Slashdot Mirror

← Back to Stories (view on slashdot.org)

NASA Eagleworks Has Tested an Upgraded EM Drive

Posted by samzenpus on from the riding-the-microwaves dept.

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."

13 of 203 comments (clear)

  1. Scientists by skovnymfe · · Score: 5, Interesting

    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.

    1. Re:Scientists by jabuzz · · Score: 5, Insightful

      The problem is that extraordinary claims require extraordinary proof. This is an extraordinary claim because it at appears to violate one of the most sacred law of physics (the conservation of momentum) for which we have previously never had even the slightest hint might not hold.

      That said unlike Mr. Rossi and his eCat for example there is no cloak of secrecy involved here. All details are out in the public for anyone to build one and test it out. This is where in part the fuss is arising because even the best labs are unable to show that it is baloney that every fibre of our beings tells us it should be.

      In the end no matter how dear we hold the principle of conservation of momentum verified experimental results trump ALL theories without exception.

      Personally I am highly sceptical of the EM drive. However I have to concede that the experimental results are so far with it, and thus further investigation is entirely warranted. In fact I would go further and say that further investigation is absolutely required.

    2. Re:Scientists by serviscope_minor · · Score: 4, Interesting

      And for those who don't understand why the conservation of momentum is one of the most "sacred" laws, you might want to check out Neother's theorem.

      If this device is real, then it means that the laws of pyhsics are not constant but instead vary across time and space. The implications are vast, and the corollary of that is that it's a very, very, very well tested law.

      It's hard to overstate how extraordinary the claims really are. And while ultimately experiment trumps all else, there have been a lot of experiments showing the contrary too and it's awfully easy to let errors slip in somewhere (see the recent articles on the number of incorrect papers being published).

      --
      SJW n. One who posts facts.
    3. Re:Scientists by pla · · Score: 5, Insightful

      The problem is that extraordinary claims require extraordinary proof.

      A working prototype counts as a pretty damned good proof of concept, at least until someone can demonstrate how it cheats.

      Sure, someone might eventually figure out a way that it doesn't really cheat conservation of momentum - And that finding might have its own useful applications.

    4. Re:Scientists by jabuzz · · Score: 5, Interesting

      Sure verified experimental results trump everything. The problem at the moment is that the forces the device produce are very small 100uN. That means there is still the possibility that there are flaws in the experiment and the effect is not real. A bit like those superluminary neutrinos a while back.

      My gut feeling at this point is stop messing about with an 80W drive, and build something a bit bigger say a few kW at least. That way the produced thrust should be large enough to rule out experimental errors. Of course this would require money...

    5. Re:Scientists by Beezlebub33 · · Score: 5, Interesting

      One of two things is going to come out of this: they will determine that it's real, in which case we'll have some new physics to work with; they will determine it is experimental error, in which case we'll have a better understanding of how to measure small forces when the device is relatively large, in both air and a vacuum.

      Either of these is a good thing; I'd bet on the second but would be happier with the first. In any case, the best course is to remain sceptically hopeful and continue testing.

      --
      The more people I meet, the better I like my dog.
    6. Re:Scientists by Anonymous Coward · · Score: 5, Interesting

      My gut feeling at this point is stop messing about with an 80W drive, and build something a bit bigger say a few kW at least.

      OK, I'm going to go into some depth here because this is common sentiment, even from what I've read coming from Eagleworks, and it's probably wrong. Here's why I say that:

      The inventor of the EMDrive is a retired aerospace engineer - he's too old to want to test anything but threw the idea for the EMDrive out there with a low-power test early in retirement as more or less an act of mental masturbation. Why is this important? Because his prior work, from which the EMDrive stems, is a laser-gyroscope functioning on the exact same principles as the EMDrive in reverse capable of measuring absolute accelerations based on relativistic effects without any outside coupling to the surrounding environment. Why is this important? Because it works so well it is in use in missile guidance systems and has been for decades. People tend to refer to Shawyer as a quack but he is the inventor of it, the invention came from sound and proven theory and all the hype about violating conservation of momentum isn't even correct based on the theory.

      How does this relate to the "make it bigger" mentality? Shawyer's theory states the greatest way to improve thrust from existing models would be to make a perfect-Q cavity, at which point 1KW of power would be enough to lift a small car at Earth gravity. This isn't a difficult test - you just need a superconducting cavity. Thus far nobody has built an EMDrive with a superconducting cavity because they think Shawyer is just a crazy guy that stumbled into something interesting.

