German Test Reveals That Magnetic Fields Are Pushing the EM Drive (arstechnica.com) 309
"Researchers in Germany have performed an independent, controlled test of the infamous EM Drive with an unprecedented level of precision," writes PvtVoid. "The result? The thrust is coming from interactions with the Earth's magnetic field." From the report: Instead of getting ahold of someone else's EM drive, or Mach-effect device, the researchers created their own, along with the driving electronics. The researchers used precision machining and polishing to obtain a microwave cavity that was much better than those previously published. If anything was going to work, this would be the one. The researchers built up a very nice driving circuit that was capable of supplying 50W of power to the cavity. However, the amplifier mountings still needed to be worked on. So, to keep thermal management problems under control, they limited themselves to a couple of Watts in the current tests. The researchers also inserted an enormous attenuator. This meant that they could, without physically changing the setup, switch on all the electronics and have the amplifiers working at full noise, and all the power would either go to the EM drive or be absorbed in the attenuator. That gives them much more freedom to determine if the thrust was coming from the drive or not.
Even with a power of just a couple of Watts, the EM-drive generates thrust in the expected direction (e.g., the torsion bar twists in the right direction). If you reverse the direction of the thruster, the balance swings back the other way: the thrust is reversed. Unfortunately, the EM drive also generates the thrust when the thruster is directed so that it cannot produce a torque on the balance (e.g., the null test also produces thrust). And likewise, that "thrust" reverses when you reverse the direction of the thruster. The best part is that the results are the same when the attenuator is put into the circuit. In this case, there is basically no radiation in the microwave cavity, yet the WTF-thruster thrusts on. So, where does the force come from? The Earth's magnetic field, most likely. The cables that carry the current to the microwave amplifier run along the arm of the torsion bar. Although the cable is shielded, it is not perfect (because the researchers did not have enough mu metal). The current in the cable experiences a force due to the Earth's magnetic field that is precisely perpendicular to the torsion bar. And, depending on the orientation of the thruster, the direction of the current will reverse and the force will reverse. The researchers' conclude by saying: "At least, SpaceDrive [the name of the test setup] is an excellent educational project by developing highly demanding test setups, evaluating theoretical models and possible experimental errors. It's a great learning experience with the possibility to find something that can drive space exploration into its next generation."
Even with a power of just a couple of Watts, the EM-drive generates thrust in the expected direction (e.g., the torsion bar twists in the right direction). If you reverse the direction of the thruster, the balance swings back the other way: the thrust is reversed. Unfortunately, the EM drive also generates the thrust when the thruster is directed so that it cannot produce a torque on the balance (e.g., the null test also produces thrust). And likewise, that "thrust" reverses when you reverse the direction of the thruster. The best part is that the results are the same when the attenuator is put into the circuit. In this case, there is basically no radiation in the microwave cavity, yet the WTF-thruster thrusts on. So, where does the force come from? The Earth's magnetic field, most likely. The cables that carry the current to the microwave amplifier run along the arm of the torsion bar. Although the cable is shielded, it is not perfect (because the researchers did not have enough mu metal). The current in the cable experiences a force due to the Earth's magnetic field that is precisely perpendicular to the torsion bar. And, depending on the orientation of the thruster, the direction of the current will reverse and the force will reverse. The researchers' conclude by saying: "At least, SpaceDrive [the name of the test setup] is an excellent educational project by developing highly demanding test setups, evaluating theoretical models and possible experimental errors. It's a great learning experience with the possibility to find something that can drive space exploration into its next generation."
THIS is science (Score:5, Insightful)
This is what we should be teaching in schools and promoting in daily life/culture.
Re:THIS is science (Score:4, Informative)
OK, I've found what your second point refers to. "The laws of mathematics are very commendable, but the only law that applies in Australia is the law of Australia." [independent.co.uk]
The first point probably has so many examples I can't be bothered looking for them, but if I did, I'd start with climate change.
Re: THIS is science (Score:3)
If you think that they "overruled botanical categories" then you clearly haven't even read your own link.
