under the assumption that the effects measured in the lab are real.tokamac wrote:There are already theories that don't break the laws of physics. We simply don't know yet if any of them corresponds to the EmDrive physics. I tried to sum up all proposed working principles for the EmDrive, the good ones and the bad:

Radiation pressure: Roger Shawyer's explanation about radiation pressure due to different EM group velocities upon the two end reflectors of the tapered cavity seems to break conservation of momentum, even resorting to different frames of reference in special relativity.

Lorentz force imbalance: Juan Yang at NWPU and Guido Fetta at Cannae LLC both refer to a Lorentz force imbalance acting on the lectron trajectories upon the two end reflectors of the cavity, using classical electromagnetism. Same breaking of the laws of conservation of momentum.

Quantum vacuum virtual plasma: Harold "Sonny" White at NASA has a conjecture about Quantum Vacuum Fluctuations (QVF). He thinks thevirtualparticles that pop in and out of the vacuum state can be treated as arealplasma. So he tries to impart momentum on this virtual plasma using magnetohydrodynamics (MHD) i.e. a Lorentz force produced by crossed electric and magnetic fields that accelerates electrically conducting fluids. So White's Q-thruster is like an electromagnetic plasma thruster, except the propellant that is pushed back is avirtual plasmacreated from the vacuum by quantum fluctuations. The fact that momentum could be imparted tovirtualparticles is not proved and quite dubious though. The model predicts a force output scaling proportional to the E-field strength to the fourth power (V^4).

Scalar-tensor theory: Fernando Minotti from CONICET explains that a scalar-tensor theory of gravity, of the Brans-Dicke type (proposed by Mbelek & Lachièze-Rey) would account for the thrust produced by RF resonant tapered cavities. Within this S-T theory, the thrust is the result of the gravitational force on the cavity walls. The metric tensor has a negative effective source. With the different EM resonant modes (TE or TM) in the cavity, the corresponding total effective source is zero, with differentiated regions where it is either positive or negative (the latter should thus be located as close as possible to the walls). Moreover this theory is compatible with an increased thrust due to the presence of a dielectric resonator inside of the cavity near an end reflector, which would distort the source distribution in the right direction. The effective source is proportional to the time average of B^2 – (E/c)^2

S-T theory is easily falsifiable in the lab:

- First, for fixed EM resonant mode and power, but different operating resonant frequencies, thrust could be higher with certainlowerfrequencies, and thrust should reverse for other frequencies. Those special frequencies can be precisely calculated, from cavity dimensions.

- Second, still for fixed EM resonant mode and power, the thrust should increase with the mass of the cavity. One does not even have to change the cavity, but simply wrap it with a layer of some heavy material.

Mach effect: James Woodward at CSUF has integrated Sciama's work about Mach's principle and Wheeler-Feynman "action at a distance" theory within the framework of General Relativity, that led to the description of relativistic Mach effects. This work led to experimental testing of propellantless Mach Effect Thrusters (MET) and a theoretical development involving Transient Mass Equation (TME). The TME could explain why an RF resonant tapered cavity like the EmDrive, with a dielectric material inside, would produce thrust when the dielectric increases its internal energy, storing energy from the microwaves. It could also explain why such a version of the same cavity lacking its internal dielectric would still produce a (smaller) thrust, due to the metal of the cavity walls which is weakly electrostrictive. The model predicts a force output scaling to the second power (quadratic).

I hope ME ends up being the winning explaination.