Agreed, but do they have enough data yet to rule out super-symmetry (for example)? I'm not a particle physicist, so I don't understand how significant the limit on cross sections in this energy range is.
By excluding the existence of particles with certain properties, LHC eliminates some theories and that has real scientific value. In a sense the "value" of the measurements is in how different they are from theory. If LHC had NOT see a Higgs boson, that in many ways would have been more interesting than their having see one. Since the most widely accepted theories predicted a Higgs, showing that it didn't exist (within the range of expected properties) would have been very interesting. That would be similar to the Michelson Morley experiment which expected to find the "ether" but didn't.
It turns out that LHC saw the Higgs, but so far nothing else new. Since that was expected, it is not very exciting but its still useful science.
The great majority of science experiments find was was expected. The are good experiments, but its the few lucky ones that find a surprise that are most interesting.
No, I don't think it has any practical value. It is just the last and greatest of the ocean liners, a piece of history. It is (for irrational reasons) sad to see a great piece of technology rot away.
There are a lot of deep ethical problems here. Do we want to "cure" conditions that cause people to be troublesome and not follow orders?
I'd like to see careful discussion about what is and isn't OK. That isn't unusual - I'm not allowed to just build a nuclear reactor in my back yard either - dangerous projects require reasonable review .
Maybe if I saw random clips and pictures from the Olympics I might think about watching through some approved channel. As it stands, I likely will forget they are on and not watch at all.
Whether or not this is interesting really depends on the expected power / area and cost (production and operating) of an engineering version. It is better than bio-fuels by those measures?
How does a non-expert know whether this really is secure or has a NSA / FBI / Chinese etc back door. The government can easily afford to pay people to post on public forums like this claiming that any particular software is or is not secure.
Open source doesn't really help since very few people are expert enough (or have time) to review the code, and its impossible to tell if other "experts" are paid to spread misinformation.
A wire pendulum suspension (like used on LIGIO) is probably the most sensitive. do it in hard vacuum to get rid of convection currents. Power the device with batteries, and put it all in an insulated box whos outside temperature doesn't change significantly during a short run. Then pulse the engine at the pendulum frequency . Its a doable experiment but quite a lot of work to get right.
For subsonic planes like airlines, the "jet" engines are high bypass and the majority of the thrust comes from the ducted fan . Ducted fans behave like propellers, the ducts improve efficiency at near sonic speeds, but otherwise there is not much difference. There is a little thrust from the jet exhaust, but that is low efficiency because its velocity is so much higher than the aircraft efficiency.
If you looked at the ISP of a prop plane it would be very high since the reaction mass is moving slowly. This sounds counter-intuitive becuase for a rocket a high exhaust velocity -> high ISP. The difference is that for a rocket the energy source and the reaction mass are the same thing. The momentum goes as MV, while the energy goes as 0.5MV^2 . So the energy / momentum goes as V. If you have an external medium to move (air), you want a low exhaust velocity (about the same as the aircraft speed). If you have to carry the reaction mass you want a high exhaust velociyt.
Its interesting (surprising) that turbine engines are actually a bit less efficient than most piston engines. See: https://en.wikipedia.org/wiki/... Note that the 1996 turboprop engine is less efficient than the simlar size and application piston engine. The turbine engine is much lighter so the overall aircraft efficiency is better. Similarly the diesel ship engines are more efficient that turbine ship engines of similar sizes.
In turbines the maximum combustion temperature has to be within the operating range of the turbine blades. For a piston engine, the high temperatures in the middle of the cylinder don't have time to melt the metal before it is cooled on the next cycle. Piston engines can run with hotter combustion temperatures so they have better base Carnot efficient. There is a fantastic set of books by Taylor: "the internal combustion engine in theory and practice" that is great reading for anyone really interested in how engines work. I found a lot of surprises.
You mention that the high exhaust velocity of jets reduces their efficiency in low speed applications. That is in addition to the above thermodynamic efficiency.
