EmDrive

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Re: EmDrive

Unread postby Zyxzevn » Mon Oct 31, 2016 3:57 pm

willendure wrote:Take a look at this work:

http://physicsfromtheedge.blogspot.co.u ... ta-3d.html


With powers around 1000 watt, I think that the electromagnetic interference from the cables is gigantic.
And I was looking for a push caused by the electric currents and the machine, possibly in combination with
resonating effects and in combination with Earth's magnetic field.

But I found another problem as well:
"
It consists of a truncated metal cone (cavity) with a magnetron inside that inputs EM radiation with the same wavelength as the size of the cavity
"
That means that the cavity becomes a transmitter, like an antenna.
Problem solved, if you ask me.
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Re: EmDrive

Unread postby upriver » Tue Nov 08, 2016 2:01 pm

Zyxzevn wrote:
willendure wrote:Take a look at this work:

http://physicsfromtheedge.blogspot.co.u ... ta-3d.html


With powers around 1000 watt, I think that the electromagnetic interference from the cables is gigantic.
And I was looking for a push caused by the electric currents and the machine, possibly in combination with
resonating effects and in combination with Earth's magnetic field.

But I found another problem as well:
"
It consists of a truncated metal cone (cavity) with a magnetron inside that inputs EM radiation with the same wavelength as the size of the cavity
"
That means that the cavity becomes a transmitter, like an antenna.
Problem solved, if you ask me.


The magnetron is the transmitter and the cavity is the absorber. The cavity absorbs the kinetic energy from the EM waves.

"Resonant cavities have finite extent in the axial direction. Electromagnetic waves are reflected at
the axial boundaries, giving rise to the standing-wave patterns that constitute resonant modes"

See 12.7 TRANSMISSION LINE TREATMENT OF THE RESONANT CAVITY

http://web.mit.edu/22.09/ClassHandouts/ ... CHAP12.PDF
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Re: EmDrive

Unread postby Zyxzevn » Tue Nov 08, 2016 4:30 pm



In 12.8 there is something what I meant:
.. Furthermore, it is possible to transport particle beams in a waveguide in
synchronism with the wave phase velocity so that they continually gain energy. ..

This means that the standing electromagnetic wave becomes stronger and stronger.

Now let us consider the surface currents (which I could not find in the book).

While these are usually small, the rest of the underlying metal need to compensate for the
changing electromagnetic fields inside the cavity.
And these currents need to be compensated again.
This usually gives the surface penetration of EM waves a exponential reducing character.
But if all of these are standing waves, these minuscule EM waves can still grown larger,
and thus giving a standing wave at the outside of the cavity, not just inside in the surface layer.

I saw a good example of this on electromagnetic shielding on youtube, but can't find it now.
It showed that microwaves of certain frequencies can penetrate shielding.
It depends on material and thickness, so it would be possible to test.
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Re: EmDrive

Unread postby willendure » Thu Nov 10, 2016 4:11 pm

Zyxzevn wrote:With powers around 1000 watt, I think that the electromagnetic interference from the cables is gigantic.
And I was looking for a push caused by the electric currents and the machine, possibly in combination with
resonating effects and in combination with Earth's magnetic field.

But I found another problem as well:
"
It consists of a truncated metal cone (cavity) with a magnetron inside that inputs EM radiation with the same wavelength as the size of the cavity
"
That means that the cavity becomes a transmitter, like an antenna.
Problem solved, if you ask me.


Here is the paper, supposedly it was RF shielded:

https://regmedia.co.uk/2016/11/09/q_thruster.pdf
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Re: EmDrive

Unread postby allynh » Mon Nov 14, 2016 2:02 pm

The Fact and Fiction of the NASA EmDrive Paper Leak
http://motherboard.vice.com/read/the-fa ... paper-leak
November 14, 2016 // 05:00 AM EST
If humanity ever wants to truly explore the outer reaches of our solar system or travel to other stars, we’re going to have to build a better engine for our spacecraft. In fact, this engine will have to be so good that it will be capable of generating thrust without consuming propellant. That’s right: If we ever want a four-hour trip to the moon or a two-month trip to Mars, we’re going to need a rocket engine that doesn’t need rocket fuel.

