Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[forsaken1111]

It's been disproven in the sense that the people trying to measure an effect have not measured an effect.

The claim that the thing produces thrust has not been proven or disproven, as far as I have seen, and likely won't be. It seems like nobody is even willing/able to do a proper test.

What, for you, would constitute "disproof"?

Well I'm not a scientist, or even all that bright really, but to me it would seem that should someone construct the device according to the specific instructions of the creator and the device does not produce any measurable thrust at any power level applied, then it will have been more or less proven not to do what the inventor claims, no?

Conversely, I would expect such an inventor to accompany his or her claim with some experimental data to back it up, an experiment which could be independently verified and tested.

It seems like neither of these things have actually happened.

I'm not sure where my failure of logic is?

You act like there's anything to disprove.

There is an initial claim which could be disproven. I'm not sure why anyone would bother since there is no evidence that the initial claim is true.

[Karlito]

Well I'm not a scientist, or even all that bright really, but to me it would seem that should someone construct the device according to the specific instructions of the creator and the device does not produce any measurable thrust at any power level applied, then it will have been more or less proven not to do what the inventor claims, no?

Yeah, fair enough. It just seems that, if you trust the Wired article above, that's already happened.

Eagleworks’ results so far are very close to the threshold of detection—which is to say, barely perceptible by their machinery. That makes it more likely that their findings are a result of instrument error, and their thrust measurements don’t scale up with microwave input as you might expect.

[Descan]

On another note, commercially disproven would mean "Sure, it works, but you can't scale it up economically, and it's not powerful enough to get us into space/to other planets at any reasonable time-frame."

[forsaken1111]

Well I'm not a scientist, or even all that bright really, but to me it would seem that should someone construct the device according to the specific instructions of the creator and the device does not produce any measurable thrust at any power level applied, then it will have been more or less proven not to do what the inventor claims, no?

Yeah, fair enough. It just seems that, if you trust the Wired article above, that's already happened.

Eagleworks’ results so far are very close to the threshold of detection—which is to say, barely perceptible by their machinery. That makes it more likely that their findings are a result of instrument error, and their thrust measurements don’t scale up with microwave input as you might expect.

I have no issue with the Wired article but I'd prefer to see something more than an article based on a forum post, you know? Maybe some actual data, some independent verification from other labs. Or even a few repeat tests?

I know that if I had invented a drive that requires no propellant, only electricity, I would be aggressively trying to get that shit to market. I would be pushing for testing and validation to make people aware of it. I would be building the drives and shipping them to labs myself for testing if that's what it took.

[Zrk2]

Well I'm not a scientist, or even all that bright really, but to me it would seem that should someone construct the device according to the specific instructions of the creator and the device does not produce any measurable thrust at any power level applied, then it will have been more or less proven not to do what the inventor claims, no?

Yeah, fair enough. It just seems that, if you trust the Wired article above, that's already happened.

Eagleworks’ results so far are very close to the threshold of detection—which is to say, barely perceptible by their machinery. That makes it more likely that their findings are a result of instrument error, and their thrust measurements don’t scale up with microwave input as you might expect.

I have no issue with the Wired article but I'd prefer to see something more than an article based on a forum post, you know? Maybe some actual data, some independent verification from other labs. Or even a few repeat tests?

I know that if I had invented a drive that requires no propellant, only electricity, I would be aggressively trying to get that shit to market. I would be pushing for testing and validation to make people aware of it. I would be building the drives and shipping them to labs myself for testing if that's what it took.

But if you were NASA you might not. You might be trying to confirm your results, especially given the problems that surround them so far; the alleged leak, resolution issues, etc.

[BoredVirulence]

Having read a few of the articles, and certainly maintaining a very healthy amount of skepticism, the skeptical journalism basically accounts to:

• Physics says no. Therefore experimental results must be false
• Its not in a peer-reveiwed journal. It didn't happen
• Those people are crazy

Sure, the measurements are really small. They could be caused by something else. But stating that they see no reason for the results to occur, therefore it must be false isn't science.. Thats like saying that (before the "theory of gravity" was proposed...) there is no reason for objects to fall, therefore they do not. There are plenty of reasons to be skeptical, but science isn't saying, "Thats just not possible, no matter what results they may have gotten." Science is saying, "What? They got results? I'm gonna do my own experiment and prove them false!"

As for my opinion. If I had access to the equipment I'd be testing it. I wouldn't be investing in building a spacecraft from microwaves. Sometimes scientists are their own worst enemies. Anyone care to remember how obviously false Relativity was before it was conclusively proven? Or how Einstien refused to believe in quantum physics despite it now being considered one of the most successful scientific theories? Be cautious, test it, and be open minded. People are wrong every day.

[wierd]

I'm not sure where my failure of logic is?

You act like there's anything to disprove.

