# NASA Paper Claims EM Drive Works. Newslink **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [November 21, 2016, 11:29pm UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695 "2016-11-21T23:29:19Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [November 23, 2016, 2:31am UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/41 "2016-11-23T02:31:18Z")
> [@Declan](#): > > At the moment, any ansewers would be guesses, but does this scale up or does it run into a mass wall at some point, ie like using an outboard motor to move a freighter. Yes, this is a big question. I would assume that the size of the chamber correlates to the standing wave reflection of the EM emissions. If this is the case, building a larger device would most likely result in lower relative output. You could, maybe, try longer wavelength EM to better fit the larger chamber, but longer waves, IIUC, require more input to match the energy of shorter waves. On the other hand, if you tried running thousands of these things to get lots of output, your mass-to-thrust ratio would be fairly flat, I think. Looks like they have a ways to go to get to “70 days to Mars” or Biff’s hoverboard. > [@](#): > > Second, what would the on ramp speed be for this drive, something like the plasma drive which takes a while to get up to speed, or a Jeremy Clarkson power on demand. The paper that **Grey** linked to shows ramp graphs. ---
**Author:** ![JRDelirious](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jrdelirious/32/9531_2.png) [@JRDelirious](https://boards.straightdope.com/u/JRDelirious)\ **Post date:** [November 23, 2016, 2:34am UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/42 "2016-11-23T02:34:17Z")
> [@Llama\_Llogophile](#): > > I can’t remember where I read this - I’m a space history geek, so I’ve read a lot of that stuff. I’ll post it when it comes to me. Answered by \*\*Leaper \*\*in post #34. ---
**Author:** ![Declan](https://avatars.discourse-cdn.com/v4/letter/d/ecae2f/32.png) [@Declan](https://boards.straightdope.com/u/Declan)\ **Post date:** [November 23, 2016, 2:40am UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/43 "2016-11-23T02:40:40Z")
> [@eschereal](#): > > Yes, this is a big question. I would assume that the size of the chamber correlates to the standing wave reflection of the EM emissions. If this is the case, building a larger device would most likely result in lower relative output. You could, maybe, try longer wavelength EM to better fit the larger chamber, but longer waves, IIUC, require more input to match the energy of shorter waves. On the other hand, if you tried running thousands of these things to get lots of output, your mass-to-thrust ratio would be fairly flat, I think. Looks like they have a ways to go to get to “70 days to Mars” or Biff’s hoverboard. > > The paper that **Grey** linked to shows ramp graphs. Thanks, will check that out ---
**Author:** ![Llama\_Llogophile](https://avatars.discourse-cdn.com/v4/letter/l/49beb7/32.png) [@Llama\_Llogophile](https://boards.straightdope.com/u/Llama_Llogophile)\ **Post date:** [November 23, 2016, 2:56am UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/44 "2016-11-23T02:56:42Z")
> [@JRDelirious](#): > > Answered by \*\*Leaper \*\*in post #34. Thanks - I missed that post somehow. But I’m still trying to remember where I came across it. Might have been something Andrew Chaikin wrote - will come back when I find it. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [November 23, 2016, 4:11am UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/45 "2016-11-23T04:11:12Z")
One thing worth noting is that the tests described in the paper only went up to 80W, so the claim of 1.2mN/KW is not substantiated. It is only a projection. It seems likely that 1KW might cause problematic deformations in the device due to excessive thermal expansion. Making more powerful Q-drives will almost certainly be challenging. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 23, 2016, 7:01am UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/46 "2016-11-23T07:01:10Z")
> [@Sage\_Rat](#): > > Not entirely true. If I put a big hunk of steel on one side of a table and a super powerful electric magnet on the other, and hit the on switch, there will be no thrust moving the magnet toward the steel block. > > I could theorize (based on nothing whatsoever) that the EM device acts on a similar principal, using attraction to move itself, but somehow is able to shield itself from the attraction on one side, so that it is able to move any desired direction it wants. > [@eschereal](#): > > But if you put both the magnet and the block of steel on an operating air hockey table (frictionless surface), the two will be drawn together, to a barycenter (point closer to the heavier mass). To move the block all the way across the table, the electromagnet must have a counterforce (it is effecting thrust against whatever it is mounted on). That’s right - in fact if you put the table on frictionless castors, you would see the block move a bit, and the table recoil a bit - the centre of mass of the system would be unchanged. Without the castors, the reaction force exerted on the table is transmitted into the ground - the reaction is still real, but the ground is big enough to make it impossible to measure. It’s no different to me pushing the block across the table with my finger - my feet push against the floor - the block moves in one direction - the other part of the system (the earth and me) moves in the opposite direction, imperceptibly. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 23, 2016, 7:26am UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/47 "2016-11-23T07:26:22Z")