Re:THIS is science (Score:5, Informative)
Dear Gods, not again. Can we please just kill this thing once and for all?
*"Vegetable" is not a botanical category.*
"Vegetable" is a culinary term.
All vegetables are some part of a plant.
Botany always has a specific name for that part, but that does not exclude them from vegetables,
Salad does not cease to be vegetable for being botanically leaves or buds.
Celery does not cease to be a vegetable for being botanically a leaf stalk.
Artichoke does not cease to be a vegetable for being botanically a flower.
Carrot does not cease to be a vegetable for being botanically a root.
Tomato does not cease to be a vegetable for being botanically a fruit. Nor do squash, peppers, eggplant, cucumber, okra, avocado, or any number of others.
"Vegetable" refers to basically any part of a plant used for food, except those commonly placed firmly in more specific categories. One of those more specific categories is "fruit" (in the culinary sense), which usually requires it to be sweet and/or tart and used substantially for those qualities.
Some of the others are grain (usually botanically fruit before threshing), nuts (always botanically fruit), spices (includes a number of fruits botanically speaking), and herbs.
Culinary terms are made for utility in cooking, not for classification of plants - for that we have botany.
Thus the distinctions are inherently vague:
How big or mild-flavored does a leaf have to be to move from herb to vegetable?
At what size, mildness, or degree of dessication does a chili move from vegetable to spice?
How sweet would a plantain have to be to leave the vegtable section and move in with the banana?
Is it not fair to look for sugar cane and rhubarb in the fruit section, even though botanically they are not?
Is the sweet potato with the vegetables bacause it is a root or because of its usage? Or maybe in your shop it is not?
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You've only talked about vegetables there. They might not be a defined botanical category, but surely fruit is.
And if I understand the law correctly, it distinguishes between fruit and vegetables. So how does it get to un-fruit a fruit?
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Because there are two words called fruit. One is botanical, the other is culinary. The legal language was interpreted as fitting the culinary use of the term.
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Fruit: a fruit is the seed-bearing structure in flowering plants (also known as angiosperms).
However you look at it, thus, tomatoes are fruits.
Since the case was about whether it is a vegetable OR a fruit, and it definitely is a fruit, what that does is the court 'un-fruiting' a fruit. Makes no sense.
EVEN if your explanation would be valid, one would have to explain, logically and rationally, why a fruit shouldn't be considered a fruit anymore. After all, with all your examples, this is not the case. For in
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As your parent pointed out: many fruits are considered vegetables, and that includes tomatoes.
In other words: it is not an either or, it is an overlapping definition. While a lettuce or a cabbage is definitely not a fruit, the cabbage is considered a vegetable and the lettuce a salad (no one would call it vegetable in France or Germany, no idea about the brits). While apples and pears are definitely fruits and don't fall into the vegetable category, an eggplant or tomato or even a celery is a fruit: and is
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Very insightful. The other thing I hate is when people say, "A spider is not a bug, because a bug is an insect! A spider is an arachnid!" But "bug" was never a scientific category anyway, and its definition never meant "insect." A "bug" is defined culturally, not scientifically, and culturally we tend to think of spiders as bugs.
The problem here is more than just the fact that there's lots of annoying and whiny people in the world. The problem is that we tend to have a strange assumption that science can co
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A "bug" is defined culturally, not scientifically, and culturally we tend to think of spiders as bugs. ... a spider has none.
Then *your* culture must have changed considerably. A bug has wings
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A "bug" is defined culturally, not scientifically, and culturally we tend to think of spiders as bugs. ... a spider has none.
Then *your* culture must have changed considerably. A bug has wings
Lots of bugs don't have wings. Pill bugs, for instance.
Re:THIS is science (Score:4, Interesting)
A "bug" is defined culturally, not scientifically ...
100% False. Bugs are a specific order of insects [wikipedia.org] whose defining characteristic is a particular arrangement of sucking mouthparts. Examples include tree-hoppers, box elder bugs, and stink bugs.
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Nah, I'd say 50% false. Bug is defined culturally and scientifically, so half of it is right.
