18 ms·

NASA presents evidence that microwave thrusters seem to work

406 points by jchesters 12y ago

FatalLogic 12y ago
Previous discussion, from six years ago: https://news.ycombinator.com/item?id=314297 https://news.ycombinator.com/item?id=314297 Some interesting comments, and much skepticism
api 12y ago
Third replication then? This stuff has been hovering (pun intended) at the edge of detection for some time: spinning superconductors, this thing, etc. all claiming to provide evidence of tiny amounts of thrust in apparent violation of standard conservation of momentum. Obviously skepticism is in order, but either something is very wrong with all these experiments or there's something here. What's interesting about this one is that the original inventor has something resembling a theory. It may not be a complete theory, but it tries to explain it via relativity in a way that makes physical sense. I'm always really skeptical of these things, but not in the knee-jerk total dismissal sense. I just say show me the replications. They're doing the right thing. Now we need more people to build these and test them under different conditions. The ultimate test would be to launch one, since you can't really screw up detection of a big delta-V change in space.
- mabbo 12y ago
  Not being very familiar with the the topic, what would it cost to build a usable version of this? How massive would it be? Constant thrust using only solar power and no propellants says to me that one could certainly shut the skeptics up by flying a microsatellite to Mars and back.
  - XorNot 12y ago
    It would be a lot cheaper to lock one in a vacuum chamber and see if it still works.
  - seanflyon 12y ago
    Constant thrust using only solar power and no propellants is already possible. Just shine a light backwards, or better yet turn that solar panel into a mirror. What makes this so strange is that it is emission-less even counting photons.
- codeflo 12y ago
  I'm not a physicist and I can't debunk this theory point by point, but actually, you don't need to know much physics to see how this must be wrong. Special Relativity requires conservation of momentum, in every observer's frame of reference. If someone claims to explain supposed non-conservation of momentum by invoking "Special Relativity", they are just attempting to trick you. (As far as crackpot theories go, I'm actually surprised they didn't throw in a "quantum" or two for good measure.) (Edit: I'm not saying that the experiment itself is invalid. It might be, I don't know. What I'm saying is the supposed theory[1] is necessarily wrong, because you can't get non-conservation of momentum out of Special Relativity without suggesting new laws of physics, which is not at all discussed in the "paper" I linked below.) [1] http://www.emdrive.com/theorypaper9-4.pdf http://www.emdrive.com/theorypaper9-4.pdf
  - api 12y ago
    Like I said, the best test would be to put one in space. If you fire the thing up an the satellite's orbit changes, that's kind of a hard measurement to screw up. (Let it orbit with the drive off for a while as a control.)
    - cstross 12y ago
      If you fire the thing up an the satellite's orbit changes, that's kind of a hard measurement to screw up. Caution: a re-reading of the Pioneer Anomaly is in order before you start assuming things in microgravity move because of new physics ...
  - XorNot 12y ago
    No idea why you're being downvoted for this. You're completely correct as to why this device's claimed physics are bunk (and why, as I note above, the way it always gets tested is highly suspect).
  - T-A 12y ago
    But they did throw in a "quantum" or two. This is basically what they are shooting for: http://en.wikipedia.org/wiki/Quantum_vacuum_plasma_thruster http://en.wikipedia.org/wiki/Quantum_vacuum_plasma_thruster
- bazzargh 12y ago
  Not sure this counts as a replication, yet. This is an un-refereed conference paper, I'd really want to see a proper publication. The other strange thing in the paper, but not mentioned in the article, is that the 'null device' produced thrust: Thrust was observed on both test articles, even though one of the test articles was designed with the expectation that it would not produce thrust. Specifically, one test article contained internal physical modifications that were designed to produce thrust, while the other did not (with the latter being referred to as the "null" test article).
- jbb555 12y ago
  I think most people think that by far the most likely thing is that they missed something and this isn't doing what they "claim". While quietly hoping it does :P
daeken 12y ago
Wow. My gut tells me something is wrong here, and that this is being mismeasured. However, this would be an enormous breakthrough if it pans out, even at the low levels NASA has seemingly confirmed. We're very good at generating power in space; solar is basically infinite in the inner parts of our solar system, and we have a lot of experience with RTGs and other power generation mechanisms. If we can directly turn power into thrust without burning fuel in the process, this truly changes everything. But as I said, I think this will end up not panning out for one of these reasons: 1) The microwaves bouncing around cause a small amount of material to be lost and be sent out of the device, causing the thrust. 2) The RF in play is throwing off detection (this, to me, seems most likely -- it could explain the thousandfold difference in detected thrust levels between the Chinese and US tests). 3) Some sort of effect that is linked to gravity. No idea what, though. I really look forward to further testing. Edit: Given that I'm terrible with the scale of small numbers, I decided to do some quick math. If you were to use that thrust of 50 micronewtons to drive the Voyager spacecraft (722kg) full out for one year from a starting velocity of 0m/s, you would end up at 0.0911259m/s at the end of the year. By comparison, Voyager is currently traveling at 17km/s.
- asuffield 12y ago
