The current scientific understanding of the Warp Drive is critically flawed, for example presently there are two distinct classes of warp drive being the Alcubierre Warp Drive [1] and the Krasnikov Tube [2] (see section I).  The first model proposed by Alcubierre takes advantage of an arbitrary (top hat) function, which creates an expansion and contraction of the local spacetime coordinates.  While the Kransnikov Tube generates an exotic energy field which causes the spacetime coordinates to arrange themselves according to a projection scheme provided by the exotic energy field.  The Krasnikov Tube is perhaps the simplest warp drive model because it does not suffer from "horizon" problems, however it also requires the need for a spacecraft capable of approaching the speed of light (which creates problems of its own).  The purpose of this short article is to address these issues of warp drive and their possible solutions to advanced the current understanding of Warp Drive Physics.

Let us first discuss the Alcubierre Warp Drive, it requires a contraction of spacetime in front of a potential spacecraft with an expansion behind it.  At relatively high energy densities s (i.e. Warp Velocities), the spacetime in front becomes causally disconnect from the warp drive spacetime from s.  Meanwhile the spatial coordinates to the rear of the spacecraft are required to expand under the same magnitude, becoming disconnected from the so called "warp  bubble" (locally flat spacetime) as well.  Commonly Cosmologist use this type of causally disconnected spacetime(s) (horizons) when discussing the Big Bang Epoch, observable astronomy, and the theoretical "Big Crunch" singularity.  Simply put in cosmological terms this terminology discusses what portions of the universe are visible at a given location at a given epoch.  In regards to the theory of Warp Drive, this means that once the warp drive bubble has formed the local observer has no means to control it.

One way to solve the horizon problem is with Cosmology itself, although the Big Bang is generally excepted as scientific fact, little is known on what may have caused its rapid inflation.  Perhaps at this epoch there was a great unified field of the physical forces which caused what we conceive as gravitation to behave radically different from its observed nature.  Which intern may suggest that at higher and higher energy densities the inflation problem of the early universe could be solved, however this model contains to many unknowns.  However, recent observations with type Ia Supernova indicate a slight expansion effect hidden with the Hubbell Constant [3].  In short it appears that there exist something mysterious in the universe which is causing gravitation to repel as opposed to attract, this mysterious substance has been given the name Quintessence.  The idea of Quintessence relies less on the theoretically difficult Big Bang and perhaps may give a better understanding of this unknown gravitational effect given time and research (Einstein invented a similar concept  represented by the greek symbol L which he later withdrew calling it the biggest blunder of his life).

What we do know of the warp drive comes from the most simplistic derived model.  It is quite possible that this simplistic model completely misses important effects such a gravitational back reaction (the gravitational field interacting with itself), not to mention the interaction of the gravitational field with the background quantum vacuum [which may not be possible to fully understand without a solid theory of "quantum gravity"], and other energy sources.  We however, do know that we can negotiate around the amount of negative energy, or exotic matter (see section II) required for the trip, by the metric proposed by Van Den Broeck [4].  The Alcubierre Warp Drive, may one day be the most realistic model for the warp drive as our understanding of gravitation increases, but at present this is not the case.

We now can see that they many nagging issues of the warp drive could be solved if people just but their minds to it.  But as opposed to going around in circles with questions we can not answer, one should revert to a more simple, but more realistic model.  The Krasnikov model is known as the "Subway to the Stars," in this model no elaborate spacetime constructions are needed.  But what is required is a form of exotic matter which acts to twist on space generating a short cut within global spacetime, resulting in an Alcubierre-like Warp Drive for the return trip.  Thus perhaps one of the simplest models in verifying warp drive would be to advance our understanding of so called "exotic" matter.

Advances in observational astronomy and theoretical physics will undoubtedly make the warp drive more and more feasible as time progresses.  Although slow advances are often considered credible in academia, it can grind truly groundbreaking ideas to a halt.  So advances should be continued within the warp drive field which do not rely strictly on the accepted scientific principles of the day.  One method is to take Superstring theory, one may use wormholes for the expansion and contraction of the Alcubierre metric.  Wormholes can be viewed as doorways to parallel universe, or simply distant locations within the same universe.  If one can construct a local relative brane which is connected to an expanding spacetime and contracting one, the negative energy requirement of the Alcubierre Warp Drive breaks down.  This approach takes the best of both worlds from the Alcubierre and Krasnikov approaches, however in the long run this method may prove to be incredibly difficult.  Although this method would likely help to prove or disprove existing concepts, while at the same time going beyond the current horizons to arrive at a profound new truth.

References

[1] Alcubierre M. The Warp Drive: Hyper-Fast Travel Within General Relativity. Class.Quant.Grav. 11 (1994), L73-77. available: gr-qc/0009013

[2] Krasnikov S. Hyperfast interstellar travel in general relativity. available: gr-qc/9511068

[3]  Perlmutter S, et al. Measurments of W and L From 42 High-Redshift Supernovae. Astrophys.J. 517 (1999) 565-86 astro-ph/9812133

[4]  Broeck C. A `warp drive' with more reasonable total energy requirements. Class.Quant.Grav. 16 (1999) 3973-79 available: gr-qc/9905084

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