.....Then too, one of the dark matter candidates has extremely low mass, (long wavelength) but no interaction ?
Here is a little thought experiment:Imagine a perfectly reflective metal cavity, into which a photon from the outside is injected through a tiny hole in the cavity walls. When the photon hits the inner wall for the first time, it imparts 2x its impulse on the cavity (when being absorbed and then emitted again). Thus, the cavity gains a little momentum and moves a little bit into the photon's original impulse direction, aka translation. Then the reflected photon hits the opposite inner wall and effectively stops the cavity's movement again. But: Out metal box moved for a nanosecond or so, and hence the box has experienced a translational movement. At the same time, conservation of momentum was not violated: It's time-averaged ZERO. Still, we got a translation.What do you think?
Quote from: CW on 09/20/2014 03:22 pmHere is a little thought experiment:Imagine a perfectly reflective metal cavity, into which a photon from the outside is injected through a tiny hole in the cavity walls. When the photon hits the inner wall for the first time, it imparts 2x its impulse on the cavity (when being absorbed and then emitted again). Thus, the cavity gains a little momentum and moves a little bit into the photon's original impulse direction, aka translation. Then the reflected photon hits the opposite inner wall and effectively stops the cavity's movement again. But: Out metal box moved for a nanosecond or so, and hence the box has experienced a translational movement. At the same time, conservation of momentum was not violated: It's time-averaged ZERO. Still, we got a translation.What do you think?1) In your model you assume that one of the cavity is porous to photons but the other end is reflective2) As per previous posts, even a photon rocket has specific force orders of magnitude lower than the reported values
I think the original photons momentum was transferred to the cavity. The doppler shifted reflected photon is what now balances forever in a lossless cavity.
Quote from: Notsosureofit on 09/20/2014 03:31 pmI think the original photons momentum was transferred to the cavity. The doppler shifted reflected photon is what now balances forever in a lossless cavity.Yes, the original photon adds to the system. After that, any reemitted photons zipping around are part of the system.
Well, what if it were electrons instead of photons? Somehow (help me out here) electrons originate in the dielectric, and are scattered in all directions by the high Q RF wave magnetic/electric fields. Electrons all speed to the conducting cavity walls and of course some of them travel axially toward the base plate. In the travel toward the base plate they encounter the resonating RF waves, one set of magnetic/electric fields resonating perpendicular to the end plates, another resonating parallel to the base plate. Now will the magnetic/electric fields of the RF wave turn the direction of travel of the electrons such that they never reach the base plate but instead are turned to the side and neutralized on the metallic sides of the cavity? In that situation the side forces would average to zero but the end-to-end forces would transfer momentum to the thruster body. Ok - the momentum originates in the electron acceleration from the dielectric by the RF energy which reacts with the cavity but are turned by the RF energy at the base which does not react with the cavity. hmm.
Dr. White's hypothesis is precisely that electron/positron pairs of virtual particles emerge from the Quantum Vacuum and the EM drive behaves as a MagnetoHydroDynamics plasma. Frobnicat, others and I have raised questions about that hypothesis. It is a fact that has to be addressed by any (classical or exotic) explanation that:No dielectric resonator = No measured thrustOff center-of-mass position of dielectric resonator --> direction in which thrust is measuredElectrical Field in the dielectric resonator is orders of magnitude >> than in the rest of the cavity
DissipatedPower per unit volume = 72973 W/m^3 = 0.0729 W/cm^3
Quote from: Rodal on 09/20/2014 07:44 pmDissipatedPower per unit volume = 72973 W/m^3 = 0.0729 W/cm^3Is that just waste heat, or is that waste heat and thrust?
Ok, I used 17 watts in the following, so it will need to be reduced a little to allow for the dissipated heat power.I calculated that the number of electrons, 2.54E+12 from before carry a charge of 4.07E-07 C so the current flow is 4.07E-07 amps. 17 watts of power, P = I*V gives Voltage across the cavity of 41.8 MV . This is a little higher (factor of 10 higher) than the striking voltage in air so glow discharge might be a problem.Other than that, does physics allow this mechanism?
In my model, one photon would be recycled by, say, 10^9 times.