  Given that it has so far been detected as working by two independent organisations that tried very hard to get the test right, some new science has clearly been done here. We don't yet have clear evidence that it's a new propulsion technology, as it's possible that what has been discovered is an entirely new mechanism for confounding measurement instruments, but that does not lessen the scientific value of this discovery. There is new knowledge here. Perhaps new physics. I slightly wish I was a physicist so that I could go and find out.
  - josu 12y ago
    >two independent organisations Sorry, but one of them being Chinese, I would say that there is only one reliable source, and the chances that they made a mistake are high.
    - 12y ago
cpfohl 12y ago
Although unrelated, the title reminded me of a certain Improbability Drive..."Not again..."
PaulHoule 12y ago
This is one of these things which is just a few percent less crazy than it sounds. The issue is that special relativity isn't quite compatible with quantum gravity, see http://en.wikipedia.org/wiki/Doubly_special_relativity http://en.wikipedia.org/wiki/Doubly_special_relativity What it comes down to is that quantum gravity has a length scale and a time scale, both of which are unthinkably tiny. However, special relativity says there is nothing special about any particular space or time interval because if somebody was going fast enough, an interval that looks like a planck interval to most people could get expanded or shrunk to something big like a kilometer or an hour. But following that line of reasoning is problematic if there is no special reference frame, since for all I know I already am going incredibly fast relative to some imaginary observer. Doubly-special relativity manages to preserve the invariance of the speed of light under ordinary conditions but also preserve the invariance of plankian quantities under extreme conditions. Related theories also bring in the idea of a special reference frame which means you might be able to "push" against the vacuum. The main trouble jiving that with these experiments is that the energy scale at which DSS effects come into play is huge, way out in grand unification country, so it's hard to believe it could be probed by these experiments.
deleted 12y ago
[deleted]
louthy 12y ago
For all those saying this is impossible because of X, I think the great Richard Feynman put it best: "If it disagrees with experiment, it's wrong" https://www.youtube.com/watch?v=OL6-x0modwY https://www.youtube.com/watch?v=OL6-x0modwY
- bcoates 12y ago
  Of course, but there's still a lot of things consistent with the experiment that are less improbable than reactionless thrust. This is still an important experiment, though -- if your testing methods are discovering 'impossible' effects, they are discovering effects that are possible but wrong, too. This is something worth getting to the bottom of. Every contradiction is a discovery, even if it's not the discovery you want.
- ceejayoz 12y ago
  Assuming you can perfectly rule out measurement, experimental design, etc. flaws, of course.
- Steuard 12y ago
  Experiments this delicate are very difficult to get right. And it is very difficult to overstate just how much established physics would have to be scrapped if momentum conservation turned out to be violated. (Just for starters, relativity implies that non-conservation of momentum in one frame must always involve non-conservation of energy in another.) Why would quantum field theory calculations match experiment to ~12 digits of accuracy if its basic foundations were flawed? (Those calculations are affected by literally every possible quantum vacuum effect, so why wouldn't introducing some new set of momentum violating interactions completely throw off the results?) This is an astoundingly extraordinary claim, and it should thus require tremendously compelling evidence. I'm not at all convinced that these experiments are clean enough or consistent enough to even approach that standard.
- anon4 12y ago
  Isn't this drive using relativistic effects similar to what allows a magnet falling down an aluminium tube to produce an opposite magnetic field and slow down? I mean, clasically speaking that effect is also impossible.
ixtli 12y ago
Pedantic, but NASA is an acronym. Am I unaware of a British English composition rule that permits writing it "Nasa"?
- jchesters 12y ago
  This is why I changed it for the link title on here
- milliams 12y ago
  No, but I've seen the BBC do this extensively. They turn CERN in Cern all the time. Perhaps Wired UK are just copying this style. I've never seen the BBC call the BBC the Bbc though...
  - pbhjpbhj 12y ago
    CERN is an acronym and BBC is only an initialism. There is a linguistic trend to using title-case for acronyms; particularly companies seem to be turning their acronyms in to the company name. Perhaps using "Cern" is simply following that trend.
    - dragonwriter 12y ago
      British publications have been using titlecase for acronyms for a very long time, its not a recent trend.
  - jarin 12y ago
    That's because BBC is an initialism (each letter is pronounced separately) rather than an acronym (pronounced as if it were a word).
- IvyMike 12y ago
  The Guardian/Observer style guide specifically uses Nasa as an example: http://www.theguardian.com/guardian-observer-style-guide-a http://www.theguardian.com/guardian-observer-style-guide-a > Use all capitals if an abbreviation is pronounced as the individual letters (an initialism): BBC, CEO, US, VAT, etc; if it is an acronym (pronounced as a word) spell out with initial capital, eg Nasa, Nato, Unicef, unless it can be considered to have entered the language as an everyday word, such as awol, laser and, more recently, asbo, pin number and sim card. Note that pdf and plc are lowercase.
tribaal 12y ago
So, it seems from reading the paper's abstract that they did measure thrust both from the real propulsion test device and from the dummy test device. That's not very promising: http://ntrs.nasa.gov/search.jsp?R=20140006052 http://ntrs.nasa.gov/search.jsp?R=20140006052 > Thrust was observed on both test articles, even though one of the test articles was designed with the expectation that it would not produce thrust. Specifically, one test article contained internal physical modifications that were designed to produce thrust, while the other did not (with the latter being referred to as the "null" test article).
