Cannae/EmDrive

[Streetwind]

6 hours ago, Frozen_Heart said:

Looks like the NASA paper has passed peer review. Hopefully this either proves or disproves it.

 

Single papers rarely prove anything... the paper NASA submitted will likely say little other than "these are the results we got, this is the experimental setup we got them from, and these are the steps we took to eliminate false positives". The peer review process has vetted the experimental setup and the error-checking steps, but it has not declared "the EMdrive is without a doubt real". Such a thing can only come from a mathematically accurate description of how exactly it generates thrust in accordance with the laws of physics, which doesn't exist yet.

Still, having a peer reviewed paper is good news nonetheless. It means that scientists agree that Eagleworks hasn't made any mistakes in their experiments so far. Since those experiments produced reasonably consistent thrust (I think someone spoilered the number "around 1.2 micronewtons per kW" on NSF), that offers a great foundation for further research.

Edited August 31, 2016 by Streetwind

[Shpaget]

8 minutes ago, Streetwind said:

The peer review process has vetted the experimental setup and the error-checking steps, but it has not declared "the EMdrive is without a doubt real". Such a thing can only come from a mathematically accurate description of how exactly it generates thrust in accordance with the laws of physics, which doesn't exist yet.

Not necessarily. If the effect is evident, significant, reproducible and quantifiable, you don't need to understand how it works to be able to say that it exists and works. We can even use it without understanding it (provided that it is economical and useful, of course).

Yes, understanding how and why something works can lead to improvement and optimisation of the design, but it's not mandatory.

[Streetwind]

Yeah, but if the laboratory tells you that they have built a propellantless drive that works without a doubt, and you put it on a spacecraft and after two years of constant use discover that the engine has ablated itself kaputt because it was not propellantless after all, both you and the lab are going to look quite silly

You can always try to use something without understanding it, but the premise of the EMdrive is that it is propellantless. Therefore, in order to be able to say "this is an EMdrive and it works", you need to conclusively prove that it is indeed propellantless, not just that it produces thrust. That kind of proof is perhaps not entirely impossible, but certainly incredibly difficult to supply at scientific exactness standards without discovering and describing the underlying mechanisms.

[magnemoe]

3 minutes ago, Streetwind said:

Yeah, but if the laboratory tells you that they have built a propellantless drive that works without a doubt, and you put it on a spacecraft and after two years of constant use discover that the engine has ablated itself kaputt because it was not propellantless after all, both you and the lab are going to look quite silly

You can always try to use something without understanding it, but the premise of the EMdrive is that it is propellantless. Therefore, in order to be able to say "this is an EMdrive and it works", you need to conclusively prove that it is indeed propellantless, not just that it produces thrust. That kind of proof is perhaps not entirely impossible, but certainly incredibly difficult to supply at scientific exactness standards without discovering and describing the underlying mechanisms.

its an major difference between science and engineering. For science the purpose is to figure out how the drive work as in the theory behind it. 
For engineering the purpose is an reliable and effective drive. The theory is nice as it let you build an better drive but that is an bonus

As for EM drive its right as streetwind says, peer preview only proves that somebody else has checked their work and find no fails. Its still probably an experimental error  of some sort. 

 

[KerikBalm]

One paper means nothing, peer review can often be very leaky. Lets not pretend that there are no politics in science, and that science journals don't factor in the amount of "hype" that the paper can generate when deciding to accept or reject a paper.

 

Example:

http://science.sciencemag.org/content/332/6034/1163

Followed by:

http://www.nature.com/news/2010/101207/full/468741a.html

http://www.nature.com/news/study-challenges-existence-of-arsenic-based-life-1.9861

http://www.nature.com/news/arsenic-life-bacterium-prefers-phosphorus-after-all-1.11520

 

Do not make any conclusions based on one paper, even if it is "peer reviewed" and from a "reputable journal"

Edited August 31, 2016 by KerikBalm

[Green Baron]

There is rarely "hype" in scientific journals. The "hype" is exported to Speigel, BBC, and so on :-)

If findings start a discussion that means progress is likely to be at hand. Many ideas prove wrong, that is a natural outcome of the process of publishing and open discussion and the way it is meant to be. Journals are the base for serious discussions and presentation of the outcome of people's work.

