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The SpaceDrive Project – First Results on EMDrive and Mach-Effect Thrusters
- terravion 8y agoI think everyone that hopes for a bright future wishes the EM drive worked--an Epstein Drive in our own time! Alas, wishes do not make it so...
- roywiggins 8y agoReactionless drives are even "worse" than Epstein drives, since they break conservation of momentum entirely. Epstein drives just have wildly implausible characteristics- while they might break all known laws of, say, material and nuclear science, they don't break conservation laws since they require reaction mass.
- djsumdog 8y agoWell in the fictional universe the Epstein drive exists in, an advanced alien civilization can make wormholes through space and create microorganism with enough data on them to re-encode all surrounding organic and inorganic material into tools to create gates for those wormholes. :-P
- pocketstar 8y agoSPOILER :(
- jsmthrowaway 8y agoAll more plausible than EMDrive, it turns out.
- deleted 8y ago[deleted]
- hinkley 8y agoThanks a lot, asshole.
- ben_w 8y agoGiven what appears on screen, the Epstein Drive doesn’t even have that problem. It “only” acts like an electrostatic confinement fusion reactor with a hole in the confinement, slight enough for only the fusion products to escape, where the nozzle points. (Edit footnote: only seen s1/2, anything surprising in s3 is unknown to me).
- roywiggins 8y agoThe "Eros incident" does imply that the aliens have an interesting relationship with momentum, since ordinarily accelerating something that big that fast would grind everything to a pulp.
- SolarNet 8y agoIf I remember correctly the authors stated it was based off of the theoretical limits of efficiency for a reaction mass drive (e.g. if we could turn mass into acceleration with very little waste energy). Which is a really great conceit in my opinion because it stays hard sci-fi where it matters (e.g. besides the aliens) while still being close enough to our time to be interesting.
- sjburt 8y agoI thought when they were "flying teakettle" they were using water as a reaction mass, and the Epstein drive was an unexplained reactionless drive? At least in the books, haven't seen the TV show. Iirc, there's some mention of pre-Epstein fusion ships that needed even more water.
- roywiggins 8y agoIt's left intentionally vague, but at some point they do refuel the drive. It's meant to be an improbably efficient fusion drive. The alien forces demonstrably have a reactionless capability though (see: Eros) that utterly outmatches the Epstein drive.
- jerrysievert 8y agoyou can read the novella Drive online: http://www.syfy.com/theexpanse/drive/prequel.php http://www.syfy.com/theexpanse/drive/prequel.php where it appears to be some sort of issue that occurs to his failing fusion drive, so definitely a more efficient fusion drive.
- dogma1138 8y agoWasn’t the Epstein drive not “new” physics but rather he just fumbled into making a “standard” fusion drive extremely efficient?
- ImSkeptical 8y agoI think the EM drive would've made for a dark future. How long would it be before maniacs were accelerating asteroids into the planet? The EM drive seemed to be simpler and cheaper than a nuclear weapon. Anybody who could lift a few into space could attach to different rocks in the solar system and accelerate them to insane speeds. A weapon easier to acquire and more dangerous than nuclear weapons.
- vertexFarm 8y agoDamn it. The Epstein drive is a fusion drive. It's far more plausible than this voodoo quackery, the only thing keeping it out of reality is the fact that nothing that size could handle the wattage without becoming a rapidly expanding cloud of plasma. Everyone that hopes for a bright future would absolutely love a reactionless drive. I'd love it. But it's not real. We've seen lots of very bad methodology and things like researchers ignoring the fact that a null setup still produces the same thrust even though the drive has been modified not to work. With forces of this tiny order of magnitude it's incredibly hard to get accurate readings, and readings within the margin of error of the instrumentation should not be reported to sensationalist media as promising. This is just another one of those ufo antigravity quacks you see on youtube, but somehow they got their day in court. I can't explain how much I'd love to be proven wrong, but reactionless drives are physically ludicrous in every single way we understand the universe. Is it possible for us to be wrong? Sure. Is it possible that we're wrong about literally every observation we've ever made in the history of physics? I very much doubt it and it's going to take more than a badly set-up experiment featuring a microwave stuffed into a tuba to convince anyone of that.
- roywiggins 8y agoGiven that reactionless thrust is even less plausible on a theoretical basis than superluminal neutrinos, I really hope this doesn't come as much of a surprise to anyone.