- api 12y ago
  Meh. If that's true then Wired shamelessly went for click bait. :P
  - tribaal 12y ago
    Well, I'd love to be wrong really. Pretty please, somebody confirm my reading comprehension skills are complete garbage? :)
    - api 12y ago
      It doesn't say how much thrust the null article "produced." If there's a significant difference, that's still very suggestive. My next suspects for error would be that the device is propelling itself through heat dissipation or electrostatic ally by throwing off charged particles. Both of those possible confounding factors are testable, either by measuring heat via IR imaging and computing what propellant effect that heat would have of by dummying up the null device to produce and dissipate an identical amount of energy to the non-null device. But honestly, I'm a hacker. I'd go rent me a vacuum chamber and put it on a whirlygig and see if it makes it spin. If it spins faster and faster and faster until it flies apart (well okay maybe I'd turn it off before loss of structural integrity), something is definitely off in our understanding of physics and God really will let us have hoverboards. So give me a hoverboard.
      - 12y ago
Symmetry 12y ago
So it produced 720 mN of thrust the first try, but under more careful conditions it produced 30 uN? This smells like a spurious result, but I suppose more investigation is in order.
- moron4hire 12y ago
  Two different devices, Shawyer's "EmDrive" was the 720mN device, Fetta's "Cannae Drive" was the 30uN device.
hyperliner 12y ago
I wish this had an ELI5. Anybody out there that can help us mere mortals?
- fixermark 12y ago
  To boil it way down: The root claim is that there is a way to craft a special closed box that when you apply electricity to it, the box starts moving (linearly) without either pushing off of anything or throwing anything out. If that were true, it'd mean an awful lot for space travel; changing direction in space requires a ship to either crash into something or throw bits of itself away until it runs out of bits. If this thing works the way it is claimed to, a spaceship using it could control its motion forever, powered by merely the light of the nearest star. (... it probably doesn't work the way it's claimed to, because if it does, there's a lot of interesting things we should already have seen by now in the "closed boxes moving around as if by magic" category; the universe is a big, big place of big, big possibilities. But lack of observation doesn't make it impossible, just unlikely).
  - Natsu 12y ago
    Makes me wonder if it could somehow convert the energy to mass and throw that off, as it were. Though it's probably something more exotic, assuming it's not an error of some type.
    - marcosdumay 12y ago
      "Convert energy to mass" does not make much sense. If you throw light away, it'll propel you.
      - Natsu 12y ago
        I was thinking electrical energy, but you raise a good point that photons have momentum.
  - erikpukinskis 12y ago
    > we should already have seen by now in the "closed boxes moving around as if by magic" category I agree if it's true such phenomena must be quite likely. But maybe not in the amperage range that we witness here on earth. There are places in the universe that see amperages 10 billion times higher than what we see here. Perhaps you might see some box-ish things moving out there as if by magic. http://www.popsci.com/technology/article/2011-06/strongest-current-universe-detected-some-2-billion-light-years-away http://www.popsci.com/technology/article/2011-06/strongest-c...
batmansbelt 12y ago
That's pretty exciting news, because the sun is a strong source of microwaves. In theory a parabolic dish attached to the back of a space probe could provide a steady amount of thrust, like a star wisp type deal.
jsilence 12y ago
Quantum mechanics, dreams stuff is made of.
nsxwolf 12y ago
I've always thought it was unfair that this is impossible. It's not like you're getting something for nothing - you are still required to expend energy. So why does the universe have to be such a dick about converting electricity directly into motion?
- DickingAround 12y ago
  Where can I read more about how/why this is impossible? Isn't it just the reverse of a solar sail to send out the photons yourself rather than catching them? It seems like shining a flashlight in one direction should produce thrust in the other. Is that not true or is it something different at work here?
  - SideburnsOfDoom 12y ago
    > It seems like shining a flashlight in one direction should produce thrust in the other. Is that not true or is it something different at work here? Yes, there does seem to be something else. Classical mechanics cannot explain thrust from shining a flashlight inside your spaceship. But "the EmDrive converts electric power into thrust ... by bouncing microwaves around in a closed container"
  - nsxwolf 12y ago
    I guess a related question is "why does a flashlight in space not propel itself". And I don't know the answer to that. Edit: Ok. That makes sense. I guess it's just not a practical source of propulsion.
    - oneandoneis2 12y ago
      It does. But the propulsion is really, really tiny.
    - leishulang 12y ago
      https://answers.yahoo.com/question/index?qid=20111214233110AAicrQm https://answers.yahoo.com/question/index?qid=20111214233110A...
toolslive 12y ago
Is this the stuff Miklos Borbas was working on? https://www.youtube.com/watch?v=RbOc6R-95kk https://www.youtube.com/watch?v=RbOc6R-95kk
PaulAJ 12y ago
Could the electromagnets involved in microwave generation be interacting with the Earth's magnetic field?
- zackmorris 12y ago
  Anything's possible, so they really need to do the experiment with Helmholtz coils inside a Faraday cage: https://en.wikipedia.org/wiki/Helmholtz_coil https://en.wikipedia.org/wiki/Helmholtz_coil https://en.wikipedia.org/wiki/Faraday_cage https://en.wikipedia.org/wiki/Faraday_cage