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The tomatoes case is reasonable. Most consider them as vegetables -- fruits are sweet.
When passing the law on tariffs, the scurilous thing seems to be to facetiously claim it applies to tomatoes when the common understanding is it does not.
Same thing when the Bible "wrongly" calls bats birds -- modern classification by scientists has nothing to do with the common understanding (at that time.)
Also, Pluto is a planet, right?
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A toughness of one is infinity times tougher than a toughness of nought and half as much not tough again as a toughness of two..
Thrust is coming from interactions with the Earth (Score:5, Funny)
No problem... we will just have to take the Earth with us.
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No problem ... we can use a big EM-Drive to move the Earth along with us! We'll power the whole thing with safe, efficient cold-fusion.
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Cold fusion is so last century. Modern pseudoscientists all use vacuum-energy generators for their star drives.
Get with the program!
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Re:Thrust is coming from interactions with the Ear (Score:5, Informative)
The EM drive does use fuel - just not a propellant. It also gives such a small amount of thrust, one can only measure it with a carefully controlled setup. This experiment basically proves the thrust is created from the charged craft interacting with Earth's magnetic field.... and the thrust doesn't go up much if any as the power on the craft goes from 5 watts to 50 watts. So, we're basically looking at motion powered by Earth's EM, not the craft's EM.
We have about as much of a chance of boosting a craft into low Earth orbit with this as we do using a compass.
Perhaps it'll be useful for something one day, but all I can come up with right now would be Back to the Future II style hoverboards, but for dust mites instead of people given what little thrust it gives -- also it is hard to steer given it tends to only move in alignment with Earth's magnetic field.
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So, we're basically looking at motion powered by Earth's EM, not the craft's EM.
Well. scale it up to work on the suns EM and then you're laughing.
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Remind yourself that the idea was to use these things for deep space missions, where low but consistent acceleration is needed. This is where a high specific impulse of your propulsion system becomes more important than absolute thrust. Not having to carry any propellant with you would have been a great bonus here.
At this point we may as well u
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.... and the thrust doesn't go up much if any as the power on the craft goes from 5 watts to 50 watts. .
How do you know that?
According to TFA, they only applied 5W to the craft as the thermal dissipation system was not optimized. The control amp was brought up to 50W to rule out the effect of noise generated by the control unit, however that power was dumped into an attenuation. 50W is not all that much if you are looking to do work. Compared to the 1-2W on your phone it is a lot, but compared to a cell tower of 100-500W, it's peanuts. Let alone the 1500W of microwave energy in your kitchen.
Point is... how to
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Thrusters that work against the Earth's magnetic field are incredibly useful for station keeping and orbit adjustments on satellites. Many satellites end their lives not because they wear out but because they run out of station keeping propellant.
It's also not a new idea.
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If you had read the summary or the article, you would know: this EM drive does not work at all.
The measurement of "thrust" comes from the power lines, their small magnetic field is twisting the measuring wire.
Re:Thrust is coming from interactions with the Ear (Score:5, Interesting)
Once you've taken an EM drive and removed the useless cavity and microwave emitter, what you are left with is an electrodynamic tether [wikipedia.org] which may indeed be useful, but doesn't owe anything to the EM drive.
Re: Thrust is coming from interactions with the Ea (Score:2)
It's a torque, not a force. Can rotate, not move.. (Score:5, Informative)
Magnetotorquer bars have been used in space for dozens of years to desaturate the reaction wheels.
These are perfectly adjusted to their function (no need for fancy EM things) and generate pure torques when interacting with the Earth magnetic field.
Just, no forces, as, well, expected.
Re:Thrust is coming from interactions with the Ear (Score:5, Interesting)
The reason the EM drive was so exciting was because of the potential for interstellar travel in reasonable timeframes (sub-100 year) without having to lug around huge quantities of propellant (mass to throw out the back to accelerate you). If it actually worked, you could power it with a nuclear reactor and accelerate away without needing any propellant (violation of conservation of momentum).
