### Author Topic: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive  (Read 233699 times)

#### Mongo62

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #120 on: 04/30/2015 05:30 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.

Again, as I said above, why are you assuming constant acceleration? Constant increase in kinetic energy would eliminate this objection, at the cost of requiring a fixed inertial reference frame to measure the kinetic energy against. Standard special relativity theory does not allow this, but some newer theories that are equivalent to special relativity in their observed effects do allow this.

#### gospacex

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #121 on: 04/30/2015 05:37 PM »
There is one joker in the pack. It seems force produced falls as the payload accelerates, so this is an engine with a "top speed" limit.

This would be a violation of Lorentz invariance of spacetime wrt boosts: laws of physics would not be the same in different reference frames moving relative to each other. This is a VERY tall claim.

#### ppnl

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #122 on: 04/30/2015 05:37 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.

Ok if acceleration is not constant (The article implied that it is.) then you are creating a preferred frame of reference in violation of relativity. That would mean the laws of physics would change depending on your inertial frame. Not a good thing.

And you are still violating conservation of momentum.

#### Dmytry

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #123 on: 04/30/2015 05:37 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.

Just stick it in a shielded hermetic box, powered off a RC airplane battery on a timer, hang it off a hanging Cavendish style torsion pendulum (insensitive to shifts in CoM), and test it in different orientations to rule out magnetic effects. You'd be easily able to get all the drifts into sub-micronewton range with a fully shielded set up.

That's a lot cheaper than a satellite and a positive result would be much more convincing.

edit: a couple hundred grams of lithium batteries (non rechargeable) and 1kg of ice (for sinking heat while keeping temperature constant, if needed) would allow for 50 minutes of operation at 100 watts.
« Last Edit: 04/30/2015 05:45 PM by Dmytry »

#### tchernik

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #124 on: 04/30/2015 05:46 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.
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.

Just stick it in a shielded hermetic box, powered off a RC airplane battery on a timer, hang it off a hanging Cavendish style torsion pendulum (insensitive to shifts in CoM), and test it in different orientations to rule out magnetic effects. You'd be easily able to get all the drifts into sub-micronewton range with a fully shielded set up.

That's a lot cheaper than a satellite and a positive result would be much more convincing.

That will happen. This is not a secret technology controlled by a single guy claiming it works, or anything like that. The data on how to build one is in the open, accessible and feasible to replicate for anyone with enough resources and technical ability to do so.

And given its "eppur si muove" type claims, it will unavoidably emerge to the light if it works or not, as long as people keep an open and transparent review process for the test setup and the results.

And as more people perform replications on their own, they will certainly try this. So I'm really hopeful because we will soon known if it works, of if it was just a waste of time. Either way, we win (a revolutionary invention, or just knowledge).

« Last Edit: 04/30/2015 05:47 PM by tchernik »

#### gospacex

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #125 on: 04/30/2015 05:58 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.

Again, as I said above, why are you assuming constant acceleration? Constant increase in kinetic energy would eliminate this objection, at the cost of requiring a fixed inertial reference frame to measure the kinetic energy against. Standard special relativity theory does not allow this, but some newer theories that are equivalent to special relativity in their observed effects do allow this.

The observed effects are that laws of physics are invariant relative to Lorentz boosts. Maxwell equations of electromagnetism are explicitly invariant relative to Lorentz boosts. This is a purely electromagnetic device. Which part of Maxwell equations is wrong?

#### M Gibbons

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #126 on: 04/30/2015 06:01 PM »
Quote
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.

Perhaps the Dragon trunk section could be used as a platform for the test after separation from the capsule.  I suppose this would require the addition of thrusters of some kind to control the orientation of the solar panels.  Probably more effort than a dedicated satellite, but just a thought.

#### Star One

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #127 on: 04/30/2015 06:07 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!

I posted it in response to a question that was asked and to stop the question being repeated and derailing the thread.

#### Cherokee43v6

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #128 on: 04/30/2015 06:07 PM »
Quote
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.

Perhaps the Dragon trunk section could be used as a platform for the test after separation from the capsule.  I suppose this would require the addition of thrusters of some kind to control the orientation of the solar panels.  Probably more effort than a dedicated satellite, but just a thought.

Why not as part of a Dragonlab mission?
"I didn't open the can of worms...
...I just pointed at it and laughed a little too loudly."

#### CW

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #129 on: 04/30/2015 06:09 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.

