Well, for what its worth I calculate the skin depth for copper at 1900 MHz is about 1.5 microns. The electron acceleration I get is about 7.7 g's. Not near high enough. And note, to be precise, the cavity dimensions are about 0.25146 m major dia., 0.16764 m minor dia. 0.2286 m height. (Picked off the screen picture with a ruler scaling to the 1.5 inch cross section of the support arm.)
Quote from: aero on 10/11/2014 10:46 pmWell, for what its worth I calculate the skin depth for copper at 1900 MHz is about 1.5 microns. The electron acceleration I get is about 7.7 g's. Not near high enough. And note, to be precise, the cavity dimensions are about 0.25146 m major dia., 0.16764 m minor dia. 0.2286 m height. (Picked off the screen picture with a ruler scaling to the 1.5 inch cross section of the support arm.)7.7g If I understand Rodal, the idea would be to consider the oscillating electrons as a moving wall (a bit like the "moving mirror" in dynamical Casimir effect experiments). Those electrons wouldn't be ejected, they are accelerated back and forth but kept at stationary position (averaged on a period), it's like a "vibratory wall". During a half period that is 1/(2freq) all electrons could go for a back and forth trip of half a skin depth (considering only moves normal to the surfaces are relevant as for a moving "volume"). Give or take a 0.5 factor somewhere we are about max acceleration = skin_depth * freq² = 1.5e-6 * 1.9e9² = 5.4e12 m/s², huge but five orders of magnitude below needed acceleration for Unruh waves of 1m long (from McCulloch as reported by Rodal). That's by assuming all electrons go full back and forth oscillation at skin depth.Was that it ?One more paper to devour (?) not already linked to (??)http://arxiv.org/abs/1103.0835I like fig. 2 page 4 that links the different effects.I don't see photons could play the role of a moving wall for a cavity bouncing photons (virtual or real).
Another very good sign that EMdrive probably really works.
Quote from: Mulletron on 10/12/2014 12:25 pmAnother very good sign that EMdrive probably really works.Another good sign that the promise of the drive excites the imagination, and results in a good deal of professional interest.Film note: One of my earlier pieces.Hark ye!
2) What objects inside the cavity are accelerating to 7.2*10^17 m/s^2 ?...that is an acceleration of 730,000,000,000,000,000 times larger than 1 g.
By the way, that acceleration will exceed the speed of light in less than one cycle of the RF wave.
I get that phase velocity can out run group velocity and can even be superluminal but where's the thrust?
The walls of the cavity, in addition to the static casimir effects already postulated, could be exhibiting a weak dynamical casimir effect by virtue of the movements of the electrons. They aren't a moving mirror so this is very loosely correlated. How can a moving electron act as a moving mirror affecting any modes if any? The surface isn't exactly reflective in the optical sense, but it is to other wavelengths. Should the emdrive be silvered? Or covered in DLP like chips, to enhance this? Now I'm falling down another rabbit hole.
Quote from: Mulletron on 10/12/2014 10:20 amThe walls of the cavity, in addition to the static casimir effects already postulated, could be exhibiting a weak dynamical casimir effect by virtue of the movements of the electrons. They aren't a moving mirror so this is very loosely correlated. How can a moving electron act as a moving mirror affecting any modes if any? The surface isn't exactly reflective in the optical sense, but it is to other wavelengths. Should the emdrive be silvered? Or covered in DLP like chips, to enhance this? Now I'm falling down another rabbit hole.A sea of free electrons is a mirror, for wavelengths longer than distance between them (optical yes, microwave definitely) so moving electrons do behave as a moving mirror (with a very low inertia compared to a solid mirror). Actually it is the "recoil" of being a mirror for the microwaves that makes them move and could make them move for other wavelength. Then the space charge prevent them to leave completely : they are bound within a certain depth by the positive holes they left in the lattice by moving... Basically this is a capacitor : applied E field => proportional charge displacements. That said, I'm far form certain this makes any sense : wouldn't the free electron (of the copper walls) move tangentially rather than normal to the surfaces to "counteract" the incoming E field and making the RF wave bounce ? What are the patterns of the "eddy currents" in presence of standing waves ? Intuitively I would say we have large scale current loops trying to make a H field normal to surface, that is tangential currents, not normal back and forth like a capacitor. If the charge displacements are tangential then the "mirror" isn't really moving (constant enclosed volume).If alternating back and forth in the depth, then we have (from capacitor analogy) density of electrons rho=Q/A (Charge on Area) and electric field E=rho/eps (permittivity). From 8.5×10^28 electrons per cubic metre for copper we have 1.36e10 Coulomb/m^3 that is rho=2e4 C/m² at 1.5µm depth and E = 2e4/8.8e-12 = 2.3e15 V/m. See also permittivity D=eps E : D is same as rho (C/m²) E electric field (V/m) and eps whatever...I'm doing as if the electrons of the copper were in vacuum...Mmm, this E is not in excess of vacuum dielectric strength (1e18 V/m) What are the E fields reported for the EMdrives resonant cavities ? Because this is in far excess of air (3e6 V/m) and even teflon (up to 1.7e8 V/m) dielectric strength. So even if high Q factor could pump up E field amplitude to such levels, materials would experience breakdown. Unless I messed up a 10^9 factor somewhere again ?And such a hypothetical move of all electrons back and forth to skin depth can only make for about 5e12m/s² moving (oscillating mirror) : is it enough ?
Quote from: Rodal on 10/11/2014 10:31 pm2) What objects inside the cavity are accelerating to 7.2*10^17 m/s^2 ?...that is an acceleration of 730,000,000,000,000,000 times larger than 1 g.Quote from: aero on 10/11/2014 11:33 pmBy the way, that acceleration will exceed the speed of light in less than one cycle of the RF wave.Somebody check this? Before I call el poopo del toro?
By what logic are you assuming a photon would see unruh radiation when the speed of light is the same in all reference frames?This accelerating photon seeing unruh radiation stuff is nonsense. ...
By what logic are you assuming a photon would see unruh radiation when the speed of light is the same in all reference frames?