Rodal could you tell us in a few words if Schwinger's explanation of the Casimir effect as originating from charge effects (more like van der Waals ...) discards the ZPE/vacuum turmoil playing any (direct) role in Casimir forces ?
how the "vacuum wavelength exclusion" effect serving the Casimir way of explaining the experimental results predicts correct magnitude for flat plates ...?
BTW if you feel pedagogically inclined and know the answer : from QFT, are the wave propagation speeds c for all the fields, including those that have massive associated particles ?
[*] Yes, in a powered microwave resonator we have photons and we also have electrons (as part of the atoms on the walls of the resonator).
Quote[*] Yes, in a powered microwave resonator we have photons and we also have electrons (as part of the atoms on the walls of the resonator).We have a lot of other stuff there too. Remember the experiments were in atmosphere. I won't guess as to how much the air in the cavity ionized or if such could have simulated the second metallic plate or to what effect. Point is, the internals of the cavity and interactions are more complex than have been analyzed to date. Known physics may apply, I'm pretty sure, but we really don't know enough to claim correct application of applicable all known physics. Disregarding any unknown physics, but I'm willing to try to avoid unknown physics for now.
The thrust performance of this next generation tapered test article has been analytically determined to be in the 0.1 newton per kilowatt regime. Vacuum compatible RF amplifiers with power ranges of up to 125 watts will allow testing at vacuum conditions which was not possible using our current RF amplifiers due to the presence of electrolytic capacitors. The tapered thruster has a mechanical design such that it will be able to hold pressure at 14.7 pounds per square inch (psi) inside of the thruster body while the thruster is tested at vacuum to preclude glow discharge within the thruster body while it is being operated at high power.
Figure 26 shows the dielectric they plan for their next generation RF thruster. It looks to me like it fills the cavity completely. I can't guess how much room there will be for air. Not much?
Just a reminder that "analytical determination" is not the equal of "experimental determination".Solo dicendo.
More theoretical musing ...
.. If the thruster as a whole puts some of its parts at specific conditions, those can't be extreme conditions, space curvature, E/M field ... can't exceed what is routinely investigated in the lab (and in my microwave oven)...
Quote from: frobnicat on 09/19/2014 02:00 pm.. If the thruster as a whole puts some of its parts at specific conditions, those can't be extreme conditions, space curvature, E/M field ... can't exceed what is routinely investigated in the lab (and in my microwave oven)...Yes, but, we do not have at our homes, our microwave oven positioned on an inverted torsional pendulum (known to exhibit parasitic modes of motion due to coupling of swinging with torsional motion) where we attempt to measure microNewton torsional forces. And we don't have a magnetic damper attempting to overdamp the motion of the inverted pendulum to attempt to eliminate parasitic modes of motion.
Clearly the presence of very strong magnets and induced currents in the damping system is not desirable. Wouldn't it be possible to devise a system of much much lower stiffness, with a natural swinging motion period not shorter but longer than the experimental pulses (more than a minute), with no damping at all during the power on testing phases ?
I imagine that John is "solo dicendo" that it is unknown whether NASA's order of magnitude extrapolation will be realized in practice.
Ohm law is an emergent effect for large systems, not a fundamental elementary theory.
The "space drives" effects are measured at macroscopic scale and seems to require very specific arrangements of parts...
For the system to experience unheard of net momentum effects, then the parts would have to experience unheard of net momentum effects : the possibility of this new macroscopic effect implies the existence of new effect(s) at a microscopic scale ... This can't be just a matter of geometry, this should be understood at the level of particles ...
Evidently the thrust measurements are foremost related to the dielectric resonators.
Solo riportati
Quote from: Rodal on 09/19/2014 12:44 pmSolo riportatiSolo riporto? Don't know the idiomatic phrase.
where -pi/(24a^2) is the Casimir force between two ideal conducting plates separated by a.
Here is a paper written to describe the Casimir energy between a metallic plate and a dielectric plate within a cavity. The configuration is somewhat similar to the Tapered Cavity tested at EagleWorks. http://math.scichina.com:8081/sciAe/EN/abstract/abstract377962.shtml#I wonder if someone can help interpret this paper. To me, it does not seem consistent with what has been published elsewhere, in particular I see an unfamiliar term Quotewhere -pi/(24a^2) is the Casimir force between two ideal conducting plates separated by a.But also this paper is developed in a reference system where c=1, h-bar=1. That is a common system but how does one convert the results into standard units of measure. I forgot, if I ever knew how.
Quote from: aero on 09/19/2014 04:58 pmHere is a paper written to describe the Casimir energy between a metallic plate and a dielectric plate within a cavity. The configuration is somewhat similar to the Tapered Cavity tested at EagleWorks. http://math.scichina.com:8081/sciAe/EN/abstract/abstract377962.shtml#I wonder if someone can help interpret this paper. To me, it does not seem consistent with what has been published elsewhere, in particular I see an unfamiliar term Quotewhere -pi/(24a^2) is the Casimir force between two ideal conducting plates separated by a.But also this paper is developed in a reference system where c=1, h-bar=1. That is a common system but how does one convert the results into standard units of measure. I forgot, if I ever knew how.http://en.wikipedia.org/wiki/Speed_of_lighthttp://en.wikipedia.org/wiki/Planck_constant