Of course it is. Nearly every physicist knew this was quackery from day one. It should of course be tested properly, but nobody should be surprised.
So, first of all, the author of the paper certainly acknowledges the simple priniciples that make EM drive propulsion function. The author is simply arguing how feasible the technology would be for achieving any significant acceleration.
He doesn't claim that EM drive is in principle a perpetual motion machine, rather that 'ar some point' [during acceleration] the energy input to achieve any signiificant acceleration to make the technology feasible would require output energy greater than the possible energy input aboard an engine of a given mass (a statement which is certainly dependant on the efficiency of the 'power conversion' of the system, which can be improved with, for example, more efficient conductors/resonator cavities, etc.).
The paper is fine IMO; it's the comment that cited the paper that is inacurrate.
The problem is, when you look at an object with a given velocity v, it has a kinetic energy proportional to v^2. To accelerate it from 0 to v, you must have put in all that kinetic energy (ie, v^2 energy). But reactionless drives give you velocity directly in proportion to energy. At some point, the v^2 and v lines will cross, and your object will have more kinetic energy then you put into it in the first place.
For every unit of energy you pump into the drive, the velocity goes up by a unit, but since the kinetic energy of the object is proportional to v^2, at some point the kinetic energy you get out will be more than the electric energy you put in. The problem goes away with photon drives because that crossing point turns out to be at the speed of light.
This is the argument the paper is making: If you can generate velocity directly from energy, you will eventually end up generating more energy than you started with.
They hypothesised earlier than that, of course, but the experiments followed updated laws nearly 30 years after the new laws had become necessary because of lots of previous experiments showing Newtonian physics was wrong.
And sure, GR will be replaced with something else (it predicts but cannot fully describe black hole interiors), but…
…but expecting that upgrade, whatever it might be, to have the ability to defy known conservation laws in a measurable way in a device made of quarks and electrons, is akin to thinking one possible refinement to the shape of the Earth (curved, sphere, oblate spheroid, …) is the existence of a 29 mile long tunnel connecting Hawaii to Moscow.
Any new physics will almost certainly involve things we can only just build at this point, not stuff like the EM drive which we could’ve built by accident from WW2 onwards.
Photons are not classical and do not "launch" themselves of of an emission surface. (see more detailed response below)
No mystery, no quackery, just basic physics.
And, science mistakes are good lessons, such as "why didn't we think to check that?"
just like this famous one https://en.wikipedia.org/wiki/Faster-than-light_neutrino_ano...
or I should trust NASA, who believed there was enough interesting things to learn there that they experimented with it on their own.
It's close, but NASA wins this round.
To my knowledge, general intent to deceive was NEVER proven. Or are you using a different definition of "quackery"?
Yes, it appeared to violate known physical laws, but it was still possible that A) physicists missed a curious aspect of current models, or B) the existing models of physics are wrong or need tuning. It happens. Not common, but it happens.
I don’t think most people appreciate how solid our models of well-trodden physics is.
Any new engine is going to be more exotic than microwaves in a chamber.
The reason that I'm asking is because light has momentum. If I shine a beam of light out the back of my spacecraft, then I will accelerate in the opposite direction. Not a lot, just a little.
Was EmDrive impossible because it was claimed to generate way more thrust than could be explained from the energy levels involved? (Edit: It looks like an additional reason it's impossible is because the EmDrive was claimed not to emit radiation, and rather keep it bouncing around in the cavity. Thanks for the replies and explanations!)
Imagine that I attach a 1 megawatt laser in the 630 nm spectrum to my spacecraft. From some rough calculations based on (1), it looks like the laser will generate about 0.003 newtons of thrust (equal to the weight of 0.2 pounds on Earth), which is very little thrust, and impractical for accelerating a spacecraft over regular time scales.
(1) Momentum of a laser beam: http://umdberg.pbworks.com/w/page/50455623/Momentum%20of%20a...
What happens if you used a waveguide to turn it around 180 degrees to the front wall? Photons have no mass, so turning it in a waveguide would result in zero force on the waveguide right?
Edit: just learned light cannot be bent by electric or magnetic fields, I must have been thinking of radiation particles.
In addition to the other replies, a working EMDrive would imply that the results of physics calculations would depend on your choice of coordinate system, because of https://en.wikipedia.org/wiki/Noether%27s_theorem, which would be absurd.
Source of disproof?
From two years of atomic physics study at my university, I don't see any reason you can't generate thrust using EM emission from an anetenna attached to the object being propelled. No laws are violated.
First of all, before getting to conservation laws, the author's statement that an EM drive requires no fuel, right after stating the engine is powered by microwaves (generated by some stored energy source, a.k.a. fuel) is nonsensical.
So, about those conservation laws. EM drives absolutely fully conserve energy and momentum in the system. Anyone who studied physics at the university level should have a firm understanding that photons do not "launch" themselves off of the surface from which they are emitted, like a rocket from a platform. Instead, the energy and momentum change forms as they transfer from the source (e.g. an atom) to the photom (e.g. a microwave).
In atomic orbital decay (say spontaneous emission from an exciton), emitted photons recieve their energy and momentum from the atom's decaying orbital energy and angular momentum. That's it. See here (1) for a deeper breakdown of what's going on, but if you're generally trying to figure out where the energy and momentum are coming from, at the high level that's all there is to it - no quackery here.
If you need a mental image, just try to imagine throwing (imparting a force on) a photon emitted from a light bulb in your hand. You can't do it. A photon travels at the speed of light in a vacuum the instant it is created at the bulb's filament. Because you're hand and the lightbulb (both made of matter and traveling in the same direction as the photon) cannot travel at the speed of light, the photon will always be forward of your hand/light bulb and no energy can be transferred from your hand/light bulb to the photon, and vice versa. There is no "recoil" felt by your hand. That's exactly the same for the EM drive's antenna (or any antenna or emitter for that matter). However, that same photon can certainly interact with matter and transfer it's energy and 'linear' (angular) momentum to an incident piece of matter, for a kinetic reaction.
So, again, I don't see the problem.
1. http://www.eng.fsu.edu/~dommelen/quantum/style_a/consem.html
The claimed thrust of the EMDrive was incompatible with photon thrust- it was much too powerful.
"Since applying a constant force results in a constant acceleration, the kinetic energy of a mass driven by such a device increases quadratically with time, while the energy input increases only linearly with time. Thus, at some point, the kinetic energy of the device-driven mass exceeds the energy input, and if this energy is collected via decelerating the mass (via regenerative electromagnetic braking, for example), then there would be a net gain in energy."
With a photon drive, the break-even point is at the speed of light (which you can never actually achieve), but with any drive that's more power-efficient, the break-even point will be less, and you will be able to extract limitless free energy by accelerating the drive past that point.