Author Topic: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive  (Read 198638 times)

Offline ppnl

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #420 on: 05/06/2015 04:18 PM »
Hello everybody.
First of all, thanks to all who have made this discussion possible. I think that some good scientific discussion is being done here and in the other EmDrive thread. I have started lurking in this forum two weeks ago when the buzz about the new tests started, but only now I've decided to register and post some comments.

First of all, disclaimer: I am an engineer, not a physicist, but for my degree I had to do several exams to do with electromagnetism and even some quantum-related effects (the ones related to how a semiconductor works). So I have a healthy interest in physics, and I've read more on the matter than just what I studied for the exams, but I am not an expert.

I am perplexed by this paragraph in the article:

In Dr. White’s model, the propellant ions of the MagnetoHydroDynamics drive are replaced as the fuel source by the virtual particles of the Quantum Vacuum, eliminating the need to carry propellant. This model was also met with criticism in the scientific community because the Quantum Vacuum cannot be ionized and is understood to be “frame-less” – meaning you cannot “push” against it, as required for momentum.

I'd like to know more about Dr. White's model than just this description, and I don't know enough about the QV in terms of the complicated quantum mechanics maths, but I can wrap my head around virtual particles. I trust in their existence because they are related to black hole Hawking radiation, and we have observed that radiation. We have a model, and it works.
From what I understand of the model, though, I think I have a further observation about the model of "pushing against the virtual particles" that could lead to an experiment to disprove it.

Suppose you have a fluctuation where a particle-antiparticle couple spawns into existence and then annihilates pretty much immediately, just as in the model for virtual particles; in very simplistic terms (and I'm sure the reality is more complicated) they "borrow" some energy and momentum and "return" it when they annihilate (gah, I know, I'm butchering it, but bear with me). Now suppose that it was possible to "push" that particle-antiparticle pair as reaction mass with some (magic?) apparatus in the time while the pair is briefly in existence. The pair would gain a total momentum p equal and opposite to the apparatus pushing it.
Then the pair annihilates - but wait! Now the two particles have more momentum (and energy) than what they "borrowed" to come into existence. Because of CoM, that extra momentum must go somewhere. It can't just disappear. The system would have to transform in such a way that it's conserved.

The only way I can see this happening is if it is released as radiation (or other by-product particles). We know that radiation has momentum, so this is possible. In other words, a device using the virtual particles as reaction mass would "shine" with some extra radiation that can't be explained in any other way.
This radiation is either massive (i.e. it's made of particles) or massless (i.e. it's light).

In the latter case, energy and momentum for radiation are related by the E = pc relation. If we have measured a momentum variation p in our apparatus, and therefore we have an equivalent momentum variation to be radiated, then the energy released as radiation would be pc, which for any meaningful value of momentum would be utterly huge and it would likely destroy the apparatus. Plus, where is the energy coming from?!?

In the former case, then this extra stream of particles is radiated from the apparatus in such a way that it must be detectable by some experiment. Granted, it might be difficult (it they're neutrinos, we're basically stuffed) but it must be conceptually possible.
We might even be able to estimate a range of bounds for the average total mass generated by this interaction, because for each particle E = mc^2 + pv which can be summed over all the particles, and we know the upper bound of the total E (because of CoE that is at most what energy we pumped into the apparatus as input), the total p (which is equal to the momentum change of the apparatus) and we know that for every massive particle it must be true that 0 <= v < c.

So, I would argue that another objection to the "pushing against virtual particles" model is that since we haven't observed a huge amount of gamma rays melting the lab, then some mass must be created somehow from the expended energy. However it has not been explored in the experiments whether this extra mass was produced (and personally I suspect we won't find it, but that's just my opinion).

Does this make sense?

I think you have a fair grasp of the problem. The only thing I would add is that it takes a whole lot of energy to produce a tiny amount of mass. The energy needs of the thing would be worse than if you were only producing photons. And you would still burn down your lab with intense radiation. Even if you were producing neutrinos you would have to produce them in such numbers that they would become detectable.