This is the idea behind the radio frequency resonant cavity thruster—otherwise known as EmDrive—a theoretical reactionless engine powered by turning electricity into microwaves and bouncing them around a closed metal funnel.

The EmDrive has been dismissed as “impossible” on more than one occasion because it appears to violate Newton’s Third Law of Motion, which states that for every action there is an equal and opposite reaction. But if a leaked NASA paper posted online last Saturday is to be believed, then not only are NASA scientists pursuing an EmDrive, but they actually made one that works.

As detailed in the paper, a team of NASA physicists led by Harold “Sonny” White and Paul March—both leading figures in exotic propulsion systems—was able to generate thrust in a “tapered RF test article” (read: EmDrive prototype) during a series of tests at NASA’s Eagleworks Labs at Johnson Space Center in the fall of 2015.

In essence, the NASA EmDrive in the paper consists of a closed copper cone, the inside of which is being bombarded with microwaves. To test the EmDrive, the researchers powered it with 40, 60, and 80 watts and found that it generated up to 58, 128, and 119 micronewtons of thrust, respectively. Given that this “anomaly” was still observed by White and his colleagues after accounting for error, this suggests that the results of the experiment show an EmDrive is indeed possible.

Based on these results, the researchers estimated that their contraption would be capable of generating approximately 1.2 millinewtons of thrust per kilowatt were they to scale up the power input. To put this in perspective, the Hall thruster—one of the most powerful in development and powered by ejecting plasma—generates about 60 millinewtons of thrust per kilowatt.



The EmDrive described in the leaked NASA paper. Image: White, et al./NASA

“The issue involved here is whether the experiment is seeing something real or not,” Jim Woodward, a physicist at California State-Fullerton, told Motherboard. “I know Paul [March] does clean work and to be honest, I suspect there may really be something there. But the result they're seeing can't actually be explained in terms of the theory they're proposing. So the question is: what is causing it?”

Per Newton, if you want to propel a rocket through space, you’re going to have to eject some material in the opposite direction of the rocket’s travel. But an EmDrive appears to generate a reaction without any action—so what gives?

A number of theories have been floated attempting to explain this ostensible violation of the bedrock of physics. White has been a proponent of the quantum vacuum explanation, which posits that the EmDrive is able to generate thrust by acting on virtual particle pairs that are generated by fluctuations in the quantum vacuum (in this theory, these vacuum fluctuations are created by the electromagnetic field generated by the EmDrive). In essence, the microwaves would be ‘pushing off’ of these virtual particles within the EmDrive cavity to generate the thrust that has been observed by White and his colleagues in EmDrive experiments.

Another leading explanation is that the EmDrive’s thrust is generated by radiation pressure, a position held by its inventor Roger Shawyer. On this view, when the microwave radiation enters the copper cavity, the radiation pushes against the walls of the EmDrive and generates thrust.

Yet, according to Woodward, both of these theories are unlikely to be correct for a simple reason: Physics doesn’t allow them.

By way of example, Woodward likened explaining the results seen at NASA purely in terms of microwave pressure to arguing that you can accelerate a car by getting in the driver’s seat and pushing on the windshield.

“Can any disposition of microwaves inside the cavity produce thrust?” said Woodward. “There's a simple answer to that question: No, it cannot. Conservation of momentum dictates that any purely electromagnetic system that is enclosed cannot produce thrust. This is for both quantum theory and classical electrodynamics. It's physically impossible.”

This is what led White to his quantum-vacuum theory: If the microwaves can’t push against the inside walls in the copper cone to generate thrust, then they must be pushing off of something else within the cone—like virtual particle/anti-particle pairs that exist in the quantum vacuum. The problem is that while the existence of the quantum vacuum has been experimentally proven to exist, physicists are in pretty strong agreement that it can’t be used as a medium to generate thrust.

Although White’s quantum vacuum theory is referenced as the theoretical explanation of the thrust observed in both the recently leaked NASA paper and the first NASA EmDrive paper from 2014, it has been debunked time and time again by leading physicists within the community.



EmDrive inventor Roger Shawyer demonstrates why he thinks radiation pressure explains the EmDrive thrust

“A theoretical construct related to the quantum vacuum is nonsense,” said Woodward. “There is no experimental evidence that suggests anything remotely like [White’s theory] is a reasonable way to view the vacuum. It's something that no serious quantum field theorist takes seriously as far as I know.”