Lots of tradeoffs. Airflow over the wings helps takeoff performance, but the disrupted airflow from the props in cruise is likely top reduce efficiency. Generally for low speed aircraft you want as few total propeller blades as you can use in order to reduce the losses from blade tip vortices. (practical effects like prop diameter will often force you to more props and more blades).
Ground effect planes are interesting. The Russians did a lot with those. https://en.wikipedia.org/wiki/... I think the biggest problem is that the low altitude environment is pretty hostile - waves, birds, floating obstructions etc. In principal though they are more efficient than airplanes.
My comment really was that using buoyancy lift seems like it should provide a major fuel savings, but in practice (I've looked at other examples as well) it doesn't seem to make a lot of difference to the overall efficiency. It is very helpful if you want vertical takeoff - helicopters are very inefficient .
The examples I gave used the same technology engines so I figured that canceled out. It also turns out that aircraft piston engines are pretty efficient - its simple design, almost single operating point, so its much easier to get good efficiency than it is for a car engine) . there has been little change in aircraft piston engine efficiency since 1960. Jets are actually less efficient, but the lighter weight more than makes up for that. Going to high bypss jets has made the biggest difference. Aircraft aerodynamics has improved some. I don't know if its possible to improve the aerodynamics of buoyant craft.
Lighter than air craft have a lot of problems. The energy use isn't as as low as you might imagine - there is no drag due to drift, but the large frontal area resulst in a lot of parasitic drag except at very low speeds. Winds, ice etc can be a serious problem, and they typically can't climb above weather.
one example at http://www.zeppelinflug.de/en/ carries 16 people, 80mph, 600hp total engines, range 600 miles (they don't give detailed specs).
Compare with a 1960s beechcraft baron: 6 people, 230mph, 600HP total engines, range ~800miles
person miles / gallon seems to be in the same ballpark. The airship may be a lot more pleasant to fly in, but its isn't substantially more efficient .
Most other hardware doesn't have the external and CPU interfaces. A disk driver probably cannot do anything very useful with the data it sees if you use disk encryption. It can't read the data and probably doesn't have external network access.
This management system by design has low level access to the CPU and external interfaces. It is potentially a much more capable hacking tool.
Its not easy to think of a reason that there is not a local hardware disable since the management capabilities are not needed by a substantial number of users.
If Intel knows how to access the chip, presumably they can be ordered to do so by the government, making this a universal back door.
Black body radiation was measured a long time ago, back when we were just stating to be able to do complex quantitative measurements. It was measured in the late 1800s, and explained by quantum mechanics.
The problem with the EM drive and new physics is that it is operating under very normal conditions - modest frequencies, field strengths and length scales. There is a huge amount of experimentation, intentional, and as a side effect of normal engineering in this parameter range. There really is no reason to expect this particular experiment to find new physics because they are not doing anything particularly new.
LIGO does get a lot out of looking for common signals between detectors but it also has exceptionally good isolation from ground motion. Of course it is looking for very much smaller signals. It also only looks at non DC effects. Its really a completely different animal. (BTW I worked on the predecessor to LIGO in 1983....awesome to see those guys finally succeed!)
The problem with the EM drive is that if it generate more thrust than a photon drive would for the same input power, without using any propellant, it violates basic physics and cannot work. If it uses propellant, then it is just a rocket. If it generates the same thrust as a photon drive, then it has the same problem of requiring an impractical amount of power to produce useful thrust.
I don't believe that they have corrected for all the external effects. Its a really tricky problem to get right.
I'm an experimental physicist and I can imagine how to do this experiment, but it would be a lot of effort and expense to do it correctly. There are a huge number of effects to take into account. The basic problem is that you are changing the power to the device by a lot, which can cause heating, and then trying to measure an extremely tiny force as a result.
the gravity wave detectors take GREAT pains to make sure that noting touches the test masses except the suspension cables (which are single crystal fibers). Testing the EM drive requires power cables, or microwave waveguides - either of which can produce substantial forces when it warms up from power running through it.