Of course you can question anything, degrading it to politics or scoffing at the review process or other's reputation, but that isn't helpful. The established processes secure that we don't end up with everything being on a level of colorful magazines full of speculation, aliens, massless drives, energyshields, replicators and so on.

If noone in the community cares about a new idea then that probably means that nobody has understood it (usually the view of the ignored) or it is bogus (the view of the ignorants). But these cases are rare and don't usually find their way in the journals, or maybe as a sidenote or a letter. The process is meant to prevent it, to part the stuff from the serious things.

Discussing the possibility of arsenic as a base element of life could have been fruitful even if the outcome is "no". Being open for the negation of a hypothesis is absolutely part of the game. I could repeat that 3 times just to have it securely installed. Following those discussions one can learn a lot.

 

Edited August 31, 2016 by Green Baron

[KerikBalm]

yes, hyperbole may be a bit of an exageration.

The point is they don't publish it because the science has passed stringent scientific review as they do for most of their articles, but they publish it because of the "interest" and to "stimulate discussion".

IMO the difference between "stimulating discussion" and "hyping" is just a matter of degree. That arsenic paper was bad, and everyone knew it was bad shortly after it came out, and then labs had to waste their time disproving it.

If it hadn't been coming from NASA, that had already done its hype through a press release (I'm not blaming the science journal for that... the NASA group is responsible for the ridiculous hype - they would have had to cut a lot of crap, and been asked to do a lot more experiments like the rest of us even for less "discerning" journals.

Hype or not, the point is that one paper appearing in a high impact facotr journal doesn't mean much. You have to look at the body of literature as a whole.

[Green Baron]

10 minutes ago, KerikBalm said:

Hype or not, the point is that one paper appearing in a high impact facotr journal doesn't mean much. You have to look at the body of literature as a whole.

True. Though it takes time ...

 

Edited August 31, 2016 by Green Baron

[Scotius]

4 hours ago, magnemoe said:

its an major difference between science and engineering. For science the purpose is to figure out how the drive work as in the theory behind it. 
For engineering the purpose is an reliable and effective drive. The theory is nice as it let you build an better drive but that is an bonus

As for EM drive its right as streetwind says, peer preview only proves that somebody else has checked their work and find no fails. Its still probably an experimental error  of some sort. 

 

Experimental error that no one been able to pinpoint yet? EmDrive is not an enormous fusion reactor - it's literally a bent sheet of copper, magnetron from an off the shelf microwave and a power source (in many cases just a wall socket in someone's workshop). Since such setup has only limited number of ways to interact with its surroundings, there is not many variables to monitor. Yet, numerous experimentators report fairly consistent positive results and no one managed to disprove it once and for all.

[magnemoe]

3 minutes ago, Scotius said:

Experimental error that no one been able to pinpoint yet? EmDrive is not an enormous fusion reactor - it's literally a bent sheet of copper, magnetron from an off the shelf microwave and a power source (in many cases just a wall socket in someone's workshop). Since such setup has only limited number of ways to interact with its surroundings, there is not many variables to monitor. Yet, numerous experimentators report fairly consistent positive results and no one managed to disprove it once and for all.

Yes, I agree, I see two easy ways to get an trust, first is particles from the rear copper plate, think an ion drive with copper atoms, or even fragments. 
This can be checked by putting an second plate of plastic or similar behind the rear copper plate but still connected to the engine setup, this would cancel out any trust.

The second is an electrical or magnetic interaction with the metal in vacuum chamber or other equipment, moving the engine around and rotate it should change this but it would be a bit harder to eliminate. 

