An exotic “impossible” space propulsion technology known as “Cannae Drive,” less known than the EmDrive but equally controversial, made news headlines a few weeks ago with the announcement that it is about to be tested in space. There are speculations that the Cannae Drive could exploit physics known as “Mach Effect.” But perhaps the same physics plays a role in the EmDrive as well.
Cannae Inc., the company formed by engineer Guido Fetta to commercialize Cannae Drive technology, announced the forthcoming launch of a cubesat to test its space propulsion technology. “Cannae’s technology requires no on-board propellant to generate thrust and will provide station-keeping for a cubesat flying below a 150-mile orbital altitude,” claimed the announcement. “The demonstration satellite will remain in this orbit for a minimum of six months.”
Ending a wave of speculations on the similarities between Cannae Drive technology and the anomalous EmDrive effect, Fetta posted a clarification a few days ago:
Cannae is not using an EmDrive thruster in our upcoming launch.
“Cannae is using it’s own proprietary thruster technology which requires no on-board propellant to generate thrust,” added Fetta. “In addition, this project is being done as a private venture. Cannae is only working with our private commercial partners on the upcoming mission.”
Fetta’s statement has been interpreted as “disowning” the EmDrive approach and hinting at better ways to generate thrust without on-board propellant. “Cannae cubesat mission to use Mach-effect drive?” asks a post on the new subreddit /r/MachEffectDrive.
What is the Mach Effect Drive?
The recent Estes Park Breakthrough Propulsion Workshop – a select, invitation-only workshop in an isolated retreat – had a special focus on James Woodward’s “Mach Effect” (aka “Woodward Effect“) Drive. See also Woodward’s book, “Making Starships and Stargates – The Science of Interstellar Transport and Absurdly Benign Wormholes,” a review by Charles Platt on Boing Boing, and the related Exotic Propulsion Initiative at SSI.
“[Woodward] has pioneered ‘outside the box’ thinking aimed at solving the propulsion problem and perhaps even the problem of creating exotic matter for wormholes and warp drives,” says physicist John Cramer in his foreword to Woodward’s book. “His work has included investigations in general relativity as applied to Mach’s principle and experimental investigations of propulsion systems that propose to circumvent the third law need to eject reaction mass in order to achieve forward thrust. This line of inquiry has also led to a plausible way of satisfying the need for ‘exotic matter’ to produce wormholes and warp drives. The book you hold may offer the key to human travel to the stars.”
Mach’s principle – the idea that inertia is due to interaction with the rest of the universe, and the difference between an inertial frame and an accelerating or rotating frame is determined by distant masses and the structure of the universe at large – is taken into account in Einstein’s general relativity, but alternative theories of gravitation incorporate it more consistently. According to physicist Heidi Fearn, a collaborator of Woodward, the alternative theory of gravitation developed by Hoyle and Narlikar in the sixties, in which both retarded and advanced waves – travelling backward in time – communicate gravitational interaction is “completely Machian.”
In “Centauri Dreams – Imagining and Planning Interstellar Exploration,” an influential 2004 book on the prospect of interstellar exploration with a focus on breakthrough propulsion physics, science writer Paul Gilster notes:
No one can say which breakthrough idea, if any, may evolve into a true star drive (my money is on Woodward).
In a post on NASASpaceFlight, the unofficial online meeting point for EmDrive scientists and enthusiasts of exotic propulsion concepts, Dr. José Rodal revealed that, according to a study presented at the Estes Park Breakthrough Propulsion Workshop, the anomalous EmDrive effect could be related to the exotic physics behind the Mach/Woodward effect and the Hoyle/Narlikar theory of gravitation.
“As the Mach/Woodward effect can be derived straight from the fully covariant nonlinear Hoyle Narlikar gravitational theory or it can also be obtained from linearized General Relativity it is really as much of a gravitational effect as gravity assist,” said Rodal. “[The] Mach/Woodward effect drive perhaps should be renamed ‘Mach Effect Gravity Assist’ (MEGA) drive, to make it more obvious to the readers that the Mach Effect is a gravitational effect, and thus it would be completely incorrect to address conservation of momentum and energy without taking into account the gravitational effect.”
Images from Cannae Inc. and Space Studies Institute.