'Impossible' rocket drive works and could get to Moon in four hours

The Telegraph ^ | 28 Jul 2015 | Sarah Knapton

[MinorityRepublican]

Interplanetary travel could be a step closer after scientists confirmed that an electromagnetic propulsion drive, which is fast enough to get to the Moon in four hours, actually works.

The EM Drive was developed by the British inventor Roger Shawyer nearly 15 years ago but was ridiculed at the time as being scientifically impossible.

It produces thrust by using solar power to generate multiple microwaves that move back and forth in an enclosed chamber. This means that until something fails or wears down, theoretically the engine could keep running forever without the need for rocket fuel.

The drive, which has been likened to Star Trek’s Impulse Drive, has left scientists scratching their heads because it defies one of the fundamental concepts of physics – the conservation of momentum – which states that if something is propelled forward, something must be pushed in the opposite direction. So the forces inside the chamber should cancel each other out.

[Pelham]

“has left scientists scratching their heads because it defies one of the fundamental concepts of physics –”

I suspect that there is very little head scratching going on, other than to marvel at the gullibility of journalists.

[ckilmer]

Why wouldn’t this technology be used to create vast amounts of energy at a fraction of prices currently paid?

[Spktyr]

Because it doesn’t work very well in atmosphere, so far tests seem to indicate that it really wants to be in a vacuum.

[Rockingham]

The EM Drive uses energy in that it runs on electricity. It does not produce energy.

[ckilmer]

The EM Drive uses energy in that it runs on electricity. It does not produce energy.
.................
does it use as much energy as it produces?

[ckilmer]

Because it doesn’t work very well in atmosphere, so far tests seem to indicate that it really wants to be in a vacuum.
...............
so that’s an extra cost to create a vacuum in which the reaction can work. So once you create the vacuum you add energy and whatever else. If the result is that you get more energy out—then it would seem that this could be an energy source. the question is how expensive is that energy.

[Rockingham]

Like the electric motor on a Tesla, the EM drive uses electric energy but does not produce it. Where a Tesla motor converts electric energy into mechanical energy to turn the wheels and propel the car, the EM Drive on a spacecraft -- if it works -- converts electric energy into thrust to propel the spacecraft.

Precisely how the EM Drive could do that is disputed, with the lack of a reaction mass being expelled as hot gas from rocket nozzles on the spacecraft seen as a violation of the law of conservation of momentum. This objection need not be fatal because nature's rule book is like a bad contract, with all sorts of exceptions, loopholes, and tricks for the clever to discover and exploit. Perhaps the EM Drive is just such a trick.

[Spktyr]

This isn’t a power generation system. It’s (if it works as advertised) a method to convert electricity to propulsion. It’s not like a nuclear reactor, it’s more like an electric motor.