lutorm 12y ago
There's no mystery to producing thrust with microwaves. Photons have a momentum of E/c, so if you make photons with a power P and send them in one direction, you'll get a thrust of P/c. I think the issue is that they claim to a) not emit anything, and b) claim many orders of magnitude more thrust than could be achieved by just emitting photons.
zackmorris 12y ago
Wanted to jump in and ask, does anyone remember a site that went through the math of two magnetic rings being charged and discharged out of sync, utilizing the delay in the speed of light between the rings to create a net force? Imagine a craft shaped like a dumbbell, with the rings where the weights are: |---| 1...2 The idea was that you'd create a strong magnetic field in ring 1, and then the wave would travel outward both directions (one away from the ship, and one along it) and interact with ring 2, which has the opposite polarity. Ring 2 would be attracted to the magnetism from ring 1, and pull the ship to the left. Then ring 1 would turn off, and by the time the wave from ring 2 reached it, there would be no interaction. So the craft would feel a net thrust to the left. The process would repeat over and over again at high frequency, propelling the craft faster and faster. I believe the site said the process was 25% efficient, and didn’t violate any laws of physics. The difficulty lies with hysteresis because it takes a comparatively long time to charge a magnetic field, compared to the time it takes light to span the distance. So it went off on a tangent about using lasers to charge a superconducting ring. But I’ve always wondered if resonance could somehow be used to take the coils out of sync automatically, a bit like a tesla coil but with an imbalance the puts one ring slightly behind the other in time with respect to their frames of reference. As they move more out of phase, the net force on the coils should get stronger and stronger. This sounds similar in some ways to the the way a magnetron works, so if it can be put out of phase in a similar way, then I’m not entirely surprised by NASA’s result. If it’s true that the time delay in the speed of light can be converted to a propulsive force, then it’s going to change, well, pretty much everything about space travel. I really wish I had the link to that site.
- Terr_ 12y ago
  Was it something like this? http://arxiv.org/html/physics/9908048v2/conclusion.htm http://arxiv.org/html/physics/9908048v2/conclusion.htm > Then ring 1 would turn off, and by the time the wave from ring 2 reached it, there would be no interaction. That sounds like the magic part. "Magically, nothing will occur." IANA physicist, but it sounds like Lenz's law might be relevant. > I believe the site said the process was [...] didn’t violate any laws of physics. Well, there's the rub. It sounds like it directly violates conservation of momentum and Newton's third law.
DanielBMarkham 12y ago
"...therefore is potentially demonstrating an interaction with the quantum vacuum virtual plasma..." This could be extremely big news, like the biggest news of the last 50 years. Depends on whether it's true -- and how much it can be optimized. Field propulsion is a game-changer in humanity's relationship to the universe. Lots remain to be seen, though. Wait-and-see is the appropriate response. Still pretty neat. And it sounds like something that could easily be reproduced in college-level labs worldwide.
zerker2000 12y ago
Is anyone reminded of http://www.bibliotecapleyades.net/tesla/occultether/occultether.htm http://www.bibliotecapleyades.net/tesla/occultether/occultet...? Which is complete pseudoscience but...
cLeEOGPw 12y ago
It's logical when you think about it. Since particles pop in and out of existence all the time and the time these particles exist are > 0, then it should be possible to move those particles before they disappear. So law of conservation of momentum is not violated, neither any other law of physics. It is just counter intuitive, like most stuff related to quantum world.
- claudius 12y ago
  I’m not quite convinced. If I understand you correctly, what you’re saying is the following: Suppose we send out one photon ν of momentum p_ν. We hence gain momentum -p_ν. This photon then randomly hits a particle X of a particle-antiparticle pair and transfers its momentum/energy to the particle X, creating/altering it into a particle X'. When X' and ¬X collide again, this momentum/energy is lost and doesn’t hit the opposite wall of the cavity (where it would be transferred onto us again, causing us to lose the previously-gained momentum -p_ν). But this would require that when X' and ¬X annihilate each other, the extra momentum of X' is also annihilated. Intuitively, I’d expect it to be sent out as a photon – with momentum p_ν.
  - cLeEOGPw 12y ago
    How do you imagine annihilation of the extra momentum?
    - claudius 12y ago
      I don’t.
      - cLeEOGPw 12y ago
        So why you expect it to happen?
        claudius 12y ago
        I don’t. That’s why I wrote: > But this would require that when X' and ¬X annihilate each other, the extra momentum of X' is also annihilated. Intuitively, I’d expect it to be sent out as a photon – with momentum p_ν. I.e. annihilation of the extra momentum would be required for this to work on the basis of background fluctuations (in my understanding), but I don’t think that this happens.
Tloewald 12y ago
The top comment (on the actual article) suggests that the effect may be a result of dark matter resonance: http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.111.231801 http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.111... Which is way over my head, but interesting.
0p9o8i7u 12y ago
Relevant: http://en.wikipedia.org/wiki/Into_the_Crevasse http://en.wikipedia.org/wiki/Into_the_Crevasse Tracy's referring to this when he talks about the show being about his life: http://en.wikipedia.org/wiki/Operation_Righteous_Cowboy_Lightning http://en.wikipedia.org/wiki/Operation_Righteous_Cowboy_Ligh...

