Historical research guide · 1057 · 2004
Prospects for Breakthrough Propulsion From Physics
Marc G. Millis
In one minute
Marc Millis ran NASA’s Breakthrough Propulsion Physics project from 1996 to 2002, and this is his own summary of it, written for a NASA and Department of Defense conference. The project set three challenges: find propulsion that needs no propellant, find a way to cut transit times dramatically, and find new ways to make power on board — the third included because the first two will probably need it. Rather than chase a breakthrough head-on, Millis funded small affordable tasks aimed at the make-or-break question behind each idea, and defined success as reliable knowledge rather than a positive result. Sixteen such tasks are scored here: six came back not viable, six unresolved, four with clear openings for a sequel. The openings are the interesting part — rectangular Casimir cavities built as micro-machined devices, the demonstration that a net propulsive force can in principle be drawn from vacuum energy, warp drives and wormholes under the heading Millis calls metric engineering, and the proposal that inertia itself is a vacuum effect.
Connection
Chapter 8 asks whether a craft can be moved without throwing anything overboard, and this is NASA’s own framing of that question with the two make-or-break issues named out loud. Chapters 4 and 6 inherit the openings Millis leaves standing in the ledger: metric engineering as the route past the light-speed limit through space, and the finding that a net propulsive force can in principle be drawn from the quantum vacuum.
From the source
NASA’s Breakthrough Propulsion Physics project defined three grand challenges. First, mass: discover propulsion that eliminates or dramatically reduces the need for propellant, presumably by interacting with the properties of space or by manipulating gravitational or inertial forces. Second, speed: discover how to move near the light-speed limit through space, or manipulate spacetime to circumvent it. Third, energy: discover fundamentally new modes of onboard energy production, included because the first two may require it and because the physics underlying propulsion is closely linked to energy physics.Section 2.1, Technical Challenges
The project’s operating discipline defines success as acquiring reliable knowledge rather than as achieving a breakthrough, publishes results regardless of outcome because null results are also valuable progress, and asks reviewers to judge whether the work will produce a conclusion others can build on rather than to predict in advance whether the idea will work. Of sixteen tasks scored, six were found not viable, six remain unresolved or debatable, and four have clear opportunities for sequels; thirteen peer-reviewed journal articles came out of the eight tasks NASA sponsored directly.Section 2.2, and Section 3 opening with Section 3.1
New analytical and experimental tools were developed to study quantum vacuum energy in micro-electromechanical rectangular Casimir cavities, and Millis reports that it was shown that in principle it is possible to create net propulsive forces by interacting with this energy, even though the forces are impractically small at this stage — while conversion of minor amounts of vacuum energy without violating thermodynamic laws had already been established in the literature.Section 3.1.8, Explore Vacuum Energy, citing references 6 to 13 and 29 to 31
The space drive task named the two largest obstacles precisely: first, find a way for a vehicle to induce external net forces on itself, and second, satisfy conservation of momentum in the process. Three research avenues are left open — investigate space as a new source of reaction mass, revisit Mach’s principle to consider coupling to surrounding mass through inertial frames, and investigate the coupling between gravity, inertia and controllable electromagnetic phenomena.Section 3.1.1, Define Space Drive Strategy
Millis states the metric-engineering principle in one sentence: if one cannot break the light-speed limit through space, then alter space. He records the warp drive, which moves a bubble of spacetime carrying a vehicle inside it, and the wormhole, a shortcut created by extreme spacetime warping, as a growing topic in the scientific literature, and notes that the term metric engineering has emerged at aerospace conferences to name this class of concept.Section 3.3.1, Metric Engineering, citing references 56 to 67
Two separately funded lines of work — theoretical research sponsored by NASA Headquarters from 1996 to 1999, and privately funded programmes at the Institute for Advanced Studies in Austin and the California Institute for Physics and Astrophysics — advance the assertion that inertia is an electromagnetic drag force arising during accelerated motion through the vacuum energy, and closely related, that gravity is a consequence of quantum vacuum fluctuations. Millis records the speculation this leads to, that inertial properties might become alterable by electromagnetic means.Sections 3.2.2 and 3.3.4, citing references 39 to 41 and 79 to 88
The way in
https://ntrs.nasa.gov/citations/20040070788How to cite it
Marc G. Millis (2004) Prospects for Breakthrough Propulsion From Physics doi:10.1109/eh.2004.1310847