Make it so, Number One.
November 19, 2016 12:56 AM Subscribe

NASA's long awaited paper, Measurement of Impulsive Thrust from a Closed Radio-Frequency Cavity in Vacuum, has passed peer review and been published in the American Institute of Aeronautics and Astronautics (AIAA)’s Journal of Propulsion and Power. The takeaway? They consistently measured 1.2 millinewtons per kilowatt of thrust in a vacuum with no apparent reaction mass. Several potential sources of error were considered and examined. If the results are replicated and not the result of error our current understanding of physics would be shattered.

(spoiler alert: it is almost certainly the result of error.)

posted by Justinian (150 comments total) 33 users marked this as a favorite

NASA's Eagleworks Laboratory team have also put forward a hypothesis for a possible source of the apparent thrust. It relies on pilot wave theory which is deterministic but requires nonlocality.
posted by Justinian at 1:02 AM on November 19, 2016 [4 favorites]

spoiler alert: it is almost certainly the result of error.

Can you expand on this? My instinct is to agree, just on the basis that things which seem too good to be true probably are, but from the paper they seem to have done a decent job of identifying and controlling for sources of error. Are there any specific criticisms of the work from informed sources?
posted by metaBugs at 1:21 AM on November 19, 2016 [2 favorites]

The paper is probably too new for that yet, but in general my understanding is that it boils down to "this doesn't make any sense and if it were true it would really mess with our current understanding of the universe, and our current understanding (while far from perfect or complete) describes what we see pretty well."

Also a pretty big side order of "if it sounds too good to be true it probably is."
posted by Justinian at 1:36 AM on November 19, 2016 [5 favorites]

For example, in this comment, ryanrs argues that such a drive is fundamentally indistinguishable from a perpetual motion machine.
posted by Justinian at 1:39 AM on November 19, 2016 [3 favorites]

Lol yes. I eagerly await the discovery of the errors that led to these results.
posted by ryanrs at 1:41 AM on November 19, 2016 [5 favorites]

It's hard to describe to someone who doesn't have a good understanding of modern physics just how bizarre this effect would be.

First, it breaks conservation of momentum. That is so far beyond impossible that it's not clear how we would start building a new model of the universe.

Second, it means the universe is not translationally symmetric. We think the universe behaves the same wherever we are. The rules of physics appear to be the same everywhere. If this device works, that is no longer true.

It's also a free-energy device.

There seems to be a push to test this in space. I have no idea why you'd want to do that. If there is a reproducible effect, it's far cheaper, easier and more interesting to test it in an independent lab here.

Simply put, if this thing works then we are dealing with entirely new physics that that would be vastly weirder than the discovery of quantum mechanics.

It changes our understanding of the world in utterly wild ways.

The inventors have never addressed these implications. That in itself raises some doubts.

Other teams have had a look at this, and none of them have seen anything.

So - more tests needed. We're not going to overturn three centuries of physics without more data and independent reproduction.
posted by Combat Wombat at 1:46 AM on November 19, 2016 [39 favorites]

what if a wizard did it though.
posted by poffin boffin at 1:53 AM on November 19, 2016 [89 favorites]

There seems to be a push to test this in space. I have no idea why you'd want to do that. If there is a reproducible effect, it's far cheaper, easier and more interesting to test it in an independent lab here.

I think the rationale is a bunch of people just going "fuck this lab stuff let's just strap this puppy on to something and see if it moves!". Which, while perhaps lacking subtlety, has at least a certain straightforward cowboyesque charm to it.
posted by Justinian at 1:54 AM on November 19, 2016 [72 favorites]

As ever, relevant xkcd.
posted by metaBugs at 2:01 AM on November 19, 2016 [11 favorites]

I'm just reading this as evidence that we're living in the back-story of a bad 1960s solar empire space opera (the sort of story The Expanse cleaned up and rebooted)—Earth is going to shit because climate change/neo-nazis/holy wars/resurgent Russian empire (take your pick) but a two-fisted billionaire with a plan is going to colonize Mars for us honest folks with git-up-n-go, and then a few years later a reactionless Space Drive is going to come along and we're going to be zipping all over the solar system (those of us who haven't succumbed to Martian Hyperscabies or succumbed to famine on Earth) having space adventures. (As long as we're cishet white males, because, oh look, late 1950s/early 1960s SF.)

Can I just say, as someone who worked in a no-shit dot-com startup in the late 90s and lived the cyberpunk lifestyle for a few years, that living in a sub-Gibsonian 1980s novel sucked horribly, but that this replacement will suck even harder?
posted by cstross at 2:15 AM on November 19, 2016 [97 favorites]

In other news, ten years after their confident debut, Steorn (previously) has finally liquidated all assets and shut down.
posted by Rhaomi at 2:22 AM on November 19, 2016 [12 favorites]

what if a wizard did it though.

That wizard gets a cold iron paddling and has to write out "I will not goof around with physics" a thousand times.
posted by GenjiandProust at 2:45 AM on November 19, 2016 [10 favorites]

Dean Drive 2.0.
posted by MartinWisse at 2:57 AM on November 19, 2016 [1 favorite]

When theory conflicts with experiment, it's theory that has to change.

Here's the nice thing: Error cuts both ways. If your theory does not predict thrust, but thrust is present, then your theory about the consequences of there being thrust (like this being a free energy device) may also be incorrect.

Science -- we learn new things sometimes. It's OK.
posted by effugas at 3:01 AM on November 19, 2016 [8 favorites]

> Science -- we learn new things sometimes. It's OK.

There's no disputing something will be learned from this. We yet don't know what it is we've learned though.
posted by ardgedee at 3:12 AM on November 19, 2016 [3 favorites]

Yes. The vast, overwhelming, well-nigh unimaginable weight of experiment supports theoretical models that exclude the possibility of this mechanism working. It is possible that our interpretations of this data have been wrong, but given the great flexibility and predictive power of our current models, at this time, the odds are that this is an experimental anomaly rather that the single most significant discovery in centuries. Time will tell, but extraordinary claims require extraordinary proofs for good reason.
posted by howfar at 3:16 AM on November 19, 2016 [6 favorites]

And that's why they need to put one in space and fly it to Mars
posted by dng at 3:22 AM on November 19, 2016 [9 favorites]

There seems to be a push to test this in space. I have no idea why you'd want to do that.

Wouldn't the idea be to remove as much influence the Earth itself might somehow have on the experiment?
posted by Thorzdad at 3:34 AM on November 19, 2016 [2 favorites]

Sure, why not. Why not conservation of momentum also. Science is dead. Math is broken. The Enlightenment was a delusion. Let's just skip around the maypole, accuse people of witchcraft when we get bored, and hate and fear the people in the other village. Fuck it.
posted by officer_fred at 3:42 AM on November 19, 2016 [31 favorites]

Space is a shit place to run experiments. Unless you absolutely need microgravity, no atmosphere (for telescopes), or some other very specific conditions, it's far better to work in a lab on the surface (or deep underground if you want shielding from the Sun, etc).

The only reason fans are calling for this to be launched into space is because the people who are interested in this device are also interested in space.
posted by ryanrs at 3:44 AM on November 19, 2016 [6 favorites]

Does it involve cheddar and a particle accelerator?
posted by Mocata at 3:44 AM on November 19, 2016 [6 favorites]

And that's why they need to put one in space and fly it to Mars
posted by dng at 22:22 on November 19 [+] [!]

No. Absolutely not. Completely, categorically wrong.

I'm sorry dng - I'm picking on you not because you're wrong, but because a lot of people are spouting this nonsense, and it's harmful but I think I understand why people are saying it.

I like the "Let's quite sciencing this shit! Build it boot it and let's go to the stars!"

The universe seems to have imposed some tough limits on how hard it is to go to places other than Earth. Conservation of energy, of momentum and the speed of light are hard constraints to live with.

