Author Topic: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive  (Read 198630 times)

Offline tea monster

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #100 on: 04/30/2015 03:41 PM »
Supposing for a moment that this does actually work and space travel is eventually simpler than travelling between continents at the moment, it's going to highlight a few questions.

If you can zoom around the solar system using the product of an afternoon in the High School Metal Shop, then why haven't we been awash in vistors from nearby star systems?

Secondly, how much acceleration could this thing conceivably kick out? If you pour juice into it will it just keep accelerating? What's the limit to that? How many G's can it sustain and for how long? Are we looking at a torchship, but just without the torch?

Offline john smith 19

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #101 on: 04/30/2015 04:04 PM »
To be honest, I expected a LOT more of that sort of comment, especially on an unforgiving (mean that in the best possible way) hardcore space site like ours.
Perhaps it's because quite a lot of the people here have to measure stuff for a living and understand how thorough Dr White and his team have been to rule out experimental artifacts. AFAIK the sensationalist comments have been made by various parts of the media, IOW everyone but Dr White and his team.

The general level of physics knowledge here is also good enough to limit the number "Well I don't know much but this can't possibly work" comments.

Instead they are more likely to be specific objections, which can be quantified or demonstrated to be irrelevant. Answering such questions only strengthens the idea.

Note that teams in at least three countries using two different microwave sources and four cavity designs (as it's doubtful any were exact copies of the others) have all produced force readings.

Could they all be suffering some kind of collective delusion that makes them all ignore some major source of experimental error?  :(

Almost anything's possible, but does that sound a plausible explanation for what's been reported?

Time (and ever tighter experimental protocols) will tell.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline Rodal

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #102 on: 04/30/2015 04:11 PM »
There are several questions in this thread regarding the issue of free energy and the issue of acceleration. 

If the quantum vacuum is immutable and not degradable, as understood by mainstream physicists, Dr. White's conjecture is not viable.  Dr. White et.al. argues that the quantum vacuum is mutable and degradable, this is his latest paper arguing this:  http://hdl.handle.net/2060/20150006842 (it just came out in http://ntrs.nasa.gov/  days ago, I don't know whether it was submitted to any peer-reviewed journal).

Now, momentum and energy are mixed together in general relativity in the stress-energy tensor http://en.wikipedia.org/wiki/Stress%E2%80%93energy_tensor which contains, momentum density, energy density, momentum flux, shear stress and pressure components.  If the quantum vacuum would be degradable as conjectured by Dr.White, then, if one can extract momentum from it, one should also be able to extract energy from it, as has been repeatedly pointed out.  A very loose (and admittedly imperfect) analogy is using air for sailing (extracting momentum)  and air for windmills (extracting energy).  This is clearly not a mainstream physics concept, because if the quantum vacuum would behave that way, it would no longer be the zero-point energy (a term probably first used by Einstein), as one should not be able to extract energy from the lowest possible quantum state.

Dr. White apparently argues that the quantum vacuum may contain different levels of "lowest" energy, depending on the applied electromagnetic field, the proximity of matter, etc., and not a universal "zero-point energy".  He has also resorted to using 5 dimensional branes from string theory.  In any case, he argues for the EM Drive system to be an open system.  Paradoxes will also occur if one performs analysis for a sailing boat as a closed system, ignoring the power from the wind, as it is able to accelerate without any engine power.  To what extent one would be able to extract momentum or energy from the quantum vacuum is highly conjectural at this point, and it is difficult to discuss the consequences of such a non-mainstream conjecture.

Concerning the acceleration I agree with several posters that it is unlikely that one would be able to accelerate "forever" (if at all), just like extracting momentum and energy from open systems (using the wind, or the ocean, or the power from the Sun) necessarily runs into nature's constraints. 

Besides Dr. White's conjecture, there are several other possible explanations for what is at play here (ranging from an experimental artifact to a possible means of space propulsion based on an anisotropic nonlinearity of the quantum vacuum).

Rather than engage too deeply into conjectures (which unfortunately a lot of physics nowadays is, for example string theory and the multiverse), I agree that the best thing to do is to closely examine the experimental data in the US, the UK and China, and perform more, better, consistent experiments, replicated at separate centers (NASA Glenn?, JPL ?)  :).

Quote from: Richard P. Feynman
It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong.
« Last Edit: 04/30/2015 06:45 PM by Rodal »

Offline john smith 19

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #103 on: 04/30/2015 04:17 PM »
Supposing for a moment that this does actually work and space travel is eventually simpler than travelling between continents at the moment, it's going to highlight a few questions.

If you can zoom around the solar system using the product of an afternoon in the High School Metal Shop, then why haven't we been awash in vistors from nearby star systems?
You're confusing 2 different projects that Eagleworks is researching.

This thing is a propellentless drive, that accelerates a vehicle without propellant. It will not exceed the speed of light. The study of space warping as a drive system, is the other project they are working on.