Traveling to Alpha Centauri (4.367 light years) in 100 years (assuming constant acceleration to the halfway point, decelerating the second half of the trip, and ignoring relativistic effects) would require reaching a peak speed of
d = 0.5*vavg*t
vavg = 2*d/t = 2*(4.367 c years)/(100 years) = 0.08734 c
vmax = 2*vavg = 0.17468 c = 52,368 km/s
To accelerate, you need to dump the energy you're producing into the propellant that you're ejecting in the direction opposite you're accelerating. The energy needed reach Earth's escape velocity (11.2 km/s) and to escape the solar system from Earth's orbit (16.6 km/s) are roundoff error compared to the energy needed to reach Alpha Centauri in 100 years.
Energy for Earth escape velocity = 0.5*m*(11.2 km/s)^2
Energy for solar system escape velocity = 0.5*m*(16.6 km/s)^2 = 2.2 times the energy to escape Earth
Energy to reach Alpha Centauri in 100 years = 0.5*m*(52367 km/s)^2 = 21,861,469 times the energy to escape Earth
So a trip to Alpha Centauri in 100 years would require nearly 22 million times more energy (and propellant to absorb that energy) than needed to escape Earth's gravity.
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Might want to check your math there, Solandri. An average speed of 0.08734c gets you to Alphacent in about 50 years...
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He did not mean "average" speed.
He meant top speed at the point where he is reversing the thrust to decelerate to reach the destination.
Numbers are off (Score:2)
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Yep. In 5 billions years, give or take, our sun will become a liability. We will *have* to move our planet if we want to keep it.
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Yep. In 5 billions years, give or take, our sun will become a liability.
In less than 1 billion years earth will go into "moist earth" runaway with surface temperatures hot enough to melt iron.
We will *have* to move our planet if we want to keep it.
This is possible with current level of technology. You need only nudge a few asteroids close to earth to selectively transfer kinetic energy a few times per century to keep up with increasing output from the sun while still on the main sequence.
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Or you could mount rockets on the moon and use it as a gravitational tugboat - no messy impacts threatening to wipe out most life on the planet that way, much finer control, and assuming you're planning on taking the moon with anyway, there's no difference in impulse needed to modify the Earth's orbit.
Neither is particularly feasible with today's technology though - unless you simply mean "no fundamentally new technology would have to be discovered"
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Or you could mount rockets on the moon and use it as a gravitational tugboat - no messy impacts threatening to wipe out most life on the planet that way, much finer control, and assuming you're planning on taking the moon with anyway, there's no difference in impulse needed to modify the Earth's orbit.
Neither is particularly feasible with today's technology though - unless you simply mean "no fundamentally new technology would have to be discovered"
Small matter of conservation of momentum.
Basically you'd have to get some momentum coming from somewhere else to add to the moon-earth system to reach solar escape velocity. Developing a rocket that first generates that amount of momentum (using action/reaction) would take lots of mass or a more limited mass would have to be accelerated to quite a velocity quickly. A rocket engine that could generate high thrust at high specific impulse would qualify as fundamentally new technology as rocket concepts toda
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If you're moving asteroids, you still need a source of momentum (rockets) for that as well, though you'll be able to get a momentum-amplification effect with regards to accelerating the Earth, provided you're not using near-Earth asteroids, which already have roughly the same orbital momentum.
Of course that means bring in things from the asteroid belt or further, which are then going to be moving FAST, and do a LOT of damage when they hit (though perhaps they could be vaporized just before impact - momentum
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Okay, that could work. Slow though, and probably not very efficient - you'd probably be doing good to get as much momentum from the interaction as you had to put in to get the asteroid on a flyby course. If you're not getting substantially greater than unity momentum gain you may as well just put the asteroid into orbit and keep nudging it in the direction you want to go. Or just use the moon.
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No problem... we will just have to take the Earth with us.
or some big magnets.
