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#3060
by
spupeng7
on 22 Feb, 2016 23:48
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Just an odd observation. When building the lowest possible phase noise quartz oscillator, the crystal is loaded as lightly as possible to maintain the highest possible Q. Of course, this requires extraordinary amounts of gain in the oscillator feedback loop, and the gain had to be of the lowest possible noise figure.
Between the light coupling, and the low noise, there often wasn't enough flicker or shot noise to get the oscillator to start, sometimes for many minutes. Lightly tapping the circuit with a fingernail was usually enough to make the piezoelectric quartz output a tiny voltage glitch, and the oscillator would...oscillate. The output of the circuit could take several (as many as 15) seconds to slowly build to its final, stable, amplitude.
While a quartz crystal is piezoelectric, and the Emdrive most definitely is not, I hope it is helpful to point out that very high Q circuits can do strange and unexpected things. Inducing mechanical vibration or impulse on a quartz crystal to help it start "doing its thing" is rarely mentioned in the literature. The actual deflection of the crystal during the tap was on the order of nanometers (by calculation). These oscillators had absolute phase noise below -215 dBc/Hz at the floor (offset >100 KHz from a 10 MHz carrier).
Thank you rq3, this is what I was suggesting, that vibration (or other mechanical distortion) could briefly alter the resonant frequency of the cavity and bring it close enough to resonance, momentarily, to allow it to lock to the oscillator.
Which raises the next question, does resonance lock within a waveguide, allowing sustain of a signal at a slightly different frequency to its natural frequency. And if so, to what extent does this alter Q from that of an otherwise identical waveguide whose natural frequency is perfectly tuned to its oscillator?
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#3061
by
Rodal
on 22 Feb, 2016 23:56
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Great post by the developer of Wolfram Mathematica: Stephen Wolfram, who was motivated by the recent experimental detection of gravitational waves by LIGO:
http://blog.stephenwolfram.com/2016/02/black-hole-tech/For example, great discussion about randomness arising from the Navier-Stokes equation and the possibility of randomness also arising from Einstein's General Relativity equation and versions of Yang-Mills.
"Fields that can interact with themselves" If one works with the standard Navier–Stokes equations for fluid mechanics, it’s not very clear what’s going on—because one ends up having to solve the equations numerically, and whenever something complicated happens, it’s almost impossible to tell if it’s a consequence of the numerical analysis one’s done, or a genuine feature of the equations. I sidestepped these issues by using cellular automaton models for fluids rather than differential equations—and from that it’s pretty clear that intrinsic randomness generation is at least a large part of what’s going on. And having seen this, my expectation would be that if one could solve the equations well enough, one would see exactly the same behavior in the Navier–Stokes equations.
So what about the Einstein equations? Can they show turbulence? I’ve long thought that they should be able to, although to establish this will run into the same kinds of numerical-analysis issues as with the Navier–Stokes equations, though probably in an even more difficult form.
In a fluid the typical pattern is that one starts with a large-scale motion (say induced by an airplane going through the air). Then what roughly happens (at least in 3D) is that this motion breaks down into a cascade of smaller and smaller eddies, until the eddies are so small that they are damped out by viscosity in the fluid.
Would something similar happen with turbulence in the gravitational field? It can’t be quite the same, because unlike fluids, which dissipate small-scale motion by turning it into heat, the gravitational field has no such dissipation mechanism, at least according to Einstein’s equations (without adding matter, quantum effects, etc.). (Note that even with ordinary fluid mechanics, things are very different in 2D: there eddies tend not to break into smaller ones, but instead to combine into larger ones, perhaps like the Great Red Spot on Jupiter.)
My guess is that a phenomenon akin to turbulence is endemic in systems that have fields which can interact with themselves. Another potential example is the classical analog of QCD—or, more simply, classical Yang–Mills theory (the theory of a classical self-interacting color field). Yang–Mills theory shares with gravity the feature that it exhibits no dissipation, but is mathematically perhaps simpler. For years I’ve been asking people who do lattice-gauge-theory simulations whether they see any analog of turbulence. But with the randomized sampling (as opposed to evolution) approach they typically use, it’s hard to tell. (There are mathematical connections between versions of gravity and versions of Yang–Mills theory that have been extensively explored in recent years, but I don’t know what implications they have for questions of turbulence.)
Time Travel, faster than light travel through spacetime engineering, Alcubierre drive, negative energy, etc.
Black-Hole-Mediated Travel
In science fiction, black holes and related phenomena tend to be a staple of faster-than-light travel. At a more mundane level, the kind of “gravity assist” maneuvers that real spacecraft do by swinging, say, around Jupiter could be done on a much larger scale if one could swing around a black hole—where the maximum achievable velocity would be essentially the speed of light.