There are actually several experiments being done where a beam of neutrinos are beamed through the earth and detected elsewhere. One of them claimed that the neutrinos were going faster than light but that turned out to be a loose cable.

Offline Rodal

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #421 on: 05/06/2015 05:31 PM »
Hello everybody.
First of all, thanks to all who have made this discussion possible. I think that some good scientific discussion is being done here and in the other EmDrive thread. I have started lurking in this forum two weeks ago when the buzz about the new tests started, but only now I've decided to register and post some comments.

First of all, disclaimer: I am an engineer, not a physicist, but for my degree I had to do several exams to do with electromagnetism and even some quantum-related effects (the ones related to how a semiconductor works). So I have a healthy interest in physics, and I've read more on the matter than just what I studied for the exams, but I am not an expert.

I am perplexed by this paragraph in the article:

In Dr. White’s model, the propellant ions of the MagnetoHydroDynamics drive are replaced as the fuel source by the virtual particles of the Quantum Vacuum, eliminating the need to carry propellant. This model was also met with criticism in the scientific community because the Quantum Vacuum cannot be ionized and is understood to be “frame-less” – meaning you cannot “push” against it, as required for momentum.

I'd like to know more about Dr. White's model than just this description, and I don't know enough about the QV in terms of the complicated quantum mechanics maths, but I can wrap my head around virtual particles. I trust in their existence because they are related to black hole Hawking radiation, and we have observed that radiation. We have a model, and it works.
From what I understand of the model, though, I think I have a further observation about the model of "pushing against the virtual particles" that could lead to an experiment to disprove it.

Suppose you have a fluctuation where a particle-antiparticle couple spawns into existence and then annihilates pretty much immediately, just as in the model for virtual particles; in very simplistic terms (and I'm sure the reality is more complicated) they "borrow" some energy and momentum and "return" it when they annihilate (gah, I know, I'm butchering it, but bear with me). Now suppose that it was possible to "push" that particle-antiparticle pair as reaction mass with some (magic?) apparatus in the time while the pair is briefly in existence. The pair would gain a total momentum p equal and opposite to the apparatus pushing it.
Then the pair annihilates - but wait! Now the two particles have more momentum (and energy) than what they "borrowed" to come into existence. Because of CoM, that extra momentum must go somewhere. It can't just disappear. The system would have to transform in such a way that it's conserved.

The only way I can see this happening is if it is released as radiation (or other by-product particles). We know that radiation has momentum, so this is possible. In other words, a device using the virtual particles as reaction mass would "shine" with some extra radiation that can't be explained in any other way.
This radiation is either massive (i.e. it's made of particles) or massless (i.e. it's light).

In the latter case, energy and momentum for radiation are related by the E = pc relation. If we have measured a momentum variation p in our apparatus, and therefore we have an equivalent momentum variation to be radiated, then the energy released as radiation would be pc, which for any meaningful value of momentum would be utterly huge and it would likely destroy the apparatus. Plus, where is the energy coming from?!?

In the former case, then this extra stream of particles is radiated from the apparatus in such a way that it must be detectable by some experiment. Granted, it might be difficult (it they're neutrinos, we're basically stuffed) but it must be conceptually possible.
We might even be able to estimate a range of bounds for the average total mass generated by this interaction, because for each particle E = mc^2 + pv which can be summed over all the particles, and we know the upper bound of the total E (because of CoE that is at most what energy we pumped into the apparatus as input), the total p (which is equal to the momentum change of the apparatus) and we know that for every massive particle it must be true that 0 <= v < c.

So, I would argue that another objection to the "pushing against virtual particles" model is that since we haven't observed a huge amount of gamma rays melting the lab, then some mass must be created somehow from the expended energy. However it has not been explored in the experiments whether this extra mass was produced (and personally I suspect we won't find it, but that's just my opinion).

