How To Build a Quantum Propulsion Machine 392
KentuckyFC writes "According to quantum mechanics, a vacuum will be filled with electromagnetic waves leaping in and out of existence. It turns out that these waves can have various measurable effects, such as the Casimir-Polder force, which was first measured accurately in 1997. Just how to exploit this force is still not clear. Now, however, a researcher at an Israeli government lab suggests how it could be possible to generate propulsion using the quantum vacuum. The basic idea is that pushing on the electromagnetic fields in the vacuum should generate an equal and opposite force. The suggestion is that this can be done using nanoparticles that interact with the vacuum's electric and magnetic fields, generating the well-known Lorentz force. In most cases, the sum of Lorentz forces adds up to zero. But today's breakthrough is the discovery of various ways to break this symmetry and so use the quantum vacuum to generate a force. The simplest of these is simply to rotate the particles. So the blueprint for a quantum propulsion machine described in the paper is an array of addressable nanoparticles that can be rotated in the required way. Although such a machine will need a source of energy, it generates propulsion without any change in mass. As the research puts it with magesterial understatement, this might have practical implications."
Momentum Conservation (Score:4, Interesting)
I call shenanignans!!
Is this different from a photon drive (Score:5, Interesting)
Is dumping momentum into the quantum vacuum different from emitting photons carrying the same momentum? If not, this is just a photon drive, which is a well known concept, has brilliant specific impulse but is incredibly energy-inefficient except at high relatavistic velocities.
Probably the only chance there is (Score:2, Interesting)
Something like this is probably the only chance there is for interstellar space travel. The two biggest problems in traveling between stars are first having a source of energy that will last long enough to make it there, and second having the mass for propulsion needed to make it there. Between stars, there's not a lot you can push against so you have to carry your mass with you, and for corrections on an interstellar flight that could add up to a lot of mass. Either that or hope when you shoot out of the Solar system that you're aimed exactly right. However, if there is something to push against, problem 2 is solved.
Reactionless drives (Score:3, Interesting)
A reactionless drive would be nifty because it can gather kinetic energy very easily (that's what makes travel so cheap with one). However, there's a darker side to that coin. If you can accelerate a ship to near-c with little difficulty, there's not much stopping you from extorting the Earth by threatening to drop the ship (or for that matter, a bunch of tungsten telephone poles traveling at
Any propulsion system can be used as a weapon. Thus, the good news of the reactionless drive is that one can easily move about in space. The bad news is that one will have to.
Why did noone tell me it was the future? (Score:5, Interesting)
Does it mean that I am old because I look around every day and it feels like I am living in a surreal sci-fi story?
Reactionless drives, energy weapons, smart phones, robotic killing machines, genetically engineered super species? At this rate I wonder if I would be surprised when practical AI or faster than light travel becomes an option.
Re:what are we talking here?! (Score:4, Interesting)
Well technically the car is losing a slight bit of mass because of the energy change, but that's not relevant to the propulsion, a car isn't a rocket. The car is pushing against the earth and transferring that momentum to the earth.
Re:Reactionless drives (Score:3, Interesting)
Uuum, wouldn’t it be more like a machine that constantly digs up some soil, and throws it behind itself, to accelerate?
Of course, here the “soil” constantly digs itself up. But you’re still “taking that “stuff”, and throwing it behind yourself. It just happens to zero itself out after this, if I understand it correctly.
I would bet money, that we will get some very interesting effects and new science out of even trying this.
Like finding out why it does not work. Or why/how the symmetry is not violated because of something weird.
But why do you have to think of weapons? What you said could be said about nukes too. But it did not change much, because 1. Others will have that weapon too, and 2. To what planet will you go back after destroying it? You know... To breathe! ^^
Feigel's had this bee in his bonnet for years. (Score:3, Interesting)
See this item from 2004: [erols.com]
Wait a minute... (Score:2, Interesting)
Re:ATTENTION (Score:2, Interesting)
I just read up on "reactionless drives" and I don't agree. If this works, it will be similar to the Dean drive. From a naive point of view, it'll look like a reactionless drive. But on closer inspection, work is being done on the magnetic fields in a vacuum -- just like the Dean drive does work on the surface it rests on via friction.