- delecti 8y agoNot a surprise, but certainly a disappointment. It would have violated our understanding of physics, but it's not like that's never happened before.
- drspacemonkey 8y agoAgreed. There's nothing more exciting in science than finding out that our widely-held beliefs about something are wrong.
- beevai142 8y agoNot a surprise and not a disappointment either, when it was clear from the start that all results are within measurement error bars, so that there was neither experimental nor theoretical reason to expect to see something.
- delecti 8y agoIt wasn't clear from the start or there never would have been follow-ups. There seemed to be a measurable effect going on, so they tested it.
- monochromatic 8y agoStill, would have been nice to find a real effect. And by nice, I mean it would have changed the future of space travel.
- mrkstu 8y agoIt also would have literally meant the end of the world in a short period of time. Reactionless rockets with little to no cost or requiring high technical capability would lead to a terrorist shortly speeding up a hunk of lead to near lightspeed and slamming it into a earthside target, and that would be that.
- olliej 8y agoThe tldr for emdrive: having verified that changing the direction of the engine the thrust direction also changed, but when they attenuated the power to just the drive component, which should have changed the thrust, but it did not. Therefore the thrust being seen was not being produced by the drive itself. For the piezo one the predicted thrust was below the noise threshold in their final tests (specifically below center of mass movements that were also - to my reading - due to the control electronics)
- andrepd 8y agoIn other news, prepetual motion machine found not to work.
- inteleng 8y agoNo. Nothing was found (nailed down, proven) here except that error bounds need to be improved.
- jcims 8y agoEdit: Title has been changed, leaving this for posterity. Apologies for formatting, but the title doesn’t match the conclusion of the paper. “First measurement campaigns were carried out with both thruster models reaching thrust/thrust-to- power levels comparable to claimed values. However, we found that e.g. magnetic interaction from twisted-pair cables and amplifiers with the Earth’s magnetic field can be a significant error source for EMDrives.” There was no experimental validation of this, just speculation based on their observations. They propose a simple fix, run the experiment in a magnetically shielded environment. They suggest Mu metal for maximum shielding, which would be good, but I’m a little skeptical that the vacuum vessels used in previous tests would have allowed a substantial flux of earths magnetic field through the environment. Using my phone's basic magnetometer, I get an order of magnitude reduction in field strength by placing it ~8" inside my oven and leaving the door open. In any event they are probably on to something here. Certainly a more plausible explanation than any of the alternatives.
- deleted 8y ago[deleted]
- catpolice 8y agoYeah, it's odd that they make stronger claims in the middle of the paper (e.g. "This clearly indicates that the “thrust” is not coming from the EMDrive but from some electromagnetic interaction.") than in the conclusion.
- madengr 8y agoWhy not just replace the magnetron with a resistor. That keeps the DC effects while removing the RF. Nevermind, they are not using a magnetron like the original concept.
- vertexFarm 8y agoOh, they did that in a previous emDrive experiment. It still produced the same thrust. They ignored it. This is par for the course with reactionless drive "research."
- stale2002 8y agoI am surprised that nobody has yet to attempt the "simple" solution for testing something like this. The simple solution being to put it in space, turn it on, and see if it 'stays' in space. The claimed amount of thrust is significant enough that it will either obviously succeed or fail if you actually put it in space.
- sushisource 8y agoThat's not "simple". It's very, very, very expensive to put things in space. Trying to figure it out on the ground first makes sense for a number of reasons.
- aeternus 8y agoThey should have asked Elon to toss it in the back of his roadster.
- vertexFarm 8y agoDamn it, that would have been a great idea. We could have gotten rid of this silly concept for good. Musk, it's time to launch another car!
- nasasucks 8y agoWell, to be fair, Elon _did_ offer a free payload to NASA but they were too old and grumpy to accept the generous offer so Tesla nailed a car to it at the last minute instead.
- cjensen 8y agoYour proposed test would not be conclusive because magnetic fields are a thing which can be pushed against.
- stale2002 8y agoWho cares? That would still be an extremely useful invention. I was thinking about this more from a practical perspective. And what matters is "does it work", and much less so "how does it work". I guess if it based on magnetic fields, then it wouldn't be useful for long range space travel but it would still be extremely useful for planet scale space travel!
- madengr 8y agoThere goes my hunch that it was rectified DC currents in the cavity.