Taking conservation of energy literally or dogmatically, then energy can neither be created nor destroyed, and hence should be Zero in any coordinate at any given instance in time. And yet we obviously do (at least locally) exist as beings of matter and thus equivalent energy. It follows logically that net energy can (at least locally) be 'created' - most likely from the quantum vacuum. What kind of physical process this is, we don't know yet. Going by the simple observation that energy exists, there should logically exist a physical process to locally generate net energy from the quantum vacuum. I mean, we can't just ignore all existing matter and energy and still claim that neither of them should be able to come to be.

I think that time will tell whether or not we have a propulsion system here that can also draw usable energy from higher dimensions or whatever as a byproduct. For now, the only thing that makes sense is to do the experiments and follow the data.
Reality is weirder than fiction

#### TomH

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #130 on: 04/30/2015 06:15 PM »
Skepticism and Closed Mindedness are not the same thing. The first is an important frame of mind in scientific investigation; the second is antithetical to science.

At the close of the 19th century, virtually every physicist alive was of the belief that everything that could be learned about physics was already known. As described in Thomas S. Kuhn's The Structure of Scientific Revolutions, the world of physics was about to be turned on its head. There were more than a few who accepted neither Relativity nor Quantum Mechanics. The skeptics needed to see the proof, but a skeptic examines evidence and accepts it if reasonable. A closed minded person refuses to abandon old models, in spite of new evidence to the contrary.

For over a century now, physics has found itself in limbo, a no man's land of seemingly irreconcilable contradiction between Relativity and Quantum Mechanics. Much has been learned and new discoveries continue to happen, but there is not yet a Unified Field Theory, nor a Grand Unified Field Theory, nor a Theory of Everything (each of those has a different meaning). String Theory is the leading candidate at the moment, yet there are over ten differing models of how String Theory might work. The theory of Loop Quantum Gravity is the second favored theory, and then there are lesser known theories such as Garrett Lisi's E8 Theory.

What we understand about the fabric of spacetime, about the Quantum Vacuum is still very limited. We do, however, know that it is something and not nothing. And yet we do not need fully to understand a phenomenon in order to make use of it. Roentgen put X-Rays to use long before the mechanism behind their production was understood. In like manner, it is entirely possible that EM Drive may work and that it may be put to use before the entirity of the physics behind it is fully understood.

Reactions in this thread range from exuberance to completely closed minds. Science is not about jumping to conclusions, either that a theory is correct or that it is incorrect. Science is about approaching a hypothesis with an open mind, a neutrality regarding belief. It embraces a healthy skepticism for results that tend to be extreme outliers, but does accept them if they are shown to be independently repeatable by other scientists.

We used to ask whether the expanding universe had enough inertia to continue expanding forever at a decreasing rate, or if it would stop expanding and all mass implode into one singularity. Only recently did we discover the inflation is ocurring at an accelerating rate, leading us to theorize Dark Energy. It is all about the evidence. We have to follow the evidence. Whether we think this is the next great breakthrough in science or whether we think this is absurd, neither matters. This is not about opinion. What matters is the evidence. At present, there is no proof this is impossible, and there is no proof it is possible. We have to follow the evidence.
« Last Edit: 04/30/2015 06:26 PM by TomH »

#### Dmytry

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #131 on: 04/30/2015 06:21 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.

Just stick it in a shielded hermetic box, powered off a RC airplane battery on a timer, hang it off a hanging Cavendish style torsion pendulum (insensitive to shifts in CoM), and test it in different orientations to rule out magnetic effects. You'd be easily able to get all the drifts into sub-micronewton range with a fully shielded set up.

That's a lot cheaper than a satellite and a positive result would be much more convincing.

That will happen. This is not a secret technology controlled by a single guy claiming it works, or anything like that. The data on how to build one is in the open, accessible and feasible to replicate for anyone with enough resources and technical ability to do so.

And given its "eppur si muove" type claims, it will unavoidably emerge to the light if it works or not, as long as people keep an open and transparent review process for the test setup and the results.

And as more people perform replications on their own, they will certainly try this. So I'm really hopeful because we will soon known if it works, of if it was just a waste of time. Either way, we win (a revolutionary invention, or just knowledge).
Look at it from the point of view of a reasonable physicist. The theory makes little sense to them, so they treat it as a random attempt, those are very unlikely to succeed - an epsilon probability that it works.
The epsilon is pretty tiny because without a sensible theory we're shooting in the dark and are unlikely to hit the target.

So you hear of a positive from an experiment where there's, say, a 20% chance of a false positive or a false negative. Look up Bayes rule. You get p=0.8*epsilon/(0.8*epsilon+0.2*(1-epsilon)) ~= 4*epsilon after taking the experimental positive into account.

You need a good test with a low chance of a false positive to convince a reasonable skeptic.
« Last Edit: 04/30/2015 06:22 PM by Dmytry »

#### Dmytry

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #132 on: 04/30/2015 06:29 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.