> [@eschereal](#): > > One thing worth noting is that the tests described in the paper only went up to 80W, so the claim of 1.2mN/KW is not substantiated. It is only a projection. It seems likely that 1KW might cause problematic deformations in the device due to excessive thermal expansion. Making more powerful Q-drives will almost certainly be challenging. If it really does work, lots of little ones might be just as good as one big one - they could be embedded throughout the fabric of a vehicle. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [November 23, 2016, 7:35am UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/48 "2016-11-23T07:35:18Z")
> [@Mangetout](#): > > If it really does work, lots of little ones might be just as good as one big one - they could be embedded throughout the fabric of a vehicle. Right, but remember the old f= **m** a: every Q-drive unit itself adds mass to the vehicle. If you can generate 1 mN of thrust for each one, that is a force that gives you 1 m/s[sup]2[/sup] of acceleration per gram of driven mass. I suspect the device, as tested, weighs more than a gram. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [November 23, 2016, 7:37am UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/49 "2016-11-23T07:37:54Z")
> [@Quartz](#): > > But it emits energy, doesn’t it? Energy goes in; energy comes out. Or is the thrust detected simply a directional heat emission generated by the energy going in? What do you mean by energy? “Directional heat emission” would be sending out energy, and wouldn’t violate conservation of momentum. Any other photon emission would be sending out energy and wouldn’t violate conservation of momentum. The entire point of this drive is that the thrust is supposed to _not_ _come_ _from_ _emission_ of _anything_. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [November 23, 2016, 7:42am UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/50 "2016-11-23T07:42:21Z")
> [@eschereal](#): > > One thing worth noting is that the tests described in the paper only went up to 80W, so the claim of 1.2mN/KW is not substantiated. It is only a projection. It seems likely that 1KW might cause problematic deformations in the device due to excessive thermal expansion. Making more powerful Q-drives will almost certainly be challenging. 1.2mN/kW is a ratio. That they put in 80W and not 1kW is not relevant to the validity of that number, which quite obviously refers to the output of that specific device. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [November 23, 2016, 8:08am UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/51 "2016-11-23T08:08:41Z")
> [@naita](#): > > What do you mean by energy? “Directional heat emission” would be sending out energy, and wouldn’t violate conservation of momentum. Any other photon emission would be sending out energy and wouldn’t violate conservation of momentum. The entire point of this drive is that the thrust is supposed to _not_ _come_ _from_ _emission_ of _anything_. In fact, from the paper, it sounded like heat radiation may have been more concentrated forward, if it was not more or less isotropic. > [@naita](#): > > 1.2mN/kW is a ratio. That they put in 80W and not 1kW is not relevant to the validity of that number, which quite obviously refers to the output of that specific device. It is a ratio based on what they measured at 80W. It is not established that the device would function with a 1KW input. It might well overheat to the point of failure. In your backyard, it would probably work, but in space, shedding excess heat tends to be much more difficult. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [November 23, 2016, 8:24am UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/52 "2016-11-23T08:24:11Z")
> [@eschereal](#): > > It is a ratio based on what they measured at 80W. It is not established that the device would function with a 1KW input. It might well overheat to the point of failure. In your backyard, it would probably work, but in space, shedding excess heat tends to be much more difficult. Yes, but you didn’t write “it might not scale” you wrote “the claim of 1.2mN/KW is not substantiated”. Which was wrong, it’s a ratio, it implies nothing about input. ---
**Author:** ![N9IWP](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/n9iwp/32/3154_2.png) [@N9IWP](https://boards.straightdope.com/u/N9IWP)\ **Post date:** [November 23, 2016, 12:15pm UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/53 "2016-11-23T12:15:03Z")
Ars Technica article (basically saying that the paper isn’t very good) > **[NASA’s EM-drive still a WTF-thruster](https://arstechnica.com/science/2016/11/nasas-em-drive-still-a-wtf-thruster/)** > > New paper generates more noise than experimental thrust. Brian ---
**Author:** ![muldoonthief](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/muldoonthief/32/3188_2.png) [@muldoonthief](https://boards.straightdope.com/u/muldoonthief)\ **Post date:** [November 23, 2016, 1:16pm UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/54 "2016-11-23T13:16:16Z")
> [@Llama\_Llogophile](#): > > Thanks - I missed that post somehow. But I’m still trying to remember where I came across it. Might have been something Andrew Chaikin wrote - will come back when I find it. FWIW, that NYT editorial against Goddard is in the Unix/BSD “fortune” program database. So if you’ve used Unix, you’ve probably seen it. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 23, 2016, 5:02pm UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/55 "2016-11-23T17:02:40Z")