We *want* this to work.

The discussion around this device involves two groups: those who understand Noether's Theorem, and the Wild-Eyed Optimists.

The Wild-Eyed Optimists have decided it *must* be tested in space. Because they want Star Trek, and Star Trek was in space. I assume that's the reason. Because it's better than anything I've actually seen proposed.

The physicists (who can prove Noether's Theorem) have a different view.

It's not just a cheap way to Mars. It's a free energy device. And it's evidence that the rules of physics can change as you move. And that is too weird to explain. It's horrifyingly weird.

The people who built this thing have never even mentioned these obvious consequences. That makes me suspect that the designers are wild-eyed optimists.

I remain thoroughly unconvinced. Repeat it in an independent lab. Here. On Earth. Where they say they've already seen the result.

If they can see it here, so can someone else. *Then* we're making progress.

Strapping it to a booster and launching a one-shot experiment will just add to space debris to no purpose whatsoever.

Reproduce it independently. Understand the effect. Then we can work out what the consequences are.
posted by Combat Wombat at 3:52 AM on November 19, 2016 [29 favorites]

Sorry. I was making a crap joke (re: the extraordinary proof).
posted by dng at 4:03 AM on November 19, 2016 [3 favorites]

As ever, relevant xkcd.

Even more relevant xkcd.
posted by radwolf76 at 4:14 AM on November 19, 2016 [12 favorites]

Mocata: "Does it involve cheddar and a particle accelerator?"

Make space grate again.
posted by chavenet at 4:16 AM on November 19, 2016 [20 favorites]

We *want* this to work.

I dunno. It seems to me that most of our problems on Earth are caused by people, not reaction mass or limited energy. And I don't know that giving people limitless free energy is going to make them less problematic.
posted by ryanrs at 4:30 AM on November 19, 2016 [9 favorites]

i don't get the certainty of the physics believers here. i mean, we already have huge holes in physics - dark matter and dark energy. it doesn't seem impossible to me that, say, there is some local reference frame defined by dark matter that this effect is somehow relative to. which would save you from being forced to immediately connect this to symmetry violations.

i can't say i believe it's true, but i feel like we could fit something new in physics somehow. in a sense we have to, to solve the two "dark problems".

sorry if i'm being naive here...

[and if so, i'm surprised the effect is so large, rather than so small, as in the comic snark - you'd expect some tiny coupling constant...]
posted by andrewcooke at 4:42 AM on November 19, 2016

Space is a shit place to run experiments.

So you're not coming? It'll be fun! We're going to test if red rope licorice tastes better without gravity. It's probably the same but we don't know yet. BUT LET'S DO IT IN SPACE ANYHOW.
posted by adept256 at 4:51 AM on November 19, 2016 [9 favorites]

I remain thoroughly unconvinced. Repeat it in an independent lab. Here. On Earth. Where they say they've already seen the result.

This.

I had not been a student of this news cycle and from the headlines I'd sortof assumed that the "NASA confirms..." tone indicated some degree of replication. So yes please can some other lab run the experiment, please.

As for perpetual motion, I thought they were pumping a lot of energy INTO the system?
posted by sammyo at 5:01 AM on November 19, 2016 [5 favorites]

We learn things all the time, but our current physics explains our reality extremely well.

Newtonian Physics explains our reality extremely well too, until it doesn't.

Look, we know there are properties of the universe yet to be discovered. Identical constants show up in different places and we don't know why. We know we've had to upend our models of the universe over the course of history.

Respect the experiment. Respect the process. The credibility of what we know hinges on how we recognize what we might not. Yeah, there are a lot of cranks in this space. With every experiment, with every independent team, with every credible organization, with every peer review, another step is taken towards throwing the damn thing in orbit and seeing what happens.

The universe is strange. Good. Rigid belief in models is just tribalism; you like agreeing with your peers more than you like agreeing with reality.

To be fair, I like agreeing with the person willing to be wrong.

If nothing else, maybe there's a new source of error generation we don't know about.
posted by effugas at 5:06 AM on November 19, 2016 [13 favorites]

I am all for shooting licorice into space. Or even the Sun if you've got the delta-v.
posted by ryanrs at 5:06 AM on November 19, 2016 [3 favorites]

Repeat it in an independent lab. Here. On Earth.

NASA is the independent lab. Here. On Earth. EMDrive sure as hell didn't start out there!

I've read unconfirmed reports the Chinese have replicated this with much stronger effects. I haven't heard reports of anyone who's actually tried this, failing to see anything.

This is the process you'd hope for, for something this weird. We're not there yet, but maybe we drop the snark level a bit. We're scientists, not...I dunno. Jerks?
posted by effugas at 5:09 AM on November 19, 2016 [4 favorites]

So are there any physics blogs discussing this, because it would be interesting to hear their take on this news that's garnered some general public interest.
posted by polymodus at 5:19 AM on November 19, 2016 [1 favorite]

This is interesting for me, not just for the potential implications of the experimental outcomes, but also because it's a good way to observe scientists working through, hopefully in public, anomalous results. It's also a good example of replication procedures. How exactly do we replicate White et al.'s work? - On the same bench? Build a new bench with the same people? Build another test rig somewhere else?

And also, we shouldn't necessarily think that we are at the end of the development of scientific theory, just because our current theory works with what we can currently observe. I don't think that that is necessarily a good philosophy. But at the same time we have to throw effort into looking at explanations within the current paradigm. That seems like the most effective way to approach this. At least one beneficial outcome will be findings about and reflections upon experimental technique.
posted by carter at 5:28 AM on November 19, 2016 [1 favorite]

> "I've read unconfirmed reports the Chinese have replicated this with much stronger effects. I haven't heard reports of anyone who's actually tried this, failing to see anything."

I don't know about unconfirmed reports, but the actual 2016 paper that came out of the Chinese experiments concluded that a setup with an internal power source did not produce significant thrust, and that the thrust measured when using external power sources could be noise.
posted by kyrademon at 5:50 AM on November 19, 2016 [6 favorites]

We're living in a post-truth world, why not post-factual as well?
posted by blue_beetle at 5:50 AM on November 19, 2016 [7 favorites]

we shouldn't necessarily think that we are at the end of the development of scientific theory, just because our current theory works with what we can currently observe

Nobody is saying that we're at the end of scientific discovery. But the current unknowns are at the extremes of scale, at the quantum level and at the galactic level. But in the realm of kilowatts and millinewtons, we are pretty damn sure we understand how things work. It seems incredible such an effect would not have shown up before as a confounding error source in many other scientific experiments and practical engineering.
posted by ryanrs at 5:59 AM on November 19, 2016 [13 favorites]

IDK about you all, but I'm enjoying seeing scientists have to grapple with philosophy (of science).
posted by oddman at 5:59 AM on November 19, 2016

They consistently measured 1.2 millinewtons per kilowatt of thrust in a vacuum with no apparent reaction mass.

Physicist here. The kilowatt is not a unit of thrust. The first place to look for the error is to determine how all that power is being dissipated.

Let's just skip around the maypole, accuse people of witchcraft when we get bored

As a person who actually celebrates May Eve and practices witchcraft, this kind of bothers me.
posted by heatherlogan at 6:00 AM on November 19, 2016 [33 favorites]

That's 1.2 mN of thrust per kilowatt of input power, which is a fine statement, at least as far as the units are concerned.
posted by ryanrs at 6:14 AM on November 19, 2016 [11 favorites]

The discussion reminds me of the discovery of cosmic background radiation by Penzias and Wilson. There was an unexplained result, and after a lot of work determined it was due to an previously unknown source.

