Wouldn't you want to run tests in multiple orientations to cancel Earth fields anyway? Similar to how you would run a Michaelson-Morley interferometer experiment.
The torsion balance introduces fixed biases, and can be operated only in XY plane. So in theory you're right, in practice it's not possible.
Not canceling earth's magnetic field (an easy thing to do) when measuring microNewtons at high currents is just very poor experimental practice. Unprofessional. Amateur.
You could but that may be a bit complicated to set up, while Helmholtz coils are dead easy to make and install. It's just a frame, copper wires, 3 power supplies, a magnetometer and a PC (even an Arduino could drive it).
"The motion of the beam is damped by a pair of aluminum plates attached to the beam that move in the magnetic field of an array of small neodymium-boron magnets. The power circuit was extensively shielded to insure that stray fields did not compromise the results."
Be careful here. Magnetorquers do exactly what the name says - they create torque, which manifests as rotation around a point. If a device demonstrates linear force, it's likely to be a different effect (electrodynamic), which currently requires a rather long tether to work [1].
Right, or we can just link to the physical law itself: - Lorentz force - the force on a current carrying wire. No need for a long wire. It's in the range of micro-Newtons for few Amps, for 10cm, at earth magnetic field:
"When a wire carrying an electric current is placed in a magnetic field, each of the moving charges, which comprise the current, experiences the Lorentz force, and together they can create a macroscopic force on the wire (sometimes called the Laplace force)."
I’ve never understood this position with the EMdrive and similar technologies; wouldn’t magnetic propulsion revolutionize low-earth-orbit travel, or whatever the ceiling is for pushing against Earth’s magnetic field?
I find it quite hard to believe that this obvious question wasn't challenged by anyone. To me it is like questioning if any of the people involved prior to publishing this news are capable of solving 1+1.
It's basic. I don't think of the relevant people as idiots.
> On a clear night in March 1967, Woodward was stargazing on the rooftop of Pensión Santa Cruz, a hotel in the heart of Seville, in Spain.... As Woodward gazed up from atop his Spanish hotel, he saw a speck of light arcing across the sky and mentally calculated its path. But as he watched the satellite, it began deviating from its expected trajectory—first by a little and then by a lot.
> Everything Woodward knew about satellites told him that what he was seeing should be impossible. It would take too much energy for a satellite to change its orbit like that, and most satellites weren’t able to shift more than a couple of degrees. And yet, he had just seen a satellite double back with his own eyes. He didn't conclude that engineers at NASA or in the Soviet Union must have secretly achieved a breakthrough in satellite propulsion. Instead, he believes he saw a spacecraft of extraterrestrial origin.
Seems more likely he spotted a reconnaissance aircraft at very high altitude. I think the U2, A-12, and SR-71 were all operational in 1967.
Do you honestly think that somebody trained in astronomy could mistake a bird for satellite? Have you seen how satellites move? They traverse the sky in a perfectly straight and constant-motion fashion that is utterly unlike any bird.
Even a high-altitude plane such as the U-2 would be fairly difficult to misidentify as a satellite. For obvious reasons, U-2s and SR-71s and such didn't employ lights while operating at altitude; therefore the only way to see them would be via reflected light. It would need to be reasonably long after sunset, or else the sky isn't dark enough to credibly see a satellite -- but not so long after sunset that the plane would be in the earth's shadow. Satellites have a similar window of observability -- but it's much longer, because they're much higher. A high-altitude plane would have a very small window. Moreover, it would need to execute that turn without crossing the terminator: as soon as any reflecting object crosses the terminator, that reveals its altitude.
> Do you honestly think that somebody trained in astronomy could mistake a bird for satellite?
Yes.
> Have you seen how satellites move?
Yes.
> They traverse the sky in a perfectly straight and constant-motion fashion that is utterly unlike any bird.
That's exactly like any migrating bird. Like a goose. Well, until they suddenly switch direction and continue at a constant speed and height till they go over the horizon. Have you ever seen birds migrating?
Also, if lights in the sky that look like meteors but suddenly switch direction are aliens, then I've seen them hundreds of times walking home from the pub (no streetlights here). Never yet been offered a lift!
Would a satellite on a low-altitude Highly Elliptical Orbit be a possibility? From Earth, the apogee would make an HEO satellite go in one direction then suddenly change course. With a low enough altitude, this could seem fast enough.