[wumpus]

1 hour ago, Scotius said:

Experimental error that no one been able to pinpoint yet? EmDrive is not an enormous fusion reactor - it's literally a bent sheet of copper, magnetron from an off the shelf microwave and a power source (in many cases just a wall socket in someone's workshop). Since such setup has only limited number of ways to interact with its surroundings, there is not many variables to monitor. Yet, numerous experimentators report fairly consistent positive results and no one managed to disprove it once and for all.

I should hope the "power source" is a carefully controlled power supply.  The AC you get from the outlet is pretty hairy and optimized for electric motors and not scientific experiments.  Not sure what an "off the shelf microwave" expects, but obviously you keep following the power in and power out (and tightening the controls on all of them) until you understand what is going on.

Also not that whether an emdrive works or not, we can "create" arbitrary amounts of reaction mass by "merely" accelerating some "seed reaction mass" very fast.  Use a cyclotron as an engine and you can make your Isp arbitrarily large (just don't ask about the power efficiency, hopefully the EmDrive can do better).

[KerikBalm]

1 hour ago, Scotius said:

Experimental error that no one been able to pinpoint yet? EmDrive is not an enormous fusion reactor - it's literally a bent sheet of copper, magnetron from an off the shelf microwave and a power source (in many cases just a wall socket in someone's workshop). Since such setup has only limited number of ways to interact with its surroundings, there is not many variables to monitor. Yet, numerous experimentators report fairly consistent positive results and no one managed to disprove it once and for all.

When you're talking about thrusts of 20 micronewtons, there are many variables to monitor. I recently read that these forces are on the order ofthe force of gravitational attraction between two adult human males standing face to face.

So far at least two groups have had their "control" tests, where no thrust was expected, produce equal or greater thrust... which strongly suggests measurement error.

The last two groups were reporting much lower "thrust" than the chinese group... so they aren't disproving, as lowering and lowering the reported thrust right down to detection limits,

This is a "russel's teapot" scenario at the moment when you ask people to "disprove" it.

1 hour ago, magnemoe said:

I see two easy ways to get an trust, first is particles from the rear copper plate, ...  this would cancel out any trust.

Please... the word is thrust, not trust

"trust" has a completely different meaning that doesn't make sense in this context.

[PB666]

47 minutes ago, KerikBalm said:

When you're talking about thrusts of 20 micronewtons, there are many variables to monitor. I recently read that these forces are on the order ofthe force of gravitational attraction between two adult human males standing face to face.

So far at least two groups have had their "control" tests, where no thrust was expected, produce equal or greater thrust... which strongly suggests measurement error.

The last two groups were reporting much lower "thrust" than the chinese group... so they aren't disproving, as lowering and lowering the reported thrust right down to detection limits,

This is a "russel's teapot" scenario at the moment when you ask people to "disprove" it.

Please... the word is thrust, not trust

"trust" has a completely different meaning that doesn't make sense in this context.

Reading these comments but honestly

-lets see the paper.

-still waiting for it to be spaced.

When the second is done I will draw my conclusion.

http://www.ibtimes.co.uk/emdrive-nasa-eagleworks-paper-has-finally-passed-peer-review-says-scientist-know-1578716

"Thrust data in mode shape TM212 at less than 8106 Torr environment, from forward, reverse and null tests suggests that the system is consistently performing with a thrust to power ratio of 1.2 +/- 0.1 mN/Kw ()".

This equates to 833,333 Kw/N which makes it 360 times more efficient than a photon thruster.  This is bad news for its proponents as I will describe below. Had it been one 10th of power utilization efficiency rate of a photon drive then we could be hand waving about interactions with nuclei within a reasonable vicinity. But as we will see, such a low ISP means that many particle interactions outside the device will need to create thrust. I space such mass is not available in any reasonable vicinity.

To get matter to reach that efficiency we have

N = 2 * eff * Power/Ex Vel. 

