Advanced Space Propulsion Based on Vacuum (Spacetime Metric) Engineering
A theme that has come to the fore in advanced planning for long-range space exploration is the concept that empty space itself (the quantum vacuum, or spacetime metric) might be engineered so as to provide energy/thrust for future space vehicles. Although far-reaching, such a proposal is solidly grounded in modern physical theory, and therefore the possibility that matter/vacuum interactions might be engineered for space-flight applications is not a priori ruled out. As examples, the current development of theoretical physics addresses such topics as warp drives, traversable wormholes and time machines that provide for such vacuum engineering possibilities. We provide here from a broad perspective the physics and correlates/consequences of the engineering of the spacetime metric.
Keywords: Space propulsion, metric engineering, spacetime alteration, warp drives, wormholes, polarizable vacuum
The concept of “engineering the vacuum” found its first expression in the physics literature when it was introduced by Nobelist T.D. Lee in his textbook Particle Physics and Introduction to Field Theory . There he stated: “The experimental method to alter the properties of the vacuum may be called vacuum engineering…. If indeed we are able to alter the vacuum, then we may encounter new phenomena, totally unexpected.” This legitimization of the vacuum engineering concept was based on the recognition that the vacuum is characterized by parameters and structure that leave no doubt that it constitutes an energetic and structured medium in its own right. Foremost among these are that (1) within the context of quantum theory the vacuum is the seat of energetic particle and field fluctuations, and (2) within the context of general relativity the vacuum is the seat of a spacetime structure (metric) that encodes the distribution of matter and energy. Indeed, on the flyleaf of a book of essays by Einstein and others on the properties of the vacuum we find the statement “The vacuum is fast emerging as the central structure of modern physics” . Perhaps the most definitive statement acknowledging the central role of the vacuum in modern physics is provided by 2004 Nobel Prize winner Frank Wilczek in his recent book The Lightness of Being: Mass, Ether and the Unification of Forces :
What is space? An empty stage where the physical world of matter acts out its drama? An equal participant that both provides background and has a life of its own? Or the primary reality of which matter is a secondary manifestation? Views on this question have evolved, and several times have changed radically, over the history of science. Today the third view is triumphant.”
Given the known characteristics of the vacuum, one might reasonably inquire as to why it is not immediately obvious how to catalyze robust interactions of the type sought for space- flight applications. To begin, in the case of quantum vacuum processes there are uncertainties that remain to be clarified regarding global thermodynamic and energy constraints. Furthermore, it is likely that energetic components of potential utility involve very small-wavelength, high-frequency field structures and thus resist facile engineering solutions. With regard to perturbation of the spacetime metric, the required energy densities predicted by present theory exceed by many orders of magnitude values achievable with existing engineering techniques. Nonetheless, one can examine the possibilities and implications under the expectation that as science and its attendant derivative technologies mature, felicitous means may yet be found that permit the exploitation of the enormous, as-yet-untapped potential of engineering so-called “empty space,” the vacuum.
In Section 2 the underlying mathematical platform for investigating spacetime structure, the metric tensor approach, is introduced. Section 3 provides an outline of the attendant physical effects that derive from alterations in the spacetime structure, and Section 4 catalogs these effects as they would be exhibited in the presence of advanced aerospace craft technologies based on spacetime modification.
2. SPACETIME MODIFICATION – METRIC TENSOR APPROACH
Despite the daunting energy requirements to restructure the spacetime metric to a significant degree, the forms that such restructuring would take to be useful for space-flight applications can be investigated, and their corollary attributes and consequences determined – a “Blue Sky,” general-relativity-for-engineers approach, as it were. From such a study the signatures that would accompany such advanced-technology craft can be outlined, and possible effects of the technology with regard to spacetime effects that include such phenomena as the distortion of space and time can be cataloged. This would include, among other consequences, cataloging effects that might be potentially harmful to human physiology. . . . [read entire DIA Paper]