One thing this explanation hasn't explained clearlyis if the EM drive would still be useful in orbit for thrust maneuvers even if it won't work in deep space. I think that from this explanation it only can create torque relative to an anchored pivot point. It probably can not create momentum in orbital space even if there is a magnetic field there. But I can't quite tell from the explanation if I'm right on that.
if it can still be used for reactionless drives in orbit it's a huge gain
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The torque came from the cables providing the power, not from the "EM drive".
Using an electro magnet to push against the earth magnetic field is not as efficient as using an ion or hall drive (a hall drive is a glorified ion drive):
And not just any magnetic field... (Score:4, Interesting)
... it's the field being created by the planetary body we call Earth. Surprise! No one has ever tested an EM Drive beyond the influence of Earth. If they had, its efficacy would have quickly been dis-proven.
Mu metal? Haven't they heard of helmholtz coils? (Score:4, Interesting)
It's the field being created by the planetary body we call Earth. Surprise! No one has ever tested an EM Drive beyond the influence of Earth. If they had, its efficacy would have quickly been dis-proven.
Good grief.
If it's the Earth's field, put the device inside a pair of helmholtz coils (or the slightly more complex coil systems that can smooth out the residual ripples further). Give them enough current to cancel the Earth's field and, if the gadget is getting its thrust from this interaction, the thrust will stop. Give them twice that, reversing the field, and the thrust will be in the opposite direction.
I thought this test had already been done, by pretty much everybody including NASA.
Also: Twisted pair (Score:4, Interesting)
So, where does the force come from? The Earthâ(TM)s magnetic field, most likely. The cables that carry the current to the microwave amplifier run along the arm of the torsion bar. Although the cable is shielded, it is not perfect (because the researchers did not have enough mu metal).
Also: What's wrong with using twisted pair? The individual half-twists may interact with a DC magnetic field, but on the average across a twist they cancel out.
This has been used since at least the early days of telephony (where they used twisted pair - with the wires occasionally swapped as they go from pole to pole - not just to cancel out coupling to electrical noise from lots of sources (including power lines) but also - with different rates of twist on different pair and phantom-group - to cancel it out between different lines running along the same poles.
Just like the four pair in your cat-N Ethernet cable each have a different rate of twist, so their signals stay separate.
- - - -
(I DO like the idea of swapping in the dummy load and seeing whether the thrust disappears. B-) )
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I didn't read this article, but the one I did read noted that they are using twisted pair wires. The twist method is not perfect and, at the Lilliputian scale the thrust is measured on, those imperfections are enough to produce the resulting torque.
Legacy of GM and Rolls Royce. (Score:5, Interesting)
The researchers used precision machining and polishing to obtain a microwave cavity that was much better than those previously published. If anything was going to work, this would be the one.
Now that reminds me of a story, back in my programming-for-the-auto-industry days.
Seems that Rolls Royce, after sticking with manual transmissions for a long time, decided to consider manufacturing a car with an automatic transmission. So they got hold of the best on the hoi polloi market - the GM 350 turbo-hydramatic - to use as a reference.
First they tested the heck out of it - and found it did exactly what an auto-tranny should. So how could they make something better? So they tore it down to see if there was anything they could improve. But everything was beautifully designed and machined. Except for one surface on one part, which was a little rough.
So they machined it smooth and reassembled the transmission. And it didn't work at all. That surface was SUPPOSED to be a little rough. B-)
- - - -
Now personally, as much as I'd like to see a working reactionless electronic thruster, I'm not holding my breath waiting for a violation of the law of conservation of momentum. But it would be nice if something DID show up that worked.
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Maybe - maybe not; but why conjecture?
How hard can it be to just build a box and take up the the ISS?
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There's a wee bit of magnetic field up there too. It's far easier to cancel out the field down here where you've got lots of space, power, and engineers.
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The forces are to small to be useful for getting into orbit.
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That's even assuming that the effect was useful as propulsion in the first place, at any degree of Newtons. Have you looked at a diagram of the Earth's magnetic fields lately? The lines of force are not linear.
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Correct... but I wonder if they may be useful for in-orbit maneuvering...
