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#3320 by JohnFornaro on 24 Jun, 2016 12:16
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Might be neat to see what happens if someone does a double slit experiment with a resonator between the slits.
Hey Mull:
What do you think might be the result of that double slit experiment? -
#3321 by Mulletron on 24 Jun, 2016 12:27
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Same as the solenoid ones.
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#3322 by A_M_Swallow on 24 Jun, 2016 15:43
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Build Update: Torsional pendulum improvements walkthrough.
{snip}
A 90° turn of the equipment will produce the similar heating effects, although the direction may also change. -
#3323 by dustinthewind on 24 Jun, 2016 17:17
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All light seems to provide impulses in the form of photons.
Seems? I thought that was proven, particularly in the case of light sails. I'm not following your argument.
I suspect light can also provide a negative impulse depending on the current in the material it strikes (current is moving against the electric field of light)
If true, then if the light can't excite current at all, there should be no impulse. I would think a capacitor or some voltage source would be needed to force a current against the stimulation of the electric field of light.
On another note, I was thinking about what would happen if we had the frustum back half as a more resistant material like aluminum and then the front half as copper. Or maybe the back half as silver and the front half as superconducting. The idea being to keep a decent Q or reflective nature of the cavity but have an imbalance in the resistance to current.
wikipedia.org
Superconductor should be near zero
Copper Electrical resistivity 16.78 nΩ·m (at 20 °C)
Aluminum Electrical resistivity 28.2 nΩ·m (at 20 °C)
Silver Electrical resistivity 15.87 nΩ·m (at 20 °C)
Wouldn't this lead to a heat imbalance between the front and back half? If current is more free to accelerate with out resistance does this mean there is more of a push from the light than materials with greater resistance, or does the skin depth of penetration for the light in the material cancel out any difference in push in the long run?
The idea being some difference in push exists * Q. If Q is 10,000 then (delta_push)*10,000/2. -
#3324 by mwvp on 25 Jun, 2016 03:57
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...Other than wavelength and assuming amplitude, band width are equal, in what way is a light wave/photon different from a microwave/photon? Your help is greatly appreciated!
Addendum I guess this all comes down to the question of why microwaves cannot be focused in the same way as light (a laser)?
...I think the confusion stems from not seeing the diffraction limits at work : optical visible light has roughly 5 orders of magnitude smaller wavelength
...
A cavity could in principle "store" microwaves like an optical cavity without sidewalls but at the condition its end "mirrors" (that could be a fine mesh) are scaled accordingly
...
there is no fundamental difference that would forbid the same geometry as optical cavities for "containment" of microwaves but the scaling would be prohibitive, even if aiming at 24GHz. I think. Dr. Rodal corrects me if wrong, I'm revising old lessons of wave optics here
This is also my understanding, so I concur; Maxwell's laws can and are applied to both. I'll add a couple points, that with lasers and chemical masers atomic physics gets involved; I'm vaguely aware that atoms are classically tiny, but physically behave as much larger electromagnetic antenna.
And also, that high-gain, that is, tightly-focused antenna can be constructed wide and/or deep. A large, high-gain/tight focused phased array can cover a large surface area, its radiation perpendicular to the area, or, it can be composed of many elements in a line, parallel to the radiation.
Both, or hybrid of such antenna could be used as a resonant cavity, Q dependent on antenna gain, without sidewalls. But for a high-Q, you're going to need many wavelengths of area.
The other difference between microwaves and optics, which again, I'm only vaguely familiar with atomic physics and QM, is that microwave "photons" are virtual photons; polarization of the virtual photons present in the vacuum.
Optical photons emitted by atoms are called "real" photons. Like the real particles you, and I, and the stuff we mess with are made of. In contrast to the "virtual" particles in an empty vacuum chamber that must be heroically conjured into existence under extreme duress of ginourmous energy.
Perhaps I need sum edukating too
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#3325 by RERT on 25 Jun, 2016 10:45
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Cannae claim to have built a test facility which can measure 10^-7 N. That's the (maximum) photon thrust from a 30W light source. IIRC, NASA test facilities were asking for 10^-4 N before testing on a torsional pendulum. It's certainly plausible that Cannae have built (had to build) a state-of-the-art test facility. They state that people have approached them to use it, which under that circumstance is also plausible.