That had to do with the cosmos, however, not the basic laws of physics.
posted by SemiSalt at 6:24 AM on November 19, 2016

ryanrs - good point - I think what I meant to say (pre-coffee) was that it is an error to think that there is zero possibility of any future paradigm change. And I agree with your point re. confounders - what I'm interested in personally is how this gets tested and (veryveryveryveryprobably) refuted.
posted by carter at 6:35 AM on November 19, 2016 [2 favorites]

That's 1.2 mN of thrust per kilowatt of input power

Thanks ryanrs, indeed it is used correctly in the paper. I still want to know where the power is going. :)

I skimmed through the paper. The theory discussion in Section II.C.10 is a cartoon and not worth worrying about. That leaves the experimental results, but honestly I am not holding my breath.

I wanted to say, "maybe it's the same physics as the Pioneer anomaly!", but they mentioned in the paper that the order of magnitude is wrong.
posted by heatherlogan at 6:39 AM on November 19, 2016 [1 favorite]

I've read unconfirmed reports the Chinese have replicated this with much stronger effects. I haven't heard reports of anyone who's actually tried this, failing to see anything.

Extraordinary claims and all that. Not being snarky, this is just very parallel to the bubble of excitement following the Fleishmann and Pons announcement in 88.
posted by bonehead at 6:47 AM on November 19, 2016 [2 favorites]

Not being snarky, this is just very parallel to the bubble of excitement following the Fleishmann and Pons announcement in 88.

Cold fusion isn't real? That Keanu Reeves movie lied to me!
posted by tobascodagama at 6:48 AM on November 19, 2016 [1 favorite]

Cold fusion isn't real? That Keanu Reeves movie lied to me!

Cold fusion is real. It's just not what Fleishmann and Pons and it costs more energy to run the particle accelerator than you get back from the fusion.
posted by Talez at 6:54 AM on November 19, 2016 [2 favorites]

If a bus is going at the speed of light, and Sandra Bullock is on it, what do you do?
posted by adept256 at 6:54 AM on November 19, 2016 [1 favorite]

The Scientific Method does not include "Unconfirmed Reports". Confirmed Reports or it isn't science.
posted by nickggully at 6:57 AM on November 19, 2016 [1 favorite]

If a bus is going at the speed of light, and Sandra Bullock is on it, what do you do?

Leave her alone because I'm sure she's sick of strangers coming up to her for her entire life.
posted by Talez at 6:58 AM on November 19, 2016 [4 favorites]

It's kind of a toss-up as to whether witches or physicists throw better parties.

Is this a joke? Physicists throw terrible parties. You want to party with witches, hands down.
posted by medusa at 6:59 AM on November 19, 2016 [15 favorites]

I feel it's unfair to compare Fleishmann and Pons's cold fusion to the EmDrive. Cold fusion was way more plausible than this thing, and didn't have anything like the theoretical issues. It's hard to overstate how much less plausible the EmDrive is.
posted by ryanrs at 7:08 AM on November 19, 2016 [10 favorites]

I did some physics! The test runs described in the paper were done at 40, 60, and 80 Watts power. They also state that the device was running cooler than 90 degrees Fahrenheit at all times and the dimensions of the device are given in the paper.

If you want to be radiating off 60 Watts of power as thermal radiation, you're looking at a surface temperature of roughly 1300 degrees Fahrenheit for a blackbody of that size, and higher for a shiny copper thing (T goes like the emissivity to the -1/4 power). So the power is clearly being dissipated in some way other than thermal radiation. From my (admittedly quick) skim of the paper it does not look like any attempt was made to track this down.
posted by heatherlogan at 7:13 AM on November 19, 2016 [8 favorites]

I assume they tested for short intervals and let the apparatus cool in between runs.
posted by ryanrs at 7:23 AM on November 19, 2016 [1 favorite]

Cold fusion is real. ... it costs more energy to run the particle accelerator than you get back from the fusion.

Cold fusion is fusion without a particle accelerator, surely.
posted by ambrosen at 7:26 AM on November 19, 2016

If you want to be radiating off 60 Watts of power as thermal radiation, you're looking at a surface temperature of roughly 1300 degrees Fahrenheit

Is that right? A 60W incandescent bulb is certainly not all at 1300F (I suppose the filament is), and I thought incandescents were only about 5% efficient. Maybe the 5% number is for visible light, and the other 95% is IR? But it still seems unlikely that you could heat an insulated container to 1300F by putting a 60W bulb in it.

(I agree that your approach of seeing where the power goes is helpful, but I'm not sure you'll be able to measure temperature accurately enough to determine that some is going missing.)
posted by spacewrench at 7:28 AM on November 19, 2016

There seems to be a push to test this in space. I have no idea why you'd want to do that.

Spectacular claims require spectacular proof. You can perform all the lab tests you like and physicists (of the arm chair variety anyway¹) will spend their last breaths claiming experimental error.

¹After a few more peer reviewed experiments it will become safe for grad students to use the phenomenon as a springboard for the endless academic papers they need to produce. That's when someone will figure out that the reaction mass is spontaneously emergent photons, which will prove some theories and cause a lot of headaches but at least get the Cult of Newton folks to settle back down on their BarcaLoungers.
posted by Tell Me No Lies at 7:30 AM on November 19, 2016 [1 favorite]

A 60W incandescent bulb is certainly not all at 1300F

That is absolutely true; most of the heat is being carried off by transfer to the surrounding air followed by convection. It's really hard to cool things in vacuum because you have to rely entirely on IR radiation.

the reaction mass is spontaneously emergent photons

It's not this. The authors compared their measurement to the thrust per unit power of a light sail/laser propulsion/"photon rocket" and their measured thrust per unit power is 2 orders of magnitude larger.
posted by heatherlogan at 7:33 AM on November 19, 2016 [5 favorites]

A sophon did it and we are all bugs.
posted by Slackermagee at 7:37 AM on November 19, 2016 [7 favorites]

The filament of a 60 watt incandescent bulb is at more than 4000 F. Just look up the color temperature and convert from Kelvin.
posted by w0mbat at 7:44 AM on November 19, 2016 [2 favorites]

quick follow-up to what i said earlier, between market and lunch. the specific solution i gave wouldn't work for reasons similar to michelson morley. in a sense the problem is finding a way to see new physics at scales we already understand very well. but still (1) physics is not perfect and set in stone; (2) the refutation for this has to be more than "symmetry".
posted by andrewcooke at 7:44 AM on November 19, 2016

I think the rationale is a bunch of people just going "fuck this lab stuff let's just strap this puppy on to something and see if it moves!".

Also known as the humans in the Federation effect.
posted by Mr. Bad Example at 7:44 AM on November 19, 2016 [25 favorites]

>our current understanding of physics would be shattered.

No! Not our physics! Fuck 2016!
posted by Catblack at 7:49 AM on November 19, 2016 [10 favorites]

Just wanted to point out also that the last two cited references, on theoretical work by the same team, were published respectively in Physics Essays (alongside such shining lights as "Mass, the second time dimension---Physics without matter") and Journal of Modern Physics (a scam journal, not to be confused with the real and respectable International Journal of Modern Physics).
posted by heatherlogan at 7:52 AM on November 19, 2016 [14 favorites]

due to like, a buffer overflow kind of error in the universe I think Ken MacLeod wrote that novel. :) :)
posted by heatherlogan at 7:54 AM on November 19, 2016

Or a hidden feature.
posted by joeyh at 8:06 AM on November 19, 2016

> those of us who haven't succumbed to Martian Hyperscabies

Oh good, I can save an AskMe question: what should I do about what I suspect is an incipient case of Martian Hyperscabies? DO NOT TELL ME TO SEE A MARTIANIST, there isn't one on my health plan.
posted by languagehat at 8:09 AM on November 19, 2016 [7 favorites]

Previous discussion
posted by Brian B. at 8:34 AM on November 19, 2016 [1 favorite]

And previouslier.

