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NASA Space Transportation Technology

NASA Eagleworks Has Tested an Upgraded EM Drive 203

An anonymous reader writes: A team of researchers at NASA's Eagleworks Laboratories recently completed yet another round of testing on Engineer Roger Shawyer's controversial EM Drive. While no peer reviewed paper has been published yet, engineer Paul March posted to the NASA Spaceflight forum to explain the group's findings. From the article: "In essence, by utilizing an improved experimental procedure, the team managed to mitigate some of the errors from prior tests — yet still found signals of unexplained thrust."
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NASA Eagleworks Has Tested an Upgraded EM Drive

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  • by Anonymous Coward

    If your source for saying it is controversial is a link to another slashdot article saying it has been tested successfully by a different lab before, you are just using the word wrong.

    • Re:Controversial? (Score:5, Insightful)

      by ganv ( 881057 ) on Tuesday November 03, 2015 @11:43AM (#50855779)
      There is a simple reason this is controversial. Any Electromagnetic drive that produces more than 3.34 nanoNewtons per Watt by EM emission is a demonstration of new physics that is not included in our amazingly successful theory of quantum electrodynamics (QED). (The simple calculation is here: [] They use a reflecting mirror, so an emitting craft would have half the force.) QED has been very precisely corroborated, sometimes to more than 10 digits (see [] ). Claims of macroscopic objects that violate quantum electrodynamics simply have an extremely high prior probability of being false. (Just like claims of perpetual motion etc.). It doesn't mean we know a priori that they are false. By all means, do the experiments more precisely. But this is a claim that requires extraordinary proof because if it is true it will upset a lot of what we have good reason to think we understand about how the universe works.
      • There's another weird aspect beyond that one: the EM radiation is released into a sealed (non-microwave-permeable) chamber. The QED thrusts ought to be canceled out by the photons reflecting off both ends of the chamber.

        Given the thrusts in question, I'm not sure which is weirder, the presence of a net thrust at all given the chamber being sealed, or the roughly three orders of magnitude more thrust than a photon drive would have, but either one suggests that something very odd is happening here.

        • The QED thrusts ought to be canceled out by the photons reflecting off both ends of the chamber.

          That would be true if the walls of the test chamber were perfect mirrors. Which is pretty unlikely.

  • Scientists (Score:5, Interesting)

    by skovnymfe ( 1671822 ) on Tuesday November 03, 2015 @05:41AM (#50853757)
    It's like someone has posted a theory on the internet which is wrong, but not knowing where the thrust comes from means they can't explain to this person why he's wrong. And it irks them to no end.
    • by Twinbee ( 767046 )
      This is such a tough cookie to crack that the best way we can solve is to keep grinding at the problem like this []. Any attempt to diagnose the issue wholesale will clog up the 'machine', and ultimately slow progress down.
    • If this works, why aren't the many satellites which run radio transmitters on similar frequencies pushed out of orbit to a measurable degree? It's the same mechanism as the "emdrive", but with the feed open rather than closed at the end.
      • Wasn't this effect measured on Voyager? It is an extremely small effect, but my understanding was that there is a measurable effect from the photon pressure generated by a radio antenna. In the case of the EM drive though, the photons can't escape the system and have not been measured escaping from the test setups.

      • You're confusing the EM Drive with a photon drive. The EM Drive requires a sealed resonant cavity. A photon drive requires an open-ended reflective emitter. Photon drives are, essentially, standard reaction drives that derive their thrust from the photons being shot out the back of the drive. The EM Drive - assuming it really works - is something else entirely, because there's nowhere for the photons to go; the net thrust they impart on the chamber seems like it ought to be zero.

        As a side note, experimental

        • For me to confuse an EM Drive with a photon drive, I would have to believe in the EM Drive. I happen to be a member of a private club called AMSAT that has its latest cubesat in orbit right now, and that is OSCAR 85 in a series running since 1963. Obviously, there isn't really anything standing in the way of testing this on a cubesat. I'm sure that if you can raise something's orbit that there will be a lot more attention. Until then, color me dubious.

    • by tlhIngan ( 30335 )

      It's like someone has posted a theory on the internet which is wrong, but not knowing where the thrust comes from means they can't explain to this person why he's wrong. And it irks them to no end.

      And this is a good thing, This is just exactly how science works - people repeatedly testing it and testing it until we finally come up with a theory as to why it works the way it does, and what applecart gets upset because of it.

