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The Reactionless Space Drive?
waimate writes: "This New Scientist article describes some physics that is claimed could be the basis of a new space drive, and a reactionless one at that.
Our current knowledge of physics requires that a space craft throw most of itself away at high speed in the opposite direction to get anywhere, and this is why the Millennium Falcon won't exist any time soon.
A drive that doesn't depend on reaction mass would change all that. But is this it? The article seems to sidestep the obvious flaw." Or flaws, maybe.
Assymetric magnetic field. It sounds kind of kooky... they're making it for a brief period of time, but if such a thing were to be created for an extended period of time, a force could be generated just by being in the presence of any magnetic field, or any object which responds to magnetic fields.
They'll probably find out that either it is a wobble and not a shudder, or it will turn out to be in a random direction.. just like all the other quantum weirdness... Sort of like propelling yourself off Browninan motion... only magnetically. It looks neat under a microscope, but it would never work.
But I'm just guessing based on a reporter's interpretation of a brief interview with a scientist.
That's about the best concept I could get out of the article as well. Of course, this poses two problems:
Okay, here's a design for a system that would be entirely contained, and yet still allow you to generate inertia:
You have two counter-rotating flywheels bouncing along their axis of rotation forward and back in the ship. As they reach each end, they are accelerated in the opposite direction. As the flywheels are moving forward, increase their rate of spin, as they are moving backward, decrease their rate of spin. Since mass increases with velocity, the flywheels will have a higher mass as they are being accelerated backward than they will have as they are being accelerated forward. So you will accelerate forward.
Admittedly, it's not quite feasible, but it does show that a reactionless drive doesn't violate any physics. Yes, it does violate Newtonian physics, but that's because Newtonian physics is only an approximation to reality (and so might relativity, but a more accurate one).
If we actually understood what gravity is, we might be able to get some interesting reactionless (did Clarke just make that term up?) propulsion methods out of it. I'm thinking along the lines of making space curve like it would if there were a mass there, but whereever you want it to. Assuming thermodynamics, this would take a lot of energy, but it might be more efficient then just dumping burnt propellant out the back. Of course, this is probably impossible.
BTW, can anyone point me to a real discussion of how to build a fusion ramjet? It's a staple of a lot of sci-fi, but I'm curious how you keep from getting slowed down by collecting the hydrogen.
Here's an example:
After I testified before the House Subcommittee on Space on my participation in the passage of a couple of laws to reform NASA's rather nasty attitude toward private launch services I was pretty close to being out of money. Civic responsibility will do that to you if you don't watch it. Even so, a company whose rocket technology I liked was on the ropes -- a couple of weeks from closing their doors. The CEO gave me an impressive sounding position with the company, offered me a percentage in the company and I maxed out my credit flying around to see what I could do to help salvage the business with no guarantee of compensation.
The first day I arrived at HQ, a strange call came in to the CEO. Some guy claimed to have been referred by NASA because he wanted to find out how to obtain certain kinds of permits that the company had obtained. It turns out the guy wanted a permit to let a device he had made go into space. He said he had constructed a high power vibration stimulator as a diagnostic aid in his business, which was vibration isolation in some mechanical systems, and the damn thing malfunctioned. The problem is this particular Damn Thing, when it malfunctioned, started vibrating off to the side of the table and then it fell off -- but before it hit the floor, it turned in mid air and went up at an angle, hitting the ceiling of his shop where it hit so hard it left a dent in the metal conduit -- and it didn't just bounce off and fall to the floor, it stuck there until he unpluged the infernal contraption.
OK, well the obvious questions were asked like: "Was the conduit a feromagnetic material?" etc. "Are you sure it actually accellerated up to the ceiling or did it just jump up and somehow stick there?" -- you know, the standard Skeptics Society stuff.