Instead, Woodward thinks that the results of NASA’s EmDrive experiments can be explained without having to overturn the basic laws of physics.

“The Mach effect is the only possible way to explain this,” said Woodward. “If they are looking at a real anomalous signal, and you want to try to explain it with physics that is not nonsense, then that seems to be the only way to approach this.”

As the first person to theorize about Mach effects in 1990, Woodward should know. According to Woodward’s Mach effect theory, when a body of mass is accelerated, some of the force applied to that body does not result in kinetic energy but is stored as potential energy in the body. While the acceleration is changing the internal energy of the body changes as well, which manifests itself as a change in the resting mass of that body.

The accelerating body is essentially being squished between the force being applied in the direction of its acceleration and the pushback from the rest of the material in the universe via a gravitational field. These two oppositional forces change the internal energy of the accelerating body and no physical laws are being broken: Momentum is conserved, but small amounts of it are being temporarily “stored” in the accelerating body.

According to Woodward, this mass fluctuation effect could account for the thrust observed at the NASA Eagleworks lab. If the microwaves propagating in the EmDrive cone are applying force to the material that the cone is made of, then you might explain the thrust generated this way by the Mach effect outlined by Woodward.

Woodward has spent the last two decades building devices which have successfully demonstrated the Mach effect, although his theory is still far from mainstream within the physics community. Still, it is gaining ground as more successful experiments confirm his theory. March, for one, has worked with Woodward on a number of successful Mach effect experiments over the last decade, and, at September’s Exotic Propulsion conference in Estes Park, Colorado, three physicists besides Woodward claimed to have experimentally reproduced Woodward’s Mach effect results.

“In my view, it’s the only physics that I know and trust to not involve wishful thinking and magical fields,” said Woodward.

For now, all we know is that the paper leaked on Saturday is in fact legitimate—it has been peer reviewed and accepted for publication in the AIAA’s Journal of Propulsion and Power, where it is slated to appear in the December issue. What is unclear is how much the peer-reviewed version will have changed from the early release version leaked online.

According to Woodward, who saw a copy of the paper shortly after it had been accepted for peer review, the main difference between the accepted copy and the leaked early release is that the latter has way more theory trying to explain the results. Supposedly the AIAA would only accept the paper if White and his colleagues ditched the quantum vacuum theory and just published the results of their research without trying to explain it.

What remains to be seen is whether others can use Woodward’s Mach effect theory to reproduce the results seen in the NASA Eagleworks lab and thereby offer a compelling explanation for what White and his colleagues observed.

“Absent a convincing physical explanation that doesn't fly in the face of well-known principles of physics, you should hold in abeyance any judgment as to whether or not [the NASA results are] real,” said Woodward. “This stuff is much harder to do and get right than almost anybody who has not actually been in the trenches doing it really appreciates. The odds against anything being real in this business are very high.”
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Re: EmDrive

Unread postby kasim » Thu Nov 17, 2016 6:10 pm

You've all been blinded by science. The only law you need is the conservation of linear momentum. You see, nobody explains what happens when the photon is fired. In order for it to gain momentum as it's fired from the magnetron, the photon imparts a recoil on the magnetron in the opposite direction to the photon. That's what produces the thrust. When it reaches the back plate, it imparts momentum onto the back plate in the opposite direction to the nose of the cone thereby reducing the initial momentum gained. It would've been better not to have a back plate and all of the forward momentum would've been kept.

All that talk about F = ma and E=mc^2 is just baloney to blind unsuspecting people and convince them that it's all based on science. Shawyer is like a con artist who knows a little bit about science and uses it successfully to fool others.

But then, he's not the only one who had fooled governments into handing over hard earned cash over things that can't happen. What about the 10 billion euros spent to collect evidence to prove the existence of a particle that doesn't exist. It was just assumed to exist to give particles mass because the Standard Model equations would fail if they had mass. I mean why not just abandon the Standard Model rather than invent theories to make it work? Remember that God exists but the God Particle doesn't. I mean energy cannot be created, according to the energy conservation law, so how come we have energy. Either the energy conservation law is wrong or God created it.

My definition of the energy conservation law is: Only God can create and destroy energy; mere mortals can only change it from one form to another. I'm not religious but the science led me to God. In other words I'm still not religious, but now, I believe in a creator.

