A radio frequency (RF) resonant cavity thruster is a proposed type of electromagnetic thruster. Unlike conventional electromagnetic thrusters, a resonant cavity thruster uses no reaction mass and emits no directional radiation. Their design principles are not supported by prevailing scientific theories, apparently violating the law of conservation of momentum; as a result they are controversial.
Aerospace engineer Roger Shawyer designed the EmDrive in 2001 and has persistently promoted the idea through his company, Satellite Propulsion Research. Chemical engineer Guido Fetta designed the Cannae Drive, based on similar principles.
If they are found to work as claimed, providing thrust without consuming a propellant would revolutionise many propulsion applications.
Imagine something like the impulse drive in Star Trek. The Star Trek impulse drive may have been described in technical manual as a nuclear fusion powered drive using something like regular rocketry, but the Star Trek technical manual wanted to assist suspension of disbelief. In the Star Trek Stories Impulse drive could provide acceleration up to any limit desired by the writers and have it offset by antigravity. Also, there was generally no limit on fuel resources being expended. Therefore, the impulse drive in Star Trek per how it was used in the movies and books was more akin to a reactionless drive which provides excellent propulsion so long as the system has power. Impulse drive and EMdrive both still have speed of light (relativistic) limitations.
You would not have antigravity but whatever power level you could achieve would have constant acceleration up to relativistic limits. Limitations would be based on the energy density and energy levels of your power source.
There is write up on reactionless drives at projectrho.com
Cannae drive is preparing for another demonstration of our superconducting thruster technology in May. Here is a picture of our assembled thruster and test apparatus. The thruster is under vacuum and ready for cryogenic operation.
Various teams around the world have begun to build their own versions of the EmDrive and put them through their paces. And to everyone’s surprise, they’ve begun to reproduce Shawyer’s results. The EmDrive, it seems, really does produce thrust. In total, six independent experiments have backed Shawyer’s original claims.
How to explain the seeming violation of conservation of momentum from EMdrive and Cannae drive ? Quantized Momentum
Mike McCulloch at Plymouth University explanation is based on a new theory of inertia that makes startling predictions about the way objects move under very small accelerations.
Inertia is the resistance of all massive objects to changes in motion or accelerations. In modern physics, inertia is treated as a fundamental property of massive objects subjected to an acceleration. Indeed, mass can be thought of as a measure of inertia. But why inertia exists at all has puzzled scientists for centuries.
McCulloch’s idea is that inertia arises from an effect predicted by general relativity called Unruh radiation. This is the notion that an accelerating object experiences black body radiation. In other words, the universe warms up when you accelerate.
According to McCulloch, inertia is simply the pressure the Unruh radiation exerts on an accelerating body.
That’s hard to test at the accelerations we normally observe on Earth. But things get interesting when the accelerations involved are smaller and the wavelength of Unruh radiation gets larger.
At very small accelerations, the wavelengths become so large they can no longer fit in the observable universe. When this happens, inertia can take only certain whole-wavelength values and so jumps from one value to the next. In other words, inertia must quantized at small accelerations.
McCulloch says there is observational evidence for this in the form of the famous fly by anomalies. These are the strange jumps in momentum observed in some spacecraft as they fly past Earth toward other planets.
Arxiv - Testing quantised inertia on the emdrive
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Reposted via Next Big Future
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