I am pleased to see I have shit on this idea in all three metafilter threads.
posted by ryanrs at 8:52 AM on November 19, 2016 [18 favorites]

Oh, great. The dark matter beings got bored and are fucking with us again.
posted by Etrigan at 9:01 AM on November 19, 2016 [1 favorite]

w0mbat: "Just look up the color temperature and convert from Kelvin."

Hang on, I'm working on a pun about Kelvin Bacon.
posted by chavenet at 9:04 AM on November 19, 2016 [5 favorites]

The only reason fans are calling for this to be launched into space is because the people who are interested in this device are also interested in space.

This seems reasonable to me. It adequately explains why I want Donald Trump to be launched into space, for instance...

That said, I think the reason people are calling for space tests is because that's really the test, isn't it? If the damn thing goes to Mars, I don't care if there's an error somewhere. Write if you figure out what the mistake was. We'll be on Mars. On the other hand, if it doesn't work, then we sigh and move on. What the exact nature of the error was will be a very esoteric question of interest to a very narrow group of specialists.

> I am pleased to see I have shit on this idea in all three metafilter threads.

you are why we can't have nice things...
posted by Naberius at 9:07 AM on November 19, 2016 [1 favorite]

you are why we can't have nice things...

On this website we obey the laws of thermodynamics!
posted by ryanrs at 9:08 AM on November 19, 2016 [44 favorites]

It's not just a cheap way to Mars. It's a free energy device.

Can anyone explain this to me? I've read all of these threads as they come up, and I see this said again and again, but I don't understand. You're putting in way more energy than you're getting out of it. Is it because of the "different" types of energy? How would you get free energy out of this device?

The Wild-Eyed Optimists have decided it *must* be tested in space.

I think part of the reason people want to test it in space is because once it's up there and after a few months it's going a couple km/s, there's no denying it works (or more likely it doesn't). They want to test it the way the aeronautical and rocket fields were pioneered (with practical tests, lots of failures).

I'm not saying they're right, but it's insulting and condescending to say that everyone who wants a practical test is just a dumb sci-fi nerds who want to see it go zoom zoom in space, when culturally that's pretty much how we've created everything else that moves us around this world.
posted by mayonnaises at 9:09 AM on November 19, 2016 [4 favorites]

ryanrs: I assume they tested for short intervals and let the apparatus cool in between runs.

Good point. Their plots show a power-on run of about 40 seconds. They don't say how much the apparatus weighs, but at 1 kg and 60 W power, that would heat it by only about 6 degrees C (assuming all copper).

It's interesting that in their plots the displacement caused by what they identify as thermal expansion is larger than the displacement they identify as the "thrust" effect. And that the cool-off side of their curves is completely smooth, with no transient in the first 20 seconds caused by the turning-off of the "thrust"...
posted by heatherlogan at 9:11 AM on November 19, 2016 [1 favorite]

How would you get free energy out of this device?

Justinian linked to one of my comments in an earlier thread on how to turn a reactionless engine into a free energy device.

I assume there are very many ways to do it, but this was the first that came to mind.
posted by ryanrs at 9:16 AM on November 19, 2016 [7 favorites]

The Discussion part of the Experimentation section is interesting! They're taking a look at pilot-wave theory. And:

If the vacuum is indeed mutable and degradable as was explored, then it might be possible to do/extract work on/from the vacuum, and thereby be possible to push off of the quantum vacuum and preserve the laws of conservation of energy and conservation of momentum. It is proposed that the tapered RF test article pushes off of quantum vacuum fluctuations, and the thruster generates a volumetric body force and moves in one direction while a wake is established in the quantum vacuum that moves in the other direction.

posted by jason_steakums at 9:28 AM on November 19, 2016 [1 favorite]

If this works, it makes the problem of where all the aliens are MUCH MORE PRESSING. Like, if this is physically possible the universe should be absolutely crawling with whoever invented it first. You shouldn't be able to swing a cat without hitting a Monolith.
posted by BungaDunga at 9:32 AM on November 19, 2016 [6 favorites]

I would think that most of the power radiated out of the antenna as RF energy.

Except that the antenna is enclosed by a closed radio-frequency [resonating] cavity, and that "Leaking RF fields are kept very low by ensuring RF connections are tight and confirmed by measuring with an RF leakage meter (levels are kept below a cell phone RF leakage level)."
posted by heatherlogan at 9:33 AM on November 19, 2016

if this is physically possible the universe should be absolutely crawling with whoever invented it first

Maybe that's us!
posted by ryanrs at 9:46 AM on November 19, 2016 [9 favorites]

The one story I've never heard about this invention is a good excuse for how the idea to test such an object came about in the first place. When it comes to things we understand and can model well, few-GHz microwave cavities are pretty high on the list and have been for generations. There's nothing in contemporary physics that suggests building specific shapes into one and hooking it up to a torsion balance in a vacuum chamber would be a good idea. Why would anyone ever decide to try this, unless they performing experiments entirely at random or they were planning to sell snake-oil to investors? Finding buried treasure happens; finding buried treasure in the middle of an unmarked stretch of prairie thousands of miles from your home with no explanation for what you were doing there in the first place invites suspicion.

Sure, there are examples of good inventions with poor motivation in history. We spent decades making Lieden Jars out of glass bottles with lids on. But it was motivated by prior observations and a useful-but-wrong fluid theory of electricity that made the jar shape seem plausibly important. Early airplane wings were built by people who had no idea why they worked; but they had birds and centuries of prior art to build upon. This seems to have come out of nowhere.

Please don't anybody suggest a mechanism involving dark photons to these folks. They've already got enough entirely unmotivated explanations. Though, "magic engine turns out to be cosmogenic dark photon sail" would make a fun science fiction short story.
posted by eotvos at 9:55 AM on November 19, 2016 [5 favorites]

I'm gonna predict the effect is real, but there are limitations that will make it useless. Is it possible that the thrust is simply because the device somehow erodes its own metal enclosure to use as fuel?
posted by ymgve at 9:58 AM on November 19, 2016 [2 favorites]

You guys, the cool-off side of their displacement curves is completely smooth, with no transient caused by the turning-off of the thrust! They can turn off the electrical power and the thrust is still there! Building the free-energy machine is going to be way easier than we thought. Though I hope this isn't the discovery of an entirely new form of pollution.
posted by heatherlogan at 10:01 AM on November 19, 2016 [6 favorites]

The one story I've never heard about this invention is a good excuse for how the idea to test such an object came about in the first place.

My understanding is that Roger Shawyer decided a reactionless drive would be a useful thing to have, thought up the design, then went out and got a £45,000 grant from the British government to study it. It's a pretty shady origin story, if you ask me.
posted by ryanrs at 10:15 AM on November 19, 2016 [2 favorites]

They can turn off the electrical power and the thrust is still there!

After the power is shut off the thrust is sustained for a while because of dark capacitance.
posted by ryanrs at 10:18 AM on November 19, 2016 [9 favorites]

Put it in space.

On a conveyor belt.

That will settle the argument very shortly.
posted by Rumple at 10:21 AM on November 19, 2016 [8 favorites]

There was a theory before the invention. Updated.
posted by Brian B. at 10:22 AM on November 19, 2016

After the power is shut off the thrust is sustained for a while because of dark capacitance.

If that's the case then I would expect the same lag in the turn-on of the thrust. Or was that a dark stuff joke?
posted by heatherlogan at 10:27 AM on November 19, 2016

On a conveyor belt.

Like that problem, I suspect a well-thought free-body diagram is largely sufficient to explain what's happening here.

Too bad Jamie and Adam have hung up their blast shields though.
posted by bonehead at 10:49 AM on November 19, 2016

Though I hope this isn't the discovery of an entirely new form of pollution.