This character got my curiousity, not having ever run across one of these conservation-law-violating-sonofaguns before, so I took one of his phone calls and started asking him innocent questions -- like, "How many tests have you run on the device since that time? Have you taken any quantitative measurements? What are the numbers? What did you to do get these numbers?" etc. The interesting thing was he gave me two sets of numbers from two tests, with different weights attached, he said he conducted on a playground with a fishing line attached to the thing to pull the plug on a cellular phone battery at a given height. The numbers he gave were distance traveled vertically vs time. In one test the calculus told me his upward force was less than in the other run by a big margin. So I asked him if he had changed anything else between the two runs other than adding the weight to one of them. He said no. So I asked him to describe his test procedure very carefully. He went through the process verbally, and at one point he said he "turned the variable resistor down until the thing started to lift off -- then I backed off". "Was the resistor in the same position both times?", I asked. "I don't think so because the heavier test run required more power."
Oh, gee whiz -- here is a guy who is not only imagining he ran a levitating device straight up in the air from a playground, but he fabricated results that were inexplicable except from an error in his experimental procedure that he himself seemed not to have thought about. He also told me that on the third run he had some friends of his with him to help and the thing lifted off but then exploded leaving a "line of metallic powder across the playground asphalt". This is either one hell of a smart sociopath playing mind games or he is a covert operative or he is some sort of genius at dreaming things up on the spot that even his conscious mind couldn't have fabricated or he is, in some important sense, telling the truth.
I admit it -- he had me hooked. I invited him to dinner and even though he was a couple hundred miles away, he drove his company truck up to meet me. I won't say what the company name was, because that would give a bit too much information away but it was a company name that was like a double-entendre or pun on his activities that reflected both his mundane business and this weird business of levitating infernal devices -- just the sort of the thing that your dream state would make up and Jung would analyze for you or maybe something that Jaques Vallee would report in one of his weirder "encounter" reports or maybe something that some covert operative would do to mess your mind up or maybe something a complete psycho would do because the little man in his head told him to. So anyway, I had dinner with him and he seemed genuinely worried when I told him that if this was real, he should take precautions by placing a disclosure with an trusted accounting firm to be put in the public domain upon his death or disablement. I don't think he thought I was going to kill him but he could pick up from me that I thought he should be more cautious.
So now what? OK, so he says he is going to build another version of it, because he thinks he knows the principle of operation, but he wants it to be lower power and lower frequency so it doesn't explode and hurt someone. He tells me how his experiments are going but he never seems able to get the original, unequivocal, levitating performance -- all his reports are closer to the rest of the legendary reactionless drives that always end up with marginal effects.
Finally, I tell him to send me a video tape of the thing either accellerating upwards or in a pendulum test and if he doesn't I won't be interested in talking to him any more, but if it shows an unequivocal force, I'll fly him to SV to talk to guys with some capital. He sends me a video tape. It is a short tape with some sort of noise on it. A friend of mine said it had been degaussed but with some sort of external magnetic field -- not by a tape recorder. So I call the inventor and tell him it really isn't OK to send me an erased tape. He seems at first incomprehending and then a bit afraid but then composes himself and starts speculating on how it might have been degaussed in transit. So he says he'll send me two tapes, one via UPS and one FedEx. I never received any packages, his phone is disconnected and I never hear from him again.
To wrap up the story, sort of, he did tell me the electric motor make he used, so I went to an electric motor place -- an old one that had been around since the early 60s. I asked for the specific motor and the proprieter turned around to the assistant and said "Do you remember that guy from the Apollo program at NASA Ames back in the 60s who was building the flying saucer? Where did we order that motor from?"
OK, that's enough weirdness for now...
Seastead this.
In practice, it's difficult but not inconceivable. The effect gets stronger with the cube of the vibration rate. You need a very fast vibration, and experimentally it's really hard to accurately measure force on something vibrating that fast. So experiments so far have been somewhat inconclusive. The interesting thing is that there's no new physics postulated here--it's all a natural consequence of general relativity.
As a practicing particle theorist, let me tell you what you got right and what you got wrong (more right than wrong!):
You cannot prove that a scientific theory is the correct description of the universe as we observe it...you CAN disprove a theory by showing that it conflicts with experiments. You CAN prove that a scientific theory is logically correct, but that doesn't prove that it is physically correct.