You could do the experiment, but it would be a lot of work, and its certain to fail.
If they are confident of their security, they ought to be able to get Lloyds to insure users against any break-ins or damages at the few X 100B$ level. Oh, maybe they can't convince Lloyds that it is *that* secure?
One thing that Snowdon taught us is that even the NSA cannot protect secrets. And yes, you can fault the entire program because of a single slip up.
Looking at your link: Its true that in a waveguide electromagnetic radiation propagates at different speeds than in a vacuum. The group velocity is lower than C, and the phase velocity is higher. There is some force on each end plate, and some net longitudinal force on the tapered side walls. You could do a complicated simulation / calculation to sum up the forces (difficult to get correct due to the complex boundary conditions), or you can fall back on basic principals. Imagine that the walls are prefect conductors. Break up the volume into tiny cells. Maxwell's equations are obeyed in each volume. Those equations conserve momentum. Since momentum is conserved in each tiny volume element, it is conserved in the entire system.
The think is, they ARE claiming violation of momentum conservation. Depending on what paper you read they claim that either:
A closed system generates force without any exhaust. That is by definition violation of conservation of momentum.
OR
A system generates thrust without consuming any fuel, AND that thrust is larger for the amount of power applied than can be explained by emission of photons. To produce momentum in the rocket, you need to produce the same (opposite direction) momentum in the exhaust. If you are not consuming fuel, the mass of the exhaust must be created from the energy consumed. This is a photon drive - you create mass (photons) that are emitted at the speed of light. If you emit the mass at a lower speed it will have less momentum for the same total energy (including the energy required to create the mass).
If there was some background to push against, then the drive could work. But many many experiments (starting with Michelson Morley) have shown that there is no background ether you can push against. If there was such a background that had somehow escaped all experiments, there is no reason to think it would show up in this particular experiment.
Unruh radiation is a complete red hearing. Its only significant at extreme accelerations and it will conserve momentum
Now, to be clear: if they are only claiming the same thrust as a photon drive, then it can work through some mechanism, but its also boring - its easy to build a photon drive, just no practical way to power one.
If they are claiming that some of the mass oft he rocket is used as exhaust, then that is just a different type of rocket and that is OK.
What is not possible is for it to both not consume fuel AND produce more thrust power than does a photon drive.
Its difficult to explain to a layman because you don't have the background. Imagine explaining why 2048 bit RSA is difficult to crack to someone who doesn't have the math background.
They claim to produce thrust without any exhaust. That is a violation of conservation of momentum. If they claim that the exhaust in just photons, then that is a standard photon drive which works but has a well known power / thurst ratio that is too high for practical applications. If you generate microwaves and send them out the back of a spacecraft you will get thrust, but the power requirements are too large to be useful.
Electromagnetism is the theory of photons, microwaves, electric fields, magnetic fields. So it does cover this experiment. Electro-weak theory is an extension of electromagnetism to high energies - but the changes are not significant for this experiment..
Tunneling is understood. If the photons tunnel then some of the photons are being used as exhaust. That works but it is a standard photon drive. No point having them tunnel though, might as well just point the microwave source out the back of the spacecraft. (but see above for energy requirements). Tunneling is insignificant for think materials of the sort that they used here, so there will be essentially no emission of tunneled photons in this experiment.
My understanding is that the EM drive claims to produce thrust with no exhaust, and / or claims to produce more thrust / power than can be produce by photons. Neither of those is possible because both violate conservation of energy / momentum. (the energy/ momentum ratio of a photon is known).
To be clear I was quoting the article's INCORRECT description.
In locations where the photons fields vanish, the energy density vanishes. The probability of finding photons IN THOSE LOCATIONS goes to zero. Think of it as waves - if I drop two rocks in the water, there will be places where the waves interfere and there is not wave amplitude. That means that there are no waves in that location, but it doesn't mean that all the waves have vanished everywhere.