Does this make sense?
If you are interested in Dr. White's conjecture regarding the above, see this:   

https://en.wikipedia.org/wiki/Woodward_effect#Quantum_mechanics

and associated references.   Woodward's Mach-Effect theory predicts a transient (inertial) mass fluctuation that arises according to his transient mass equation.  The NASA Engineer (Paul March) quoted in the NSF article posits that Dr. White's and Prof. Woodward's theories are "two sides of the same coin".  The section of the NSF article dealing with Applications paraphrased numerous previously published papers of Dr. White and Paul March (and other co-authors) to show the motivation for their research.  Unfortunately there was not enough space to objectively, concisely, comprehensively and adequately discuss these conjectures in an article directed towards a larger audience.
« Last Edit: 05/06/2015 05:35 PM by Rodal »

Offline hhexo

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #422 on: 05/06/2015 05:36 PM »
The only thing I would add is that it takes a whole lot of energy to produce a tiny amount of mass. The energy needs of the thing would be worse than if you were only producing photons. And you would still burn down your lab with intense radiation.

Well, no, actually, the radiation being massive instead of massless is what saves it from burning the lab. With massive radiation most of the spent energy would go into the creation of mass and you would only get a handful of particles propelled at a high speed, just as in an ion drive. The only difference is that you've spawned the particles out of energy (how? I have no idea - but let's just discuss it).

A quick back-of-the-envelope calculation (in pure engineer style, and pure speculation at this stage)...

Let's suppose we pump a certain amount of energy in our apparatus, and let's suppose that some of it is transferred to the virtual particles, some to the apparatus, and some is dissipated, for CoE.
Suppose we have 100J (e.g. 100W for one second) going into the virtual particles, which then annihilate and the extra 100J is released as massive radiation. We have:

100 = m * c^2 + p * v = m * c^2 + m * v * v = m * (c^2 + v^2)

So, m = 100 / (c^2 + v^2). Generally in these experiments massive particles created this way have a significant velocity... I don't know what they would have in this case, let's pretend it's on the same order of magnitude as c but smaller... let's say 1*10^8 m/s (while c is 3*10^8). The square of c is about 9 times 10^16, the square of v is about 1 times 10^16. So the denominator becomes 10^17 just to make the calculation easier. :)
The generated mass of the massive radiation is in the order of magnitude of 10^-15 kg. Very small, but possibly detectable.

If as we said v = 1*10^8, then the momentum of the massive radiation is of the order of m * v = 10^-7. This is the same momentum gained by the apparatus, which however has a much bigger mass and therefore will gain a much smaller velocity.
However, we also know that the change in momentum is basically the thrust times the time it's been applied for, i.e. delta-p = F * delta-t. Since we suppose that we've pumped our energy all within 1 second, the thrust F would be again of the order of 10^-7 Newtons.

... which is not too distant from the micro-newtons they claim to have measured, actually.  :o
Vary the m and v of the generated massive radiation, and you might be able to fit the data. Maaaybe.

In other words, I think the creation of massive radiation instead of massless radiation might be closer to explaining this (and incidentally it would make this magical apparatus a plain old reaction-mass drive, not "reactionless", therefore avoiding issues with CoM and CoE), but there hasn't been any experiment that demonstrated such additional massive radiation. Nor I can see how the "magic" of mass generation would work.

... can we have an experiment just to check? :)
Personally, I think by now somebody would have detected a stream of particles with 100W of power leaving the apparatus with a momentum bias towards the back... so I'm not hopeful and I remain of the idea that "pushing on virtual particles" is probably the wrong explanation.

Also, somebody (I think in the other thread) mentioned the possibility that EmDrive could be atomizing its own shell and propelling ions just like an ion drive, which would be a much simpler explanation. Again, a massive radiation detector would give some insight on this possibility.

It's all about the experiments, after all.

Offline hhexo

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #423 on: 05/06/2015 05:38 PM »
If you are interested in Dr. White's conjecture regarding the above, see this:   

https://en.wikipedia.org/wiki/Woodward_effect#Quantum_mechanics

and associated references.

Thanks very much for the link! I will definitely look into it.

Online Chris Bergin

Interesting post from Star One moved - with responses - to the main EM Drive thread per report to mods that it is where this is being discussed, so all in one place:

http://forum.nasaspaceflight.com/index.php?topic=36313.msg1370652#msg1370652

Offline Carl G

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #425 on: 05/06/2015 11:18 PM »
A reminder of the post made by Chris several times, this is not a thread for collecting links of sites that are making a very poor attempt to cover this. This thread is for discussing the article here.