It wasn't the drive unit producing the thrust. It was the cable along the torsion arm carrying current. The EmDrive had nothing to do with it.
Yes, it is possible to use current loops with satellites to interact with Earth's magnetic field [spacenews.com], but ordinary electrical engineering is what you need to call upon. Not a Quantum Vacuum Plasma Thruster (QVPT) [libertariannews.org] as this paper chooses to call it (with zero evidence that the effect, if real, is "quantum" or "quantum vacuum" or "plasma" related).
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Not in deep space - but low orbit is only a few hundred to a few thousand kilometers up, only a 1%-30% greater distance from the center of the earth than on the surface - which with a cubic falloff still means 97% - 45% the strength, or less depending on just how deep the fields are actually generated. More than enough for a magnetic drive to be useful given the negligible opposing forces in free fall. Many different conceptual designs of "orbital electromotor" propulsion systems have been proposed over t
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It was never being considered as propulsion for launch vehicles, period. It was simply a theoretical alternative to technologies like solar sails.
Now we know that it won't even work as an alternative for that, either.
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Never heard about that. No one ever claimed strong thrusts. And no one ever claimed to use an EM drive to launch a rocket.
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No... you need to provide enough thrust to overcome drag. Once you're out of the atmosphere that's not very much.
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You need to apply enough force to generate enough acceleration to attain orbital velocity before you fall back into the atmosphere. Typically this means you need several km/s delta v in a few minutes. 5000m/s in 500 s requires 10 m s^-2 acceleration, or (close enough) 1g.
Unlike the EM drive, ion drives actually do work, but you can't use them to get into orbit because of this reason. They produce wonderful delta v, but lousy acceleration.
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That is not the only way.
If you have a lifting body design with lower acceleration than 1 g but high delta-v, you could theoretically accelerate in the upper atmosphere until you get the orbit velocity.
Basically as long as your lifting body keeps you up you do not need to devote any of your thrust to overcoming gravity, and instead you use to it to build up speed and when you have finally enough speed you go for orbit, at that point the earths gravity will slow you down as you do not have enough thrust, but
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So just use 1 billion EM drives? (/s)
Stil works then (Score:2)
If interaction is how it works, then you merely need to strap two of them together and the interactions between them will provide driving force.
But I have to say the article did not sound wholly definitive:
So, where does the force come from? The Earth's magnetic field, most likely.
AhhhHA!
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Ohhh, so you are saying you need to strap THREE of them together! Got it. You are so incredibly smart in the brain noggin!
It makes sense too since three rhymes with WHEEE which is the sound you make if propulsion pushes you! Genius!
Distant Plastic Trees (Score:2)
Their first few albums were really good.
https://youtu.be/xNEsesfBwRg [youtu.be]
Satellites (Score:4, Interesting)
Re:Satellites (Score:5, Informative)
Yes, it can be, and that system is called an electrodynamic tether [wikipedia.org], and it doesn't make use of the microwave cavity which is at the heart of the EM drive (which, according to this latest experiment, wasn't doing anything in the first place.)
I think you may be wrong (Score:2)
Yes there is an electodynamic tether. But I think it may work differently than this case. I'm not an expert but the tether's work by using a DC current travelling in one direction but not returning along the same path. To complete the circuit the two sattelites have to eject or abosrb electrons from free space.
here I think they are using wires in both directions. SO it's different, and not working on the same principle as the tethers do.
I don't fully understant it yet so If I'm wrong please do correct m
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To complete the circuit the two sattelites have to eject or abosrb electrons from free space. here I think they are using wires in both directions. SO it's different, and not working on the same principle as the tethers do.
It's all just moving electrons: electrons moving in a magnet field experience force. It doesn't matter whether they're free or in a wire.
Here Is A Link To The Actual Report (Score:5, Informative)
It was presented at the Space Propulsion 2018 [researchgate.net] conference.
No surprise (Score:5, Insightful)
The EM drive, if it works, violates conservation of momentum, which can easily be used to also violate conservation of energy. (/. commenters on previous EM drive stories have gone into this at some length.)