I believe that the drive is not in fact working. The forces that they are talking about are tiny and very difficult to measure. These are ~100 micro newton forces on a ~10Kg object. There are a lot of boring things that could mimic thrust:
Small tilts of the experimental apparatus: this could be as simple as experimenters standing on different parts of the lab floor when they turn on and off the RF power. Cable and RF waveguide expansion - there will be some heat dissipated in the RF cable, that might make it flex.
Gas desorption - the system was tested in vacuum, but when RF power is put it, it presumably gets hot and the hot parts can release gas trapped on the surface of the metal. Magnetic fields that change when the power supply is turned on. They have tried to correct for effects like this but Its a really difficult experiment to do correctly. This really is the key issue. There is no theoretical reason to think the drive should work and the experimental evidence is from an experiment that is very easy to get wrong.
The EM drive claims to produce thrust from electromagnetic fields, so electromagnetism should be able to predict the effect and it does not. GeV interactions are an example of a test of electromagnetics (+weak force) at very high energies. Planetary magnetic fields are an example of a test of electromagnetism in very weak fields. Basically electromagnetism has been tested over a very wide range of conditions, there is no reason to think it should not work for this particular experiment.
The explanations for the effect do not use standard physics - photons do not go through metal walls when the fields cancel - that doesn't make physics sense.
The best I can do is to say to remember this. You can't know which "expert" to trust, so instead wait 20 years and see whether or not this is ever turned into something real, or like cold fusion remains in the background, never actually becoming real because it doesn't work.
In the article they say "These photon pairs without net electromagnetic field do not reflect back from the metal walls but escape from the resonator" This doesn't make sense. If the electromagnetic fields from the photons cancel, then the energy density and probability of finding a photon vanishes. There is nothing in that location to escape.
The more general argument is that all known physics (including quantum, gravity and relativity) conserves momentum (4-momentum if you are using relativistic terms). Since momentum is conserved in every interaction, it has to be conserved in the overall system. It is almost exactly the same reason that you can't make a perpetual motion machine out of gears and pulleys.
Experimentally there is lots of evidence that this doesn't work. I'm an accelerator physicist, I work with high (and low) power microwave systems which cavities with much higher fields than in this experiment. Some of the superconducting cavities are extremely sensitive to loss (1e-10/cycle) and no unexpected loss is seen. No unexpected forces are seen.
Electromagnetism (with electro-weak as an extension) is understood and measured from the scale of planetary magnetic fields (maybe even galactic), to 100 GeV interactions in lepton colliders. There really is no room for new physics to be hiding
The descriptions use words that sound like science but they don't actually make scientific sense. The most charitable explanation is that the writers are confused, but of course in general they are looking for funding......
The electromagnetic field strength is linked to the energy density of the field. If the electric fields from the photons cancel in some location, then there is no energy density in that location and no probability of finding a photon there. If the photon fields cancel at the metal, then there is nothing to escape. eg. the article doesn't make any sense at all.
Conservation of (relativistic) momentum is conserved in all particle interactions - even in quantum mechanics. The only way the EM drive can work is if there is entirely new physics. There is no reason at all to expect new physics - frequencies and microwave intensities in the system are not at all unusual. Accelerator cavities have fields thousands of times stronger at similar frequencies and there is no behavior seen that isn't predicted by E&M. Particle interactions have fields enormously stronger (though at higher frequencies) and the divergence from standard electromagnetism match the predictions of electro-weak interactions which also conserve momentum.
Accurately measuring these small forces is technically very difficult, it is not at all surprising that uninteresting effects (thermal radiation pressure, cable distortion, magnetic fields, etc) are difficult to factor out of the equation.
It is as certain as anything is in science that the EM drive cannot work. Electromagnetism (with electro-weak included) has been tested over an enormously wide range of conditions, with no deviations from theory found.
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Agreed, but do they have enough data yet to rule out super-symmetry (for example)? I'm not a particle physicist, so I don't understand how significant the limit on cross sections in this energy range is.