Offline frobnicat

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #426 on: 05/07/2015 12:12 AM »
...


Em drives mounted on a rotor turning at 2000m/s tangential velocity (not easy but this is the kind of tangential velocity attained in some energy storage flywheels...). Em drives consuming 1kW microwave, radiating some (all ?) of this power as heat and thrusting at 1N : 1N/kW is in the ballpark of what has been experimentally claimed already. This gives 2000m/s * 1N = 2kW mechanical power to the shaft of the rotor. 2kW mechanical power at the shaft are converted to 1800W DC current by a generator (and 200W radiated as heat). Of this 1800W DC electrical power, 250W are diverted for any use we like. To keep it in line with the topic I put it to good use to power another Em drive but really we are free to use those 250W for whatever (creating mass for instance). The power splitter is not 100% efficient, it radiates 50W of power. 1800-250-50 = 1500W to feed the RF amplifier. The RF amplifier wastes (radiates) 500W as heat and pumps 1000W of clean microwave back into the Em drives on the rotor.

The process needs an initial investment in energy (to make rotor move at 2000m/s tangential velocity) but then this is a free energy generator for all practical purpose. If small variations in efficiency make the rotor lose a bit of velocity, just divert a little more power to the RF amplifier : this is just a regulation problem, there is ample margins to adjust and stabilize around the optimal operating point.
...

@frobnicat: how general are the statements above, concerning the hypothesis of constant "propellantless thrust" at constant power ?

Do they apply for example, to:

1) An idealized military search light used as a photon rocket (assuming, for argument's sake, in a Gedankenmodell that components have an infinite life without degradation, and you operate it an indefinite amount of time with energy supply)


zero123 concise reply on that is spot on. To make a short story long :

As often remarked : for any propellantless device yielding "given constant thrust for given constant power" (ie. a definite thrust/power ratio) there is a velocity relative to a power feedback loop system above which net power surplus can be generated (indefinitely, wear apart).
This velocity is simply the inverse of the thrust/power ratio : V (m/s) = power (W) / thrust (N).

For a perfect photon rocket, that is indeed a "propellantless device yielding given constant thrust for given constant power" the ratio thrust/power is 1/c, the velocity above which the photon rocket should run relative to a power feedback loop would be c, which it can't. This saves the photon rocket as a theoretically correct device, which is fine for the current frameworks since it is also experimentally proven.

Side note 1 : I have also often seen 2*power/thrust as the velocity above which propellantless devices start to exhibit COE issues. This is the value that is given when comparing the acquired kinetic energy relative to "start frame" (inertial rest frame of the device just when switched on) taking together :
->  Ek = 1/2 * m * V²
->  V = a t
->  thrust = m a
->  Ee = power * t
and equating Ek (acquired kinetic energy) with Ee (expanded energy, used by the drive to do its thrust)
That yields 1/2 * (thrust/a) * V² = power*(V/a) => V=2*power/thrust

This is correct to state that above velocity of 2*power/thrust there is clearly a COE issue, but it is misleading to assume it is a good upper bound, ie. that below that we are "safe" : for a device with 1.99 times the thrust/power performance of a perfect photon rocket, the velocity 2*power/thrust is just a tiny bit above c and can't be reached. That don't prevent such a device to be put to use as a power harvester above  V=power/thrust, just make it spin at 200000km/s tangential speed on the above contraption for instance. Not very practical but still frowned upon in usual frameworks.

In summary : power/thrust is the speed limit, and since apart from c all speeds are arbitrary (depend on arbitrary choice of rest frame, or arbitrarily high tangential speed in above contraption) every "propellantless device" that claims better than 3.33 * 10^-9 N/W  must either come with a hidden energy source to pump, or plainly break COE. And this is from the first second of operation : can't have a tolerance window when Ek<Ee before COE police realise there is a problem and intervene, because Ek is a fiction (depends on arbitrary frame).

