.

However, there are two classical techniques for reducing the amount of negative stress-energy to tractable amounts that can be handled by modern wormhole stabilization technology. The first is to engineer the metric to contain a lapse function, the so-called ESAA (Ex Somnium Ad Astra) metric.
The ESAA metric gives the new warp bubble thickness as:

delta (less than)= 10^2(v/c)l A0

where v = warp bubble velocity, l = Planck length, and A is the minimal lapse function in the ESAA metric. Increasing the warp bubble thickness decreases the amount of negative stress-energy, as seen in the previous equation.

The second technique is to minimize the volume of the warp bubble. A double warp metric is created: an external, microscopic metric which reduces the volume of the bubble, and an internal warp metric which increases the internal volume. Thus, picometer-sized warp bubbles are created with internal volumes on the order of 10's of meters.

However, even such 'efficient' warp bubble effects still appear to require the use of massive external generation facilities and multi-solar mass instrumentalities to create them (although the associated drive node stabilization and control devices appear to be quite compact, perhaps only a few meters across at most).

Deduced implementations of warp drive nodes are as follows:

Drive nodes consisting of extremely dense matter (magmatter grade or higher) are enclosed inside a double ESAA metric using transapient technology. Due to metric engineering constraints, each node must contain its entire fuel supply; when the node runs out of energy, it will be unable to maintain the metric. Nor can a node activate a metric by itself or reactivate one once it has been turned off. Detailed analysis indicates probable fine-scale magmatter construction with monopole-catalyzed fusion and a compressed baryonic fuel source. No node defueling/de-warping signature events have ever been observed on observation time garnered on the Argus array -- it is possible that a further transapient technology for inter-converting monopoles with baryons may exist, allowing the drive node to be completely expended. There is also evidence that in some cases a low mass singularity may be enclosed within the bubble and used to power the drive node via Hawking decay. There are also some indications that some form of wormhole based refueling process may be employed in sufficiently energetic environments.

Drive nodes are constructed in either the Alcubierre or Natario configuration: in either case, the nanoscopic nodes are linked back to the main vessel via electromagnetic fields. Due to warp metric configuration, Alcubierre nodes must always be perpendicular to the vessel and the direction of motion to achieve full thrust capability. Natario nodes must be parallel.

Although the warp motion itself is inertialess, the electromagnetic coupling between the nodes and ship is not, so the warp drive can best be described as reactionless, rather than inertialess. Furthermore, even with transapient technology it appears that the thrust per node requires many nodes to be used to achieve decent interplanetary velocity. Control/feedback issues of the nacelles are somewhat complicated by general relativistic effects, but the issue appears to be ontologically (and empirically) tractable.

A reasonable, engineered metric can generate apparent velocities at greater than the speed of light, while still maintaining a causally connected interaction region, at the cost of introducing Closed Timelike Curves within the warp metric. As current theory precludes the existence of CTCs, practical warp bubbles are limited to velocities less than c.

However, in light of the historical memetic engineering by the Archai around this topic, one cannot with certainty rule out the possibility that some Archai may, in fact, possess conveyances capable of effective faster than light travel. But the evidence on this issue is notoriously lacking, in contrast to the plentiful proof of the existence and usage of warp bubble drive vessels.

Based on the above information and observations of the major classes of reactionless drive systems we may conclude that the transapients have both developed warp bubble technology and also refined it to a level beyond even that theorized by early thinkers. To delineate the actual warp systems observed in reality from the theoretical constructs of past researchers we wish to coin the term "Void Bubble" to designate the warp bubble based technologies that I shall describe below. In the following sections we shall examine each of the major classes of reactionless drive systems and see how Void Bubble technology is employed by each of them:


Three observed classes of reactionless craft

S:4 Technologies

Displacement Drive

At Singularity level:4, a series of advances combine to enable the largest breakthrough to date, moderate sized pockets, or bubbles, of spacetime, which are larger on the "inside" than the "outside." These are the so-called Void Bubbles. At S:4, these devices can be used as engines by coupling them magnetically to the vessel. These ships are then called "Displacement Ships", as their engines are displaced out of normal space.

More on Displacement Drive


S:5 Technologies

Halo Drive

At Singularity level:5 Void Bubbles can be coupled to the craft using both gravity and magnetic forces, and a halo of void bubbles can be established at the front of the ship, essentially dragging the vessel along behind it in real space.