By excluding the existence of particles with certain properties, LHC eliminates some theories and that has real scientific value. In a sense the "value" of the measurements is in how different they are from theory. If LHC had NOT see a Higgs boson, that in many ways would have been more interesting than their having see one. Since the most widely accepted theories predicted a Higgs, showing that it didn't exist (within the range of expected properties) would have been very interesting. That would be similar to the Michelson Morley experiment which expected to find the "ether" but didn't.
It turns out that LHC saw the Higgs, but so far nothing else new. Since that was expected, it is not very exciting but its still useful science.
The great majority of science experiments find was was expected. The are good experiments, but its the few lucky ones that find a surprise that are most interesting.
No, I don't think it has any practical value. It is just the last and greatest of the ocean liners, a piece of history. It is (for irrational reasons) sad to see a great piece of technology rot away.
The risk is not just external.
There are a lot of deep ethical problems here. Do we want to "cure" conditions that cause people to be troublesome and not follow orders?
I'd like to see careful discussion about what is and isn't OK. That isn't unusual - I'm not allowed to just build a nuclear reactor in my back yard either - dangerous projects require reasonable review .
Maybe if I saw random clips and pictures from the Olympics I might think about watching through some approved channel. As it stands, I likely will forget they are on and not watch at all.
Whether or not this is interesting really depends on the expected power / area and cost (production and operating) of an engineering version. It is better than bio-fuels by those measures?
This doesn't bother me at all. I'm sure that my employer would see that I have the complete confidence in management and enthusiasm for our mission.
How does a non-expert know whether this really is secure or has a NSA / FBI / Chinese etc back door. The government can easily afford to pay people to post on public forums like this claiming that any particular software is or is not secure.
Open source doesn't really help since very few people are expert enough (or have time) to review the code, and its impossible to tell if other "experts" are paid to spread misinformation.
A wire pendulum suspension (like used on LIGIO) is probably the most sensitive. do it in hard vacuum to get rid of convection currents. Power the device with batteries, and put it all in an insulated box whos outside temperature doesn't change significantly during a short run. Then pulse the engine at the pendulum frequency . Its a doable experiment but quite a lot of work to get right.
For subsonic planes like airlines, the "jet" engines are high bypass and the majority of the thrust comes from the ducted fan . Ducted fans behave like propellers, the ducts improve efficiency at near sonic speeds, but otherwise there is not much difference. There is a little thrust from the jet exhaust, but that is low efficiency because its velocity is so much higher than the aircraft efficiency.
If you looked at the ISP of a prop plane it would be very high since the reaction mass is moving slowly. This sounds counter-intuitive becuase for a rocket a high exhaust velocity -> high ISP. The difference is that for a rocket the energy source and the reaction mass are the same thing. The momentum goes as MV, while the energy goes as 0.5MV^2 . So the energy / momentum goes as V. If you have an external medium to move (air), you want a low exhaust velocity (about the same as the aircraft speed). If you have to carry the reaction mass you want a high exhaust velociyt.
Its interesting (surprising) that turbine engines are actually a bit less efficient than most piston engines. See: https://en.wikipedia.org/wiki/... Note that the 1996 turboprop engine is less efficient than the simlar size and application piston engine. The turbine engine is much lighter so the overall aircraft efficiency is better. Similarly the diesel ship engines are more efficient that turbine ship engines of similar sizes.
In turbines the maximum combustion temperature has to be within the operating range of the turbine blades. For a piston engine, the high temperatures in the middle of the cylinder don't have time to melt the metal before it is cooled on the next cycle. Piston engines can run with hotter combustion temperatures so they have better base Carnot efficient. There is a fantastic set of books by Taylor: "the internal combustion engine in theory and practice" that is great reading for anyone really interested in how engines work. I found a lot of surprises.
You mention that the high exhaust velocity of jets reduces their efficiency in low speed applications. That is in addition to the above thermodynamic efficiency.