And if you can run up a 1MW nuclear reactor in an HS Metal shop more power to you.  :)
Quote
Secondly, how much acceleration could this thing conceivably kick out?
How good is your maths? A target figure for a developed version is 1 Newton /Kw of electricity.
Quote
If you pour juice into it will it just keep accelerating? What's the limit to that? How many G's can it sustain and for how long? Are we looking at a torchship, but just without the torch?
No. Read the article and most of your questions will be answered.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline punder

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #104 on: 04/30/2015 04:25 PM »
There are several questions in this thread regarding the issue of free energy and the issue of acceleration. 

The various posts here predicting what amounts to perpetual motion machines are, how shall I say it, distressing.  Are these posters misinterpreting something, or is violation of conservation of energy really a possible outcome?  Thanks.

Offline Dmytry

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #105 on: 04/30/2015 04:33 PM »
Before we gets lots of questions about terrestrial applications.

Quote
18.
Q. How can the EmDrive produce enough thrust for terrestrial applications?
A. The second generation engines will be capable of producing a specific thrust of 30kN/kW. Thus for 1 kilowatt (typical of the power in a microwave oven) a static thrust of 3 tonnes can be obtained, which is enough to support a large car. This is clearly adequate for terrestrial transport applications.
The static thrust/power ratio is calculated assuming a superconducting EmDrive with a Q of 5 x 109. This Q value is routinely achieved in superconducting cavities.
Note however, because the EmDrive obeys the law of conservation of energy, this thrust/power ratio rapidly decreases if the EmDrive is used to accelerate the vehicle along the thrust vector. (See Equation 16 of the theory paper). Whilst the EmDrive can provide lift to counter gravity, (and is therefore not losing kinetic energy), auxiliary propulsion is required to provide the kinetic energy to accelerate the vehicle.

http://emdrive.com/faq.html
Oookaaaay. So I start up my 1000kg hover car, in Ecuador, in the spring, and I'm going to work, at the sunrise.

See any problem with that?

Let me spell it out just in case: unless this drive is pushing against Earth, Earth's orbital energy is increasing at a rate of about 300 megawatts (according to the Sun's rest frame).

Worse if taking Sun's motion around the centre of the galaxy.
« Last Edit: 04/30/2015 04:37 PM by Dmytry »

Offline JasonAW3

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #106 on: 04/30/2015 04:35 PM »
I go with "Extraordinary claims require extraordinary evidence". The claim here defies known laws of physics. Therefore, the evidence must be very conclusive. So far, the evidence is enough to support further investigation, but not enough to believe the claim is true. As exciting as this is, there are tons of examples where extraordinary claims were crumbled to dust. Most recently: faster than light neutrinos, primordial gravitational waves, etc.

There are some extraordinary claims that came true though, bending of light through gravity, microwave background, etc. But these examples are VERY rare. Far rare than extraordinary claims that could not have been supported. So I will remain skeptical until there is really conclusive evidence. But I absolutely support the idea to generate this evidence, or at least try to.

     At present, I'd definately say that this project has passed well beyond the "Cold Fusion" bench mark into the "Something interesting is going on" territory.  Nobody's really quite sure WHAT exactly is causing the results, but it appears to be controllable, repeatable and varies in output due to both power input variations as  a modulated signal.

    While at first glance, one could be expected to write the phenomena off as "Electric Wind" or heating of the air, as this experiment has been tested in a vacume with the same results, this explaination becomes a nonsequitor.

     If the phenomena is confirmed in the next round of tests, and a test in orbit is attempted, and, if my suspicions about the nature of the phenomena are correct, then it is quite possible that, the further up the gravity well that this device goes, the more efficiently it will work, producing more "thrust" for less power.  Also, if my conjecture holds up, the optical varience with the interferometer in space should also increase the farther out of the gravity well the test item goes.
« Last Edit: 04/30/2015 06:11 PM by JasonAW3 »
My God!  It's full of universes!

Offline lcs

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #107 on: 04/30/2015 04:38 PM »
 
Quote
The various posts here predicting what amounts to perpetual motion machines are, how shall I say it, distressing.  Are these posters misinterpreting something, or is violation of conservation of energy really a possible outcome?  Thanks.

Quoting 'papers' which have not been peer-reviewed, published, presented before a skeptical, disinterested audience, etc. etc. is of little value beyond this limited enclave of sci-fi enthusiasts. 
 
« Last Edit: 04/30/2015 04:39 PM by lcs »

Offline arachnitect

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #108 on: 04/30/2015 04:41 PM »
There are several questions in this thread regarding the issue of free energy and the issue of acceleration. 

The various posts here predicting what amounts to perpetual motion machines are, how shall I say it, distressing.  Are these posters misinterpreting something, or is violation of conservation of energy really a possible outcome?  Thanks.