That line of logical fallacy can go both ways you know.   You're a sharp cat Il, Dont fall victim to hubris. You're better than that.

I wont say that the claim has been fully substantiated (There ARE serious problems with the experimental conditions it has been tested under, but in each case it has not exactly been malfeasance on the part of the researchers, more what happens when you are forced to use substandard equipment because you cant get proper accesses, because the lab admins consider your project to be of low value.-- Meaning you get vacuum chambers with leaky seals, power modulation equipment that is not rated for vacuum, etc.) However, DESPITE the problems inherent with lacklustre instrumentation, anomalous thrust has been consistently reported from researchers at difference locations that have no financially common denominator-- That's the usual feature present in snake oil, such as with the eCat trials. (Every time, Mr Snakeoil has been present to test the ashes. Big problem there.)  It is also where Cold Fusion failed; Independent lab assessments of cold fusion showed confusing results at best, and negative results as the consensus. That's why we can pretty safely say that the flavor of cold fusion promoted in the 90s does not work.

In the case of the EmDrive, we had 2 different kinds of drive, which were basically the same, with different claims as to how they operate. One is the now still in testing EmDrive, and the other was the Cannaedrive. The test to "disable" the drive that still showed anomalous thrust was the Cannaedrive, not the EmDrive.  Different vendor of snakeoil, properly shown to be a snake oil salesman. He wanted to assert that a simple metal deflector plate inside could modulate/control the thrust-- Based on his claims, a test setup was done where one of the devices was constructed in such a fashion that "It should not work"--- The unusual finding was that BOTH devices produced anomalous thrust.  This does not kill EmDrive, it kills Cannaedrive's theory of operation, and indicates further experiment to isolate the cause of the anomalous thrust.

The Chinese research team did not test in hard vacuum that I am aware of-- but they did detect some pretty substantive thrust. (Again, enough to push .72kg 1 meter in one second.)  That's data from their experiment.

Other researchers in the US are now trying to reproduce the device on a smaller scale, due to budget and lab space restrictions (as per above)  The weak results can be attributable to having a very small device without sensitive enough equipment, and improper experimental controls in place.   Further experiment is required.

Again, the REALLY INTERESTING thing that was reported was the laser interferometery data taken near the device. The statements made by the researchers (however unofficial and in web forum form) indicate a phenomenon that should not happen. (Differences in the local speed of light measured at different angles near the device, while the device is active.) You and I both know why it should not happen. I would very much like to see the laser interferometry experiment conducted in proximity to the chinese test rig, and the data compared. It being in atmosphere would be inconsequential to the laser interferometric data. The implications of this happening are much bigger than just a little microwave toaster oven being used as a thruster.

Since there IS some data to support the argument that it is doing something, One needs substantially more than just rhetoric to shut it down. So far, it has more documented evidence of doing something consistently than did the cold fusion hype bubble of the 90s. It needs proper testing with proper controls to invalidate the data collected, which is different from invalidating a claim.

At this point, the arguments are over uncertainty in the results.  The only way to remove uncertainty is to refine and repeat the experiment, removing potential sources of uncertainty from the experiment.  That means using proper equipment, and getting proper lab space. That means getting serious treatment from lab administrative staff, etc.

[BoredVirulence]

I am curious though about claims that it breaks the conservation of momentum. I see a loop hole (although I have a decent understanding of higher physics, its informal, and consider anything I propose skeptical until spoken against by a higher authority).

If this does in fact "push on the quantum vacuum," that means it applies a force to virtual particles which appear and disappear in very short time periods. So, since they disappear, the momentum is not conserved. But those virtual particles could interact with other nearby virtual particles. If I remember correctly (And here is where it gets extra fishy, call a real physicist), virtual particles "evaporate" because they no longer have enough energy to manifest as a particle. So any energy they gained has to be lost, presumably by interacting with another virtual particle, transferring the momentum. As far as I can see there is a propellent, it just exists in constant flux.

Seriously, call a physicist. I see nothing wrong with my argument, but I'm not an physicist, and the idea of matter as just a manifestation of energy always bothered me.

[Il Palazzo]

Eh, wierd. I'm past thirty. Hubris is all my toothless gums can chew.

Or was it hummus?

[wierd]

An idea just came to mind for a low-cost test setup for this device.

Parts list:

Vacuum bell jar and pedestal (large)
Vaseline jelly (For bell jar)
One of these EmDrive doohickies
A lab-grade electronic milligram scale
Drycell battery pack (To power emdrive while under vacuum)
Vacuum rated power inverter (To produce compatible power for emdrive under vacuum)
radio controlled switch (To turn the thing on and off while under vacuum)

Experiment--

Construct the EmDrive to specifications. Mount it vertically, so that it is aligned with the vector of gravitational attraction with the earth. Place the device on top of the lab grade milligram scale, turn the scale on, and zero the scale. We want the device to push downwards, not upwards. Once the scale is reading 0 grams, enclose the entire test apparatus under the bell jar, applying a good, substantive layer of vaseline jelly to the jar's edge, turn on the vacuum pump, and evacuate the jar. Once the jar is under acceptable definitions of the term 'vacuum', turn on the EmDrive using the radio controlled switch. Observe the milligram scale for changes in measured "weight".  Since we have aligned the vector of thrust of the engine with the vector of gravitation, the displayed value in milligrams indicates the thrust supplied by the engine.