      TL;DR: don't make it bigger, just make it superconducting.

    7. Re:Scientists by DrJimbo · · Score: 3, Informative

      The problem is not the absolute smallness of 100 micro-Newtons. The problem is the relative size of 100-micro-Newtons compared to the forces that exist in the experimental apparatus. It is like confusing absolute signal level with the signal to noise ratio. Yes, we can easily measure the weight of a snowflake. But if the total thrust from this 100 watt drive is equivalent to the weight of a snowflake then I am exceedingly unimpressed. If you read the fine post that is linked to, you will see that this is literally down in the level of noise that can be produced by ground loops and so on. The author is basically saying that they tried to remove even more noise sources than last time and still have not yet tracked down what is causing the extremely tiny anomalous thrust they have measured.

      I am a physicist so I am well aware of just how bloody difficult it is to track down and account for every form of noise and error in experiments like this one. Or in the experiment that measured neutrinos traveling faster than the speed of light. I am often cautioning my friends to not get too excited about weak experimental results like this that contradict foundational physical theories. I also cautioned people to not get too excited about the so-called "face on Mars" for the same reasons. Lots of fascinating things are seen in weak signals that are close to the experimental noise floor.

      In addition, I have not seen any reasonable theoretical explanation for the anomalous force that is purported to power the EM drive. There is certainly no relationship between the purported physics of an EM drive and the actual physics of a ring laser gyroscope. Nor have I seen any reasonable theoretical explanation for why the thrust should scale as a large power of the input energy. Yet many people here who ignore the experimental challenges of measuring the weight of a snowflake on top of the forces acting on an apparatus dissipating 100 watts of RF energy seem to blithely accept these remarkable and, AFAIK unfounded, theoretical claims as gospel truth.

      --
      We don't see the world as it is, we see it as we are.
      -- Anais Nin
  2. Re:physicists? by Anonymous Coward · · Score: 3, Interesting

    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.

  3. Re:Summary by serviscope_minor · · Score: 3, Interesting

    However, it's a shame that we're so bombarded with crap these days that the default conclusion is that everything is BS unless it's unequivocally shown to not be.

    It's fair to assume that an extraordinary claim of this magnitude is wrong. Think about what it's saying. There have been a lot of very precise and importantly repeatable experiments performed in physics over the years. None have found a variation in the laws of physics over space or time. A single, new experiment reporting a minute force (100nN) claims they do in fact vary.

    What's more likely? An experimental error in which 100nN on an 80W device (think about the relative scale of the device and size of the force) has been missed somewhere or the most ground breaking physics result of the last 350 years?

    Other reasons to be suspicious: the device was first invented theoretically using relativity. This was clearly wrong as relativity has conservation of momentum baked in at a fundamental level (via Noether's theorem). Eventually someone found the specific mistake he'd made in the maths.

    The device apparently works anyway but via a different mechanism. Either you've got the mother of all coincidences, or you've got a case of severe optimism mixed with the difficulty of measuring really tiny forces on large objects with a lot of power going through them.

    --
    SJW n. One who posts facts.
  4. Re:Scientists and Conservation by NReitzel · · Score: 3, Insightful

    At first glance this sounds for all the world like another perpetual motion machine. It deserves a second glance.

    We (Physicists) know for absolute fact that a phenomenon called "dragging the metric" exists. The results are small, but every attempt at verification shows that the effect exists, and that general relativity predicts the magnitude of the effects. It is conceivable (though absolutely unverified) that a device might create it's own drag on the metric, and thus provide "impossible" thrust.

    History is replete with experiments that show impossible results (two slit electron experiments, superconductivity) that have turned out to be true. Any experiment that provides verifiable evidence that contradicts theory shows that the theory is wrong, period. (Feynman Lectures)

    The ostensible effect is small, and right up against the boundaries of bad science, but it needs to be verified, again and again, until the numbers either show that it doesn't exist, or show that it does. And if it doesn't exist, it's important to know -why- the results seemed to show it. This one is a long shot, but hey, -somebody- wins the lottery. Stick with it.

    --

    Don't take life too seriously; it isn't permanent.

  5. Re:Controversial? by ganv · · Score: 5, Insightful

    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: https://www.physicsforums.com/... 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 https://en.wikipedia.org/wiki/... ). 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.

  6. Re: Controversial? by binarylarry · · Score: 3, Funny

    Who is this Einstein guy all you kids keep bringing up? Is it someone on reddit?

    --
    Mod me down, my New Earth Global Warmingist friends!