Again, as I said above, why are you assuming constant acceleration? Constant increase in kinetic energy would eliminate this objection, at the cost of requiring a fixed inertial reference frame to measure the kinetic energy against. Standard special relativity theory does not allow this, but some newer theories that are equivalent to special relativity in their observed effects do allow this.

The observed effects are that laws of physics are invariant relative to Lorentz boosts. Maxwell equations of electromagnetism are explicitly invariant relative to Lorentz boosts. This is a purely electromagnetic device. Which part of Maxwell equations is wrong?
Exactly. There's also very tight bounds on how wrong they can be. There's all sorts of highly sensitive electronics that works the same as Earth rotates around it's axis, around the Sun, in addition to Sun's high velocity around the centre of the Milky Way.

#### ppnl

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #133 on: 04/30/2015 06:33 PM »
Skepticism and Closed Mindedness are not the same thing. The first is an important frame of mind in scientific investigation; the second is antithetical to science.

At the close of the 19th century, virtually every physicist alive was of the belief that everything that could be learned about physics was already known. As described in Thomas S. Kuhn's The Structure of Scientific Revolutions, the world of physics was about to be turned on its head. There were more than a few who accepted neither Relativity nor Quantum Mechanics. The skeptics needed to see the proof, but a skeptic examines evidence and accepts it if reasonable. A closed minded person refuses to abandon old models, in spite of new evidence to the contrary.

For over a century now, physics has found itself in limbo, a no man's land of seemingly irreconcilable contradiction between Relativity and Quantum Mechanics. Much has been learned and new discoveries continue to happen, but there is not yet a Unified Field Theory, nor a Grand Unified Field Theory, nor a Theory of Everything (each of those has a different meaning). String Theory is the leading candidate at the moment, yet there are over ten differing models of how String Theory might work. The theory of Loop Quantum Gravity is the second favored theory, and then there are lesser known theories such as Garrett Lisi's E8 Theory.

What we understand about the fabric of spacetime, about the Quantum Vacuum is still very limited. We do, however, know that it is something and not nothing. And yet we do not need fully to understand a phenomenon in to make use of it. Roentgen put X-Rays to use long before the mechanism behind their production was understood. In like manner, it is entirely possible that EM Drive may work and that it may be put to use before the entirity of the physics behind it is fully understood.

Reactions in this thread range from exuberance to completely closed minds. Science is not about jumping to conclusions, either that a theory is correct or that it is incorrect. Science is about approaching a hypothesis with an open mind, a neutrality regarding belief. It embraces a healthy skepticism for results that tend to be extreme outliers, but does accept them if they are shown to be independently repeatable by other scientists.

We used to ask whether the expanding universe had enough inertia to continue expanding forever at a decreasing rate, or if it would stop expanding and all mass implode into one singularity. Only recently did we discover the inflation is ocurring at an accelerating rate, leading us to theorize Dark Energy. It is all about the evidence. We have to follow the evidence. Whether we think this is the next great breakthrough in science or whether we think this is absurd, neither matters. This is not about opinion. What matters is the evidence. At present, there is no proof this is impossible, and there is no proof it is possible. We have to follow the evidence.

It is not close mindedness to point out that violating conservation of energy and momentum create massive problems for the supposed effect. This is especially true when many of the proponents do not understand that the conservation laws are being violated or understand the consequences of those violations.

Cold fusion should have taught us to be very very skeptical of these types of revolutionary results. Instead I suspect we will see people claiming that the EM drive finally explains where the excess energy in cold fusion comes from.

It isn't impossible that there is something interesting here. It is just very very unlikely. This combination of low probability and high desire creates a strong possibility of self deception.

#### Cinder

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #134 on: 04/30/2015 06:47 PM »
Let's keep in mind that we, here and now, got to this point after 100+ pages of attitude and discussion that's on the opposite end of that spectrum.
The pork must flow.

#### Bubbinski

##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #135 on: 04/30/2015 06:48 PM »
Many thanks to the authors of the article and to NSF.com.

I've peeked at the EM drive thread but never understood what was being talked about. I'm afraid my expertise and education are at the "caveman" level with regard to physics, but this article did a good job of making the "state of play" of this tech at least slightly more understandable for me.  *If* this works it would be a total game changer for space exploration and exploitation, and I imagine it would upend a whole bunch of assumptions about what exploration architectures to use (fuel depots, SLS, etc.).
I'll even excitedly look forward to "flags and footprints" and suborbital missions. Just fly...somewhere.