406 points by jchesters 12y ago

Previous discussion, from six years ago: https://news.ycombinator.com/item?id=314297 https://news.ycombinator.com/item?id=314297 Some interesting comments, and much skepticism

api 12y ago

Third replication then? This stuff has been hovering (pun intended) at the edge of detection for some time: spinning superconductors, this thing, etc. all claiming to provide evidence of tiny amounts of thrust in apparent violation of standard conservation of momentum. Obviously skepticism is in order, but either something is very wrong with all these experiments or there's something here. What's interesting about this one is that the original inventor has something resembling a theory. It may not be a complete theory, but it tries to explain it via relativity in a way that makes physical sense. I'm always really skeptical of these things, but not in the knee-jerk total dismissal sense. I just say show me the replications. They're doing the right thing. Now we need more people to build these and test them under different conditions. The ultimate test would be to launch one, since you can't really screw up detection of a big delta-V change in space.

mabbo 12y ago
Not being very familiar with the the topic, what would it cost to build a usable version of this? How massive would it be? Constant thrust using only solar power and no propellants says to me that one could certainly shut the skeptics up by flying a microsatellite to Mars and back.
- XorNot 12y ago
  It would be a lot cheaper to lock one in a vacuum chamber and see if it still works.
- seanflyon 12y ago
  Constant thrust using only solar power and no propellants is already possible. Just shine a light backwards, or better yet turn that solar panel into a mirror. What makes this so strange is that it is emission-less even counting photons.
codeflo 12y ago
I'm not a physicist and I can't debunk this theory point by point, but actually, you don't need to know much physics to see how this must be wrong. Special Relativity requires conservation of momentum, in every observer's frame of reference. If someone claims to explain supposed non-conservation of momentum by invoking "Special Relativity", they are just attempting to trick you. (As far as crackpot theories go, I'm actually surprised they didn't throw in a "quantum" or two for good measure.) (Edit: I'm not saying that the experiment itself is invalid. It might be, I don't know. What I'm saying is the supposed theory[1] is necessarily wrong, because you can't get non-conservation of momentum out of Special Relativity without suggesting new laws of physics, which is not at all discussed in the "paper" I linked below.) [1] http://www.emdrive.com/theorypaper9-4.pdf http://www.emdrive.com/theorypaper9-4.pdf
- api 12y ago
  Like I said, the best test would be to put one in space. If you fire the thing up an the satellite's orbit changes, that's kind of a hard measurement to screw up. (Let it orbit with the drive off for a while as a control.)
  - cstross 12y ago
    If you fire the thing up an the satellite's orbit changes, that's kind of a hard measurement to screw up. Caution: a re-reading of the Pioneer Anomaly is in order before you start assuming things in microgravity move because of new physics ...
- XorNot 12y ago
  No idea why you're being downvoted for this. You're completely correct as to why this device's claimed physics are bunk (and why, as I note above, the way it always gets tested is highly suspect).
- T-A 12y ago
  But they did throw in a "quantum" or two. This is basically what they are shooting for: http://en.wikipedia.org/wiki/Quantum_vacuum_plasma_thruster http://en.wikipedia.org/wiki/Quantum_vacuum_plasma_thruster
bazzargh 12y ago
Not sure this counts as a replication, yet. This is an un-refereed conference paper, I'd really want to see a proper publication. The other strange thing in the paper, but not mentioned in the article, is that the 'null device' produced thrust: Thrust was observed on both test articles, even though one of the test articles was designed with the expectation that it would not produce thrust. Specifically, one test article contained internal physical modifications that were designed to produce thrust, while the other did not (with the latter being referred to as the "null" test article).
jbb555 12y ago
I think most people think that by far the most likely thing is that they missed something and this isn't doing what they "claim". While quietly hoping it does :P

daeken 12y ago

Wow. My gut tells me something is wrong here, and that this is being mismeasured. However, this would be an enormous breakthrough if it pans out, even at the low levels NASA has seemingly confirmed. We're very good at generating power in space; solar is basically infinite in the inner parts of our solar system, and we have a lot of experience with RTGs and other power generation mechanisms. If we can directly turn power into thrust without burning fuel in the process, this truly changes everything. But as I said, I think this will end up not panning out for one of these reasons: 1) The microwaves bouncing around cause a small amount of material to be lost and be sent out of the device, causing the thrust. 2) The RF in play is throwing off detection (this, to me, seems most likely -- it could explain the thousandfold difference in detected thrust levels between the Chinese and US tests). 3) Some sort of effect that is linked to gravity. No idea what, though. I really look forward to further testing. Edit: Given that I'm terrible with the scale of small numbers, I decided to do some quick math. If you were to use that thrust of 50 micronewtons to drive the Voyager spacecraft (722kg) full out for one year from a starting velocity of 0m/s, you would end up at 0.0911259m/s at the end of the year. By comparison, Voyager is currently traveling at 17km/s.

asuffield 12y ago
Given that it has so far been detected as working by two independent organisations that tried very hard to get the test right, some new science has clearly been done here. We don't yet have clear evidence that it's a new propulsion technology, as it's possible that what has been discovered is an entirely new mechanism for confounding measurement instruments, but that does not lessen the scientific value of this discovery. There is new knowledge here. Perhaps new physics. I slightly wish I was a physicist so that I could go and find out.
- josu 12y ago
  >two independent organisations Sorry, but one of them being Chinese, I would say that there is only one reliable source, and the chances that they made a mistake are high.
  - 12y ago

cpfohl 12y ago

Although unrelated, the title reminded me of a certain Improbability Drive..."Not again..."