It is highly unlikely that all components in a system are bottlenecks at the same time, and 100% in use. Roughly, if they are in a design phase and it takes longer to design and build a new version than it takes to test it, they may easily have spare test time. I don't see why a start-up wouldn't 'sweat their assets' and rent out their test stand at a decent return if they could. One can imagine scenarios where their recent news might be negative, but I don't think it's necessarily so. Just one opinion. -
#3326 by Rodal on 25 Jun, 2016 13:59
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1) Micro-thrust testing instruments
The 100 microNewton project goal to justify the expense of EM Drive thrust verification at another NASA testing facility (other than Eagleworks at NASA Johnson) being referred to was not due to NASA lacking micro-thrust test stands that could measure less than 100 microNewton (see NASA JPL micro-thrust facilities, NASA JPL has a Nano-Newton Thrust Stand (nNTS): http://dst.jpl.nasa.gov/thrusters/testbeds.htm
), or that a 2*10^-7 Newton test stand claimed by Cannae is pushing the "state of the art" in 2016. The (several) micro-thrust test facilities at NASA JPL and NASA Glenn are being used around the clock for research purposes in a number of development projects. Concerning state of the art, fifteen years prior to that, in 2001, "state of the art" was the Busek micro-thrust torsional stand, developed with MIT's Aero & Astro Professor Martínez-Sánchez (an expert on electric micro-thrusters for several decades), that had a resolution of less than 0.01 μN = less than 10^-8 Newton (that is 20 times less force than claimed by Cannae).
http://erps.spacegrant.org/uploads/images/images/iepc_articledownload_1988-2007/2001index/235_2.pdf
There are several companies that have micro-thrust testing equipment, for example Aerospace Corporation, who is presently collaborating with MIT on developing electric micro-thrusters to propel a new generation of CubeSats, with the potential to scale the technology to larger satellites.
One thing that we have learned in these threads from the efforts of DIY like Li ("Tellmeagain"), SeeShells and Monomorphic among others, is that the ability to inexpensively make a torsional test instrument to measure small forces is not the cost deterrent.
Rather, instead of the thrust measuring instument itself, the vacuum chamber is the cost deterrent (Shawyer has never reported a single test in vacuum in decades since inventing the EM Drive), and for that (vacuum chambers), the facilities at NASA excel.
2) Typical entrepreneurial pressure to focus and develop and market a technology as fast as possible
Time spent in testing for competitors is not what US venture capital or angel investors usually have in mind to get a timely return for their capital when they fund ventures to develop a new technology.
SpaceX during their development phase did not rent their testing facilities for competitors.
Entrepreneural biotechnology companies do not rent their facilities for other competitors to do testing, instead they concentrate their efforts in reaching their own development milestones as fast as possible. Time is money, and for entrepreneural companies the clock runs fast, as investors expect to get a return for their investment in a timely manner.
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#3327 by Bob Woods on 25 Jun, 2016 18:03
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By Cannae renting their testing services they are advertising that they don't have enough testing of their own to fully occupy their testing equipment around the clock
That may be true Doc, but if others can take advantage of the equipment to further their own experiments, it seems to me that science wins in the end regardless of whether the results are positive or negative.
Everyone has bills. Cash Flow = Good. -
#3328 by Rodal on 25 Jun, 2016 18:41
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yes, you are right that this is a possibility, as this is common and well-known with venture companies that run into development problems
When running into development (or funding) problems, naturally one will tend to try to use whatever you have to get some cash flow, even testing devices from competitors, even though that was not the original intent...
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ConcerningQuote from: Bob Woodsothers can take advantage of the equipment to further their own experiments,
the last stage of a failed venture is precisely to auction all their hardware, testing equipment, and all other assets, so that the investors can at least get some money back. One can purchase very good testing equipment from such auctions resulting from companies in financial distress. There was a lot of distress during the net.com bust in the early 2000's and again during the 2008 financial crisis.
We all sincerely hope that these companies are not anywhere near that stage where "others can take advantage of the equipment to further their own experiments".
We sincerely hope that these companies can succeed ! and put a working EM Drive in Space
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#3329 by FattyLumpkin on 26 Jun, 2016 17:57
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Not to long ago a I posted a link (video) where Dr. White was discussing "Q thrusters". Following a short study of the literature it seems that the data from the RF devices has been conflated with the M-L thruster data. While all of the above are placed in the same categories the M-L force thruster seems to generate a significant amount more thrust than the RF devices.
Attached is the link to the M-L paper: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110023492.pdf
and below we can find what we recognize to be the "Anomalous Thrust production....
http://www.libertariannews.org/wp-content/uploads/2014/07/AnomalousThrustProductionFromanRFTestDevice-BradyEtAl.pdf
Any thoughts of the members as to whether the "closed" or "open" devices might (should be) put into separate categories?
0.22 grams force = 2.15746 Newtons
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#3330 by meberbs on 26 Jun, 2016 19:15
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...
The other difference between microwaves and optics, which again, I'm only vaguely familiar with atomic physics and QM, is that microwave "photons" are virtual photons; polarization of the virtual photons present in the vacuum.