It's worth noting that if a propellentless drive works, it will probably generate free energy. This may adjust your expectations on how likely this idea is. How likely is a free energy device (ie, one that reliably gives you more energy out than you put in)? Well, this thruster can't be any more likely, because it would produce free energy.
> the kinetic energy of a mass with a constant force applied will increase with the square of time, while the electrical energy input only increases linearly with time. A mass with such a drive attached would eventually have a kinetic energy greater than the energy input.
...
> For example, an evacuated track 10km long and supplied with 1 GW of power that is fed via induction along the track to a 100 kg mass equipped with an EM drive would result in the mass experiencing an acceleration of 4000 m/s2(i.e., 407 g’s) and having a velocity of 8.94 km/s at the end of the track, at which point the mass would have a kinetic energy of 4 GJ. The time to accelerate the mass is only 2.23 seconds,however, so the energy input required is only 2.23 GJ. At the end of the track, the mass could be decelerated via regenerative braking, generating more energy out (4 GJ) than was input (2.23 GJ), for a net gain of 1.76 GJ free energy.
Not precisely free; it moves energy around(1) by interacting with the inertial mass of other objects in the galaxy and applying force to them at a distance (the details of how, which objects, and how much force, at least in the Wikipedia summary, are really sparse).
In theory, if we could run an unbreakable string from Earth to Mars and twist it around a spindle, the differing orbits of Earth and Mars would pull that string taut and that string yanking the spindle around would generate energy that wasn't "free," but (like solar) would be free for all practical purposes. Do too much of it, and Mars crashes into Earth of course, but there's a LOT of energy that could be siphoned off from the planets' different velocities before something like that happened.
It's the same kind of "free" spacecraft get making a gravity-assist maneuver; they slow (or speed up) the orbit of the body they're assisting off of imperceptibly.
(1) ... of course hypothetically. The details of the mechanism are not well-understood and appear mostly theoretical.
> [..] while the electrical energy input only increases linearly with time.
This is the fallacy. In an electric motor the power required to exert a force is proportional to the speed, so if you want to keep the acceleration constant you need to increase the electrical power (i.e. rate of energy use) linearly over time. Hence the total energy input increases with the square of the time, just like the kinetic energy imparted. If the system is 100% efficient then the total electrical energy used will be equal to the kinetic energy of the mass.
In what reference frame? It's not obvious to me how this works in a space drive. How does it "know" how much speed it gets per unit energy?
I guess if it's a sort of Dean drive that swims through the gravitational field of the visible universe, then that's the reference frame. It's still weird!
The schemes I'm familiar with claim to extract energy from the vacuum, essentially. It sounds a lot like hocus pocus to explain away free energy. Great if physically possible, but exceedingly doubtful.
Did you read Mach's Principle? It would not create free energy. And yes, it's quite probably people more specialized in this field would've asked this question before.
Wiki:
(...) Woodward states there is no violation of momentum conservation in Mach effects:
If we produce a fluctuating mass in an object, we can, at least in principle, use it to produce a stationary force on the object, thereby producing a propulsive force thereon without having to expel propellant from the object. We simply push on the object when it is more massive, and pull back when it is less massive. The reaction forces during the two parts of the cycle will not be the same due to the mass fluctuation, so a time-averaged net force will be produced. This may seem to be a violation of momentum conservation. But the Lorentz invariance of the theory guarantees that no conservation law is broken. Local momentum conservation is preserved by the flux of momentum in the gravity field that is chiefly exchanged with the distant matter in the universe.
Interesting caveat about traveling close to the speed of light...if you run into hydrogen atoms, which is near 100% likely, your ship violently explodes because at very high speeds, there is a huge reaction on tiny matter collisions. I just learned this and it was like learning that sound doesn't travel in space when I was young and ruined many a starwars movie effects. I keep learning how ignorant and dumb I am the more I follow SpaceX and become curious about space.
At least Star Trek tries to answer this in some way even though bs but still cool for the effort, mainstream space is definitely dumbed down compared to that.
Interstellar ships will be shaped like pencils to deflect rather than impact gasses. They will also have to have consumable nose cone sections with old ones in the front being removed and new ones installed at that back. Like a mechanical pencil.
The turn-around takes place at the half-way point of the journey. This means that for the entire second half of the journey, the engine is pointed at the oncoming dust.
Engines used in such long journeys will likely emit a thin stream of particles at extreme velocities. This stream is not wide enough or thick enough to stop space dust from hitting the engine. An unshielded forward-facing engine will get destroyed. So we must shield the engine.