Side note 2 :
One may wonder how the above unlimited energy generator scheme would behave with a conventional action/reaction thruster, those being known to have much better than 3.33 * 10^-9 N/W. Since such a reactor needs to expel mass, it needs to be fed mass (otherwise the scheme is no longer "unlimited" as the thruster would deplete quickly). If the mass flow goes through the shaft and is distributed radially to the tangentially mounted thrusters, the apparent "Coriolis forces" acting from the propellant flow on the radial pipes would yield a counter torque of such magnitude that it would keep the energetic cycle below breakeven (or just at breakeven assuming no losses at all, which is impossible). Reality of COE is implacable.

The device depicted above would work as an unlimited energy generator only with a better than photon rocket propellantless drive (given the fact that the Coriolis effect of an energy flow is negligible due to the extreme lightness of energy compared to conventional reaction mass, so to speak, this would need further justification when talking about relativistic conventional action/reaction thruster). Happen to be that this is not only a thought experiment but it becomes a technologically achievable possibility starting at about 1N/kW Em drive (if such a thing exists). Note that I took care of inefficiencies in the feedback cycle (there is some margin). Even more so above the 10N/kW some are dreaming of : an unlimited energy generator then becomes trivial, and with quite a good power/mass ratio at that.

Quote
2) Woodward's propellant-less Mach Effect (assuming, for argument's sake, that Woodward's conjecture is valid, and you can operate it an indefinite amount of time with energy supply)

If there are differences that constrain the energy paradox between the above two and the EM Drive, please point out the differences, as it may be instructive for this discussion to unveil these differences regarding what is possible and what is not possible (under conservation of energy and conservation of momentum).

Thanks

There is no difference of consequence : with a better than photon rocket propellantless drive at hand, there is an unlimited energy generator possible, at least in principle, and in practice starting at above 1N/kW (steady state, or averaged steady state). This derives directly from the phenomenology of the device, not its operating principle.

The difference being that Woodward theory (and ME thruster assumed principle) posits an exchange of energy/momentum with rest of the Universe (past and future), the energy problem gets "diluted" to the horizon of it all, kind of. So, some proponents of ME thrusters seem less reluctant to state explicitly, on some forum, that the device is indeed a cheap energy harvester (and that operating could be accelerating the demise of reality BTW, and that dark energy is the signature of all people, past and future, using ME thrusters on cosmic scales). My knowledge of GR is way too feeble to tackle seriously the pros and contras of "Mach principle" and derived Woodwards works, but my gut feeling is not good. Looks like it's just a more sophisticated way to be wrong.

Obviously no one (Woodward, White, Shawyer) wants to make too much publicity about how their drives are good unlimited energy generators, but they all sell those same drives for energetically dirt cheap fast space transportation, which really is the same. Using steady state thrust/power ratio to put forward impressive mission profiles, and failing to say at the same time that those very same steady state thrust/power ratios imply "apparently free energy", is lie by omission. If not outright deceit I dare say when in the same paper the issue of COE is supposedly addressed as an ill defined lowering thrust/power and in the next chapter a constant thrust/power used with no remorse to reach deep space.

Trying to make the propellantless drives to comply with apparent COE yields so much inconsistencies that I'm convinced that, if they are for real (which I'm not convinced), they must indeed be energy harvesters, and COE is to be saved by determining what is (silently) harvested. For White this means altering/lowering the ZPF density (which in principle can't be done since it's already a baseline). Could be detected locally. For Woodward this means imparting some entropy (unsure about that one) on the spatio-temporal walls of reality. Would be hard to prove, but experimental proof of apparently unlimited energy generation from a closed box could be indirect evidence. For Shawyer, propellantless drives do comply with apparent COE, there is therefore nothing harvested (except momentum ?) but as a consequence a lot of inconsistencies.

« Last Edit: 05/07/2015 12:25 AM by frobnicat »

Offline LasJayhawk

I'm confused about something ( o.k. many things). I have now read many articles that say this can't work and is all junk science. It violates COM/COE etc.