The EM drive was originally designed using standard physics (I think electromagnetism and possibly special relativity) and the inventor's calculations showed it would produce thrust. They did not realize that as the input physics conserved momentum but their calculation result violated it, this guaranteed their calculation was in error.
The chances of this result being real were always really tiny. I'm happy there is now a good explanation for the anomalous experimental results.
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This is most unfortunate. It would have been nice if we had a "magic" reacitonless drive. I guess when Mother Nature means no free lunch, she means, No Free Lunch.
But now that I think about it. If it works with the Earth's magnetic field, that would explain a test I read where they said the trust doesn't change with the direction the drive is pointing.
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she means, No Free Lunch
Here's one fantasy alternative: The Free Lunch [wikipedia.org], although the summary here doesn't provide the necessary details. In a nutshell a dying future sends it's tech and personnel back into the past.
If it were real I'm sure that Disney would already have a 28, 42, 55, 75, 95, 105, 170, unlimited copyright [wikimedia.org] on it. Heck, maybe that was the original CAUSE of their problem to start with.
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The EM drive, if it works, violates conservation of momentum, which can easily be used to also violate conservation of energy. (/. commenters on previous EM drive stories have gone into this at some length.)
It was hilarious watching the responses to that too. The argument went something like:
1. The device violates conservation of momentum
2. If you arrange it as X and the device works it makes a perpetual motion machine
3. Sice perpetual motion machines are impossible, the device doesn't work.
The response was
Re:No surprise (Score:5, Interesting)
Moreover, if you violate the conservation of momentum then Noether's theorem [wikipedia.org] tells you that you've violated the principle of invariance under translation. If that were true, no two observers in different locations could ever agree on the laws of physics because the outcome of identical systems would be different if they were in different places.
The correspondence between conservation laws and physical symmetries is immensely useful when reasoning about systems like these. Noether's theorem doesn't require conservation of momentum to be true, but it explains the consequences if it is/isn't.
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I think this is well put: if your input for the model is electromagnetism then there will necessarily be conservation of energy and momentum and their calculations had to be wrong.
How you can say 'possibly special relativity' I don't understand. The model was tested statically in a room. Are you thinking of applications in space?
Special relativity is included in electromagnetism. If you take Coulomb force and special relativity, put it in a box and shake, out comes electromagnetism. If you take a wire and p
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The EM drive, if it works, violates conservation of momentum, which can easily be used to also violate conservation of energy.
1) Momentum is not conserved in our universe.
2) Conservation of momentum is not required for conservation of energy
3) Energy is not conserved in our universe
Your argument is so over-simplifying physics that it's nonsense. Conservation of energy and of momentum are mathematical consequences of Euclidean space and time, by Noether's theorem. [wikipedia.org] We don't, of course, live in Euclidean space or time. Note that the two conservation principles are unrelated - conservation of momentum comes from spatial symmetry, w
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First of all: if an EM drive would work, it would not violate the laws of conservation of momentum. Otherwise: it would not work, plain and simple.
And if one here can give an example why "violation of conversation of momentum" automatically implies violation of "conversation of energy" I would be surprised.
Re:No surprise (Score:5, Insightful)
My understanding is that the 'thrust' comes from radiation pressure in a truncated cone cavity, and the false result comes about by accounting for radiation pressure on the ends of the cone but ignoring it on the conical sides. If you include the conical sides in your calculation, you find zero thrust.
However, it isn't actually necessary to point out the exact error. If you give me a list of numbers to add up, and all the numbers in the list is even, and I tell you I've calculated the total, and the total is an odd number, you know I've messed up. It isn't necessary to go over my calculations with a fine tooth comb to identify exactly where I went wrong. This case is the same - input physics conserves momentum, calculated result does not, calculations must be in error.
They say nothing in whole universe beats stupid... (Score:2)
Not "case closed" yet... (Score:5, Interesting)
..If the folks over at nasaspaceflight [nasaspaceflight.com] are to be believed
Looks like the setup was very sloppy indeed.. with the wattage too low making any signal disappear into noise..