I've written a free to download book about the fallacies of science: The One Force of Nature It also gives an alternative Standard Model that doesn't need fixes...yet.
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Re: EmDrive

Unread postby allynh » Mon Nov 21, 2016 2:34 pm

NASA's Peer-Reviewed Paper on the EmDrive Is Now Online
http://motherboard.vice.com/en_au/read/ ... now-online
20 November 2016 // 08:00 AM CET
Earlier this week we wrote about a leaked paper that apparently confirmed that NASA had built a working electromagnetic drive (or EmDrive), a theoretical (and "impossible") rocket propulsion system that seemingly violates Newton’s Third Law of Motion. It's such a controversial subject that the the moderators of the /r/Physics subreddit deleted their thread with our post out of a conviction that the EmDrive is unscientific.

But yesterday, following months of rumors and criticisms, the full and official peer-reviewed paper regarding the drive appeared online through the American Institute of Aeronautics and Astronautics (AIAA)’s Journal of Propulsion and Power. It's a big milestone, but keep in mind that peer-review doesn't mean the argument necessarily holds water, only that the measures taken to arrive at the conclusion were considered sound.

The content is much the same as what we saw last Monday, but the latest version is notable for confirming that, yes, NASA EmDrive consistently performs at 1.2 millinewtons per kilowatt of thrust in a vacuum, even after a "number of error sources were considered and discussed." This, even though nothing about its design adheres to the notion that "everything must have an equal and opposite reaction" for thrust.

Faster thrust is available with rocket fuel, but the entire appeal of an EmDrive is that it doesn't need rocket fuel at all. Instead, as we described it earlier this week, it works by "turning electricity into microwaves and bouncing them around a closed metal funnel." It's thus extremely light, and the paper affirms that the EmDrive performs "two orders of magnitude higher than other forms of “zero-propellant” propulsion, such as light sails, laser propulsion, and photon rockets." And with the heavy loads from rocket fuel out of the picture, the EmDrive could be the engine that gets us to Mars and perhaps beyond.

Of course, the EmDrive still seems to violate the established laws of physics, even though it apparently worked fine in multiple tests. By way of explanation, the paper somewhat briefly proposes that the answer might have something to do with pilot-wave theory, a deterministic approach to quantum mechanics that states that particles have fixed locations, but that the physics must act in strange ways for this to be the case. Veritasium’s Derek Muller recently posted a good video on the subject to YouTube:

Is This What Quantum Mechanics Looks Like?
https://www.youtube.com/watch?v=WIyTZDHuarQ

More tests need to be run, of course, and there's plenty of reason to be skeptical. But the paper does much to nudge the concept closer to scientific fact. And in an era when science itself seems to be under bombardment, it's a massive thing to be excited about.

For a more in-depth discussion of the physics involved, be sure to read Daniel Oberhaus' article from Monday.
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Re: EmDrive

Unread postby Keith Ness » Mon Nov 21, 2016 5:00 pm

A few years ago, an astronomy professor introduced me to the idea of radiation pressure by making the distinction that a photon has no mass but does have momentum, and then saying that a standard test question he always asks of his basic astronomy students is, "Suppose you're an astronaut stranded in space a ways from your space station, and you've lost all your tools except a flashlight. How do you get back to the station?" The answer is, clearly enough, to point the flashlight away from the space station. This is more or less a flashlight with the large end covered. My guess as to why this still works with the large end closed is that the source is midway between large and small end, but by virtue of being smaller, the smaller end is on average closer to the source and, since waves dissipate in intensity over time, this imbalance means the smaller end gets more intensity overall.

Per Newton, if you want to propel a rocket through space, you’re going to have to eject some material in the opposite direction of the rocket’s travel.


That's only assuming you're using the rocket's traditional method of ejecting mass. Not only is radiation pressure suitable, but just imagine sitting on a swing and trying to get swinging from a still, sitting position without touching any fixed object. You don't eject mass, you manipulate it by the way you move your body to generate anisotropic momentum, just like I am proposing the Emdrive works above.