Lots of tradeoffs. Airflow over the wings helps takeoff performance, but the disrupted airflow from the props in cruise is likely top reduce efficiency. Generally for low speed aircraft you want as few total propeller blades as you can use in order to reduce the losses from blade tip vortices. (practical effects like prop diameter will often force you to more props and more blades).
Ground effect planes are interesting. The Russians did a lot with those. https://en.wikipedia.org/wiki/...
I think the biggest problem is that the low altitude environment is pretty hostile - waves, birds, floating obstructions etc. In principal though they are more efficient than airplanes.
My comment really was that using buoyancy lift seems like it should provide a major fuel savings, but in practice (I've looked at other examples as well) it doesn't seem to make a lot of difference to the overall efficiency. It is very helpful if you want vertical takeoff - helicopters are very inefficient .
The examples I gave used the same technology engines so I figured that canceled out. It also turns out that aircraft piston engines are pretty efficient - its simple design, almost single operating point, so its much easier to get good efficiency than it is for a car engine) . there has been little change in aircraft piston engine efficiency since 1960. Jets are actually less efficient, but the lighter weight more than makes up for that. Going to high bypss jets has made the biggest difference. Aircraft aerodynamics has improved some. I don't know if its possible to improve the aerodynamics of buoyant craft.
Lighter than air craft have a lot of problems. The energy use isn't as as low as you might imagine - there is no drag due to drift, but the large frontal area resulst in a lot of parasitic drag except at very low speeds. Winds, ice etc can be a serious problem, and they typically can't climb above weather.
one example at http://www.zeppelinflug.de/en/
carries 16 people, 80mph, 600hp total engines, range 600 miles (they don't give detailed specs).
Compare with a 1960s beechcraft baron:
6 people, 230mph, 600HP total engines, range ~800miles
person miles / gallon seems to be in the same ballpark. The airship may be a lot more pleasant to fly in, but its isn't substantially more efficient .
Most other hardware doesn't have the external and CPU interfaces. A disk driver probably cannot do anything very useful with the data it sees if you use disk encryption. It can't read the data and probably doesn't have external network access.
This management system by design has low level access to the CPU and external interfaces. It is potentially a much more capable hacking tool.
Its not easy to think of a reason that there is not a local hardware disable since the management capabilities are not needed by a substantial number of users.
If Intel knows how to access the chip, presumably they can be ordered to do so by the government, making this a universal back door.
Black body radiation was measured a long time ago, back when we were just stating to be able to do complex quantitative measurements. It was measured in the late 1800s, and explained by quantum mechanics.
The problem with the EM drive and new physics is that it is operating under very normal conditions - modest frequencies, field strengths and length scales. There is a huge amount of experimentation, intentional, and as a side effect of normal engineering in this parameter range. There really is no reason to expect this particular experiment to find new physics because they are not doing anything particularly new.
LIGO does get a lot out of looking for common signals between detectors but it also has exceptionally good isolation from ground motion. Of course it is looking for very much smaller signals. It also only looks at non DC effects. Its really a completely different animal. (BTW I worked on the predecessor to LIGO in 1983....awesome to see those guys finally succeed!)
The problem with the EM drive is that if it generate more thrust than a photon drive would for the same input power, without using any propellant, it violates basic physics and cannot work. If it uses propellant, then it is just a rocket. If it generates the same thrust as a photon drive, then it has the same problem of requiring an impractical amount of power to produce useful thrust.
I don't believe that they have corrected for all the external effects. Its a really tricky problem to get right.
I'm an experimental physicist and I can imagine how to do this experiment, but it would be a lot of effort and expense to do it correctly. There are a huge number of effects to take into account. The basic problem is that you are changing the power to the device by a lot, which can cause heating, and then trying to measure an extremely tiny force as a result.
the gravity wave detectors take GREAT pains to make sure that noting touches the test masses except the suspension cables (which are single crystal fibers). Testing the EM drive requires power cables, or microwave waveguides - either of which can produce substantial forces when it warms up from power running through it.