- lutorm 8y agoSince you can launch cubesats for comparatively little money these days, someone should actually launch one.
- vertexFarm 8y agoUnfortunately it would have to be a little further from Earth's magnetosphere to get a good test. Cubesats are kind of atmosphere skimmers.
- njarboe 8y agoPoor title. It is sad to see academic descend into click-baitness. Even the abstract does not tell you the key point of the paper. The most one gets from the abstract is: Our results show that the magnetic interaction from not sufficiently shielded cables or thrusters are a major factor that needs to be taken into account for proper µN thrust measurements for these type of devices. Reading the paper one can finally get to what we want to know, "Do these thrusters work?" The answer is no and/or can't tell yet. Under the EMDrive section: This clearly indicates that the “thrust” is not coming from the EMDrive but from some electromagnetic interaction. Under the Mach-Effect section: This again indicates that there must be some electromagnetic interaction or thermally induced center of mass shift that is masking any real thrust value. Edit - I did not read the whole paper but skimmed for these descriptions of if they found any real thrust signal.
- ggm 8y agoI want to believe the same way I suspend disbelief when I read S.F. -Its temporally applied. Stop reading the S.F.? no time travel or FTL. So my wishes aside, I feel like this is very tenuous, and is going to come down to "better measurement isolated an effect causing this" more then "there is now a tractable reactionless drive at scale for big things"
- rjplatte 8y agoThe fact that no-one has conclusively disproven this yet gives me hope. My desperate desire for this to be real has nothing to do with that hope whatsoever. I feel like, if this is real, it's one of those sci-fi MacGuffin technologies. Literally changes everything.
- jimmcslim 8y agoAssuming the effect of the EMDrive were real and practically exploitable, what does that say about the Fermi paradox?
- Animats 8y agoTesting of propellantless propulsion concepts requires a highly sophisticated thrust balance that must be able to reliably detect very small thrust with a resolution down to the nano-Newton range, block electromagnetic interactions as much as possible and limit any balance-vacuum chamber wall interactions. The thrust, if any, is so weak it's down in the noise. For a propulsion system, that's a big problem. It's like cold fusion in that way.
- Animats 8y agoNano-Newtons. For comparison, the tiny rockets used for attitude control on satellites have a thrust of about four Newtons. Falcon 9 booster, about 7,000,000 Newtons. This thing, if it works, maybe 0.00000001 Newton.
- TangoTrotFox 8y agoI think it's reasonable to speculate that the air force is already carrying out live tests. The reason for this is that NASA went through a substantial amount of effort to trial and test the EM drive to their greatest ability, and it came out on top with everything they could throw at it. And it's just been a black out since then. That was about 1.5 years ago. In the interim the air force has sent up the classified X-37 [1]. They've stated it's mission purpose is "risk reduction, experimentation, and operational concept development for reusable space vehicle technologies, in support of long-term developmental space objectives". That's certainly a horoscope style description, but at the same time it does seem to fit quite well for live testing of propellantless drives, even if not as a primary mission. Furthermore, if the EM-drive did work, it would have a beyond revolutionary impact on everything and so it would not be surprising that it would end up getting classified after passing the initial slew of tests thrown at it. [1] - https://en.wikipedia.org/wiki/Boeing_X-37 https://en.wikipedia.org/wiki/Boeing_X-37
- dandare 8y agoI don't understand how the EMDrive came to be a serious topic. First, someone proposed a design that violates both conservation of momentum and conservation of energy, but that's cool because you know, fuck physics. Then there was a hoax and yellow journalism and in the end, several experiments failed to confirm/reproduce the effect, but that's cool because we have this awesome theory we are trying to confirm, right? By the way, I am looking for a team of physicists that will confirm my revolutionary Tooth Fairy Drive(tm).
- JTbane 8y agoI'm still convinced EMDrive is the latest cold fusion, perpetual motion, panacea, whatever they are calling it these days.
- tomatotomato37 8y agoI always doubted the reactionless drive aspect of this, but has anymore research gone into the apparent spacetime warping effect that one NASA group discovered? Even if it can't do anything more than disort light more effectively than lots of magnetism doesn't make it useless
- c-smile 8y agoDamn, the picture "killing of glorious idea by disgusting facts" again. Sigh, will wait for the next "deformator of space/time curvature" device for the human race to reach stars ...