It breaks conventional physics no matter what. If it breaks something too obvious, they adjust the theory to break something else instead.

Offline Davinator

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #109 on: 04/30/2015 04:42 PM »
Before we gets lots of questions about terrestrial applications.

Quote
18.
Q. How can the EmDrive produce enough thrust for terrestrial applications?
A. The second generation engines will be capable of producing a specific thrust of 30kN/kW. Thus for 1 kilowatt (typical of the power in a microwave oven) a static thrust of 3 tonnes can be obtained, which is enough to support a large car. This is clearly adequate for terrestrial transport applications.
The static thrust/power ratio is calculated assuming a superconducting EmDrive with a Q of 5 x 109. This Q value is routinely achieved in superconducting cavities.
Note however, because the EmDrive obeys the law of conservation of energy, this thrust/power ratio rapidly decreases if the EmDrive is used to accelerate the vehicle along the thrust vector. (See Equation 16 of the theory paper). Whilst the EmDrive can provide lift to counter gravity, (and is therefore not losing kinetic energy), auxiliary propulsion is required to provide the kinetic energy to accelerate the vehicle.

http://emdrive.com/faq.html
Oookaaaay. So I start up my 1000kg hover car, in Ecuador, in the spring, and I'm going to work, at the sunrise.

See any problem with that?

Let me spell it out just in case: unless this drive is pushing against Earth, Earth's orbital energy is increasing at a rate of about 300 megawatts (according to the Sun's rest frame).

Worse if taking Sun's motion around the centre of the galaxy.

We should be discussing the article, not an external link that we have nothing to do with.  Star One seems addicted to posting as many links as his fingers will allow him! ;D

Offline watermod

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #110 on: 04/30/2015 04:46 PM »
If one assumes it does work, what would it cost to make a heavily instrumented small sat test bed and carry it up as a secondary payload on an ISS or commercial launch?

Sort of a sink or swim test.

Offline indigodarkwolf

@Rodal
This is the kind of information I was hoping to see more of in the article.

The analogy I've latched onto is a boat motor, pushing against the quantum vacuum the way a propeller would push against water. The idea of a sailboat and wind, instead, is interesting but I'm struggling with how it would introduce limits to the technology. A sailboat has a maximum speed determined by "however hard the wind blows, versus the resistance of the ocean". But it's hard to understand how there would be a resistance factor to prevent arbitrary acceleration, or a maximum "velocity" of the quantum vacuum since we would always be thinking in a reference frame relative to the Emdrive. Wouldn't an Emdrive always be able to extract force from the quantum vacuum, regardless of velocity relative to an object?

Unless the medium we're pushing against is, itself, a product of another object in space. I wonder if there's a shoestring way to experimentally determine whether the medium that the Emdrive is acting on is a product of, or dragged along by, the Earth itself.

Offline Norm Hartnett

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #112 on: 04/30/2015 04:47 PM »

Quote
The various posts here predicting what amounts to perpetual motion machines are, how shall I say it, distressing.  Are these posters misinterpreting something, or is violation of conservation of energy really a possible outcome?  Thanks.

Quoting 'papers' which have not been peer-reviewed, published, presented before a skeptical, disinterested audience, etc. etc. is of little value beyond this limited enclave of sci-fi enthusiasts. 
 

Yes, I wish that the entire "Applications" section of the article had been omitted, not really up to NSF standards. EM may be viable but it is difficult to evaluate when it comes with such wildly speculative window dressing.
“You can’t take a traditional approach and expect anything but the traditional results, which has been broken budgets and not fielding any flight hardware.” Mike Gold - Apollo, STS, CxP; those that don't learn from history are condemned to repeat it: SLS.

Offline nadreck

So, I was 100% skeptic, and save having glanced at the EM Thread a couple of times because of it's high traffic, I was not taking it any more seriously than I currently take Ponds/Fleischmann's stuff. However, I was interested and hopeful when Ponds/Fleischmann's work hit the news way back when, but it failed to be reproducible.  When Chris Bergin (thanks man!) brought attention to it again a week or so ago I delved much deeper in to the thread and then gobbled up the article that came out. Now I am interested and hopeful, but also I don't need to be skeptical because this seems something that can be verified experimentally and is being. As far as I can tell, there is enough information out there for many groups to experiment. I think that if this attention from NSF has done anything, it has brought the attention of a lot of people who could work on verifying this to the topic and in a way that is surprisingly supportive.

What I do presume is that whatever force interactions are at play in the results to date is that what has been seen seems to indicate that rethinking underlying principles of physics (which we have had to do before) is required. Also what is observed seems to be applicable to spacecraft.  So on with more research, please!