Universal grid disturbance aka "Warp Rifts" are a thing, you know. I hope you're not one of those Romulan denialists.
posted by bonehead at 10:52 AM on November 19, 2016 [2 favorites]

what if a wizard did it though.

What's the lead author's name again? Harry.

(well close enough)
posted by xigxag at 11:04 AM on November 19, 2016

> Like, if this is physically possible the universe should be absolutely crawling with whoever invented it first. You shouldn't be able to swing a cat without hitting a Monolith.

Spoiler: the cats are the aliens. They came, they saw, they curled up by the fire and enjoyed the treats.
posted by languagehat at 11:07 AM on November 19, 2016 [3 favorites]

I don't see the problem. If it seems to work only because there is an inherent error in the experimental apparatus, just build the engine to include the error in the experimental apparatus. Then it will work. Alpha Centauri here we come! Heck, Rigel.
posted by Zerowensboring at 11:10 AM on November 19, 2016 [1 favorite]

we already have huge holes in physics - dark matter and dark energy.

idk about dark energy but last i heard dark matter isn't super mysterious

when matter is really far away, by far our best way of determining its properties is by analyzing photons that it shoots at us

but most matter doesn't do that.

dark matter is just literally dark. it's not glowing. so we can't see it.

so yeah it's mysterious in that we can't tell what it looks like, what it's made of, or what it's doing, but none of this requires physics to behave in a way that isn't already well-understood

it's a lot of information that is just completely unavailable to us, which is something i think humans sort of instinctually resent, but the fact that the information is unavailable fits perfectly well with our theoretical models. like, something that's a million light years away is only gonna be visible to us if it was emitting light in our direction a million years ago. simple physics.

mind you this is all a lay understanding and i am probably wrong about all of it
posted by reprise the theme song and roll the credits at 11:26 AM on November 19, 2016 [2 favorites]

I think part of the reason people want to test it in space is because once it's up there and after a few months it's going a couple km/s, there's no denying it works (or more likely it doesn't).

It would, in fact, be much easier to deny a failure under these conditions. Think of all the things that could go wrong. Wanting to test something like this in space simply isn't justifiable except as a faith based proposition.
posted by howfar at 11:35 AM on November 19, 2016 [5 favorites]

After the power is shut off the thrust is sustained for a while because of dark capacitance.

I know you're joking, but any version of events that starts to semi seriously converge with Primer is alarming.
posted by fifthrider at 11:37 AM on November 19, 2016 [1 favorite]

So around the end of the 19th century the Aliens saw that we were making technological progress at a rate that, if unchecked, would lead to FTL travel within decades. And they saw the state of our cultures and social institutions and said, "we obviously can't let those people up here". The Aliens gathered a working group of cultural experts and superintelligent AIs (not their best, mind you, we're not that important), and the group decided that the safest way to delay our discovery of FTL was to plant a trap scientific theory that would be plausible, and elegant, and explain all the experimental evidence we would likely have access to, and yet incorrectly disallow FTL travel. Not only would it directly delay FTL for many decades, but later, when the fundamentally incorrect trap theory couldn't be unified with other theories, the attempts to reconcile the irreconcilable would derail progress for many more decades.

And that trap theory was relativity.
posted by Pyry at 12:29 PM on November 19, 2016 [14 favorites]

Metafilter: because of dark capacitance.
posted by sammyo at 12:47 PM on November 19, 2016 [1 favorite]

Like, if this is physically possible the universe should be absolutely crawling with whoever invented it first. You shouldn't be able to swing a cat without hitting a Monolith.

Don't do this though. The Monoliths hate it. AMHIK.
posted by Horkus at 12:50 PM on November 19, 2016 [3 favorites]

My approach to EM drive news is quiet hopefulness, but low expectations. Right now it appears to be a cool effect, but may be a mirage. So I read FPPs like this and smile, strain to figure out what they're saying, then go on with the day. No wild fantasies yet, but at least the effect has yet to be disproved. So far so good...
posted by Kevin Street at 12:56 PM on November 19, 2016 [1 favorite]

Spoiler: the cats are the aliens.
I saw that movie.
posted by fings at 1:15 PM on November 19, 2016 [1 favorite]

I think it runs on N rays.
posted by surlyben at 1:24 PM on November 19, 2016 [3 favorites]

It would be easier for me to understand if someone here would just say this is "Some kind of _____"
posted by OHenryPacey at 1:40 PM on November 19, 2016 [1 favorite]

Sure, but can it bake a potato
posted by the uncomplicated soups of my childhood at 1:43 PM on November 19, 2016

kyrademon: "I don't know about unconfirmed reports, but the actual 2016 paper that came out of the Chinese experiments concluded that a setup with an internal power source did not produce significant thrust, and that the thrust measured when using external power sources could be noise."

My (very rudimentary and second-hand) understanding of the Chinese result is that their experimental setup (some kind of three-wire torsion pendulum) wasn't capable of measuring forces as small as the ones detected previously. They were looking to see if the effect would be stronger with greater power, but couldn't find an effect that was distinguishable from error.
posted by Kevin Street at 1:43 PM on November 19, 2016

It would be easier for me to understand if someone here would just say this is "Some kind of _____"

The wikipedia page about the whole concept might help a bit...
posted by hippybear at 1:44 PM on November 19, 2016

If I absolutely had to make a guess under the assumption that the measured thrust was real, I'd guess it was a variation on the Casimir effect, and somehow makes the force associated with the Casimir effect push harder on one wall than the opposite wall.

The Casimir effect is a vacuum energy effect (under one theory), and its magnitude depends on the "cosmological constant", but I'm not sure whether that's the same cosmological constant associated with dark energy.

If it is an aspect of the Casimir effect, it would seem to be limited by that magnitude, which is small -- but that hasn't stopped people from nominating the Casimir effect as a source of free energy.
posted by jamjam at 1:58 PM on November 19, 2016

Empirical verification of the pilot wave would be huge. It'd be a reason to prefer Bohm's QM, and nature could turn out to be deterministic!
posted by persona au gratin at 2:13 PM on November 19, 2016 [1 favorite]

We experience light all the time. And we need QM to explain it. Or at least concepts from it.
posted by persona au gratin at 2:17 PM on November 19, 2016

How does the pilot wave version of hidden variables get around the Bell inequality tests, which experimentally rule out hidden variable theories? Or do the proponents just ignore this and live in a fantasy world?
posted by heatherlogan at 2:35 PM on November 19, 2016

If we try to test this thing in space, here's what I guarantee will happen.

First of all, it won't work. The only reason things work in space is that we understand them thoroughly and test them here on Earth, which we haven't done here. The effect is so small it would be easy for some other factor to ruin it.

Second, since it's in space, it will be harder to figure out why it didn't work: some will say the effect doesn't exist, and some will say the effect is real but some other factor ruined it. We'll need more tests to say for sure.

The way things like this succeed is through iteration: each test gives us some data which helps us learn how to design better tests. The more quickly and cheaply we can run each test and the more we learn each time, the faster we can figure out what's going on. Testing in space is slower, more expensive, and gives us less data.
posted by panic at 2:57 PM on November 19, 2016 [6 favorites]

It seems like NASA has really started to do a lot of hyped-up but likely-wrong science lately, which does not sit right with me. This reminds me a lot of the "arsenic life" paper, which was essentially a bunch of technical artifacts that got national attention because of their PR machine; it was rightly savaged upon publication and eventually definitively disproved, wasting a lot of other researchers' time in the process. I don't know what the problem is or even if this is a real tendency I'm noticing and not confirmation bias on my part, but if it is real they're going to waste a ton of their hard-earned scientific credibility and I would find that really sad. I want to be able to be proud of NASA.
posted by en forme de poire at 3:00 PM on November 19, 2016 [2 favorites]

It accommodates nonlocality and Bell's theorem. I don't know the details, though, as it's not my area of work. But I've talked with those whose it is, and they tell me Bohm is consistent with Bell.
posted by persona au gratin at 3:40 PM on November 19, 2016

The pilot wave is a nonlocal hidden variable from what I gather.
posted by persona au gratin at 3:42 PM on November 19, 2016 [1 favorite]

My approach to EM drive news is quiet hopefulness, but low expectations. Right now it appears to be a cool effect, but may be a mirage.

