the quantum vacuum plasma thruster works

[sykavy]

Until yesterday, every physicist was laughing at this engine and its inventor, Roger Shawyer. It's called the EmDrive and everyone said it was impossible because it goes against classical mechanics. But the fact is that the quantum vacuum plasma thruster works and scientists can't explain why.

Shawyer's engine is extremely light and simple. It provides a thrust by "bouncing microwaves around in a closed container." The microwaves are generated using electricity that can be provided by solar energy. No propellant is necessary, which means that this thrusters can work forever unless a hardware failure occurs. If real, this would be a major breakthrough in space propulsion technology.

Obviously, the entire thing sounded preposterous to everyone. In theory, this thing shouldn't work at all. So people laughed and laughed and ignored him. Everyone except a team of Chinese scientists. They built one in 2009 and it worked: They were able to produce 720 millinewton, which is reportedly enough to build a satellite thruster. And still, nobody else believed it.

Now, American scientist Guido Fetta and a team at NASA Eagleworks—the advanced propulsion skunkworks led by Dr Harold "Sonny" White at the Johnson Space Center—have published a new paper that demonstrates that a similar engine working on the same principles does indeed produce thrust.

NASA: New "impossible" engine works, could change space travel forever

[RAMSET]

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I like this Guys explanation of the technology

61Reply
swiftdropkick

Because it's proposing the equivalent of you sitting in your car, on a level road, with the transmission in neutral, with a baseball in your hand, and then bouncing said baseball repeatedly against the windscreen in order to make the car move forward.

Intuitively, it shouldn't work, since by Newton's Third Law when you throw the baseball forwards, there is an equal and opposite force pushing you (and the car seat back behind you, and thus the entire car) backwards. When the ball bounces off the windscreen, the car gets pushed forward by the baseball, but since there was already a backwards force on the car caused by you throwing the ball in the first place, the effect of the two forces will cancel each other out. The car won't move, no matter how many times or how hard you bounce the ball (i.e. no matter how much energy you supply to the system).

Replace "your car" with "sealed metal cavity", "baseball" with "microwaves", and yourself with a microwave generator (which is bolted to the sealed metal cavity, just like if you were seated right against the car seat's back), and you get the EmDrive.

Of course, my explanation was assuming "classical" mechanics (where all of Newton's Laws apply). The inventor of the EmDrive claims that there are some quantum effects at play that make it possible. Not knowing much, if anything, about the minutiae of quantum mechanics, I reserve my comments.

(Incidentally, even if you weren't sitting with your back right up against the seat back (which I assumed, for simplicity's sake), the car still wouldn't move as you bounced the baseball; you would move backwards for a bit, and the car would have a forward force acting on it once the baseball hits the windscreen, but you'd eventually hit the seat back, providing a backwards force to the car, and thus canceling out the movement