In General Relativity, the only way to effectively go faster than light is to modify the structure of spacetime. For example, one can imagine a “wormhole” or tube that directly connects different places in space. In General Relativity there’s no way to form such a wormhole if it doesn’t already exist—but there’s nothing to say such wormholes couldn’t already have existed at the beginning of the universe. There is a problem, though, in maintaining an “open wormhole”: the curvature of spacetime at the end would tend to create gravity that would make it collapse.
I don’t know if it can be proved that there’s no configuration of, say, orbiting black holes that would keep the wormhole open. One known way to keep it open is to introduce matter with special properties like negative energy density—which sounds implausible until you consider vacuum fluctuations in quantum field theory, inflationary-universe scenarios or dark-energy ideas.
Introducing exotic matter makes all sorts of new solutions possible for the Einstein equations. A notable example is the Alcubierre solution, which in some sense provides a different way to traverse space at any speed, effectively by warping the space.
Could there be a solution to the Einstein equations that allows something similar, without exotic matter? It hasn’t been proved that it’s impossible. And I suppose one could imagine some configuration of judiciously placed black holes that would make it possible.
It’s perhaps worth mentioning that in the models I’ve studied where the underlying structure of spacetime is a network with no predefined number of space dimensions, wormhole-like phenomena seem more natural—though insofar as the models reproduce General Relativity on large scales, this means such phenomena can’t originate on those scales.
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#3062
by
Monomorphic
on 22 Feb, 2016 23:58
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While running sims for the photonic/laser emdrive, I came upon a new geometry that may be of interest. For obvious reasons, I'm calling it a
Hyperfrustum. This geometry has advantages over a typical frustum, but is harder to fabricate.
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#3063
by
mwvp
on 23 Feb, 2016 00:14
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...
I'd almost rather have a hydrofluoric acid burn. On second thought, no I wouldn't.
FWIW, if you research bio-EMF effects you'll find a lot of stuff, even at low levels. DNA damage, cellular ion efflux at low frequencies with magnetic fields (cyclotron-resonance), accounts of heart attacks around intense pulsed fields, microwave workers having unusually high incidents of female births, military pilots prone to cataracts. Pulsed microwaves are purported, VHF - S band, to induce audio perception and brainwave entrainment. Some people are allergic to all kinds of things.
Anyways, experimenters should consider using carbon fabric in between metal shielding layers. Its cheep. What scares me most is the thought of getting a visit from the FCC because of an interference complaint. They can give you a very bad day. I have heard they can confiscate every electronic device in your possession. Since 2.45 GHz is in the Wifi band, interfering with local LANs could very well result in a visit from government folks who will not be coming to help
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#3064
by
mwvp
on 23 Feb, 2016 00:24
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#3065
by
glennfish
on 23 Feb, 2016 00:27
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OK OK I get it.
I won't play with EMdrive prototypes without adult supervision.
I think we get it. I can add my horror story too, working in the telco industry the last few years. We loose about 1 field tech every few months who dangles in front of a microwave transmitter. It's amazing how many people who get these cautions don't know that it pertains to them.
Some communities want microwave towers removed because they don't like the smell of cooked birds that fly in the path of the beam.
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#3066
by
mwvp
on 23 Feb, 2016 00:39
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Yang-Mills lecture, worth a look beyond the laborious speaker introduction
Thanks a lot for the link. It was really neat how he tied together Maxwell, Schrodinger, Klein-Gordon and Yang-Mills in a coherent narrative. That qualifies as my Big Dummies guide, I think.
I don't like the answer to the question at the end about "what's waving". I would have answered charge and mass fields, as philosophic axioms in our present theories, rather than leaving the impression theory is just mathematical abstraction.
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#3067
by
SeeShells
on 23 Feb, 2016 00:50
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Just an odd observation. When building the lowest possible phase noise quartz oscillator, the crystal is loaded as lightly as possible to maintain the highest possible Q. Of course, this requires extraordinary amounts of gain in the oscillator feedback loop, and the gain had to be of the lowest possible noise figure.
Between the light coupling, and the low noise, there often wasn't enough flicker or shot noise to get the oscillator to start, sometimes for many minutes. Lightly tapping the circuit with a fingernail was usually enough to make the piezoelectric quartz output a tiny voltage glitch, and the oscillator would...oscillate. The output of the circuit could take several (as many as 15) seconds to slowly build to its final, stable, amplitude.
While a quartz crystal is piezoelectric, and the Emdrive most definitely is not, I hope it is helpful to point out that very high Q circuits can do strange and unexpected things. Inducing mechanical vibration or impulse on a quartz crystal to help it start "doing its thing" is rarely mentioned in the literature. The actual deflection of the crystal during the tap was on the order of nanometers (by calculation). These oscillators had absolute phase noise below -215 dBc/Hz at the floor (offset >100 KHz from a 10 MHz carrier).
Thank you rq3, this is what I was suggesting, that vibration (or other mechanical distortion) could briefly alter the resonant frequency of the cavity and bring it close enough to resonance, momentarily, to allow it to lock to the oscillator.