But isn't that taking a Newtonian view of something operating at a quantum level? Tunnel diodes have negative resistance, but they are quantum tunneling diodes after all. We have been making tunnel diodes for 50+ years but the logic that says the emdrive can't work, in my mind, says tunnel diodes can't work either.

Am I missing something?

Offline PushHigher

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #428 on: 05/07/2015 01:53 AM »
If you study the shape of the new frustum being used - it basically redirects the photons toward center-line of the spherical end plates.  If a photon bounces say a billion times in the chamber before dissipating into heat - it will eventually focus in on that center-line along with many of the other photons in the chamber.  This is momentum along that axis.  Turning the frustum in any direction would be the 3D equivalent of turning a spinning flywheel - energy loss.
« Last Edit: 05/07/2015 01:57 AM by PushHigher »

Offline Damon Hill

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #429 on: 05/07/2015 01:53 AM »
Tunnel diodes have been in mass production for decades.

Massless propulsion devices, not so much.  If the effect can be reliably duplicated, that may change.

Offline Nilof

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #430 on: 05/07/2015 02:02 AM »
I'm confused about something ( o.k. many things). I have now read many articles that say this can't work and is all junk science. It violates COM/COE etc.

But isn't that taking a Newtonian view of something operating at a quantum level? Tunnel diodes have negative resistance, but they are quantum tunneling diodes after all. We have been making tunnel diodes for 50+ years but the logic that says the emdrive can't work, in my mind, says tunnel diodes can't work either.

Am I missing something?

Quantum mechanics and quantum field theory still has conservation of energy-momentum. As mentioned, it is even more explicit there than in classical physics. Tunnel diodes were a straightforward application of known physics and have no relation to this.
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline LasJayhawk

I'm confused about something ( o.k. many things). I have now read many articles that say this can't work and is all junk science. It violates COM/COE etc.

But isn't that taking a Newtonian view of something operating at a quantum level? Tunnel diodes have negative resistance, but they are quantum tunneling diodes after all. We have been making tunnel diodes for 50+ years but the logic that says the emdrive can't work, in my mind, says tunnel diodes can't work either.

Am I missing something?

Quantum mechanics and quantum field theory still has conservation of energy-momentum. As mentioned, it is even more explicit there than in classical physics. Tunnel diodes were a straightforward application of known physics and have no relation to this.

I do understand that, kinda.  :) 

What I am thinking of is the PEPCON explosion in 88. A spark from a welder wound up setting off a million pounds of AP. BOOM! A small energy input released a large amount of stored chemical energy.

If the QV is a large storage of negative energy, I might only need to put a little in to get a lot out?? I didn't put the same energy in as I got out, I just just my small energy to tap a large pile of stored energy. That wouldn't be a violation of COE, would it?

Offline Rodal

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #432 on: 05/07/2015 03:59 PM »
....

If the QV is a large storage of negative energy, I might only need to put a little in to get a lot out?? I didn't put the same energy in as I got out, I just just my small energy to tap a large pile of stored energy. That wouldn't be a violation of COE, would it?
Good point.  My understanding is that @frobnicat attempts to address that with what he calls "Harvesting" energy from the Quantum Vacuum or "Harvesting" energy from the universe in Woodward's formulation.

Quote from: frobnicat
Trying to make the propellantless drives to comply with apparent COE yields so much inconsistencies that I'm convinced that, if they are for real (which I'm not convinced), they must indeed be energy harvesters, and COE is to be saved by determining what is (silently) harvested. For White this means altering/lowering the ZPF density (which in principle can't be done since it's already a baseline). Could be detected locally. For Woodward this means imparting some entropy (unsure about that one) on the spatio-temporal walls of reality. Would be hard to prove, but experimental proof of apparently unlimited energy generation from a closed box could be indirect evidence.
« Last Edit: 05/07/2015 04:02 PM by Rodal »

Online sanman

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #433 on: 05/09/2015 03:28 PM »
You mean accelerating the "heat death" of the universe? Who cares - we'll all be long dead before that happens.