Optical photons emitted by atoms are called "real" photons. Like the real particles you, and I, and the stuff we mess with are made of. In contrast to the "virtual" particles in an empty vacuum chamber that must be heroically conjured into existence under extreme duress of ginourmous energy.
Perhaps I need sum edukating too
No, the difference between microwave and optical photons is just the frequency (and energy per particle and wavelength which are all directly related), not a real/virtual dichotomy. The difference between real and virtual photons has nothing to do with their frequency.
Microwaves and visible light seem vastly different to people because they interact with matter differently due to resonance frequencies of atomic matter and the size of atoms which introduces a scale factor. Also there is the human scale factor where scaling an optical system to microwave would require a factor of 100000 scaling which would be huge, which is one reason we use fundamentally different methods of interacting with the different frequencies. -
#3331 by X_RaY on 26 Jun, 2016 20:09
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Fully agree...
The other difference between microwaves and optics, which again, I'm only vaguely familiar with atomic physics and QM, is that microwave "photons" are virtual photons; polarization of the virtual photons present in the vacuum.
Optical photons emitted by atoms are called "real" photons. Like the real particles you, and I, and the stuff we mess with are made of. In contrast to the "virtual" particles in an empty vacuum chamber that must be heroically conjured into existence under extreme duress of ginourmous energy.
Perhaps I need sum edukating too
No, the difference between microwave and optical photons is just the frequency (and energy per particle and wavelength which are all directly related), not a real/virtual dichotomy. The difference between real and virtual photons has nothing to do with their frequency.
Microwaves and visible light seem vastly different to people because they interact with matter differently due to resonance frequencies of atomic matter and the size of atoms which introduces a scale factor. Also there is the human scale factor where scaling an optical system to microwave would require a factor of 100000 scaling which would be huge, which is one reason we use fundamentally different methods of interacting with the different frequencies.
The energy of a photon is governed by
Wherein f is the frequency of the electromagnetic field(in Hz) and h is Planck's constant.
Therefore microwaves are simply photons with greater wavelength but lower energy than visible light, x-rays or γ-rays.
Virtual photons are a concept in quantum fied theory and is used in Feynman-diagrams and to describe interactions of particles.
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#3332 by FattyLumpkin on 26 Jun, 2016 23:50
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X_Ray, following on from above discussions; what would you calculate the minimum cavity (closed cavity) dimensions to be in order to order to achieve the same "recycling" that is undergone in photonic thrusters for 2.45GHz microwaves?... Given the aforementioned points made about the different rules of governance between micro and laser light wave lengths and energies.
This is not an unreasonable question given that modern interstellar probe designs are calculated to be 1 kilometer in length and posses a mass of 45,000 metric tonnes. -
#3333 by Tcarey on 27 Jun, 2016 05:15
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yes, you are right that this is a possibility, as this is common and well-known with venture companies that run into development problems
When running into development (or funding) problems, naturally one will tend to try to use whatever you have to get some cash flow, even testing devices from competitors, even though that was not the original intent...
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ConcerningQuote from: Bob Woodsothers can take advantage of the equipment to further their own experiments,
the last stage of a failed venture is precisely to auction all their hardware, testing equipment, and all other assets, so that the investors can at least get some money back. One can purchase very good testing equipment from such auctions resulting from companies in financial distress. There was a lot of distress during the net.com bust in the early 2000's and again during the 2008 financial crisis.
We all sincerely hope that these companies are not anywhere near that stage where "others can take advantage of the equipment to further their own experiments".
We sincerely hope that these companies can succeed ! and put a working EM Drive in Space .
I agree about the cash flow logic. Also, the requirement to have a particular piece of test equipment does not automatically mean that it needs to be used all the time. Nasa has engine test stands that are idle the vast majority of the time, but when it is time to test nothing else will do the job. If you have an asset that is not used much of the time then it makes sense to use it to generate cash flow when you don't need it. After all, as the owner you are in a position to schedule your projects ahead of others as needed.
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#3334 by X_RaY on 27 Jun, 2016 07:40
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X_Ray, following on from above discussions; what would you calculate the minimum cavity (closed cavity) dimensions to be in order to order to achieve the same "recycling" that is undergone in photonic thrusters for 2.45GHz microwaves?... Given the aforementioned points made about the different rules of governance between micro and laser light wave lengths and energies.
This is not an unreasonable question given that modern interstellar probe designs are calculated to be 1 kilometer in length and posses a mass of 45,000 metric tonnes.
To increase the lifetime of the photons inside a closed cavity, I would focus in superconductive walls.