This also somehow reminds me of a psychology test my psych professor told our class about, where a subject is told to join two ropes hanging way further apart than the subject's arms span, and is given only one of a variety of objects, like a clock, a hammer, or a gerbil. He then reassured us that, if a test subject were to actually try to tie the gerbil to one rope and then swing it while walking to the other rope and waiting for the other to swing into reach, they would have stopped the experiment! :)

*edit: and by small/large ends, I am referring of course to the larger or smaller half of the cone, not just the actual flat ends themselves; i.e., the walls of the smaller half of the cone to one side of the source are on average closer to the source than those of the other half...
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Re: EmDrive

Unread postby LunarSabbathTruth » Mon Nov 21, 2016 5:38 pm

Keith Ness wrote:A few years ago, an astronomy professor introduced me to the idea of radiation pressure by making the distinction that a photon has no mass but does have momentum, and then saying that a standard test question he always asks of his basic astronomy students is, "Suppose you're an astronaut stranded in space a ways from your space station, and you've lost all your tools except a flashlight. How do you get back to the station?" The answer is, clearly enough, to point the flashlight away from the space station. ....


Uh, did he actually try this flashlight propulsion experiment and know that it produced thrust?

- joe
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Re: EmDrive

Unread postby Keith Ness » Mon Nov 21, 2016 6:54 pm

LunarSabbathTruth wrote:
Uh, did he actually try this flashlight propulsion experiment and know that it produced thrust?

- joe


It's well-known basic physics. See, for example:

https://en.wikipedia.org/wiki/Radiation_pressure

https://en.wikipedia.org/wiki/Solar_sail

Of course, other factors indirectly resulting from this anisotropic pressure, such as seen in Crooke's radiometer, could be involved:

https://en.wikipedia.org/wiki/Crookes_radiometer

Even heat differences resulting from pressure differences could be involved, since the heat of molecules also dissipates over time...

It's not like it would be very effective; the point is that radiation pressure does exist.


*edit: "the heat of molecules also dissipates over time..." Well, I suppose more importantly, their momentum dissipates over time with collision and scattering, et c..
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Re: EmDrive

Unread postby Keith Ness » Thu Nov 24, 2016 12:30 pm

So here's an example of a particle analogue of the effect I think they're seeing in their EM drive model, and how "equal and opposite" might be universally true, but still only in a limited sense.

Say you're in a spacesuit inside an enclosed cube with no engine in a Zero-g vacuum. You need to get moving somewhere, and all you have are 15 billiard balls which you either don't want to or can't just throw into space outside the cube; they must come with you one way or another. How do you get moving in one direction more than another? Well, you arrange 14 of the billiard balls in a certain way in the middle of the cube, put your back up against one wall near that wall's middle, and throw the 15th billiard ball at the other billiard balls in such a way that the ball pushes you against the wall, propelling the cube forward, while the ball travels to 2 of the other balls, hits them so it stops relative to where the other 2 balls were before it hit them, and sends each of them in 45 degree angles to the thrown ball's trajectory before it hit them. Then those two hit balls each hit two more balls each, each of which in turn also travels at 45 degrees to the former trajectory of the ball which hit it, and so on, until some of the balls are even travelling in the direction the cube is travelling. Assuming you threw the ball hard enough to give the cube enough momentum, the cube will slow down but not stop when it collects all of the balls on the far wall, because not all of the original counterthrust of the thrown ball is going in the opposite direction of the cube when the cube collects the balls bearing that counterthrust.

billiards 01.jpg


The general idea is to throw a finite number of particles into a numerically and voluminously larger but still finite group of particles, so the momentum of the thrown particles can scatter via the larger group into directions which are not exactly opposite in direction to the counter-momentum given to the vessel by the thrown particles before the particles bearing that momentum are recaptured by the vessel.

So a more advanced example might be an enclosed cylinder containing air. A fan with a diameter significantly smaller than the cylinder's diameter is fixed to the cylinder, close to and in the middle of one end of the cylinder, facing and blowing the air in the cylinder towards the other end of the cylinder, and we let some sort of convective system do it's work. I don't know what the optimal power/periodicity of fan use would be, nor the optimal temperature/pressure/chemistry/dimensions of the various components would be, but that's the basic idea. A heat source exciting particles instead of a fan blowing them might also suffice.

cylinder 01.jpg


It might even be that an astronaut stranded in space with nothing but a spacesuit could propel himself forward by simply tapping his finger to the front of his suit near his center of mass repeatedly.