Quantum mechanics HAS been confirmed time and time again, but we ALREADY KNOW that QM is incomplete, just like we know that Newtonian Mechanics is incorrect (the point particles of quantum mechanics have been replaced by the quantized fields of Quantum Field Theory). QM is, however, "accurate enough" for almost all purposes where Newtonian Mechanics fails, and in the correct domain of application (anywhere where the corrections from QFT are small), QM is still used. I would go so far as to say that there are no practicing physicists who don't believe in the validity of QM; it would take some truly astonishing discovery to unseat quantum theory (it may happen, but I wouldn't hold my breath, just like I wouldn't hold my breath for any evidence that Newtonian mechanics ever fails on macroscopic scales).
There are four generally accepted forces (gravity, strong, weak, and electromagnetic), and there is a QFT model that "unites" the weak and electromagnetic force (and is called the electroweak force), although it isn't technically proper to call it a "single" force, but that is a nitpicking detail (having to do with the fact that the gauge theory describing electroweak interactions is not based on a "simple Lie group", but that is neither here nor there for purposes of this discussion...).
There is currently NO accepted quantum theory of gravity, although string theory provides a mathematically consistent physical theory which includes gravity. String theory (probably) has no currently testable consequences (we need a lot more work before we'll be able to ask questions that experiments have a real hope of answering).
While it WOULD be extremely surprising to discover a fifth force that operates over macroscopic distances, most (particle) physicists fully expect that there are additional microscopic forces that will be discovered in the next decade (supersymmetry is the sexiest these days, but there are many others: topcolor, technicolor, etc.)
QCD is well accepted as the proper description of the strong force, and is well tested at HIGH energies (not low). At LOW energies, it is a very hard theory to perform calculations in, and we have to resort to lattice monte carlo methods, which are computationally speaking, among the most demanding computer applications yet devised (for those with undergraduate physics backgrounds: you can't do a pertubation expansion in the low energy theory, as the coupling constant is a number of order 1, not a small expansion constant, and technically, we can't calculate what the fundamental degrees of freedom are in the low energy limit.)
Where are you reading where the guy who proposed this idea is absolutely confident it will work? I read it more as if he was saying "hey, this is kind of cool. I'd like to see if it actually works out..."
Eviscerati.Org: All Hail the Eviscerati
A rail gun typically has two rigid conducting rails surrounded by a large electomagnet. A projectile is placed between the rails. The projectile usually is coated with a thin conducting layer.
The magnetic field is created by applying a large current to the coils. Then, a large current applied to the rails. The resulting "short" circuit vaporizes the conducting layer on the projectile producing a conductive plasma.
The projectile is the propelled down the "barrel" of the rail gun by both the expansion of the plasma but more so by the resulting Loretz forces that are result of the interaction of the electrical discharge and the magnetic field. This force is perpendicular to the magnet field and direction of the current flow and can be quite substantial. It is this force that accellerates the projectile to a very high velocity. Damage to a target is primarily because of the kinetic energy of the projectile strike the target.
The military examined rail guns in the 80's. There was talk of "electric" ships that contained rail guns and lasers at the height of the Reagan "Star Wars" era. The problem with rail guns is they produce a very flat trajectory making them useless for over the horizon applications. Reducing the velocity of the projectile would reduce the kinetic energy of the projectile thus requiring heavier projectiles or explosive projectiles.
Another problem with early generation rail guns involved alignment of the rails. The forces produced in a rail gun often destroyed the rails or knocked them out of alignment. Thus, early generation RGs were limited in their ability to achieve sustained firing rates. I read a few years back that this problem had been corrected. Haven't heard much about rail guns since.
But, the approach of this "juddering" engine and a rail gun at not similar at all. And, until somebody proves otherwise, rail guns are stil confined to the laws of Newtonian physics. Hence, RGs have one hell of a recoil. That is why they were planned for use on ships and tanks as they are the only vehicles massive enough to absorb the recoil. Even the mighty IOWA class battle ships were pushed sideways several feet in the water when she fired her guns broadside.