PaulHoule 12y ago

This is one of these things which is just a few percent less crazy than it sounds. The issue is that special relativity isn't quite compatible with quantum gravity, see http://en.wikipedia.org/wiki/Doubly_special_relativity http://en.wikipedia.org/wiki/Doubly_special_relativity What it comes down to is that quantum gravity has a length scale and a time scale, both of which are unthinkably tiny. However, special relativity says there is nothing special about any particular space or time interval because if somebody was going fast enough, an interval that looks like a planck interval to most people could get expanded or shrunk to something big like a kilometer or an hour. But following that line of reasoning is problematic if there is no special reference frame, since for all I know I already am going incredibly fast relative to some imaginary observer. Doubly-special relativity manages to preserve the invariance of the speed of light under ordinary conditions but also preserve the invariance of plankian quantities under extreme conditions. Related theories also bring in the idea of a special reference frame which means you might be able to "push" against the vacuum. The main trouble jiving that with these experiments is that the energy scale at which DSS effects come into play is huge, way out in grand unification country, so it's hard to believe it could be probed by these experiments.

deleted 12y ago

[deleted]

louthy 12y ago

For all those saying this is impossible because of X, I think the great Richard Feynman put it best: "If it disagrees with experiment, it's wrong" https://www.youtube.com/watch?v=OL6-x0modwY https://www.youtube.com/watch?v=OL6-x0modwY

bcoates 12y ago
Of course, but there's still a lot of things consistent with the experiment that are less improbable than reactionless thrust. This is still an important experiment, though -- if your testing methods are discovering 'impossible' effects, they are discovering effects that are possible but wrong, too. This is something worth getting to the bottom of. Every contradiction is a discovery, even if it's not the discovery you want.
ceejayoz 12y ago
Assuming you can perfectly rule out measurement, experimental design, etc. flaws, of course.
Steuard 12y ago
Experiments this delicate are very difficult to get right. And it is very difficult to overstate just how much established physics would have to be scrapped if momentum conservation turned out to be violated. (Just for starters, relativity implies that non-conservation of momentum in one frame must always involve non-conservation of energy in another.) Why would quantum field theory calculations match experiment to ~12 digits of accuracy if its basic foundations were flawed? (Those calculations are affected by literally every possible quantum vacuum effect, so why wouldn't introducing some new set of momentum violating interactions completely throw off the results?) This is an astoundingly extraordinary claim, and it should thus require tremendously compelling evidence. I'm not at all convinced that these experiments are clean enough or consistent enough to even approach that standard.
anon4 12y ago
Isn't this drive using relativistic effects similar to what allows a magnet falling down an aluminium tube to produce an opposite magnetic field and slow down? I mean, clasically speaking that effect is also impossible.

ixtli 12y ago

Pedantic, but NASA is an acronym. Am I unaware of a British English composition rule that permits writing it "Nasa"?

jchesters 12y ago
This is why I changed it for the link title on here
milliams 12y ago
No, but I've seen the BBC do this extensively. They turn CERN in Cern all the time. Perhaps Wired UK are just copying this style. I've never seen the BBC call the BBC the Bbc though...
- pbhjpbhj 12y ago
  CERN is an acronym and BBC is only an initialism. There is a linguistic trend to using title-case for acronyms; particularly companies seem to be turning their acronyms in to the company name. Perhaps using "Cern" is simply following that trend.
  - dragonwriter 12y ago
    British publications have been using titlecase for acronyms for a very long time, its not a recent trend.
- jarin 12y ago
  That's because BBC is an initialism (each letter is pronounced separately) rather than an acronym (pronounced as if it were a word).
IvyMike 12y ago
The Guardian/Observer style guide specifically uses Nasa as an example: http://www.theguardian.com/guardian-observer-style-guide-a http://www.theguardian.com/guardian-observer-style-guide-a > Use all capitals if an abbreviation is pronounced as the individual letters (an initialism): BBC, CEO, US, VAT, etc; if it is an acronym (pronounced as a word) spell out with initial capital, eg Nasa, Nato, Unicef, unless it can be considered to have entered the language as an everyday word, such as awol, laser and, more recently, asbo, pin number and sim card. Note that pdf and plc are lowercase.

tribaal 12y ago

So, it seems from reading the paper's abstract that they did measure thrust both from the real propulsion test device and from the dummy test device. That's not very promising: http://ntrs.nasa.gov/search.jsp?R=20140006052 http://ntrs.nasa.gov/search.jsp?R=20140006052 > Thrust was observed on both test articles, even though one of the test articles was designed with the expectation that it would not produce thrust. Specifically, one test article contained internal physical modifications that were designed to produce thrust, while the other did not (with the latter being referred to as the "null" test article).