What are your thoughts? Did I miss something?
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Re: EmDrive

Unread postby Zyxzevn » Thu Nov 24, 2016 4:59 pm

Because it is an "enclosed" system, there are 2 possible conventional causes:
1) forces caused by the transport of energy from the device.
2) forces caused by the transport of energy into the device.

1-> There are many possibilities for that. Where does the energy go, produced by the device?
It does not just function as a battery: the energy goes out somewhere.
The amount of force is so small, it could be anything. Heat is the most common,
but sound might also be possible.
Note: if there would be no leaking at all, the device would become hotter and hotter.

Because the force is measured when the frequency resonates with the "cover" of the system,
it looks to me that the electrical currents in the device will be resonating due to the EM-waves.
This means that the electrical currents that are common with EM-waves hitting a conductor,
will reach deeper levels than normal. Usually these are only surface currents, but if large enough
they will simply reach deeper. This will cause the shielding to fail.
And this will cause some leakage of the EM-waves to the outside.

2-> A study in Germany thought it might have been this after they did not measure any force when they put
the energy-source inside the device.

As I look at the "scientific" work of the device, I do not see proper analysis of the currents in the device.
Instead of a common EM-analysis that goes into the above points, they jump into quantum physics nonsense.

And this again shows that the NASA has a lack of people educated in common Electromagnetism,
as we also can see in their analysis of the sun.
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Re: EmDrive

Unread postby Keith Ness » Sat Nov 26, 2016 1:35 pm

Note: if there would be no leaking at all, the device would become hotter and hotter.


Yes, but as in Olbers' paradox, I expect only logarithmically towards an asymptote, as amplitude dissipates at the rate it does even without any collision.

Because the force is measured when the frequency resonates with the "cover" of the system,
it looks to me that the electrical currents in the device will be resonating due to the EM-waves.
This means that the electrical currents that are common with EM-waves hitting a conductor,
will reach deeper levels than normal. Usually these are only surface currents, but if large enough
they will simply reach deeper. This will cause the shielding to fail.
And this will cause some leakage of the EM-waves to the outside.


I'm not familiar with how electrical currents interact with EM waves, but the relationship with wavelength and cone length does seem suspiciously like the parameters of a laser, whose light breaks out via resonance. At the same time, one would think they would know enough to monitor for leakage. I also expect that some of the energy would find its way out through the source, albeit possibly at a greatly reduced amplitude from when it went in.

Furthermore, if the resonant energy strikes one end of the resonance chamber with more force than the other because force was lost en route due to the inherent amplitude dissipation of waves, then the resonance chamber would be pushed more in one direction than the other. Remember, the light bouncing off Jupiter hits Jupiter with more force than when it continues from Jupiter to us and hits us, and not just because some of it was absorbed in Jupiter, but also because it took time for the wave to get here so it dissipated just by travel time. Even in a closed chamber with a spherical wave expanding, if the wave began nearer one end than the end opposite that end, I expect that would result in momentum of the chamber overall more in one direction than another.

2-> A study in Germany thought it might have been this after they did not measure any force when they put
the energy-source inside the device


With a wave source inside the chamber, I would expect that the size, position, and facing of the source relative to the ends of the chamber would make a difference in whether the effect was observed or not.

Regardless, I think conventional physics actually expects my explanation to play a role generally. For another example of my explanation, let's take a mechanical wave variant. To eliminate thrust from the source as a possible contaminant, take two equal audio speakers significantly smaller in diameter than the cylinder I mention above, and position the two speakers back to back next to each other near one end of the cylinder, and such that an imaginary line connecting the centers of each end of the cylinder also go through the centers of the speakers, with one speaker facing the near end and the other facing the far end.

When the speakers generate equal sound, the sound waves bounce off the near end at amplitude X, but because the waves take longer to get to the far end, they bounce off the far end at amplitude less than X (with the speakers significantly smaller in diameter than the cylinder, much of the sound waves expand beyond the diameters of the speakers and bounce around without much hitting the speakers at or near angles perpendicular to the length of the cylinder, and thus make significant use of the difference in distance to the two ends). We would thus, by conventional physics if I'm not mistaken, expect more push on the near end than the far end, whether any wave energy was leaking or not. And if you wanted to amplify this effect through resonance, then I suppose you could design a mechanical wave variant with more resonance.
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Re: EmDrive

Unread postby Keith Ness » Tue Nov 29, 2016 5:36 pm

Yes, but as in Olbers' paradox, I expect only logarithmically towards an asymptote, as amplitude dissipates at the rate it does even without any collision.