RD
It's not a reactionless drive per se, but solar sails do not have to carry around their reaction mass.
I'm not sure if I'm real.
Any time you put metal in a magnetic field it causes a force on both the magnet and the metal.
This is the principle that is used in a rail gun.
I would think that this would be a little like trying pick yourself up off of the ground by your own hair. The forces involved will cancel themselves out. Maybe their is some physics involved that the article did not describe.
Environmentalists are their own worst enemy. ~tricklenews.com
1. The article acknowledges that this may go nowhere.
2. This is how most scientific 'advances' are made. Somebody notices something cool about the world around them and builds on it.
3. Seems like a reasonable idea (from a 2nd year physics major) but then again I'm no expert on super-conductors or magnetic fields.
4. Everyone agrees that a new propulsion form(s) is needed for space exploration to become a viable and regular occurrence.
5. This is my first post on slashdot so...just take it for what you will.
Comment removed based on user account deletion
For those of you who are trying to remember exactly what law of physics this violates, it's Newton's Third Law of Motion, For every force there is an equal and opposite force. This means if you don't have something to push off from, you can't go anywhere. (Just for those few of us from the slow class: You can push out a stream of high pressure rocket fuel byproducts, which is how these things usually work.)
I don't see how an asymmetric magnetic field and superconductors help you out--where's the opposite and equal force supposed to come from? It's hard to see how the thing COULD do anything but 'sit there and vibrate'.
OK, normally I don't like to post a bunch of links but your post has me wondering. Is this accident just an effect of some type of inertial gyroscopic propulsion? I have heard of such systems (admitedly from the 'alternative' side of fun things related to space) where forced opposition of gyroscopes casues a similar effect. Here are a few links to sites that discuss this phenominon: some patented gyro propulsion ideas
an open source gyroscopic inertial thruster
a list of space drive patents
someone with way too much time on his hands
100 anti grav links Take a look at some of those links (with a grain of salt). I would be willing to bet this guy had some sort of setup that upon 'falling' forced the unit mass against the gyroscopic forces of the motor and thats why his result was it 'flying'. I am not a scientist so excuse my ignorance on the mechanics/physics of this subject. It is fascinating...
Prospecting Stinks. Stop Wasting Time on Cold Calling.
Ok. I push on the magnet, which pushes back on me with equal and opposite force. I move one way. The magnet moves the other. Oops...magnet is now farther away. If I keep doing this, the force of the magnetic field on the magnet falls off with the square of the distance from it. So, you technically CAN keep accelerating, but eventually the effect will be essentially zero. Oops! Well, what if the magnet is fixed into some frame of reference? If the frame of reference isn't fixed relative to your spacecraft, then what I described will happen. If it is fixed relative to your ship (ie, you bolted it to the rear bumper), then you'll just cause internal stresses within the ship-magnet system. That might generate some heat, but it won't get you anywhere. Sorry...
I remember in the neighborhood of 15 or so years ago there were some people claiming ot be UFO abductees and Robert Lazarr(SP?) who claimed that the ETs had told them/reverse engineered a UFO and their propulsion system was magnetic in nature.
My first problem with this is if every action has an equal and opposite reaction then how does the movement of the superconducting magnets cause any real change? Sure, their inertia will have an effect, but as soon as they move back into their original position their inertia will cause the opposite reaction.
Imagine standing on a kickboard in the middle of a swimming pool trying to propell yourself with the action caused by swinging a bowling ball. I don't see how you'd get anywhere with THIS particular scheme.
LK
"Hi. This is my friend, Jack Shit, and you don't know him." - Lord Kano
In this metaphor, to cut the string, you'd have to actually have an infinitely long string, which equates to never shutting off the solonoid, which means you get one 'jolts' worth of accelleration, for as long as you keep the charge in the solonoid.
For the picky, rotating the solonoid 180 degrees while charged wouldn't work either, as it would have exactly the same effect on accelleration as shutting it down and charging it up again with a reversed polarity, so charging, turning, discharging, turning, etc wouldn't work at all. It's like a gyroscope in that capacity.