This sort of attitude seems well-represented here and everywhere. Maybe it's true, keep an open mind, let's hope for the best. In the future maybe those of you who feel this way, when you're wondering how anyone can believe, or suspect, despite the full weight of evidence and reason, that global warming is a hoax, that the candidates in the election are all equally bad, that earthquakes are caused by homosexuality, or that Coldplay belongs in a list of the top ten most relaxing songs of all time, you can just think back and reflect on this moment.

Yes, it may be a mirage; it's either that or a fraud. Maybe we'll find out eventually.
posted by sfenders at 4:28 PM on November 19, 2016 [2 favorites]

I don't think that's a fair comparison. "This is very probably false but wouldn't it be cool if it were true?" isn't the same as "I continue to believe this thing that has demonstrably terrible effects on the world despite the overwhelming consensus against it."
posted by Justinian at 4:34 PM on November 19, 2016 [7 favorites]

The reasons why people believe, or at least halfway accept the probability of these things may all be different, so maybe a bit unfair yes. There is something in common though, in so many things that end up with the same result of "continuing to believe" some thing despite overwhelming evidence against it. It seems very comparable to climate change denial in particular, of the variety that says something to the effect of "they can't really know what's going on" since the world is such a mysterious place and there are still unanswered questions. You know, questions like "what about dark matter?"

"Wouldn't it be cool" sort of understates the motivation for believing this one as well. It would be beyond cool.
posted by sfenders at 4:53 PM on November 19, 2016

Further to the above comments, my immediate thought on this was that if it's fully verified then a likely, if not the most likely, explanation is that the simulation hypothesis is right and we've just discovered a bug.
posted by Major Clanger at 7:58 AM on November 19 [6 favorites]

Or a hidden feature.
posted by joeyh at 8:06 AM on November 19 [1 favorite]

I'm holding out for it being an Easter Egg! That would be very pleasing.
posted by BillW at 5:26 PM on November 19, 2016 [2 favorites]

It seems very comparable to climate change denial in particular, of the variety that says something to the effect of "they can't really know what's going on" since the world is such a mysterious place and there are still unanswered questions.

I don't think these are comparable at all. First, as Justinian rightly points out there is a big difference between "This is almost certainly false (since we have overwhelming evidence that it is false), but it would be neat if true," and "I don't believe that this is almost certainly false, despite overwhelming evidence that it is false." The first is the attitude you're seeing here. The second is climate science denialism.

Second, to say that something is almost certainly false admits that there is some chance that it is true. It's on the basis of that chance -- and the massive implications if it is true -- that people here are saying the EmDrive should be tested further. I expect that almost all of us here would wager that further testing will show that there is no real effect in the EmDrive case. That's because we don't believe that there is any effect, i.e. we are believing in line with our best current scientific evidence. Only if repeated testing shows that there is really an effect would you see people here saying that there is probably an effect. Climate science deniers are not betting on climate change being real despite holding out hope that it is not real. They are betting that it isn't real, despite the evidence. If climate science denialism were really analogous, then we should expect the deniers to be saying, "Climate is probably changing in virtue of human activity, but further observation might show that it's not." But I've never encountered a denialist saying anything like that.

Third, there is a difference of stakes and practical action. In the case of the EmDrive, it's not crucial that we act on the basis of our current best evidence. We can wait to see how further testing goes. In the case of climate science, our best current evidence tells us that we can't really wait. Hence, anyone who really has an attitude with respect to climate change analogous to the attitude here of "There's probably nothing to the EmDrive, but further testing might prove us wrong," is going to be advocating various forms of action designed to avert a climate catastrophe. Again, denialists aren't doing that. They don't have an analogous attitude to the one being expressed here.
posted by Jonathan Livengood at 5:39 PM on November 19, 2016 [15 favorites]

to say that something is almost certainly false admits that there is some chance that it is true.

Seizing on that chance, pointing out its existence, suggesting its importance, expressing hope that it comes to pass, suggesting far-fetched ways that its size might be exaggerated, reiterating that there is no certainty, and generally making a big deal out of it, do not seem to me the same thing as whole-heartedly "betting" against it. Anything stands some small chance of being true, even Russel's Teapot.
posted by sfenders at 6:04 PM on November 19, 2016

Considering it further, the proposition of "Russel's Teapot", that somewhere between Earth and Mars there is a china teapot revolving in an elliptical orbit, seems very plausible by comparison. Maybe some jokers at NASA managed to smuggle such a teapot aboard one of their missions to the outer solar system and somehow deploy it in the appropriate orbit. Not wanting to get involved in any stupid arguments about atheism, NASA carefully and methodically covered up the whole thing. It'll be centuries before anyone finds it, they had to use a very small 2-cup teapot to save weight. It's possible, I sure hope it turns out to be true.

"Climate is probably changing in virtue of human activity, but further observation might show that it's not." But I've never encountered a denialist saying anything like that.

Perhaps denialist is too strong a term for such people. I Just realized though, that's exactly what my father used to say.
posted by sfenders at 6:31 PM on November 19, 2016 [1 favorite]

So here's a link to an Internatinal Business Times story claiming that the U.S. Air Force and the Chinese are already testing EM drives, in orbit.
posted by newdaddy at 6:39 PM on November 19, 2016

heatherlogan: the displacement caused by what they identify as thermal expansion is larger than the displacement they identify as the "thrust" effect.

So all we need is some copper and a really long lever. Mars ahoy!
posted by sneebler at 6:50 PM on November 19, 2016 [1 favorite]

What a weird thing IBT is. Do they just run stories to manipulate share prices, or is there some other rationale behind their entirely opaque editorial policy?
posted by howfar at 6:56 PM on November 19, 2016 [1 favorite]

Here is a paper by German scientists Tajmar et al. describing experiments done in Dresden and presented at the AIAA/SAE/ASEE Joint Propulsion Conference in 2015, in which they also saw this unexplained force.
posted by newdaddy at 7:01 PM on November 19, 2016

"I don't think these are comparable at all. First, as Justinian rightly points out there is a big difference between "This is almost certainly false (since we have overwhelming evidence that it is false), but it would be neat if true," and "I don't believe that this is almost certainly false, despite overwhelming evidence that it is false." The first is the attitude you're seeing here. The second is climate science denialism. "

Thank you, I agree completely with what you said.
posted by Kevin Street at 7:02 PM on November 19, 2016 [1 favorite]

This is the Chinese paper (Yang Juan et. Al. 2012) describing an experiment with much stronger effects.
posted by newdaddy at 7:09 PM on November 19, 2016

And here's the page listing experimental results from the EM drive wiki.
posted by newdaddy at 7:18 PM on November 19, 2016 [1 favorite]

Okay okay but what if we put one of these drives on a plane and put it on a conveyor belt going exactly as fast as the plane
posted by Ghostride The Whip at 7:52 PM on November 19, 2016 [1 favorite]

Apparently this device is simple enough to build and test at home.

DIY positive for thrust.

And in reverse.

Another example.
posted by Brian B. at 7:55 PM on November 19, 2016

Unfortunately, snarkily dismissive is my sincere opinion. These guys have nothing on the cold fusion people, who have already set up their own parallel cargo-cult-science world complete with conferences [warning: rabbit hole].
posted by heatherlogan at 8:33 PM on November 19, 2016 [1 favorite]

Here is another article in IBT, this one pointing out a paper suggesting an alternative mechanism by which this might work. I'd be curious to hear people's sincere (rather than snarkily dismissive) opinions about this.
posted by newdaddy at 9:50 PM on November 19 [1 favorite +] [!]