Ok, the idea that, in a perfectly reflective and closed chamber (even one which bounces light around incoherently), amplitude would dissipate as it does in open space is more of a weak and probably wrong assumption than an expectation. Regardless, the important mystery is not whether the energy leaks or not, but whether it would leak more in one direction than another as efficiently as it appears to.

I think the resolution to the mystery is to be found in Shawyer’s discussion. Shawyer talks about how it’s long been well demonstrated that light (group speed) slows down as the aperture it is travelling through decreases in size, and indicates that the end result motion of the Emdrive is in the direction of the small end. So it seems to me that the reason momentum decreases overall as aperture decreases (e.g., as light travels towards the small end), is that the momentum of the light is converting into momentum of the aperture in the same direction increasingly efficiently as aperture decreases. Reports also show the large end hotter, so maybe that’s evidence that the transfer of linear momentum onto the large end is more converted into omnidirectional thermal radiation than transfer of the same amount of energy onto the small end. So maybe a good mechanical analogy would be throwing two ice balls towards the center of a wall at a right angle to the wall. One ice ball smacks into the wall still frozen and without shattering, and so imparts almost all of its momentum into linear momentum of the wall in the same direction; the other ice ball passes through a furnace on its way to the wall, and so hits the wall at the same speed but as a liquid, spreading out laterally on impact, converting some of its momentum towards the wall into lateral motion of droplets dispersing radially and parallel to the wall, and thus imparting less momentum to the wall.

Here’s an even better way of looking at it. For simplicity, imagine the cone is a right circular cone, with the lateral surface reaching from apex to base at a 45 degree angle. A wave within the cone is travelling perpendicular to the base, toward the base. When that wave hits the base, 100% of the radiation pressure of that wave impacting the base pushes the base directly away from the apex. Then the wave bounces back in precisely the direction it came from. When it hits the lateral surface, it does so at a 45 degree angle, so half the impact of the radiation pressure pushes the lateral surface in the direction of the apex, and the other half pushes the lateral surface directly away from the center of the cone in a direction parallel to the base. Then the wave travels to the opposite inner side of the lateral surface, and reverses the process of the previous impact, which means half the impact pushes the cone in a direction parallel to the base and opposite the direction the previous impact pushed. Then the wave again heads toward the base, perpendicular to the base, and again dumps all its impact into a direction directly away from the apex. Instead of just throwing the wave out the back end as in a normal photon rocket, the process then repeats indefinitely, with the light dissipating in amplitude as it transfers it to the cone through radiation pressure. I may have the exact fractions more or less wrong, but the point is the radiation pressure is more widely distributed when striking the lateral surface than when striking the base.

Now you might think that this results in motion of the chamber from apex to base because you have two half momentum hits towards the apex on the lateral surface versus two full momentum hits towards the base on the base, but it doesn’t, because, in a complete circuit of the impacts, the half-momentum impacts occur twice as often. HOWEVER, the fact that momentum hits more or less hard DOES make a difference. So the base gets hit half as often but twice as hard, that’s fine, but the impact from the hits on the lateral surface are twice as distributed (or perhaps more, since one can see the distribution as occurring over a 90 degree arc when hitting a lateral surface, versus some smaller arc, or maybe no arc, when hitting the base), which means that the hits on the base express themselves more as radial structural damage to the base, i.e. heat. For example, a tow truck driver drives up to assist your stalled vehicle, and says, “I can either push your car with my hand for a few minutes, or compact all that energy into one rifle shot at your car. It’s the same amount of energy, so it shouldn’t matter which one I use on your car, right?” Wrong, of course. The rifle shot will convert more of its energy into lateral momentum expressed as tearing a hole through your car, and won’t do much to move your car. The long hand push will move your car though, because it converts less into lateral momentum of your car. Now overall, the shape of the cone prefers light paths in which light hits the base more directly than the lateral surface, so the base receives more heat, and the lateral surface receives more momentum. No fictitious or obscure forces, all forces accounted for.