If 1.2 mN = 2 * 1000/ ? Then ISP = 170000s (1666666v) (or higher since the efficiency is probably lower) we are talking about a very efficient ion drive, but what are the ions.

If the thrust is in the 5 e -6 range then

16666666 then mass rate, if we argue these are net velocity vector electrons defecting per moment of time. that comes to 5E-6/1.666E6 = 3 x 10-12 kg per second.

THat may not seem like much but an electron weighs very little and are highly weight efficient charge carriers (less if the electrons are reflected at 1.5 E-12) That is roughly 6 micro-moles/second of electrons be stripped off their atoms (presumably something) deflected off of something electrons and returned to the device.

6 micro-moles a second is a heap of electrons. Lets just examine this. Emission of plasma around the sun is 1.3×10³⁶ per second. This comes out to about 1.3 E 36/8E32 per passing per square meter at 200,000 m/s. Or about 1600 hydrogen per 200,000 cubic meters outside the earths magnetic field. 1/40th of a hydrogen per cubic meter. Thus means you need how much volume behind the drive to generate thrust. 1E-26 moles of gas per meter, sometimes as high as 1E -21 sometimes lower depending on the direction of the plasma in space. Lets take the higher number,

6x-6 /1E-21 you would need a volume of space 1E15 cubic meters in size to achieve the acceleration. What is the minimum radius of that volume? 130 kilometers.

So here is my prediction if the Cannae drive is working off of electron resonance generated by the electron cavity to produce a 5 micronnewton of thrust it would have to be, on average resonating electron out 100km in deflection path that is a million kilometers in an orbit.

My prediction is that in space, the thrust production saturates very quickly, in the nanonewton-micronewton range with rather low power utiliization. On the bright side it will not need alot of panels, because utilization is comparably low and blowing out parts will also not be a probem, and so lightweight designs will be useful, but instead of being able to make Hohmann transfers it will have to spiral to its destinations over years. Will likely not be able to break low earth orbit. I should point out that resonant electron orbitals have no confined range, they can act over great distances, but the probability that they can act over great distances diminishes with distance in most situations that im aware of. A bigger lighter-weight cavity, a lower wavelength and we might be able to magnify the distances, but at what cost to ISP, lower is the enemy here. They can in a graphene sheet act over a near infinite range, but given no dimensional facilitation for such a cavity resonator outside the cavity, the distance of interaction is probably going to be a small multiple of the wavelength and the shape of the cavity. An electron travelling through such an open expanse of space may find no atoms to interact and return back with most of its departure energy intact.

 

 

 

 

 

Edited August 31, 2016 by PB666

[rtxoff]

Thankfully it's not forbidden to dream. Else reality would be to hard to swallow.

[Whackjob]

I figured I'd weigh in ever so briefly.  I don't this thing will work.  I think the readings they've gotten are either instrumental or human error, and that it will be tracked down eventually.  I don't think we've stumbled upon a magical machine that violates known physics.  Which is a bummer.  I'd infinitely prefer something small and easy like this to open the universe to us.  I wish it were real.

[simonh]

The detected measurement persisting even after the experiment has been disabled. The thrust disappearing when the drive is powered by an internal battery and only appearing again when external power cables are added. Different experiments differing in measurements by orders of magnitude and no two experiments really matching up.

It's not looking good for the EM Drive.

Simon Hibbs

[YNM]

Well, putting this on a probe and let it off won't be a very hard thing, right ? When will they start doing it ?

On science & engineering : science supports engineering by letting them know what might be possible. Engineering supports science by ideas shortage (you need to science it) and making tools for more science.

So strapping this device to a probe and let it off is engineering helping science, IMHO. (and then science helping engineers, at least we can tell does it work or not.)

[RocketSquid]

On 8/31/2016 at 11:13 AM, KerikBalm said:

So far at least two groups have had their "control" tests, where no thrust was expected, produce equal or greater thrust... which strongly suggests measurement error.