api 12y ago
Meh. If that's true then Wired shamelessly went for click bait. :P
- tribaal 12y ago
  Well, I'd love to be wrong really. Pretty please, somebody confirm my reading comprehension skills are complete garbage? :)
  - api 12y ago
    It doesn't say how much thrust the null article "produced." If there's a significant difference, that's still very suggestive. My next suspects for error would be that the device is propelling itself through heat dissipation or electrostatic ally by throwing off charged particles. Both of those possible confounding factors are testable, either by measuring heat via IR imaging and computing what propellant effect that heat would have of by dummying up the null device to produce and dissipate an identical amount of energy to the non-null device. But honestly, I'm a hacker. I'd go rent me a vacuum chamber and put it on a whirlygig and see if it makes it spin. If it spins faster and faster and faster until it flies apart (well okay maybe I'd turn it off before loss of structural integrity), something is definitely off in our understanding of physics and God really will let us have hoverboards. So give me a hoverboard.
    - 12y ago

Symmetry 12y ago

So it produced 720 mN of thrust the first try, but under more careful conditions it produced 30 uN? This smells like a spurious result, but I suppose more investigation is in order.

moron4hire 12y ago
Two different devices, Shawyer's "EmDrive" was the 720mN device, Fetta's "Cannae Drive" was the 30uN device.

hyperliner 12y ago

I wish this had an ELI5. Anybody out there that can help us mere mortals?

fixermark 12y ago
To boil it way down: The root claim is that there is a way to craft a special closed box that when you apply electricity to it, the box starts moving (linearly) without either pushing off of anything or throwing anything out. If that were true, it'd mean an awful lot for space travel; changing direction in space requires a ship to either crash into something or throw bits of itself away until it runs out of bits. If this thing works the way it is claimed to, a spaceship using it could control its motion forever, powered by merely the light of the nearest star. (... it probably doesn't work the way it's claimed to, because if it does, there's a lot of interesting things we should already have seen by now in the "closed boxes moving around as if by magic" category; the universe is a big, big place of big, big possibilities. But lack of observation doesn't make it impossible, just unlikely).
- Natsu 12y ago
  Makes me wonder if it could somehow convert the energy to mass and throw that off, as it were. Though it's probably something more exotic, assuming it's not an error of some type.
  - marcosdumay 12y ago
    "Convert energy to mass" does not make much sense. If you throw light away, it'll propel you.
    - Natsu 12y ago
      I was thinking electrical energy, but you raise a good point that photons have momentum.
- erikpukinskis 12y ago
  > we should already have seen by now in the "closed boxes moving around as if by magic" category I agree if it's true such phenomena must be quite likely. But maybe not in the amperage range that we witness here on earth. There are places in the universe that see amperages 10 billion times higher than what we see here. Perhaps you might see some box-ish things moving out there as if by magic. http://www.popsci.com/technology/article/2011-06/strongest-current-universe-detected-some-2-billion-light-years-away http://www.popsci.com/technology/article/2011-06/strongest-c...

batmansbelt 12y ago

That's pretty exciting news, because the sun is a strong source of microwaves. In theory a parabolic dish attached to the back of a space probe could provide a steady amount of thrust, like a star wisp type deal.

jsilence 12y ago

Quantum mechanics, dreams stuff is made of.

nsxwolf 12y ago

I've always thought it was unfair that this is impossible. It's not like you're getting something for nothing - you are still required to expend energy. So why does the universe have to be such a dick about converting electricity directly into motion?

DickingAround 12y ago
Where can I read more about how/why this is impossible? Isn't it just the reverse of a solar sail to send out the photons yourself rather than catching them? It seems like shining a flashlight in one direction should produce thrust in the other. Is that not true or is it something different at work here?
- SideburnsOfDoom 12y ago
  > It seems like shining a flashlight in one direction should produce thrust in the other. Is that not true or is it something different at work here? Yes, there does seem to be something else. Classical mechanics cannot explain thrust from shining a flashlight inside your spaceship. But "the EmDrive converts electric power into thrust ... by bouncing microwaves around in a closed container"
- nsxwolf 12y ago
  I guess a related question is "why does a flashlight in space not propel itself". And I don't know the answer to that. Edit: Ok. That makes sense. I guess it's just not a practical source of propulsion.
  - oneandoneis2 12y ago
    It does. But the propulsion is really, really tiny.
  - leishulang 12y ago
    https://answers.yahoo.com/question/index?qid=20111214233110AAicrQm https://answers.yahoo.com/question/index?qid=20111214233110A...

toolslive 12y ago

Is this the stuff Miklos Borbas was working on? https://www.youtube.com/watch?v=RbOc6R-95kk https://www.youtube.com/watch?v=RbOc6R-95kk

PaulAJ 12y ago

Could the electromagnets involved in microwave generation be interacting with the Earth's magnetic field?

zackmorris 12y ago
Anything's possible, so they really need to do the experiment with Helmholtz coils inside a Faraday cage: https://en.wikipedia.org/wiki/Helmholtz_coil https://en.wikipedia.org/wiki/Helmholtz_coil https://en.wikipedia.org/wiki/Faraday_cage https://en.wikipedia.org/wiki/Faraday_cage

lutorm 12y ago

There's no mystery to producing thrust with microwaves. Photons have a momentum of E/c, so if you make photons with a power P and send them in one direction, you'll get a thrust of P/c. I think the issue is that they claim to a) not emit anything, and b) claim many orders of magnitude more thrust than could be achieved by just emitting photons.