Quoting:
Looking at the pictures of Tajmar's experiment, no wonder they are seeing nothing but Lorentz. First of all their twisted pairs do not appear to be twisted enough. There should be at least two twists per inch. In the image below it appears that there is maybe one twist per two inches or so. And then look at the location of the main amplifier and the length of the main leads! :o
At only 2W of RF power, no wonder they are only seeing Lorentz. It's almost like they designed their experiment to be susceptible to this form of error.
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A sure sign of pseudoscience is the post hoc explanation
Sometimes a sure sign of pseudoscience is the experiment which is designed in such a way specifically to prompt post hoc explanation. Quite often you see this in perpetual motion machines, but completely the other way around. "Oh you forgot to unplug your perpetual motion machine from the wall".
The only thing that is "sure" is that existing theoretical physics doesn't account for something which ultimately biases everyone's thinking against it, which is why we will justify something as obvious through any a
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Well, we can be fairly certain the EM drive does not work. The only question is why does it appear to work. Just like the 'faster than the speed of light neutrinos" https://en.wikipedia.org/wiki/... [wikipedia.org] we KNOW that the result is impossible, the question is WHY are we seeing what we are seeing. The Germans may have been too sloppy (Germans? Sloppy?) to find the exact cause. Their use of the word "may" really concerns me. Regardless, the German explanation is far more likely to be true than a reversal of the "la
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Yes, philosophically speaking, nothing is proven. But I'd say that for all practical purposes, the case is closed. We've tested QED and relativity to exquisite precision at both higher and lower scales than this device. Sure we know physics isn't compete but not here at small macroscopic scales and low energies.
An equivalent would be Eratosthenese using a very long journey and sticks to measure the size of the earth, it'd be like him stepping through a door in Rhodes and exciting in Egypt.
if it's a reaction
Still useful for interplanetary flight? (Score:2)
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The effect is tiny.
They were hoping to use it for long-range drives (e.g. Voyager etc.) to get a "cheap" push to allow them to reach ludicrous-speed.
But it likely won't work in space, or near most planets at all. And likely won't be strong enough to accelerate or stop ANYTHING on its own.
Sure, once in orbit, you MAY be able to push yourself out... and then you're stuffed. But the weight of the engine + the power required to do that wouldn't be worth it if it has to be launched normally anyway, and has to
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Finally the nonsense is over (Score:2)
Finally we can lay this idiocy, nonsense and stupidity to rest. For years it was clear to anyone with a grain of understanding that the discrepancies were due to artefacts, measure-errors or influences they didn't account for. Instead, pipe-dream-believers - or rather fanatics - kept insisting the hype was real.
Now that it's been shown it is, indeed, the latter - as a rational person would expect - no doubt the die-hards EM-fanfappers will claim some conspiracy theory, but ultimately, the case has been sett
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Other theories being evaluated as well.. (Score:2)
Mike McCulloch has been awarded ~$1m UKP for experimentally testing his theory of QI.
http://physicsfromtheedge.blog... [blogspot.ca]
This theory has done a very good job of explaining several physics anomalies, and in particular, makes some interesting predictions for anomalous thrusters.
Something to watch, a good read, and he's a pretty accessible and nice guy too.
STILL GOOD NEWS (Score:3)
Okay, so the propulsion is likely coming from Earth's magnetic field. Still good news. Imagine how much longer satellites could stay in orbit if they could utilize Earth's own magnetic field to propel themselves outward from Earth. That is still very useful.
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I think this has been studied. A conductive tether attached to a satellite that produces a force when interacting with the Earth's magnetic field.
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Correct.
Re:How Embarrassing (Score:5, Informative)
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Many of the experiments have been done by people with no vested interest. The main problem is that the error sources are very, very, hard to eliminate in a setup.
So these people had the resources to eliminate error sources better than the other groups. Which is great and expected. And kind of sad given that we have no new physics.
Now to see if they can eliminate mach thrusters as a propulsion system. Unlike the EM drive it is theoretically compatible with known physics which is a huge plus.
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