More information on Halo Ships here


S:6 Technologies

Void Ships

At the level of the greatest Archailects, Singularity level:6, void bubbles reach their highest state of advancement, and allow the construction of craft entirely enclosed within the bubble. These craft are invisible to observers in the outside universe, except as an acute distortion of space-time.

More Information on Void Ships here


A note on the Conservation of Momentum

There is a popular misconception that Transapient Reactionless Drives violate the Conservation of Momentum. In fact the momentum gained by the spacecraft with displacement, halo, and void drives is stored in the void bubbles, and when the void bubbles are turned off the momentum is left with the mass that was inside them.

The Alcubierre warp metric used in this class of propulsion essentially sets the property v, the proper velocity between asymptotically flat spacetime and the metric, to whatever value is desired. "Turning off" the warp metric means setting v = 0 again.

Since the drive sets velocities between metrics rather than objects embedded in metrics, it is reactionless and inertialess.

This is possible because mass-energy and momentum are not globally conserved in GR (since it's impossible to unambiguously define their totals), although any tensorial definition will always produce local conservation.

Reactionless Drive Vessels and Space Debris

Spacecraft using reactionless drive can traverse the interstellar medium at very high fractions of the speed of light. However interstellar space is not empty; it contains dust and larger particles of solid matter, as well as thinly spread gases. These materials will interact very energetically with a ship travelling at very high speed. Fast, conventional ships such as conversion drive vessels have very effective passive and active shield systems to defend the craft against friction with the interstellar medium.

A ship powered by Displacement drive is, in essence, a "rocketless rocket", so all the usual deleterious effects that happen to a rocket also happen to a displacer ship; for this reason displacement drive vessels require very effective shielding, usually an active cloud of smart, shielding particles maintained at a suitable distance in front of the ship.

A Halo drive ship is somewhat protected by its halo, which will interact gravitationally with the debris. Given the rapid speeds, this reaction is likely to be energetic, sometimes to the point of causing one or more void bubbles to fail prematurely; in this case the remaining bubbles will be automatically re-arranged to compensate for the loss. The halo is deliberately arranged to deflect particles away from the main body of the ship, acting as a so-called metric shield.

A Void ship will generally ignore most classes of debris, i.e. non-exotic matter, being able to otherwise slip between molecules. Exceptions are things like magmatter, neutronium, q-balls, event horizons, or singularities (such as the track of a Thunderbolt).

Another rumoured hazard is a burst of carefully modulated gravitational radiation designed to destructively cancel the void bubble; such a weapon could conceivably be used in warfare between the archai, although there are no reliable reports of its use to date.

 
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Development Notes
Text by Todd Drashner and Adam Getchell
additions by Luke Campbell and Steve Bowers
Initially published on 19 January 2007.

References


Alcubierre on warp drives
The warp drive: hyper-fast travel within general relativity, M. Alcubierre
http://arxiv.org/PS_cache/gr-qc/pdf/0009/0009013.pdf

Natario version
Warp drive with zero expansion, J. Natario
http://arxiv.org/PS_cache/gr-qc/pdf/0009/0009013.pdf

Warp bubble thickness difficulty
The unphysical nature of Warp Drive, M. Pfenning, L. Ford
http://arxiv.org/PS_cache/gr-qc/pdf/9702/9702026.pdf

Reducing negative-stress energy
Reduced total energy requirements for a modified Alcubierre warp drive spacetime, F. Loup, D. Waite, E. Halerewicz
http://arxiv.org/PS_cache/gr-qc/pdf/0107/0107097.pdf

A warp drive with more reasonable total energy requirements, C. Van Den Broeck
http://arxiv.org/PS_cache/gr-qc/pdf/9905/9905084.pdf

Drive nacelle coordination
Null geodesics in the Alcubierre warp drive spacetime: the view from the bridge, C. Clark, W. Hiscock, S. Larson
http://arxiv.org/PS_cache/gr-qc/pdf/9907/9907019.pdf

Drive speed limitations
On the warp drive space-time, P. Gonzalez-Diaz
http://arxiv.org/PS_cache/gr-qc/pdf/9907/9907026.pdf
 
 
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