A highschool physics department should be able to scrounge up these parts, and do this test.

Get enough positive results, and it becomes much harder to attribute to experimental error.

[wierd]

Eh, wierd. I'm past thirty. Hubris is all my toothless gums can chew.

Or was it hummus?

You too?  I just know it would be a waste of my energies to pursue a career in academia at my age. Getting published without a super-duper bombshell of a paper would be next to impossible. That does not mean I don't absolutely love science though.

And hummus is awesome. Garlic Sabra on cheddar sunchips. Mmmm.....

[SirQuiamus]

How accurate are the published specifications, by the way? With the current data, can an independent researcher construct a resonance chamber that's geometrically similar to the ones they're using? I'm assuming that that's the most important part in reproducing the experiment, because magnetrons and other such components are easy to come by.

If the published papers are all vague and mysterious about the details, then it sounds less like an honest error, and more like P. T. Barnum stuff.     

[RedKing]

I can understand reluctance to publish specifications because patents. If this is legit, owning the patents on this technology will make the inventor(s) wealthy beyond imagination.

Look at the early days of flight to understand the reluctance. There were some very bright early aeronautical pioneers who completely missed out on the gravy train because someone else came along and swooped up their idea and made a company out of it.

That said, I'm cautiously optimistic. I'll be more optimistic if they can do a scaled-up test in hard vacuum and micro-gravity, although I realize the capacity to do this testing in space is a huge problem in and of itself.

The most annoying thing about the naysayers is that the bulk of opposition seems to boil down to two things:
1. "Physics says this shouldn't work, therefore it doesn't work. The fact that it has demonstrated thrust in every test so far means nothing."
2. "You can't explain how it works, therefore it doesn't work."

The second one in particular riles me. That kind of objection totally fails in sciences like pharmacology. We use thousands of drugs every day that we don't fully know HOW they work (in a biochemical sense), but we know that they've been clinically proven to work.

[wierd]

How accurate are the published specifications, by the way? With the current data, can an independent researcher construct a resonance chamber that's geometrically similar to the ones they're using? I'm assuming that that's the most important part in reproducing the experiment, because magnetrons and other such components are easy to come by.

If the published papers are all vague and mysterious about the details, then it sounds less like an honest error, and more like P. T. Barnum stuff.     

Unless there are some nifty internal features inside the chamber, the published photographs and some skill in reverse engineering will net you a suitable analog of the resonance chamber.
I have some vocational history with producing CAD/CAM models, and could produce blueprints from such reverse engineering if really requested. There would be some pretty large margins of error involved though, which could seriously kill this kind of device. (A few mm of distance off can make a serious impact on effective waveguide manufacture, which is what this IS, essentially. A special waveguide for a magnetron resonator of a specific frequency.)

Take for instance, this image of the assembled EmDrive resonance cavity.

Spoiler: oooh.. shiny.. (click to show/hide)

With a little more data, such as the drive frequency of the magnetron used, we can compute much of the values required for this cavity, and thus reproduce a blueprint for it.

Personally, what I would consider to be the appropriately "Tunable" version of this device, would use a resonant klystron drift tube instead of a magnetron, as the resonator.  A klystron is not only 1) frequency tunable, it is also 2) MUCH MORE EFFICIENT than a magnetron at producing microwaves of a given frequency, AND 3) produces a MUCH cleaner signal. (narrow band width)  A reference signal produced by a small semiconductor microwave signal source could be applied to the drift tube as the input signal, and the drift tube turns that into a raging wave of high power emissions at the other end, where it would be fed into this special resonance chamber. 

As the wikipedia article points out, klystrons can produce focused microwave emissions in the many megawatts of power output scales-- compared to what you can get out of a magnetron, that is like comparing a flashlight to a searchlight. Granted, it increases the costs of manufacture quite a bit, but you get some absurd increases in device power that way.

[MehMuffin]

I'm kinda confused as to how the EM drive is supposed to work anyways. From what I understand, it works by basically bouncing microwaves around in a chamber, but given how the overall velocity change from that should equal zero...

There's a (widely criticized) theory that the drive effectively "pushes" against quantum vacuum. Which is tough when quantum vacuum is supposed to be, well, vacuum. But I haven't seen anything else as to how it's supposed to work other than "Uhhhh... Magic?" which is probably why everyone seems so hesitant of it.