Instead of having two shields and turning the ship around, just turn the engine around. Make the engine emit streams forward from the sides of the ship.
Zubrin, in Entering Space, introduced me to the idea of using a solar or much larger magnetic sail to drag against the outcoming solar wind of the destination star. So that's one way to spend no energy slowing down for interstellar travel.
Interstellar space is full of particles flying around. There's plenty of hydrogen in the galaxy. Between galaxies not so much but we're not talking inter-galactic space.
It is because the payoffs would be so enormous that business like this and "overunity motors" continue to gain attention. All of those other elixirs were shams, but this one will work! Finally, immortality! The enormity of the reward causes the payout matrix to lead people astray.
Don't get me wrong, I see a vacuum chamber, which is light years ahead of most of these enterprises, but I would not spend a dime on it until it has been proven to work in a region of space relatively far from the Earth's magnetic field.
That said, Woodward does not seem to be an actual charlatan, so I don't have a problem with funding him. At least he might turn up something fun and/or interesting, even if I don't think it's going to usher in a new space age.
I personally believe he rides that line of charlatanism where he's not pursuing this theory in bad faith at all, but he of course recognizes that tromping around on the edge of a theoretical branch that most physicists don't think is worth exploring garners attention he wouldn't otherwise receive.
I strongly suspect that whether history remembers him as a charlatan will depend heavily on whether one of the supports of his branch proves false and it snaps off, or whether he's been right this whole time and we suddenly oops ourselves a propellantless drive that operates by coupling to the gravitational field and pushing distant objects around. ;)
Propellant-less propulsion within the confines of Earth's magnetic field or gravity well is still pretty valuable. The entire space economy at the moment is Earth satellites, all of which are constrained by propellant.
Being able to build boxes that are bigger on the inside than on the outside would also be very valuable - like a standard 40ft shipping container that fits in your pocket.
And that's very close to the kind of thing we're talking about here.
One should note that propellantless propulsion systems exist. They are called lasers. It is just that the thrust to weight ratio of such an engine is very low.
A quick google search does not bring back any designs or research papers of such a system, as the results are swamped by the idea of using ground based lasers to push spacecraft instead of the craft itself containing the laser.
So, I have to ask: If Elon Musk is working on propulsion tech to go to Mars, and Bob Lazar claims to have worked on reverse engineering propellentless tech and is one of the single digit number of living people to have encountered it directly, and NASA is slow rolling their own understanding of it, given the limited available expertise in this area how can Musk afford to not hire Lazar? From a due diligence perspective, Musk would need to know with a high degree of certainty that Lazar is full of crap.
While this might sound insane, from a portfolio perspective, if a VC firm is invested in SpaceX, Blue Origin, Virgin Galactic, or anyone else in the space, it seems negligent to not have some exposure to a company with someone like Lazar involved in it, unless you really knew for sure, as he and people like him present an existential risk to rocket-based tech companies. That guy is the ultimate hedge.
Your logic assumes only one such person. The problem is that there are tens of thousands of similar people with, let's be super kind, unlikely ideas. If you hire them all that's not a hedge that's a huge cost with an almost 0% probability of payoff.
I'd bet the number of such people with unreasonable ideas will go drastically up if you start hiring them too.
The analog I'm thinking of is that space propulsion could turn out to be as much of a sandbox as cybersecurity and crytpo have been, where there was always a ceiling above which everyone just agreed to not look. I'm being super charitable about Lazar, but having been in the security field both pre- and post- Snowden, Lazar is more like a Binnie or Drake figure, with the full extent of the issue still further off in the future. What good technologists suspected about crypto and saw little edges of, vs. what ultimately came out implies companies like those mentioned above would need to have done some deeper arguments and analysis beyond blowing him off as just a kook. Musk's opinion on Lazar would be interesting for its own sake.
However, this is also like saying you have to rule out every "free energy" conspiracy before starting a battery company as well, so it's not really that much of a forcing function at all.
I'd agree, but if we're trading tropes, the absence of evidence is not evidence of absence either. He's easy to discredit and dismiss, and it's meaningless to my life whether he's real or not, but if you've got billions on the line in the space propulsion game, I'd think you'd need to have gone deep into his claims to determine he's full of it.
The answer is that any entrepreneur who focuses on what their competition is doing rather than what they are doing is guaranteed to fail.