You could do the experiment, but it would be a lot of work, and its certain to fail.
If they are confident of their security, they ought to be able to get Lloyds to insure users against any break-ins or damages at the few X 100B$ level. Oh, maybe they can't convince Lloyds that it is *that* secure?
One thing that Snowdon taught us is that even the NSA cannot protect secrets. And yes, you can fault the entire program because of a single slip up.
Are you a physicist?
Looking at your link: Its true that in a waveguide electromagnetic radiation propagates at different speeds than in a vacuum. The group velocity is lower than C, and the phase velocity is higher. There is some force on each end plate, and some net longitudinal force on the tapered side walls. You could do a complicated simulation / calculation to sum up the forces (difficult to get correct due to the complex boundary conditions), or you can fall back on basic principals. Imagine that the walls are prefect conductors. Break up the volume into tiny cells. Maxwell's equations are obeyed in each volume. Those equations conserve momentum. Since momentum is conserved in each tiny volume element, it is conserved in the entire system.
The think is, they ARE claiming violation of momentum conservation. Depending on what paper you read they claim that either:
A closed system generates force without any exhaust. That is by definition violation of conservation of momentum.
OR
A system generates thrust without consuming any fuel, AND that thrust is larger for the amount of power applied than can be explained by emission of photons. To produce momentum in the rocket, you need to produce the same (opposite direction) momentum in the exhaust. If you are not consuming fuel, the mass of the exhaust must be created from the energy consumed. This is a photon drive - you create mass (photons) that are emitted at the speed of light. If you emit the mass at a lower speed it will have less momentum for the same total energy (including the energy required to create the mass).
If there was some background to push against, then the drive could work. But many many experiments (starting with Michelson Morley) have shown that there is no background ether you can push against. If there was such a background that had somehow escaped all experiments, there is no reason to think it would show up in this particular experiment.
Unruh radiation is a complete red hearing. Its only significant at extreme accelerations and it will conserve momentum
Now, to be clear: if they are only claiming the same thrust as a photon drive, then it can work through some mechanism, but its also boring - its easy to build a photon drive, just no practical way to power one.
If they are claiming that some of the mass oft he rocket is used as exhaust, then that is just a different type of rocket and that is OK.
What is not possible is for it to both not consume fuel AND produce more thrust power than does a photon drive.
Its difficult to explain to a layman because you don't have the background. Imagine explaining why 2048 bit RSA is difficult to crack to someone who doesn't have the math background.
They claim to produce thrust without any exhaust. That is a violation of conservation of momentum. If they claim that the exhaust in just photons, then that is a standard photon drive which works but has a well known power / thurst ratio that is too high for practical applications. If you generate microwaves and send them out the back of a spacecraft you will get thrust, but the power requirements are too large to be useful.
Electromagnetism is the theory of photons, microwaves, electric fields, magnetic fields. So it does cover this experiment. Electro-weak theory is an extension of electromagnetism to high energies - but the changes are not significant for this experiment..
Tunneling is understood. If the photons tunnel then some of the photons are being used as exhaust. That works but it is a standard photon drive. No point having them tunnel though, might as well just point the microwave source out the back of the spacecraft. (but see above for energy requirements). Tunneling is insignificant for think materials of the sort that they used here, so there will be essentially no emission of tunneled photons in this experiment.
My understanding is that the EM drive claims to produce thrust with no exhaust, and / or claims to produce more thrust / power than can be produce by photons. Neither of those is possible because both violate conservation of energy / momentum. (the energy/ momentum ratio of a photon is known).
What do you see as their claim?
To be clear I was quoting the article's INCORRECT description.
In locations where the photons fields vanish, the energy density vanishes. The probability of finding photons IN THOSE LOCATIONS goes to zero. Think of it as waves - if I drop two rocks in the water, there will be places where the waves interfere and there is not wave amplitude. That means that there are no waves in that location, but it doesn't mean that all the waves have vanished everywhere.