Online KelvinZero

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #434 on: 05/09/2015 10:45 PM »
If true, wouldn't this degrade the universe by using up a finite resource?

Perhaps other advanced species figured this out at some point, and hense a solution to the Fermi paradox!
There is another way this could explain the fermi paradox.

Interstellar travel is hard, even with free energy. Free energy implies free mass. Why not just build more places to live right here? there is plenty of spare space. Growth is now exponential. Any group that shuns this technology will simply be outcompeted. However exponential growth always reaches a limit. In this case it will happen when the mass in your vicinity makes the escape velocity to any other galaxy exceed the speed of light.. crunch. ;)


Offline Rodal

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #436 on: 05/10/2015 02:05 AM »
....
If true, wouldn't this degrade the universe by using up a finite resource?

Perhaps other advanced species figured this out at some point, and hense a solution to the Fermi paradox!

http://www.scientificamerican.com/article/how-wind-turbines-affect-temperature/
« Last Edit: 05/10/2015 02:06 AM by Rodal »

Offline Rodal

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #437 on: 05/11/2015 04:53 PM »
Good post about shooting out tachyons. 

Concerning  the above-referenced posts in a blog, it is full of insults and name calling, but devoid of substance not already known by scientists and engineers.  Same arguments were made much more succintly in the NSF article (conservation of momentum, that the Quantum Vacuum is inmutable and not degradable, etc.).

In contrast to the insults in that blog post, which never bothers to offer a scientific explanation for the measurements (except non-scientific arguments like "it could be a mosquito"), I worked out the following detailed explanation as a thermal buckling artifact, (which contains equations instead of insults):

https://www.researchgate.net/publication/268804028_NASA%27S_MICROWAVE_PROPELLANT-LESS_THRUSTER_ANOMALOUS_RESULTS_CONSIDERATION_OF_A_THERMO-MECHANICAL_EFFECT

Concerning the EM Drive thread, even the tachyon comment discussed above was previously posted in the EM Drive thread by @frobnicat who also has worked tirelessly to objectively address the experimental measurements and the paradoxes that accompany the EM Drive.
« Last Edit: 05/11/2015 05:07 PM by Rodal »

Offline Jared

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #438 on: 05/11/2015 06:04 PM »

https://www.researchgate.net/publication/268804028_NASA%27S_MICROWAVE_PROPELLANT-LESS_THRUSTER_ANOMALOUS_RESULTS_CONSIDERATION_OF_A_THERMO-MECHANICAL_EFFECT


As an observer, I have been taking huge interest in the ongoing discussion for the last couple of weeks. I am deeply convinced that the discovery of even the slightest possibility of feasible and realistic interstellar superluminal travel would profoundly and positively alter our species' trajectory. Thus, I want to thank all of you for investing so much in this slight chance.

However, Dr. Rodal's paper seems to effectively end these investigations with respect to the EM Drive, as it makes a lot of sense with a very strong argument.
« Last Edit: 05/11/2015 06:04 PM by Jared »

Offline Rodal

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Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #439 on: 05/11/2015 06:39 PM »

https://www.researchgate.net/publication/268804028_NASA%27S_MICROWAVE_PROPELLANT-LESS_THRUSTER_ANOMALOUS_RESULTS_CONSIDERATION_OF_A_THERMO-MECHANICAL_EFFECT


As an observer, I have been taking huge interest in the ongoing discussion for the last couple of weeks. I am deeply convinced that the discovery of even the slightest possibility of feasible and realistic interstellar superluminal travel would profoundly and positively alter our species' trajectory. Thus, I want to thank all of you for investing so much in this slight chance.

However, Dr. Rodal's paper seems to effectively end these investigations with respect to the EM Drive, as it makes a lot of sense with a very strong argument.
Thanks. But not the end I'm afraid, as buckling is very sensitive to initial imperfections, and hence unlikely to affect all experiments in the same direction.  There are other mechanisms that could explain the measurements.

Thus the thread, as well as life goes on. 

Hopefully such discussions will lead us to find the truth, and if we don't get there, at least they are fun  :)
« Last Edit: 05/11/2015 07:04 PM by Rodal »

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