The concept of the "laser mirror thruster" compared to a closed cavity is very different. In the cavity case, all mirrors are mechanically connected to each other, consequently the force related to each single bounce on any mirror acts on the whole cavity and due to Maxwell all forces cancel each other for standing wave solutions. In the not connected case of a "laser mirror thruster" the involved mirrors are free to move relative to each other. -
#3335 by Rodal on 27 Jun, 2016 13:17
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Yes, the fact that an optical cavity without side walls, using lasers is very different from a microwave resonant cavity like the EM Drive.X_Ray, following on from above discussions; what would you calculate the minimum cavity (closed cavity) dimensions to be in order to order to achieve the same "recycling" that is undergone in photonic thrusters for 2.45GHz microwaves?... Given the aforementioned points made about the different rules of governance between micro and laser light wave lengths and energies.
This is not an unreasonable question given that modern interstellar probe designs are calculated to be 1 kilometer in length and posses a mass of 45,000 metric tonnes.
To increase the lifetime of the photons inside a closed cavity, I would focus in superconductive walls.
The concept of the mirror thruster and a closed cavity is very different. In the cavity case, all mirrors are mechanically connected to each other, consequently the force related to a bounce on any mirror acts on the whole cavity and due to Maxwell all the forces cancel each other. In the not connected case of a laser mirror thruster the involved mirrors are free to move relative to each other.
People have written that "Maxwell equations are the same" and that is just a matter of making the end walls kilometers long. Besides the important fact of the practicality of making end walls kilometers long to operate at microwave frequencies (why would anybody want to operate something like the photonic laser thruster at microwave frequencies and have end walls kilometers long ), there is the fact that the solution to Maxwell's equation for an optical cavity is diferent: the mode shapes are not any longer TM or TE as in the EM Drive but are TEM modes in an optical cavity . The electric field pattern at a point (x,y,z) for a beam propagating along the z-axis is given by
depending on the waist, spot size, radius of curvature, and Gouy phase shift as given for a Gaussian beam and H_{k} is the kth physicist's Hermite polynomial.
This solution is different from the one of an EM Drive !!!
I don't see much at all in common with any experiment by Shawyer, Yang, NASA, Tajmar or with what the DIY are experimenting with !
And this thing about "recycling" photons in the photonic laser thruster depends again on one of the mirrors being in a resource vehicle that must move in the complete opposite direction as the spaceship !!! Completely different from the EM Drive concept.
I understand: the inventor of the EM Drive had an explanation that does not make sense, and the photonic laser thruster is something that makes sense and does not violate physics. Both use photons. But they are very, very different: the photonic laser thruster is open and the resource vehicle has to travel backwards for the spaceship to travel forward. There is no resource vehicle in the EM Drive !!! -
#3336 by Rodal on 27 Jun, 2016 13:50
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Not to long ago a I posted a link (video) where Dr. White was discussing "Q thrusters". Following a short study of the literature it seems that the data from the RF devices has been conflated with the M-L thruster data. While all of the above are placed in the same categories the M-L force thruster seems to generate a significant amount more thrust than the RF devices.
Attached is the link to the M-L paper: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110023492.pdf
and below we can find what we recognize to be the "Anomalous Thrust production....
http://www.libertariannews.org/wp-content/uploads/2014/07/AnomalousThrustProductionFromanRFTestDevice-BradyEtAl.pdf
Any thoughts of the members as to whether the "closed" or "open" devices might (should be) put into separate categories?
0.22 grams force = 2.15746 Newtons
Conflating RF resonant thruster data with the MLT data?
To explain the difference, as well as the relationship, I drew this Venn diagram some time ago, and incorporated it in the wiki page:
https://en.wikipedia.org/wiki/Quantum_vacuum_thruster
The MLT you are referring to is shown as "Lockheed Martin/ March". It is in a different set than the set of RF resonant cavity thruster concepts.
The open optical cavity "photonic laser thruster" does not belong anywhere near that set.
The open optical cavity "photonic laser thruster" is based entirely on known classical physics. It is not controversial.
The open optical cavity "photonic laser thruster" is outside the set of Q thrusters. It is inside the set of space propulsion advanced concepts based on well accepted classical physics.
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#3337 by RotoSequence on 27 Jun, 2016 15:21
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On a charge parity symmetry violation tangent, the Barium-144 nucleus is pear shaped.
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#3338 by tchernik on 27 Jun, 2016 21:04
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Found an interesting link to a paper while browsing Mike McCulloch's site, shared by the user qraal. It may be relevant to the current discussion:
https://www.academia.edu/11093756/Confinement_of_Light_Standing_Wave_Transformations_in_a_Phase-Locked_Resonator
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#3339 by WilliamDS on 27 Jun, 2016 22:02
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