#### indigodarkwolf

##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #136 on: 04/30/2015 06:57 PM »
What I'm not following from ppnl's (and other perpetual-motion theorizers') argument is how a constant thrust, sans propellant, results in a perpetual-motion, inventing-energy-from-nowhere scheme. Surely, even with a propellant-based thruster, there exists some threshold V relative to some reference frame, wherein the loss of M from propulsion is completely dominated by the increase in V, since KE = (1/2)M*V2?

Looking at KE, or dKE/dt, seems fallacious to me for that reason. Maybe I just don't understand the math well enough.

#### Mongo62

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #137 on: 04/30/2015 07:18 PM »
It is not close mindedness to point out that violating conservation of energy and momentum create massive problems for the supposed effect. This is especially true when many of the proponents do not understand that the conservation laws are being violated or understand the consequences of those violations.

You are assuming that conservation of energy or momentum would be violated. This is only true if the device (and its attached spaceship, if any) is a closed system, but the basis of the proposed theories of how it works is that it is NOT a closed system. Instead it is coupled to the quantum vacuum somehow, and the change in momentum of the device could be balanced by an equal but opposite change in the local momentum of the quantum vacuum, which could propagate from virtual particle to virtual particle in a wave-like manner (like a sound wave) until it is transfered to (possibly quite distant) non-virtual matter. Although by then the momentum transfer per unit mass would be so tiny that it would probably be quite undetectable.

#### TomH

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #138 on: 04/30/2015 07:18 PM »
It is not close mindedness to point out that violating conservation of energy and momentum create massive problems for the supposed effect. This is especially true when many of the proponents do not understand that the conservation laws are being violated or understand the consequences of those violations.

Cold fusion should have taught us to be very very skeptical of these types of revolutionary results. Instead I suspect we will see people claiming that the EM drive finally explains where the excess energy in cold fusion comes from.

It isn't impossible that there is something interesting here. It is just very very unlikely. This combination of low probability and high desire creates a strong possibility of self deception.

I agree, it isn't closed minded to point that out. However it is closed minded if you believe what has been accepted as a LAW of physics can never be disproven or modified. That was the problem of many Newtonian physicists at the end of the 19th century. You are not going to prove this issue one way or the other through logic. It will only be proven by experimentation.

It's just like the transit time of Mercury across the sun. The measured time was said to be impossible because it violated accepted mathematical theory. All manner of bizarre explanations were proposed, until Einstein proved that the sun's gravity was warping spacetime in Mercury's orbit. Newtonian physics had to be altered to acommodate Special and General Relativity. Einstein was proven right via experiment when the moon's gravity warped spacetime and allowed the sun's corona to be seen during a total lunar eclipse. (The moon covers a slightly wider angle of the sky than the sun.) Thus was proven gravitational lensing.

Regarding these posters who are specualting about perpetual motion machines or machines with higher output than input, my skepticism is much greater about that than it is about the ability of EM to push against something in the Quantum Vacuum. Air turbine engines have much higher ISP than bi-propellant chemical rocket engines due to the ability of the turbofan to focus and thermally expand the air coming into the turbine. I do highly doubt that anything will violate conservation of momentum and energy. Nevertheless, a nuclear reactor might provide the energy for the EM Drive to push against something in the fabric of spacetime/Quantum Vacuum. We also do know that sub-atomic particles enter our universe, apparently out of sub-space. That violates the Law of Conservation from a certain POV. Perhaps the EM Drive may be activating some kind of potential energy in the Quantum Vacuum that we otherwise have not yet detected and changing it to kinetic energy. If so, that would not violate the Law of Conservation.

This theory will not be disproven by logic. It will only be disproven, or proven, by scientific experimentation and examination of emperical evidence. Anyone who thinks it will be proven solely by logical argument of currently known physics IS CLOSED MINDED. You have to experiment according to scientific method protocol and then you have to FOLLOW THE EVIDENCE.
« Last Edit: 04/30/2015 07:34 PM by TomH »

#### Ludus

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##### Re: FEATURE ARTICLE: Evaluating NASA's Futuristic EM Drive
« Reply #139 on: 04/30/2015 07:58 PM »
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.

This seems about right and is a major reason I'm skeptical. Lab experiments are pointless for convincing anyone. Based on everything reported it should be quite easy to put an EMdrive on a little satellite paid for by Kickstarter and get it a free ride in the trunk of a Dragon. It just has to change it's orbit in a way that according to claims should be easy for First Gen EM drive but also be impossible for any accepted technology. It should be able to keep up orbital maneuvering long after it would be impossible using any known design. This would be transparent and open to the world. Cue Nobel prize, whatever funding they want, Heinlein prize, eternal glory. What's stopping this?

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