zackmorris 12y ago

Wanted to jump in and ask, does anyone remember a site that went through the math of two magnetic rings being charged and discharged out of sync, utilizing the delay in the speed of light between the rings to create a net force? Imagine a craft shaped like a dumbbell, with the rings where the weights are: |---| 1...2 The idea was that you'd create a strong magnetic field in ring 1, and then the wave would travel outward both directions (one away from the ship, and one along it) and interact with ring 2, which has the opposite polarity. Ring 2 would be attracted to the magnetism from ring 1, and pull the ship to the left. Then ring 1 would turn off, and by the time the wave from ring 2 reached it, there would be no interaction. So the craft would feel a net thrust to the left. The process would repeat over and over again at high frequency, propelling the craft faster and faster. I believe the site said the process was 25% efficient, and didn’t violate any laws of physics. The difficulty lies with hysteresis because it takes a comparatively long time to charge a magnetic field, compared to the time it takes light to span the distance. So it went off on a tangent about using lasers to charge a superconducting ring. But I’ve always wondered if resonance could somehow be used to take the coils out of sync automatically, a bit like a tesla coil but with an imbalance the puts one ring slightly behind the other in time with respect to their frames of reference. As they move more out of phase, the net force on the coils should get stronger and stronger. This sounds similar in some ways to the the way a magnetron works, so if it can be put out of phase in a similar way, then I’m not entirely surprised by NASA’s result. If it’s true that the time delay in the speed of light can be converted to a propulsive force, then it’s going to change, well, pretty much everything about space travel. I really wish I had the link to that site.

Terr_ 12y ago
Was it something like this? http://arxiv.org/html/physics/9908048v2/conclusion.htm http://arxiv.org/html/physics/9908048v2/conclusion.htm > Then ring 1 would turn off, and by the time the wave from ring 2 reached it, there would be no interaction. That sounds like the magic part. "Magically, nothing will occur." IANA physicist, but it sounds like Lenz's law might be relevant. > I believe the site said the process was [...] didn’t violate any laws of physics. Well, there's the rub. It sounds like it directly violates conservation of momentum and Newton's third law.

DanielBMarkham 12y ago

"...therefore is potentially demonstrating an interaction with the quantum vacuum virtual plasma..." This could be extremely big news, like the biggest news of the last 50 years. Depends on whether it's true -- and how much it can be optimized. Field propulsion is a game-changer in humanity's relationship to the universe. Lots remain to be seen, though. Wait-and-see is the appropriate response. Still pretty neat. And it sounds like something that could easily be reproduced in college-level labs worldwide.

zerker2000 12y ago

Is anyone reminded of http://www.bibliotecapleyades.net/tesla/occultether/occultether.htm http://www.bibliotecapleyades.net/tesla/occultether/occultet...? Which is complete pseudoscience but...

cLeEOGPw 12y ago

It's logical when you think about it. Since particles pop in and out of existence all the time and the time these particles exist are > 0, then it should be possible to move those particles before they disappear. So law of conservation of momentum is not violated, neither any other law of physics. It is just counter intuitive, like most stuff related to quantum world.

claudius 12y ago
I’m not quite convinced. If I understand you correctly, what you’re saying is the following: Suppose we send out one photon ν of momentum p_ν. We hence gain momentum -p_ν. This photon then randomly hits a particle X of a particle-antiparticle pair and transfers its momentum/energy to the particle X, creating/altering it into a particle X'. When X' and ¬X collide again, this momentum/energy is lost and doesn’t hit the opposite wall of the cavity (where it would be transferred onto us again, causing us to lose the previously-gained momentum -p_ν). But this would require that when X' and ¬X annihilate each other, the extra momentum of X' is also annihilated. Intuitively, I’d expect it to be sent out as a photon – with momentum p_ν.
- cLeEOGPw 12y ago
  How do you imagine annihilation of the extra momentum?
  - claudius 12y ago
    I don’t.
    - cLeEOGPw 12y ago
      So why you expect it to happen?
      - claudius 12y ago
        I don’t. That’s why I wrote: > But this would require that when X' and ¬X annihilate each other, the extra momentum of X' is also annihilated. Intuitively, I’d expect it to be sent out as a photon – with momentum p_ν. I.e. annihilation of the extra momentum would be required for this to work on the basis of background fluctuations (in my understanding), but I don’t think that this happens.

Tloewald 12y ago

The top comment (on the actual article) suggests that the effect may be a result of dark matter resonance: http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.111.231801 http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.111... Which is way over my head, but interesting.

0p9o8i7u 12y ago

Relevant: http://en.wikipedia.org/wiki/Into_the_Crevasse http://en.wikipedia.org/wiki/Into_the_Crevasse Tracy's referring to this when he talks about the show being about his life: http://en.wikipedia.org/wiki/Operation_Righteous_Cowboy_Lightning http://en.wikipedia.org/wiki/Operation_Righteous_Cowboy_Ligh...