There are far more likely ways for SpaceX to fail than that some random professor replaces rockets with a drive using novel physics. And even if said professor does produce that drive, it wouldn't threaten SpaceX's main business unless the drive was able to produce sufficient thrust to escape the Earth's gravity well. (Flash notice, not even the professor in question thinks it will.)
Therefore Musk should continue to be focuses on what he is doing and not even think about this unless there is a working prototype validated by NASA.
If he wasn't full of crap, then you also running the risk of the government/some other group not wanting the tech out there and then preventing the success of your investment.
> Mike McDonald, an aerospace engineer at the Naval Research Laboratory in Maryland, will be among the first [attempt to replicate their results]. He leads an internal program for independently testing advanced propulsion systems, which has previously shot down promising results from the EmDrive.
The U.S Naval Research Laboratory also has several facilities in MD. Including at Patuxent River, Chesapeake Beach and Blossom Point. Given the nature of the work I would guess it is referring to the facility at Blossom Point.
Nit: "as Newton put it, inertia is why an object at rest tends to stay at rest." No, what Newton said is that an object in motion tends to continue in motion at the same velocity (and an object at rest tends to remain at rest, i.e. with velocity=0).
While this doesn't have a lot to do with the original article (hence my "nit"), it was revolutionary at Newton's time. People had observed objects at rest staying there; that's why you can sit on a chair. But they had also observed that any object in motion (except for those in the sky) slowed down and eventually stopped, unless you kept pushing them. Newton attributed this to friction.
This theory--which contradicted what people could plainly observe with their eyes--is what makes possible satellites (and keeps the moon in orbit), since being outside the atmosphere, they experience very little friction. Of course the other thing necessary for man-made satellites is a way to get them moving fast enough, for which Newton's third law comes in handy (it's why rockets accelerate, even outside the atmosphere).
So, https://xkcd.com/955/ appears to be relevant. If someone were to take it, I'd make a bet that this is not real. If it is not real, then I win the bet, but if it is real, then I'd be too fascinated by the result to care.
It's really disappointing that a human can work on something for 30 years and only get a tiny amount of thrust. Our science needs to go in different directions it seems we are stuck living in the past.
People don't like to see quack science take funding from legitimate science. I am not qualified to judge whether or not this is quack science, but it certainly reeks of the same claims as previously documented quack science.
Even more than the funding, I hate the perpetual fueling of the narrative that magic is just around the corner. Why bother learning actual, boring science when a revolution is going to make everything different tomorrow, bringing us flying cars and gorgeous green Martian girls in steel bikinis?
There's an enormous amount of science denial, at least in the United States. A lot of things go into that, but I don't think it helps that stories like this present scientists as wedded to orthodoxy and general killjoys who hate imaginative iconoclasts. Instead, people lurch from one self-styled Galileo to another, as they fade from view without even reading the confirmation that their work was wrong.
Meantime, science produces a steady stream of advances both fundamental and practical. And those are taken for granted, unless scientists something you don't want to believe, when they can be presented as scientists are in stories like this.
> the perpetual fueling of the narrative that magic is just around the corner
Do you know why humans went to the moon in 1969?
It wasn't just that people suddenly woke up one day and wanted to. The earliest known story of a voyage to the moon was written by Lucian of Samosata, CE 125. It wasn't that people woke up one day and were smart enough; the orbital mechanics were hard math, but the basics were understood since Newton.
It was that in 1935, the Aluminum Association was founded. Extraction of aluminum was only started in 1825, and we only had the array of necessary technologies to do it in mass quantities, reliably, with the development of massive power stations. Aluminum is useful for several things, but most importantly: it can be hammered into a thin but solid material that can form aerodynamic shells and contain pressures against vacuum. It was, basically, a miracle metal. It made the aviation age cheap and (coupled with other breakthroughs like radio, which is still only a 100-year-old-technology) the space age possible. One generation after the founding of the AA, humanity set foot on the moon.
I believe people think magic is just around the corner because the previous two or three generations have lived through one miraculous invention after another. And you're right; these inventions don't spring from nowhere. They come from people observing unexpected phenomena, dogging that phenomena until it can be understood and reliably manifested or controlled, and putting ingenuity on what could possibly be done now that the rules of the world have changed, because, in a sense, magic just happened. At least from the point of view of the average person living through the technological revolutions as they come one after another.