Argh, I took the bait. First, it's clear that you read neither the article in the original post nor the article you just linked. If you had you would have noticed that the article in the original post does consider the possibility of "photon exhaust" and discards it as providing two orders of magnitude less thrust per unit power than their apparent measurements.
posted by heatherlogan at 8:42 PM on November 19, 2016

Can anyone explain this to me? I've read all of these threads as they come up, and I see this said again and again, but I don't understand. You're putting in way more energy than you're getting out of it. Is it because of the "different" types of energy? How would you get free energy out of this device?

Fundamentally, the reason is that the EM drive is, or appears to be, a constant thrust device. That much is typical of rocket engines. Thrust is measured in units of force (newtons, pounds, tons).

Energy is force multiplied by distance. That’s literally the definition of energy in Physics 101 (the definition gets more entries in later classes).

As a direct consequence of these two facts, rocket engines become more efficient the faster you’re already going.

Think of it like pushing a heavy cart. As the cart gains speed, you find yourself unable to push as hard. It’s not because you can’t walk fast enough to keep up—putting the same force into the cart simply takes more effort. Rockets don’t suffer from that. If your rocket engine pushes with 1 ton at 1 mph, it will push at 1 ton at 100 mph. The distance the cart covers in the same interval of time is much greater at 100 mph, so so is the energy the rocket engine added to the cart.

Now, ordinary rocket engines burn fuel, and if you work out the numbers, while they get more efficient, their efficiency never exceeds 100%. That’s not true of the EM drive.

With the EM drive, at a certain speed, you can, in one second, put x energy in and find that your machine gained greater than x energy in that same second.

At the stated efficiency of 1.2 millinewtons per kilowatt, that break‐even number is 833 km∕s. Once you get whatever the EM drive is attached to to that speed, you can extract some of its energy (e.g. via magnets acting on copper wire, like in an electric generator) to run the EM drive, and still have energy left to run a toaster or a city or the World.

833 km∕s is pretty fast and presents technical challenges to harnessing the EM drive for free energy, but it still completely violates our understanding of physics. It’s less than 3% the speed of light, which is nothing in cosmic terms.

If you can’t imagine extracting the energy, imagine pointing an EM drive‐equipped spacecraft at Alderaan and letting it accelerate for a good long while, to a large fraction of the speed of light. It would strike with incredible energy, far more than you put into it.
posted by Fongotskilernie at 9:36 PM on November 19, 2016 [6 favorites]

Alderaan isn't there anymore. It hasn't been since a long time ago.
posted by hippybear at 9:43 PM on November 19, 2016 [5 favorites]

reprise the theme song and roll the credits: dark matter needs to be something fundamentally different than ordinary matter -- it can't be made up of protons, electrons, or any of the types of neutrinos we know exist (protons & electrons interact with light and would be detectable, whereas neutrinos have too low a mass to act like dark matter needs to). The sort-of exception would be that certain mass ranges of black holes haven't been ruled out as being the dark matter. I'm not sure if you'd count them as ordinary or not :)

There are lots of plausible extensions to the standard model of particle physics that would act like dark matter, though. That's very different than the case here; as noted, if the EM drive works, a lot of physics as we know it gets broken. It's not something you just patch on to the existing theories.

What is simple about dark matter is how to treat its effects of the rest of the Universe. Since it doesn't interact by the EM or strong forces, we only need to worry about how it interacts gravitationally, which is easy to simulate.
posted by janewman at 9:49 PM on November 19, 2016

a reactionless Space Drive is going to come along and we're going to be zipping all over the solar system

On 1.2 millinewtons? Guess it's time for that crash diet.
posted by Twang at 10:10 PM on November 19, 2016

Our test campaign can not confirm or refute in any way the claims of the EMDrive but intends to independently assess possible side-effects in the measurements methods used so far. We did find a number of side-effects in the previous setups that indeed can produce large false signals.

This is the Chinese paper (Yang Juan et. Al. 2012) describing an experiment with much stronger effects.

And this is a link to the abstract (no full text currently shared for free publicly, that I can see) of the follow-up in 2016 by the same team, which states:

Within the measuring range of three-wire torsion pendulum thrust measurement system, the independent microwave thruster propulsion device did not detect significant thrust. Measurement results fluctuate within ± 0.7 mN range under the conditions 230 W microwave power output, and the relative uncertainty is greater than 80%."

The 2016 results, from what I can gather from Wikipedia (which cites another non-public version of the paper), seems to point to a possible cause of interference from externally placed power sources in such experiments.

I think it is probably unhelpful to add links to the thread while suggesting that independent research is replicating the Eagleworks findings, when the reality is that the current state of other research points towards confounding factors as the most likely cause of any observed effect.

If the reactionless propulsion effect is there, the Eagleworks findings will be replicated in time, with all confounders eliminated. At the moment, though, the available experimental data are nowhere near clear enough to support the view that hundreds of years of physics is incorrect.
posted by howfar at 2:21 AM on November 20, 2016 [4 favorites]

I think it is probably unhelpful to add links to the thread while suggesting that independent research is replicating the Eagleworks findings,...

The Tajmar paper is worth reading and is clearly related to the FPP. "Our measurements reveal thrusts as expected from previous claims (due to a low Q factor of <50, we observed thrusts of +/-20 μN) however also in directions that should produce no thrust. We therefore achieved a null measurement within our resolution which is on the order of the claimed thrusts." My sense is that the measurements agreed with Shawyer's predictions in positive and negative X directions (horizontally) but that when they reoriented the cavity vertically the measurement came in negative of what the expectation would be. I don't see how that's an uninteresting result. If it were just noise then it wouldn't be consistent. If it were some systematic error in the method or the test setup then it still remains to be seen what that is.

I don't think I misrepresented the paper - but I can see how you might disagree. It seems like there are several efforts that are clearly relevant but if the point of the post was to nakedly link to the Eagleworks paper and have a good laugh over it, rather than gather in some of this related work and engage with it, well then I'm sorry I missed that.
posted by newdaddy at 3:35 AM on November 20, 2016

gather in some of this related work and engage with it

Then I guess we should start linking in here every paper ever that has tested conservation of momentum and energy and Maxwell's electromagnetism and quantum field theory. But I don't think that would be useful either.

I see here the same disease that afflicts the cold fusion people: holding up every thing that mentions the words EM Drive as evidence-for without actually reading it (!!!) or thinking about whether the various claims are even quantitatively compatible with each other.

newdaddy, you posted a link to an IBT article with a possible "theory" mechanism. Do you realize that that theory predicts an effect quantitatively incompatible with the FPP article, and that therefore one or the other (or both) must be wrong? Which one of them do you think is wrong? If you ask others to critically engage, you should at least do your own homework.
posted by heatherlogan at 5:34 AM on November 20, 2016 [7 favorites]

Do you realize that that theory predicts an effect quantitatively incompatible with the FPP article, and that therefore one or the other (or both) must be wrong? Which one of them do you think is wrong?

I don't know which of them is wrong, IANAP (I am not a physicist.) I wrote "I would be curious to hear people's sincere opinions about this" and I meant that. The Eagleworks paper doesn't show any of their work, that I could see, in dismissing the Finnish hypothesis, it says:

The eighth error photon rocket force, RF leakage from test article generating a net force due to photon emission. The performance of a photon rocket is several orders of magnitude lower than the observed thrust. Further, as noted in the above discussion on RF interaction, all leaking fields are managed closely to result in a high quality RF resonance system. This is not a viable source of the observed thrust.