When will people stop making this mistake!?

In all cases where the "null" article has produced thrust, said "null" article was not a control group but a test for an alternate chamber design. It was originally assumed that the drive required slots to function. The null articles did not have slots, and thus the original theory predicted that they would not produce thrust. However, they did, proving the original theory wrong. The actual control groups, on the other hand, had non-resonating chambers and predictable produced no thrust.

See here.

Also, it turns out that they are commercializing the Cannae drive and hopefully testing it in space soon. See details here.

[StrandedonEarth]

2 hours ago, simonh said:

The thrust disappearing when the drive is powered by an internal battery and only appearing again when external power cables are added.

I thought this would have pretty much put it to rest....

[magnemoe]

15 minutes ago, StrandedonEarth said:

I thought this would have pretty much put it to rest....

How could you power it with an internal battery? The drive is connected to an microwave generator who is then powered. An internal as in on the test rig inside the vacuum chamber would require an vacuum rated battery, even vacuum rated components for the RF generator is outside of the budget. 
 

[PB666]

3 hours ago, simonh said:

The detected measurement persisting even after the experiment has been disabled. The thrust disappearing when the drive is powered by an internal battery and only appearing again when external power cables are added. Different experiments differing in measurements by orders of magnitude and no two experiments really matching up.

It's not looking good for the EM Drive.

Simon Hibbs

Lets not add information that is not published.

52 minutes ago, RocketSquid said:

When will people stop making this mistake!?

In all cases where the "null" article has produced thrust, said "null" article was not a control group but a test for an alternate chamber design. It was originally assumed that the drive required slots to function. The null articles did not have slots, and thus the original theory predicted that they would not produce thrust. However, they did, proving the original theory wrong. The actual control groups, on the other hand, had non-resonating chambers and predictable produced no thrust.

See here.

Also, it turns out that they are commercializing the Cannae drive and hopefully testing it in space soon. See details here.

That order is vested. You test in space first, then you think about commercializing. Other than the ethical concerns here, the primary problem as I have stated above concerns the power up and distribution of thruster. You may want underpowered thrusters (lightweight as possible) spread out in space. Otherwise you are wasting a KW of power for a nanoNewton of thrust.

[KerikBalm]

1 hour ago, RocketSquid said:

When will people stop making this mistake!?

In all cases where the "null" article has produced thrust, said "null" article was not a control group but a test for an alternate chamber design. It was originally assumed that the drive required slots to function. The null articles did not have slots, and thus the original theory predicted that they would not produce thrust. However, they did, proving the original theory wrong. The actual control groups, on the other hand, had non-resonating chambers and predictable produced no thrust.

See here.

Also, it turns out that they are commercializing the Cannae drive and hopefully testing it in space soon. See details here.

Oh look, a link not to the scientific paper, that ex post facto tries to tell us what the goal of the test was.

Oh, and a post ignoring the second test...

[rtxoff]

I already posted a scientific paper here that clearly debunks it in a series of experiments. However you can't possibly do anything here to convince believers into non believing. Even if NASA officials would say it's not working people here would accuse them of conspiracy.

[PB666]

1 hour ago, gpisic said:

I already posted a scientific paper here that clearly debunks it in a series of experiments. However you can't possibly do anything here to convince believers into non believing. Even if NASA officials would say it's not working people here would accuse them of conspiracy.

NASA says the opposite, this group never ceases to create 100 irrelevent side arguements.  They have stated the thrust output at power. 

[RocketSquid]

6 hours ago, KerikBalm said:

Oh look, a link not to the scientific paper, that ex post facto tries to tell us what the goal of the test was.

Oh, and a post ignoring the second test...

I could find no information about the second test. Also, you claimed that the BOTH tests had failed.

Since you doubt my first source, here's another one.

I am NOT arguing that it does or does not work. I am arguing that people keep making the same mistake regarding an "error" that doesn't exist, and it's getting on my nerves.