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How To Build a Quantum Propulsion Machine
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."
I bet this could be done even easier with cats, but the ASPCA people won't like it.
Vacuum doesn't suck, it pushes?
doesn't the introduction of particles make it NOT a vacuum?
FOXTROT UNIFORM CHARLIE KILO
Well.
A non-reaction mass drive. That makes my head hurt. It just gave a slight air of plausibility to a few million bad SF novels.
How does this preserve momentum conservation? In the Casimir effect, the force occurs between two plates; as the plates are pushed in opposite directions, total momentum is conserved. Here, it seems as though you get momentum out of thin air (although energy is reffered to as "being spent", but with no indication how).
I call shenanignans!!
John Walker called such a device a vacuum propeller. He didn't have any particular ideas about how the device would work, but he does have a nice analogy involving propellers.
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.
That's not at all connected. What you are thining of is as velocity of an object increases its mass will increase (this is actually a little more complicated. This is only true for things with positive rest mass. If you have zero rest mass for example then this doesn't happen, but you will always be traveling at the speed of light anyways. If you are a tachyon and hus have imaginary rest mass and move faster than the speed of light in a vacuum then what happens as you change velocity is more complicated). This will still happen. The key to this sort of drive is that you don't *lose* mass as part of your reaction. Rockets, ion engines, and pretty much every other method of moving things requires you to push against something else to move. A rocket works by sending out particles from one end and so conservation of mass forces it in the other direction. An ion engine works the same way but instead of using hot fast particles uses little ions accelerated by a magnetic field.
The key to this sort of engine is that it doesn't do that, It can accelerate without throwing off mass. But the object will still gain mass as it accelerates nearer to the speed of light. In practice, the second part really won't matter for any practical engine since we will be moving so much slower than the speed of light. The key idea at some level is that you don't need to lose fuel to accelerate (you just lose energy).
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.
ZPM's! We'll be able to retire the aging buttered cat array fleet!
How To Build a Quantum Propulsion Machine
At first glance I thought it said How To Build a Quantum Popsicle Machine. Then I thought Quantum Popsicle would have been a great name for a hair band in the 80's.
You could have flavors like Lime Quark and Strange Berry, put the stand up outside the Hadron Collider.
That's our life, the big wheel of shit. - The Fat Man, Blue Tango Salvage
If I'm reading the summary right, that's basically a reactionless drive: a device that can accelerate in space without having to throw anything out the back.
.99c) on them.
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.
This sounds a whole lot like the way the engines work in the anime Kidou Senkan Nadesico. There's even a helpful animation played to explain it all to the crew and passengers.
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Until we find out that if you leave it on for a million years, it might just accelerate a space ship of one cubic centimetre up to a few millimetres per hour.
With due apologies to the authors if this estimate turns out to be a gross underestimate.
Well you're not going to get to a decent fraction of light speed if you need to squirt stuff out of the back of a rocket. A propulsion system that doesn't depend on squirting stuff out of the back of the ship opens up all sorts of possibilities.
E.g. a spaceship that could accelerate at 1g would have all sorts of useful properties. Firstly 1g feels like gravity. Secondly you could zip around the solar system pretty quickly. Last but not least, due to time dilation you could circumnavigate the known universe in 50 to 100 years ship time. Of course back on Earth millions of years would pass so the trip would be one way. Still you could imagine making decades long (I guess, I'm too lazy to do the math) trips to a star like Sirius.
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.
echo -e 'global _start\n _start:\n mov eax, 2\n int 80h\n jmp _start' > a.asm; nasm a.asm -f elf; ld a.o -o a;
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.
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.
This is exactly what they're saying. A quantum propeller.
You push off of stuff that already exists in space to move forward, instead of having to throw stuff backwards to move forward.
The KEY is that space is not a true vacuum. It is a "working fluid" in the sense that you can push at it with magnetic fields. It can be interacted with.
With the first link, the chain is forged.
If a spacecraft carries reaction mass, the total mass of the spacecraft is increased by the amount it is carrying at any one time. This mass must also be accelerated and decelerated. So the more you carry, the more you spend because you're carrying it. There are various side effects too, for instance, since the vehicle's mass changes over time, course change calculations have to keep track of that. Also, for every bit of mass you have to carry that is fuel, that's less cargo you can move from point A to point B.
If you have an energy source that is relatively mass constant - a nuclear reactor, or a set of solar panels - and you can piddle along without any tanks full of "stuff", you're going to be able to carry more payload; you're going to be able to go a lot longer without "refueling"; you're going to have more freedom and more range. Headed for asteroid X? Something interesting over there on Asteroid Y? No bothersome fuel constraints, you just go and take a look. That's the kind of benefit that has very positive ramifications.
The reason reaction mass is used in space is because in a vacuum, one has to push against something in order to move. That's the role of the reaction mass. You spend energy in X direction and get sent off in the -X direction with the same amount of energy.
Think of how a nuclear sub works underwater. Because it has something to push against (water), its ability to move is constrained only by the degree of push it can generate - it doesn't have to carry anything to push against, it's surrounded by water that will serve the purpose. The reactor provides a lot of energy to push with, using a propeller, which is designed so as to create a forward vectored force when spinning in the water. That's what the article suggests for space craft; that there is something there to push against, and therefore, one doesn't need to carry reaction mass. Spaceships using this method would be very much analogous to that nuclear submarine.