But the Finnish paper (Grahn et. al. 2016) was written in good faith by actual working scientists,not IBT, and to my knowledge those authors haven't yet responded to the Eagleworks paper. I don't claim to know all the answers or to even have a coherent theory but I feel like the effort invested in these experiments, and care to be unbiased in the writing of these papers should by answered by readers with a similar soberness rather than the drive-by "LOL perpetual motion" that I see here. Would you take the same attitude if you were in a room with the authors of those papers?

Everybody gets it - the EM drive, if it works, it would call for a big reappraisal of existing physics. Extraordinary claims require extraordinary proofs. But when all the snarking is done, though, we still don't have a coherent answer.
posted by newdaddy at 7:40 AM on November 20, 2016 [4 favorites]

Argh, I took the bait. First, it's clear that you read neither the article in the original post nor the article you just linked. If you had you would have noticed that the article in the original post does consider the possibility of "photon exhaust" and discards it as providing two orders of magnitude less thrust per unit power than their apparent measurements.....

newdaddy, you posted a link to an IBT article with a possible "theory" mechanism. Do you realize that that theory predicts an effect quantitatively incompatible with the FPP article, and that therefore one or the other (or both) must be wrong? Which one of them do you think is wrong? If you ask others to critically engage, you should at least do your own homework.

The original article does not appear to use the phrase "photon exhaust" at all. It addresses photon emissions and a related measurement. The IBT article in question does mention photon exhaust, but reports a theory that they might be leaving in pairs at 180 degrees out of phase, making them undetectable under current conditions. The original article never addressed this theory. Also, if photons are leaving in pairs, undetected, then this would be interesting in itself, independent of anyone else's notions of what is going on.
posted by Brian B. at 7:50 AM on November 20, 2016 [2 favorites]

If it does end up being real I wonder if the casimir affect (or something else) also introduces very tiny friction that prevents infinite acceleration?
posted by forforf at 2:41 PM on November 20, 2016

Someone else mentioned the simulation hypothesis above... As someone who's dealt with floating-point artifacts in a game engine before, I wonder if one could derive net thrust from Planck-scale rounding errors.
posted by NMcCoy at 3:07 PM on November 20, 2016 [1 favorite]

Setting aside the theoretical problems discussed upthread, I hope we can at least agree that ion thrusters look much cooler than the EmDrive. They have a cooler name, too. I hope that future work by Shawyer et al. will address these shortcomings along with the issue of conservation of momentum.
posted by ryanrs at 2:08 AM on November 21, 2016 [2 favorites]

Man, I've wanted the EM drive to be a thing for so long. I check the sub-reddit fairly often and have pestered my physicist friends about it.

....it's almost certainly not a thing.
posted by lumpenprole at 3:28 PM on November 21, 2016 [1 favorite]

I'm still not quite on board with the free-energy-thus-impossible thinking. What we have at the moment is a reported experimental result in the literature. There are various theories about it, some of which predate any actual experiments, and none of them hold up to a stern gaze. But it could be that the effect is an actual new phenomenon, but one that will sibsequently be shown to behave in a way that doesn't do unspeakable things to sacred cows. And it might be all that, and then not that interesting once it's better characterised and, say, falls in line with the universe we know and love.

It wouldn't be the first time that science based around a particular theory ends up showing something interesting while not confirming - perhaps even falsifying - the initial idea. Maxwell arrived at his equations while thoroughly believing in and using the concept of luminiferous aether, which remained scientific orthodoxy for quite some time afterwards until it suddenly wasn't there and a rather different picture of the universe arrived at (by a chap with a photo of Maxwell on his wall). And now we all know that a pervasive field that encompasses the entire universe is old hat, albeit one that the Higgs field wears at a jaunty angle.

I'm sure it's experimental error almost 100 percent, and the fractional credence I have is almost 100 percent itself 'it's not fundamental new physics'. But I want people to keep poking it with a stick; it's not a terribly expensive or dangerous or unethical thing to look at (the Eagle people were held up for a while because they didn't have the budget for vacuum-rated electrolytic capacitors, ISTR, so this isn't a porky boondoggle), it's all happening in the open without some scammer refusing to release the secret sauce, and we all get a canter around quite a lot of interesting science.

And I want to believe. Can't pretend otherwise.

Plus, 2016. It's an odd year for certainties.
posted by Devonian at 4:50 PM on November 21, 2016 [3 favorites]

And I want to believe.

That's how I felt the first time this story showed up all over the news. By now it's about the twelfth time I've seen it, metafilter alone has featured it at least five times, and I'm just thoroughly sick of it. It's too hard to even slightly believe, perhaps even harder than believing that the "photons 180 degrees out-of-phase are magic" theory is still being taken seriously by anyone at all. The first time around it was sort of fun to look into the theories behind it and figure out why they were nonsense. By now I expect they've had time to come up with more difficult to decipher theories to make that more of a chore. But it's too late, the novelty has worn off, it's just sadness and disappointment left over.

If they've really got something "consistently performing" at a well-quantified thrust-to-power ratio then it shouldn't be too hard to come up with something better-looking than that r²=0.75 graph. Maybe try an order of magnitude more power for a start, something approaching the awesome power of a household microwave oven, so that vibrations from distant waves in the Gulf of Mexico aren't larger than the force you're trying to measure.

No disrespect intended to anyone earnestly running experiments at NASA or anywhere else, but I'd rather not hear about it any more until they have incontrovertible results commensurate with the extraordinary nature of the claim.
posted by sfenders at 9:05 PM on November 21, 2016 [4 favorites]

"It's hard to describe to someone who doesn't have a good understanding of modern physics just how bizarre this effect would be.” - Combat Wombat

This is true. It’s bizarre to the level where their paper can't even be self-consistent, because their conclusions would invalidate their assumptions. For every truth I can think of in physics, conservation of energy or momentum comes in as an absolute fundament. Since I’m ignorant about cosmology, you could possibly convince me that momentum conservation is violated under very unusual and limited circumstances. That is, if Stephen Hawking says it happened during the first femtosecond of the universe, I’ll defer to him. On earth, right now, in anything larger than an atom, I just cannot see that happen. Especially not in a head-sized piece of copper driven with regular old microwaves.

I don’t deal with propulsion or cosmology, but I’m an experimental physicist and know enough about their methods to follow the paper. My main takeaway is this: Even if the phenomenon they look for had a conventional explanation, the paper does not provide striking evidence for it.

The effect they claim to see is tangled up with a strong thermal artifact, which isn’t even intrinsic to the device under study but comes from heating in their RF amplifier (!). They spend a lot of effort trying to separate out the "real" signal in their analysis, with moderate success. Nine other error sources are treated, but only cursorily, mostly on a basis of “doesn’t seem likely” rather than “is unequivocally ruled out”. I would not at all dismiss electromagnetic interactions as summarily as they do, for example. Overall, the fidelity of the experiment seems limited by petty things, like the big chunks of metal in the surroundings, inertia in the torsion balance, thermal issues with the amplifiers, and the small size of the vacuum chamber. Parts of the presentation also strike me as amateurish (e.g. parameters given with five digits when the data support two), but that’s perhaps beside the point.

This paper was published in a minor engineering journal, of the kind where you can get away with quite a lot also with peer-review. You don’t have to be correct about everything or treat every scenario, it can still be useful to others who are trying to do similar things. As evidence for extraordinary new physics though, I'm not sure this paper is better than no paper at all.
posted by Herr Zebrurka at 6:08 PM on November 22, 2016 [6 favorites]

I'm not equipped to evaluate this, but this Reddit comment looks closely at the paper and points out what he thinks is a measurement flaw that explains the anomalous result.

Rather than a "physics-breaking new effect," the simple explanation is that the RF equipment heats their equipment and changes the equilibrium position of their balance-beam.

posted by Nelson at 8:52 AM on November 26, 2016 [4 favorites]

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