> [@eschereal](#): > > Right, but remember the old f= **m** a: every Q-drive unit itself adds mass to the vehicle. If you can generate 1 mN of thrust for each one, that is a force that gives you 1 m/s[sup]2[/sup] of acceleration per gram of driven mass. I suspect the device, as tested, weighs more than a gram. Yeah, I think it will probably be hard to get anything useful or effective - I guess I was thinking there might be a way to design these things to be useful as structure in their own right, with the added benefit of being tiny engines. Or maybe if they could be miniaturised to MEMS scale and built onto a solar panel - which then becomes a _thrust_ panel. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 23, 2016, 5:48pm UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/56 "2016-11-23T17:48:22Z")
There are a lot of valid reasons why one would want to test one of these things in space. For one thing, it makes it a heck of a lot easier to isolate the device away from other potential sources of force. For another, letting it run for a significant time without any other forces on it would make it a lot easier to see any effect. Just putting it in a drop pit or the Vomit Comet wouldn’t be good enough, because you can’t run the experiment for a long enough time in those. And for this reason, if it isn’t debunked first on Earth, NASA will surely eventually launch one of these things. But that “if it isn’t debunked first” is key: There are still a heck of a lot of tests that can be performed here on Earth, a lot more cheaply than launching one. There’s no point paying for a launch until you’ve done all the cheaper things first. Personally, my gut instinct is that it’s interacting in some way with the magnetic field of the Earth (in which case, it might even still work in orbit, though not in interplanetary space). But I’m not an experimentalist, and I haven’t studied this in any sort of real detail, so don’t give too much credence to my gut. ---
**Author:** ![D18](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@D18](https://boards.straightdope.com/u/D18)\ **Post date:** [November 23, 2016, 6:19pm UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/57 "2016-11-23T18:19:26Z")
Is this the drive that was being described in the popular press as a “warp drive”? I’m guessing this is an exaggeration, but is there any credible way it can be described as such? ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [November 23, 2016, 6:35pm UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/58 "2016-11-23T18:35:48Z")
> [@D18](#): > > Is this the drive that was being described in the popular press as a “warp drive”? I’m guessing this is an exaggeration, but is there any credible way it can be described as such? No, what you’re referring to is something entirely different, the Alcubierre Drive. > **[Alcubierre drive](https://en.wikipedia.org/wiki/Alcubierre_drive)** > > The Alcubierre drive (\[alkuˈβjere\]) is a speculative warp drive idea according to which a spacecraft could achieve apparent faster-than-light travel by contracting space in front of it and expanding space behind it, under the assumption that a configurable energy-density field lower than that of vacuum (that is, negative mass) could be created. Proposed by theoretical physicist Miguel Alcubierre in 1994, the Alcubierre drive is based on a solution of Einstein's field equations. Since those Obj... There are a few experiments to investigate fundamental principles related to this idea, but the drive itself is no more than highly speculative theory at this point. [https://en.wikipedia.org/wiki/Warp-field\_experiments](https://en.wikipedia.org/wiki/Warp-field_experiments) > **[Harold G. White](https://en.wikipedia.org/wiki/White%E2%80%93Juday_warp-field_interferometer)** > > Harold G. "Sonny" White (born October 8, 1965) is a mechanical engineer, aerospace engineer, and applied physicist who is known for proposing new Alcubierre drive concepts and promoting advanced propulsion projects. > White obtained a B.S. degree in mechanical engineering from University of South Alabama, an M.S. degree in mechanical engineering from Wichita State University in 1999, and a Ph.D. degree in Physics from Rice University in 2008. > White attracted the attention of the press when he beg... ---
**Author:** ![Chimera](https://avatars.discourse-cdn.com/v4/letter/c/8e8cbc/32.png) [@Chimera](https://boards.straightdope.com/u/Chimera)\ **Post date:** [November 23, 2016, 6:44pm UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/59 "2016-11-23T18:44:39Z")
But some reporters have been mixing them up and calling this one a “warp drive”. No such thing as editors anymore ---
**Author:** ![Grey](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grey](https://boards.straightdope.com/u/Grey)\ **Post date:** [November 23, 2016, 6:50pm UTC](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695/60 "2016-11-23T18:50:46Z")
> [@D18](#): > > Is this the drive that was being described in the popular press as a “warp drive”? I’m guessing this is an exaggeration, but is there any credible way it can be described as such? Not even a little. [Previous page](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695.md?page=2) [Next page](https://boards.straightdope.com/t/nasa-paper-claims-em-drive-works-newslink/772695.md?page=4)