I've fallen off your lawn, and I can't get up.
No. Think of the virtual particles as a loan that *must* be repaid. The more that is loaned, the quicker that it must be repaid. electron/positron virtual pairs exist for a loner time than say virtual proteon/antiproton pairs do. There is no way to use the creation of virtual pairs to create free energy or break the conservation laws.
Sigs are too short to say anything truly profound so read the above post instead.
a few millimetres per hour
This is still orders of magnitude better than the Northern Line, however...
Thanks for the thorough information. How does this throwing off mass thing relate to electric cars? Do electric cars accelerate without loosing mass?
It's not about losing mass necessarily, it's about Newton's 3rd Law / Conservation of Momentum. For something to accelerate forward, something else (the surface of the earth) must accelerate in the opposite direction such that momentum is conserved.
The concept of Conservation of Momentum and rocket propulsion is often explained using the analogy of a boat on the lake with a bunch of rocks in it. If you throw rocks off the back of the boat, conservation of momentum means your boat will be propelled forward. Now, that's a pretty silly way to propel a boat when you can just use a paddle or propeller to push the water backwards and your boat forward.
Rockets in space don't have that luxury. So they pretty much have to carry a bunch of "reaction mass" with them and throw it at high speed out the ass end of the rocket.
This invention, if it pans out, would be more like a propeller for spacecraft, pushed by and pushing against the short-lived particles that spring in and out of existence in vacuum. I have to imagine that the amount of thrust would be miniscule, but not having to carry reaction mass would be a huge advantage.
The enemies of Democracy are
THIS SOUNDS LIKE A REACTIONLESS DRIVE. NOW THAT I HAVE PROPERLY CATEGORIZED IT FOR YOU, YOU CAN JUST GO STRAIGHT ON TO BEING SKEPTICAL, SINCE EVERYONE KNOWS REACTIONLESS DRIVES ARE BALONY. THIS HAS BEEN A SERVICE ANNOUNCEMENT FROM THE SOCIETY FOR THE PROTECTION OF THE STATUS QUO IN ENGINEERING. THANK YOU.
(We had to bribe Slashdot editors to let us write the above in all caps. They are total suckers for lower-case letters. It's a fetish of theirs, probably. Poor little letters. Cut to CmdrTaco doing a lower-case 'a' in the butt. Oh, ffs, will this filter ever let me through? rthwerg erg qergqegqerg qerg qegqegqreghqer gqer gq erg qer gqe gqergqergeqrgerg)
First, assume you have a magnetic monopole. From there, the math is easy.
I've abandoned my search for truth; now I'm just looking for some useful delusions.
See this item from 2004:
Your fuel source does not change its mass. The gas in your tank combines with the local air and releases pollutants into the air. Furthermore, it achieves actual movement by turning a wheel which interacts with the ground.
A spacecraft has no ground to interact with. Rockets produce movement by throwing away their mass. This engine (if it works) would not have to throw away its mass.
There are other ways to get around without throwing mass. Light sails produce it by interacting with photons that the sun (or a ground laser) throws at them. There's a plasma drive I can't quite remember the name of that interacts with the local magnetic field, in essence pushing on the sun from far away. The "flashlight rocket" (also called a "photon drive") mentioned just below this post throws photons away and achieves movement without losing mass. Ion drives don't count, because they do throw away mass -- tiny amounts of it, but they do.
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.
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
The existence of particles in a vacuum? That sounds exactly like the aether, a scientific theory that was abandoned about 200 years ago!
I suggest you read this book: QED The Strange Theory of Light and Matter
As the author of the introduction, Zee notes: "According to Feynman, to learn QED you have two choices: you can go through seven years of physics education or read this book"
This is the best book there is that I know of that will give you the grounding to get Quantum Electrodynamics. You will discover that particles do in fact, exist in a vacuum. The quantum world does not work anything like the macro world that we are used to. You have to get used to ideas like electrons traveling back in time and emitting a photon before they actually received a photon that caused them to emit said photon.
If you don't want to read that, then at the very least, read this: Vacuum Energy
Try to hack my 31337 firewall!
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.
I'd rather you rationally disagree than irrationally agree.
Aether was intended to explain the propagation of light in a vacuum, before it was realized that light did not need a transmission medium. Up to that point scientists always figured you needed a medium to transmit energy. Once we dismissed that concept, the idea was thrown out. Proving that something might pervade vacuum is a little different than bringing back the theory of aether. ;-)
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.
The more people I meet, the better I like my dog.
The computer you're typing on is a rather good example of quantum mechanics on an industrial scale. It's been estimated that quantum mechanics is in some way responsible for a large fraction (can't remember exactly - two thirds?) of our economy.
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).
So if this is the future...where's my jet pack?
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.
There are literally billions of stars in the galaxy- even if a thousand civilizations spent a sizable portion of their energy lobbing (largely pointless) space probes all over the place, there're still no guarantees that one would be in the solar system during the (astonishingly brief) period that humanity have been looking for them.
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.
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.
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.
Build a man a fire, he's warm for one night. Set him on fire, and he's warm for the rest of his life.