Kevin Fox
Kevin Fox
"Look at that blubber fly!"
- Homer Simpson, underappreciated propulsion physicist
---
Goodwin says the metal objects create the judder effect by inducing a "brief asymmetry in the magnetic field" as it is set up when the magnet is turned on. This initial disturbance of the magnetic field, he says, creates a repulsive force on the magnet and pushes it away.
So it's not quite the same thing as a railgun (especially because they claim the magnet is repelled from, rather than attracted to, the metal).
Unfortunately, you might still be right that it's like trying to pull yourself up by your hair. As Mills says at the end, "It's a definite possibility that any forces arising from Goodwin's concept will only act within the components of the device itself, resulting in no net force. There are a lot of unresolved physics issues to address."
So, it is possible, but they just don't know yet.
"The question of whether a computer can think is no more interesting than that of whether a submarine can swim" -EWD
Ouch .. this hurts! I am sorry dudes but I just can't get my head around this. Reason:
/2, then coast at top velocity for a time , then decelerate over a time T /2.
/2. The total trip time is the time spent accelerating/decelerating plus the time spent coasting.
/dt times the square of the exhaust velocity.
I begin with the classical (ie. non-relativistic) rocket equation (I use the classical version because relativistic effects only become important for exhaust velocities greater than about 95% the speed
of light, which is not the case for the powers and speeds we are talking about here).
The rocket equation is:
dv = u ln [ ( M + m ) / M ]
where:
dv = change in ship velocity
u = exhaust velocity
M = ship mass, without including reaction mass
m = reaction mass ejected from ship
Now in general, to get from one place to another a ship must accelerate for some time T
The total change in velocity is v, but since the ship speeds up and slows back down to rest, the maximum velocity is v
Now the power required to eject the reaction mass at the given exhaust velocity is equal to the rate of change of kinetic energy of the reaction mass, which is half the mass-loss rate dm
And that's that!
Conservation of energy isn't that much of a big deal, it's conservation of momentup that causality kinda hinges on, and I like causality. I think "reactionless" should be read as "not carrying reaction mass", not "there is no reaction to the action". If it's using the sun's magnetic field, then the sun will get pushed back as the ship mnoves forward. Not by much though.
Just got pointed here this morning, which has a good overview of reaction drive technology now and in the future. Seemed sort of relevant.
http://astp.msfc.nasa.gov/4thgen_main.htmlSee the link 'Really Advanced Propulsion Research' down side bar.
I'm a number, not a free man!
For every action there is an equal and opposite reaction...
Magnet josts one direction, spaceship jolts the other.
Spaceship retracts magnet to repeat process, spaceship is retracted towards magnet EXACTLY as much as initial jolt.
This is a GOOD way to make a vibrator, but a bad way to make a space ship.
Official GOD FAQ.
The relevant thing here would be the law of conservation of momentum.
Pedantry aside, the only effect I could think of that might cause this, outside of an external field (due to sun, earth etc) would be the time delay between one end of the coil carrying a current and the other end carrying a current due to light travel time difference effects between the superconductor and the free space inside the coil. One end of the coil would be magnetised to a fairly high field and and the other would not, for the time it takes the current to build up in the coil. This time would be at tleast the time it takes for an EM wave to propagate down the coil (including going around all the loops). In the meantime a large magnetic field would build up in the space inside coil, with the speed of build up of the field limited only by the light travel time from one end of the coil to the other, and be expelled by the build up of eddy currents in the superconductor coil, before the driving current got there.
As for the law of conservation of momentum, the above effect, could possibly cause a large EM pulse to be emitted, which would have a momentum in one direction, and so there would be an impulse in the other direction. I don't know if the same effect would be observed on suddenly switching off the current, as I think the impulse produced _may_ depend on the switching speed, and if the magnet isn't switched off as quickly as it is switched on, a net momentum may develop. If this isn't the case, the magnet will just sit there and vibrate.
This is all just thinking straight into the comment, so I've got quite a high chance of being wrong. (more so than usual)