I believe that the drive is not in fact working. The forces that they are talking about are tiny and very difficult to measure. These are ~100 micro newton forces on a ~10Kg object. There are a lot of boring things that could mimic thrust:
Small tilts of the experimental apparatus: this could be as simple as experimenters standing on different parts of the lab floor when they turn on and off the RF power. Cable and RF waveguide expansion - there will be some heat dissipated in the RF cable, that might make it flex.
Gas desorption - the system was tested in vacuum, but when RF power is put it, it presumably gets hot and the hot parts can release gas trapped on the surface of the metal. Magnetic fields that change when the power supply is turned on. They have tried to correct for effects like this but Its a really difficult experiment to do correctly. This really is the key issue. There is no theoretical reason to think the drive should work and the experimental evidence is from an experiment that is very easy to get wrong.
The EM drive claims to produce thrust from electromagnetic fields, so electromagnetism should be able to predict the effect and it does not. GeV interactions are an example of a test of electromagnetics (+weak force) at very high energies. Planetary magnetic fields are an example of a test of electromagnetism in very weak fields. Basically electromagnetism has been tested over a very wide range of conditions, there is no reason to think it should not work for this particular experiment.
The explanations for the effect do not use standard physics - photons do not go through metal walls when the fields cancel - that doesn't make physics sense.
The best I can do is to say to remember this. You can't know which "expert" to trust, so instead wait 20 years and see whether or not this is ever turned into something real, or like cold fusion remains in the background, never actually becoming real because it doesn't work.
In the article they say "These photon pairs without net electromagnetic field do not reflect back from the metal walls but escape from the resonator" This doesn't make sense. If the electromagnetic fields from the photons cancel, then the energy density and probability of finding a photon vanishes. There is nothing in that location to escape.
The more general argument is that all known physics (including quantum, gravity and relativity) conserves momentum (4-momentum if you are using relativistic terms). Since momentum is conserved in every interaction, it has to be conserved in the overall system. It is almost exactly the same reason that you can't make a perpetual motion machine out of gears and pulleys.
Experimentally there is lots of evidence that this doesn't work. I'm an accelerator physicist, I work with high (and low) power microwave systems which cavities with much higher fields than in this experiment. Some of the superconducting cavities are extremely sensitive to loss (1e-10/cycle) and no unexpected loss is seen. No unexpected forces are seen.
Electromagnetism (with electro-weak as an extension) is understood and measured from the scale of planetary magnetic fields (maybe even galactic), to 100 GeV interactions in lepton colliders. There really is no room for new physics to be hiding
The descriptions use words that sound like science but they don't actually make scientific sense. The most charitable explanation is that the writers are confused, but of course in general they are looking for funding......
The electromagnetic field strength is linked to the energy density of the field. If the electric fields from the photons cancel in some location, then there is no energy density in that location and no probability of finding a photon there. If the photon fields cancel at the metal, then there is nothing to escape. eg. the article doesn't make any sense at all.
Conservation of (relativistic) momentum is conserved in all particle interactions - even in quantum mechanics. The only way the EM drive can work is if there is entirely new physics. There is no reason at all to expect new physics - frequencies and microwave intensities in the system are not at all unusual. Accelerator cavities have fields thousands of times stronger at similar frequencies and there is no behavior seen that isn't predicted by E&M. Particle interactions have fields enormously stronger (though at higher frequencies) and the divergence from standard electromagnetism match the predictions of electro-weak interactions which also conserve momentum.
Accurately measuring these small forces is technically very difficult, it is not at all surprising that uninteresting effects (thermal radiation pressure, cable distortion, magnetic fields, etc) are difficult to factor out of the equation.
It is as certain as anything is in science that the EM drive cannot work. Electromagnetism (with electro-weak included) has been tested over an enormously wide range of conditions, with no deviations from theory found.