      Perhaps there's some new science out there. Maybe. Or it's something that's just been

  • by ThorGod ( 456163 ) on Tuesday November 03, 2015 @06:20AM (#50853855) Journal

    How does the "law of conservation of momentum" square with the the momentum imparted by photons? (iirc it's the light pressure from fusion that keeps stars from collapsing on themselves)

    • Photons carry momentum away from the electron when they are emitted ("recoil") and to the electron that absorbs them ("pressure"). This momentum is real and measurable. []

    • Re: (Score:3, Interesting)

      by Anonymous Coward

      Due to the photons being pushed forwards and backwards in the cavity, that cannot be the reason. Harold White postulates that the law of conservation of momentum is not affected, that the drive is indeed transferring momentum to space-time though an interaction with the virtual particles that are continuously popping and collapsing everywhere.

      • by tomhath ( 637240 )

        Harold White postulates

        In other words, he's making stuff up with nothing to support it.

        • by sjames ( 1099 )

          Not really. More like he has shown some way that claiming the effect to be real is NOT equivalent to claiming that conservation of momentum is violated. Basically that the claim of the EM drive producing thrust is not as outrageous as the detractors claim it is.

        • That's what you do as a scientist when faced with evidence that does not fit with the rules as you know them. You try and postulate reasons for why you might be getting those results. Some of those might be as simple as "the conditions for the original experiment didn't eliminate all external interference."

          You then go back and conduct more experiments to try and prove or disprove some or all of those postulates. Rinse, repeat, refine.

          It's like what happens when you discover that in certain conditions, t
    • by naasking ( 94116 )

      iirc it's the light pressure from fusion that keeps stars from collapsing on themselves

      It's ordinary pressure, not light pressure that keeps stars from collapsing.

  • by Anonymous Coward

    My my how technology continues to march on. I haven't even upgraded any of my systems to the new-fangled solid-state drives. Is this new EM drive going to have a higher storage capacity or are they just faster?

  • by Anonymous Coward

    Really really slowly.

  • There is a reason why it doesn't get past peer review. Things like last time, no statistically significant force, "but look its a force"! Sheesh.
    • by tnk1 ( 899206 )

      It didn't get past peer review because:

      1) they aren't presenting a theory as to what is causing it which can be evaluated.
      2) the lack of said theory means that there is a violation of a well accepted principle of the Conservation of Momentum and no one is explaining why that isn't the case, or how that could be possible.
      3) there is reason to believe that the experimental apparatus is unable to account for all variables and noise, particularly for the very small discrepancy which has been observed.

      and of cou

  • An erg, as my high school physics teacher related to us, is equivalent to one mosquito push-up.
  • by sjames ( 1099 ) on Tuesday November 03, 2015 @12:19PM (#50856149) Homepage Journal

    This is genuinely confusing. Who the hell is claiming that this is a violation of the conservation of momentum? I haven't seen any such claims from any of the people actually doing the experiments. There's probably a zillion alternative explanations, all more likely.

    Once and for all, this violation of conservation of momentum BS is a strawman.

  • First, I am a physicist.

    Second, why is this controversial? Light (including microwaves) has momentum, and we absolutely use it to move things around. We have been using optical tweezers in labs for a long time. Without including pressure from photons, we wouldn't understand stars.

    If you told me that a magnetron and horn antenna produced absolutely no impulse at all, I wouldn't believe you.

    This is VERY interesting. How do you maximize thrust? But it's not shaking the foundations of physics.

    • This particular experiment doesn't allow the photons to escape. The device is a horn with no opening in it.

      • Yeah, ok, see that one's pretty hard for me to believe. I don't even believe they've tested for that yet.

        They're getting a bunch of non-linear mixing and don't know what's coming out or where, or they're getting heating somewhere unusual,l or something like that. One way or another, there are photons coming off that thing as a result of powering up that magnetron.

    • I am not very familiar with their mechanism, but from what I read, no light is emitted. So it is absolutely irrelevant that light has momentum.

      Their claim is that they are extracting mommentum from the ( quantum )vacuum. Something very dubious.

  • When I saw this post my first thought was "Oh cool, a fight to watch". As usual it didn't disappoint.
    It's like Dawkins -v- Christians. Neither side is going to win, both are pretty angry with the other.
    A total waste of time and emotion.

    When the hell did Science become an official world religion?
    My guess is that it's a legacy from church persecution for challenging their version of "truth"

    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an

The party adjourned to a hot tub, yes. Fully clothed, I might add. -- IBM employee, testifying in California State Supreme Court