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Here are a couple more simple mechanical/particle variants of my explanation which improve on my understanding of my explanation in previous posts.

To stabilize motion, there are two identical propulsion chambers in a spaceship arranged bilaterally symmetrically to each other. Each chamber has a propellant launch site at the front and near the center of the ship, where a person throws a racquet ball directly aft simultaneously with the person in the other chamber, causing the ship to move forward. The racquet balls travel for a while, then each ball simultaneously hits a separate 45 degree angled deflector at the rear of the ship. This causes ¼ of each ball’s momentum to continue aft, reducing but not eliminating the ship's forward momentum, ¼ of each ball’s momentum to push laterally on the opposite chamber, resulting in pressure on the ship’s structure itself from both balls directed at each other, and the remaining ½ of each ball’s momentum to change direction 90 degrees to directly away from the opposite chamber, towards the outer side edge of the ship. The balls continue travelling away from each other for a while, and then each hits another 45 degree angled deflector, this time deflecting each ball at half the NEW ball speed again after venting ¼ of the NEW momentum aft again, and ¼ of the NEW ball momentum into the outer edge of the ship’s structure. The balls travel forward until each ball reaches the front of the ship and hits yet another 45 degree angled deflector, this time directing the ball back inwards towards its launch site after reducing its speed by half yet again and directing ¼ of the ball’s momentum forward, and ¼ of the ball’s momentum into the outer side edge of the ship again. At the launch sites, the throwers recapture the balls, and prepare to repeat the process, but the ship is still moving slightly forward relative to to when they prepared to throw the balls the last time.

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The reason this works where something simpler like throwing a ball at a wall perpendicular to you and letting all its momentum go into first impact with that wall does not work is that you are instead changing the direction of some of that momentum.

If you can see how the previous variant works, then you can see how two hollow rings fixed next to each other in the same geometric plane, with each having a fan in its side closest to the other ring, and each fan blowing air directly aft inside its ring, would also work. When a fan pushes the air immediately around it, and some of that air leaves the fan blades and heads directly aft, the pressure on the fan from that air moving directly aft is an equal and opposite momentum directly forward. However, the fans keep all of their equal share in forward momentum, while the air in each ring keeps bumping into the outer walls of its ring at all angles, and thus dissipates some of its momentum omnidirectionally, resulting in more momentum forward than backwards overall. The result would be very inefficient on Earth, where propellant and friction are both in abundance, but in the micro/zero-g vacuum of space, where propellant and friction are both scarce, it works out much better.

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The problem with Newton’s third law of “equal and opposite reaction” is that it deals only with relatively simple interactions and consequences, and does not take conversion of momentum into change in direction fully into account. I have long been suspicious of Newton’s use of fictitious forces for rotating systems, since I can replicate a circle with a stone on a string by, instead of swinging the stone from a central point, simply walking in a large circle with the stone dragging behind me, where it is clear that the stone follows a circular path only because I am constantly applying energy into changing direction while I walk. The problem is that it is easy to see the inconspicuous source of the force at the center of a stone whirling in a circle as doing nothing but pulling the stone inward, easy to obsess on the tension in the string as strictly an inward force, but the source of the pull on the stone is actually not just pulling the stone, but also constantly changing the direction in which it is pulling the stone. So the force countering the inward pull of the string is not any of Newton’s fictitious forces, rather it is simply the very real force of inertia from his first law. In Newton’s bucket experiment too, as I have described elsewhere, no absolute frame of reference is necessary, but only because all motions can be discerned by simply looking at one history or another of the inertias of the objects associated with that motion. Newton defines inertia, and then fails to fully understand the implications of that definition, leaving the door open for him and others to bring in all manner of fictitious forces.

“Hai Yai Forces!”
- Susumu Hirasawa
Keith Ness
 
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Re: EmDrive

Unread postby Keith Ness » Thu Dec 01, 2016 5:04 am

I continue posting on my explanation for the Emdrive in the New Insights and Mad Ideas sub-forum thread below, since my explanation suggests a significant limitation to Newton’s third law, and doesn’t explicitly refer to electric universe theory:

viewtopic.php?f=10&t=16544
Keith Ness
 
Posts: 38
Joined: Fri Jun 06, 2014 6:53 am

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