Re:Doesn't sound exciting at all... (Score:3, Interesting)
Getting energy into space is easy. You can grab it from nearby stars, or you can carry a nuclear reactor with you. Because a nuclear reactor converts mass to energy via E=Mc^2, it produces a lot of energy from a small mass.
The real problem is reaction mass. You have to have something to push against in order to move. Getting a lot of reaction mass into space is difficult. If you can push against the vacuum of space, that problem is solved.
Re:On earth it's called Magnetohydrodynamic drive (Score:3, Interesting)
There's no reason quantum propulsion couldn't be used on earth, except maybe it wouldn't be very efficient. It could be used to make helicopter-like machines, which levitate without distorting the air around it. Or ships that don't leave a trail. Come to think of it, this might one day be a big thing in military stealth vehicles.
Re:Momentum Conservation (Score:3, Interesting)
Re:Implications? (Score:3, Interesting)
Actually I like the idea of sending out a plague of self replicating machines in devices like these, to bring the Word Of Dawkins to the stars and troll the inhabitants of other star systems.
The idea of sending out self-replicating devices doesn't depend on this very much. Using standard propulsion and gravity slingshots, we can get objects to about 1/1000 speed of light, and so it will just take that much longer for our self-replicating devices to get where they are going. It's not like they need to be in a hurry. And such devices should be realizable in the not-to-distant future (say, 200 years or so). Since the Milky Way is only 100,000 light years across, it would take only take 100,000,000 years for devices to make it through out the galaxy. This is a comparatively short amount of time, compared to either the life of the planet or the universe.
Actually, the (relative) ease at making these devices indicates to some people that either intelligent life is rare in our galaxy or that they think differently than we do. Assuming technology continues to improve, I can't imagine that someone eventually won't try this. And if other intelligent life has done this, then there would be space probes flying around through our solar system. Maybe we're just missing them.
Something to consider: (Score:4, Interesting)
The paper is a one-author publication in a non-peer-reviewed journal and doesn't seem to be published anywhere else. The author's affiliation is an applied R&D institute not an academic institute with a strong theoretical background. I'm not saying that discredits it, but it certainly means that it should be taken with a grain of salt. I would suggest that anyone who wants to assess the merits should read through some of the references (which are good publications) and see if the present article appears plausible. Even without any technical expertise, the abstracts could probably provide a feel for the state of the art.
I couldn't be bothered to do that reading myself, but I would suggest that any momentum transfer to the vacuum would involve the production of real particles from the zero-point fluctuations. Conservation of momentum demands that there would be something carrying momentum in the opposite direction of the spacecraft and, by definition, it can't be an unexcited quantum field. There would have to be excitations of the field to carry the momentum (real particles).
Re:Momentum Conservation (Score:4, Interesting)
Hybrid space ships! (Score:3, Interesting)
Something that nobody has mentioned yet is that if we're coupling to the surrounding vacuum to accelerate ourselves, we should be able to couple to the vacuum to decelerate ourselves, _and store the energy from the deceleration_.
Given big enough energy storage devices, we can then use that energy to accelerate on the next trip, and the net energy cost per trip is substantially reduced.
reclaim energy when slowing down? (Score:3, Interesting)
Given that there is little friction in space, I wonder if it would be possible to generate and store energy when slowing down at the end of the journey (like a hybrid car) and use it to accelerate back up to speed again on the next trip.
This would dramatically reduce the overall energy consumption, but would need some serious energy storage capacity.
I think fuel constraints are still an issue (Score:3, Interesting)
A nuclear reactor simply converts mass to energy, very inefficiently. So just by virtue of running it, you are losing fuel mass. There's no free lunch.
In the absolute best case for an energy source, you could convert mass directly to energy, and use that to power your quantum drive. But if you can convert mass directly to energy, you can just dump that energy out the back in the form of photons and get the exact same level of thrust...maybe more if your quantum drive has any inefficiencies. So I don't really see how this would be any more useful than a photon drive. In either case the hard part is the energy source, not the drive mechanism.