But it's a misunderstanding. I see things like this space drive as different, because they're supposed to be based on physics that hasn't been figured out.
Real revolutionary and amazing technology comes from physics that came way before, which in turn came from math that was even older.
Today people mostly can't imagine what the world was like, technologically and socially, a hundred years ago when relativity and quantum mechanics were on the cusp of being developed.
The things which will transform or devastate the world in the next few decades have been growing for the last 50 years even if most haven't noticed. It will look like coming out of nowhere, but it won't be in the way that this space drive is.
Where does quack science end and legitimate science begin? There's a real bottleneck in theory right now and I don't see how pushing the envelope in various directions could be a bad thing (especially given the relatively low cost this seems to have been). The surest way we can stagnate is by NOT funding this type of thing.
There are other kinds of quack science, but in this area, anything that seems to contradict the basic laws of motion and/or conservation of energy is recognizably quack science. Especially when doing so experimentally first (instead of first coming up with a theoretical/mathematical framework). Even especiallier when using electrical effects in Earth's magnetic field and measuring minute effects.
Where did quantum mechanics come from [1]? Where did general relativity come from [2]? They came from _experiments_ and _observations_ that couldn't be explained by the current theories. You don't just take theories to produce experiments (though this can happen to verify or to gain accuracy) - usually it works the other way around. Experiments are done to power new theory. Except a growing number of people are becoming content as you are in the existing theories because it is costlier now to probe the edges of our theories than it used to be. There are major problems though even in established theory [3].
I'm not an expert in general relativity, but there are some major unknowns (and in fact known problems) with it and to assume that our current interpretation (because as far as I can tell, the issue is mostly with the interpretation of inertia rather than the actual formalization of gravity itself) is 'correct' is just so arrogant and counter-productive. Does that mean all fringe ideas should have money poured into them? Certainly not. But if we have no funding going into experiments differing from the 'consensus', that's the surest possible approach to guaranteeing the consensus never improves.
I believe a total of $620,000 over a span of several decades. I am personally quite happy to fund one-off random projects like this. The amount of money is a trivial rounding error. Funding 100,000 failures at this level would be worth it if one, just one, worked.
I do understand that others might think differently. I like moonshots.
Put another way: modern chemistry is in many ways a descendant of alchemy. It's the outcome of people pursuing ultimately failing experiments but identifying other interesting things along the way. It laid the foundation for laboratory practices and uncovered a lot of the basics.
Even if all of these experiments fail, chances are some of them will come across findings that are useful in unexpected ways.
If nothing else falsifying these theories will help create a baseline of effects that needs to be accounted for in the investigation of future theories like this.
We spend about $150 billion per year on science funding in the US. I don't think we're being irrational by giving moonshots roughly 0.00003% of the funding. That's a generous percentage, too, considering the funding for Jim Woodward spans many decades.
The sense I get is NASA is tossing money at it because if it doesn't work, it falsifies some hypotheses that have been sitting around at the edge of relativistic physics for awhile.
Did the EMdrive have a solid understanding of why it would work, rather than just being a discovered curious effect?
What's interesting about this one is that there is a theory at least. Experiments aside, someone whould be able to either confirm or reject the theory on its own.
The EMdrive also had a "why." Note, if you investigate these sorts of devices, they typically have a why. It's just that the why tends to ignore a bunch of other things and it's a disappointment in the end.
Really, if you're curious, you should dig into the history of all kinds of devices like these, anything in the Impossible Class. The inventor spends decades grinding away at it, getting inconsistent, odd little results which are just tantalizing enough to keep them stumbling forward.
I have often considered a taxonomy of these sorts of enterprises, with three orthogonal systems of reckoning. The first, a type really, is what principle is being violated (Second Law of Thermodynamics, Newton's Third ...). The second is psychological: misunderstanding, self-deception, or duplicity (typically to bilk inventors), with the understanding that the inventor typically starts with misunderstanding and proceeds onward. The third would, finally, be the discovered actual source of the odd results, which could be bad experimental design, not accounting for oddly-radiating services, vibration, friction, and so forth.
Look closely at the picture of the test chamber in the article. Do you see Helmholtz coils surrounding the entire apparatus? Nope.
https://en.wikipedia.org/wiki/Helmholtz_coil
It's the same story as the EMdrive: they run something at high current, without cancelling earth's magnetic field.
high current + earth magnetic field = force. This method is used to move satellites:
https://en.wikipedia.org/wiki/Magnetorquer