I would like to remind the readers of SF of James Blish's Cities in Flight where a new space drive technology was quite simple and easy to build, but that verifying and understanding the physics of it became mankind's largest Giga project.  However this works out in the end, I don't think any of us have any certainty of how that will be.
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline indigodarkwolf

If one assumes it does work, what would it cost to make a heavily instrumented small sat test bed and carry it up as a secondary payload on an ISS or commercial launch?

Sort of a sink or swim test.
What's the cheapest EM spacecraft design that should do clearly impossible things?

About $10,000. You could Kickstarter it and get it on the next Dragon flight, ala A3R. Heck, there's cubesats that have flown for less.

Offline Mongo62

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #115 on: 04/30/2015 05:04 PM »
There are several questions in this thread regarding the issue of free energy and the issue of acceleration. 

The various posts here predicting what amounts to perpetual motion machines are, how shall I say it, distressing.  Are these posters misinterpreting something, or is violation of conservation of energy really a possible outcome?  Thanks.

I have read those objections. They all seem to be working from an unstated assumption: that the device produces a constant thrust and therefore acceleration for a given power input. If that were the case, then the kinetic energy would indeed eventually exceed the total input of energy into the drive.

So the obvious solution is that for a given energy input, thrust is not linear, but delta kinetic energy is linear instead. So as the kinetic energy increases, the thrust for a given power input would decrease, but the kinetic energy imparted would continue to increase at a steady rate over time.

This would mean that there must be a local reference frame for the velocity and hence kinetic energy to me measured against, which contradicts standard SR but is in agreement with some more recent relativistic theories.

This would also mean that trip times for a given input energy would be longer than in the article, but you still avoid the negative effects of the rocket equation, so they remain a lot better than with conventional propulsion.
« Last Edit: 04/30/2015 05:16 PM by Mongo62 »

Offline chipguy

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #116 on: 04/30/2015 05:13 PM »
I think the article should have stuck with the new test results and a brief history of research in this area. This whole "warpstar-1" extrapolation of an EM drive equipped craft could " travel from the surface of Earth to the surface of the moon within four hours" when even unambiguously measuring any thrust at all under lab conditions is problematic is just way too far out there and does disservice to this site.

Offline Dmytry

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #117 on: 04/30/2015 05:18 PM »
There are several questions in this thread regarding the issue of free energy and the issue of acceleration. 

The various posts here predicting what amounts to perpetual motion machines are, how shall I say it, distressing.  Are these posters misinterpreting something, or is violation of conservation of energy really a possible outcome?  Thanks.

I have read those objections. They all seem to be working from an unstated assumption: that the device produces a constant thrust and therefore acceleration for a given power input. If that were the case, then the kinetic energy would indeed eventually exceed the total input of energy into the drive.

So the obvious solution is that for a given energy input, thrust is not linear, but delta kinetic energy is linear instead. So as the kinetic energy increases, the thrust for a given power input would decrease, but the kinetic energy imparted would continue to increase at a steady rate over time.

This would mean that trip times for a given input energy would be longer than in the article, but you still avoid the negative effects of the rocket equation, so they remain a lot better than with conventional propulsion.
1 m/s^2 acceleration of 1kg object, according to an observer moving in the direction of the rear of the drive, at 1 meter per second, is raising the kinetic energy at an instantaneous rate of 1 joule per second (1 watt). According to an observer moving at the velocity of 1km/s , by 1000 watts .  Which observer is correct?

Keep in mind that anything stationary on Earth is moving at hundreds kilometres per second relatively to, say, cosmic microwave background, or any other such frame of reference than you could pick as preferred.

If you were to try to build a theory it would have to simultaneously produce such thrust and not alter the behaviour of microwaves in any equipment ever built sufficiently for someone to have gone "that's funny, why is this device's parameters vary as a sine wave in the course of a day?"
« Last Edit: 04/30/2015 05:22 PM by Dmytry »

Offline john smith 19

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #118 on: 04/30/2015 05:20 PM »
If one assumes it does work, what would it cost to make a heavily instrumented small sat test bed and carry it up as a secondary payload on an ISS or commercial launch?

Sort of a sink or swim test.
The problem with that would be the power requirement.

Dr White's test setup produces something around 50-80 x 10^-6 N of force for 100w of input.

The last time I checked triple junction PV cells have hit 43% and thin film types around 16%. A 4 wing roll out design would need 4 wings 10cm x about 1.3m, or 18 10x10cm plates of rigid plates.

Either way you're looking at a fairly tricky mechanism construction job to unfold enough array to be useful.  :(
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline ppnl

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #119 on: 04/30/2015 05:24 PM »
Yeah... I'm not getting how this does not violate conservation of momentum and energy. For example if this works you should be able to construct a perpetual motion free energy machine. If constant electrical power produces constant acceleration you have a problem since kinetic energy increases with the square of velocity. You will quickly reach a point where your kinetic energy vastly exceeds the electrical energy input.

Sorry, I smell the stench of cold fusion. 

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