Sky Captain wrote:If EMDrive pushes against some kind of medium to generate thrust why would it break down physics any more than pretty much any other vehicle that's not pure rocket? Cars, airplanes and ships don't become perpetual motion machines after reaching certain speed just because they all use existing medium to push against. You could put maglev train in vacuum tunnel with no drag and no matter how fast it would go there would be no way to get out more energy than put in. Why EMDrive would be any different?
That's kind of the point. IF the EMDrive works by pushing on a medium it doesn't break conservation of momentum.
But it DOES create problems by implicitly creating a privileged frame of reference.
Do you mean de Broglie's theory? Or do you mean something cooked up more recently by a more quacky individual?
The problem with de Broglie's "pilot wave" theory is that it is nonlocal.
Locality is a physics concept used widely in current theories, stating that an object is only directly affected by the things that happen at its specific location. A nonlocal theory basically states that Object A can have a 'magical' effect on Object B that is independent of the obstacles between them. Furthermore, it tends to involve cause-and-effect propagating faster than light, though I am not sure this is a specific problem with de Broglie's pilot waves.
I imagine that even if this thing is put into space and appears to work as advertised that doesn't mean much? Especially if private companies end up being the ones building and testing it in space? I'd imagine the creators would have a pretty good reason to fudge the results.
"I reject your reality and substitute my own!" - The official Troll motto, as stated by Adam Savage
I actually wasn't aware how much of conman Shawyer was. To claim that you can achieve some small but steady thrust that over great distances would decrease the average travel time to Jupiter or something is one thing. But going on about hower cars and solving world's energy problems...
But if the forces of evil should rise again, to cast a shadow on the heart of the city.
Call me. -Batman
My understanding is that the more outlandish claims about emdrive's potential applications are based on theoretical models by Shawyer or White which say that the thrust-to-power ratio can be improved by orders of magnitude if they are able to make a better drive (I think I remember hearing about having a superconducting version for maximum efficiency). Of course Shawyer's theory about how it works is utter nonsense, but it is possible his mathematical model may have an empirical or semi-emperical basis, in which case it could be predictive even if the device doesn't work, as he could actually be modelling the error source.
