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The 'Impossible' EM Drive Being Tested By NASA May Finally Be Explained (technologyreview.com)
MarkWhittington writes: The EmDrive, the so-called "impossible" space drive that uses no propellant, has roiled the aerospace world for the past several years ever since it was proposed by British aerospace engineer Robert Shawyer. In essence, the claim advanced by Shawyer and others is that if you bounced microwaves in a truncated cone, thrust would be produced out the open end. Most scientists have snorted at the idea, noting correctly that such a thing would violate physical laws. However, organizations as prestigious as NASA have replicated the same results, that prototypes of the EmDrive produces thrust. How does one reconcile the experimental results with the apparent scientific impossibility? MIT Technology Review suggested a reason why.
Short version: photons seem to have inertial mass after all.
Second, if you want to appeal to Noether's theorem, note that the theorem refers to smooth manifolds. If space is quantized, then Noether's theorem doesn't apply (despite being true). It's possible that Noether's theorem will break down at small scales. (If space is smooth, ie *not* quantized, then the true location of any particle is a [mathematical] real number with infinite entropy and it's action is non-computable. Not that having a non-computable universe is a problem, but...)
Theres something about this that reminds me of Zenos paradoxes.
The Eleatics had the idea that they could logically prove that reality is nothing like anything we can imagine.
First, if you assume that space or time are discrete, you are led to paradox. So they can't be discrete.
Second, if you assume that space or time are continuous, you are led to paradox. So they can't be continuous.
So space and time can be neither continuous nor discrete, nor can they be both continuous and discrete.
What is left? Nothing we can imagine. There appears to be no other option than continuous or discrete.
Therefore time and space, reality, must be something unimaginable.
Yes, there were people thinking like this a very very long time ago.
In the free world the media isn't government run; the government is media run.
Photons do not have rest mass, but they do carry both energy and momentum.
A photon imparts a force and thus may transfer momentum onto a reflecting mirror. The Mirror has mass and is thus subject to this quantized acceleration.
Also. The idea that the speed of light in a vacuum varies in a electromagnetic cavity is largely accepted as part of Quantum Electrodynamics.
This is closely related the Casimir force that developed between two uncharged metal plates. Empty space is filled with a continuum of virtual electromagnetic modes ( field fluctuation of every size). As the plates come together more and more long wave modes are excluded from the vacuum between the plates... but not "outside" , thus Vacuum between the plates is literally more empty, and the plates experience an attractive force. This is crazy.. but it had been actually measured.
Now....
In accelerating reference frames some of the virtual modes of the vacuum are converted into real modes this is the"Unruh radiation"... thus space looks like a heat bath when your are accelerating. it is not so clear how time in a heat bath becomes the generator of momentum, and inertial mass, unless General Relativity makes the Radiation bath An-isotropic ( not the same in all directions). thus the radiation pressure form the thermal radiation retards acceleration, acting exactly like inertial mass..... Hmmmm
so if you try to impart momentum on a small element embedded withing a larger cavity. The smallest change in momentum allowed is now a function of the size of the cavity , and lowest frequency mode that the cavity will support......
This is right out of an area in physics call Quantum Cavity Electrodynamics ( Google it).... Cool idea There may be something to it... Hell, Why it does NOT work may also be just as interesting. I like it! It been a long time since the Physics degree.
Short version: photons seem to have inertial mass after all.
You cannot just rewrite fundamental physics to fix one issue without also looking at the implications of your theory for other predictions which is it likely to change. Worse it seems that nobody has tested these drives for the emission of charged particles. A far, far simpler explanation is that this drive works by electron emission. There are a variety of way this can work which all work in a vacuum but whic would unfortunately not work in space where you are electrically isolated and would eventually build up a counter charge and cause the thrust to reduce to zero over time. This all uses established fundamental physics so it would be nice to see this ruled out BEFORE coming up with crazy new physics. It might be less exciting but it is better science.