Which raises the next question, does resonance lock within a waveguide, allowing sustain of a signal at a slightly different frequency to its natural frequency. And if so, to what extent does this alter Q from that of an otherwise identical waveguide whose natural frequency is perfectly tuned to its oscillator?
Even with a thermally stabilized magnetron with a clean DC source it takes the heater ~4 seconds to stabilize it's output until the heater turns off. Until that time the signal is jittery all over the spectrum. This alone slams the frustum in and out of resonance lock. You can literally hear it lock and unlock during that time as the VSWR changes.
Got my magnetron finished off and will be doing some testing very soon. The reason for the cooling scheme is to cool the magnetron better over longer runs and stabilize frequency drift.
Back to work...
Shell
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#3068
by
rfmwguy
on 23 Feb, 2016 01:39
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Nice work shell...not to rain on a parade, but thought I read somewhere that the alum cooling fins were also called yokes. It may be nothing, but this term implies it might impact resonance or directivity. anxious to see if u notice any output freq or level variance. I view them as grounded cooling fins only btw.
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#3069
by
SeeShells
on 23 Feb, 2016 01:55
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Nice work shell...not to rain on a parade, but thought I read somewhere that the alum cooling fins were also called yokes. It may be nothing, but this term implies it might impact resonance or directivity. anxious to see if u notice any output freq or level variance. I view them as grounded cooling fins only btw.
Thanks! Great question!
I will let you know if there is any significant frequency changes. I used these references.
http://www.ets-lindgren.com/pdf/emctd_1293_weibler.pdfhttp://hyperphysics.phy-astr.gsu.edu/hbase/tables/magprop.htmlI suspect I'll see a small shift but considering the thickness of the copper walls and the thin aluminum sheets used on the magnetron it should be very little. I'm looking to stabelize the magnetron over longer runs and a slight center frequency shift I can work with in my tuning scheme.
Shell
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#3070
by
zen-in
on 23 Feb, 2016 03:12
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Just an odd observation. When building the lowest possible phase noise quartz oscillator, the crystal is loaded as lightly as possible to maintain the highest possible Q. Of course, this requires extraordinary amounts of gain in the oscillator feedback loop, and the gain had to be of the lowest possible noise figure.
Between the light coupling, and the low noise, there often wasn't enough flicker or shot noise to get the oscillator to start, sometimes for many minutes. Lightly tapping the circuit with a fingernail was usually enough to make the piezoelectric quartz output a tiny voltage glitch, and the oscillator would...oscillate. The output of the circuit could take several (as many as 15) seconds to slowly build to its final, stable, amplitude.
While a quartz crystal is piezoelectric, and the Emdrive most definitely is not, I hope it is helpful to point out that very high Q circuits can do strange and unexpected things. Inducing mechanical vibration or impulse on a quartz crystal to help it start "doing its thing" is rarely mentioned in the literature. The actual deflection of the crystal during the tap was on the order of nanometers (by calculation). These oscillators had absolute phase noise below -215 dBc/Hz at the floor (offset >100 KHz from a 10 MHz carrier).
Thank you rq3, this is what I was suggesting, that vibration (or other mechanical distortion) could briefly alter the resonant frequency of the cavity and bring it close enough to resonance, momentarily, to allow it to lock to the oscillator.
Which raises the next question, does resonance lock within a waveguide, allowing sustain of a signal at a slightly different frequency to its natural frequency. And if so, to what extent does this alter Q from that of an otherwise identical waveguide whose natural frequency is perfectly tuned to its oscillator?
With a high Q piezo oscillator any mechanical stimulus will generate a voltage, due to the piezo properties. A Copper cavity will not generate a voltage when it is tapped. Some piezo materials can generate a very high voltage when flexed or stressed. You can see this happen the next time you press the red button on your Weber grill.
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#3071
by
SeeShells
on 23 Feb, 2016 03:38
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Just an odd observation. When building the lowest possible phase noise quartz oscillator, the crystal is loaded as lightly as possible to maintain the highest possible Q. Of course, this requires extraordinary amounts of gain in the oscillator feedback loop, and the gain had to be of the lowest possible noise figure.
Between the light coupling, and the low noise, there often wasn't enough flicker or shot noise to get the oscillator to start, sometimes for many minutes. Lightly tapping the circuit with a fingernail was usually enough to make the piezoelectric quartz output a tiny voltage glitch, and the oscillator would...oscillate. The output of the circuit could take several (as many as 15) seconds to slowly build to its final, stable, amplitude.
While a quartz crystal is piezoelectric, and the Emdrive most definitely is not, I hope it is helpful to point out that very high Q circuits can do strange and unexpected things. Inducing mechanical vibration or impulse on a quartz crystal to help it start "doing its thing" is rarely mentioned in the literature. The actual deflection of the crystal during the tap was on the order of nanometers (by calculation). These oscillators had absolute phase noise below -215 dBc/Hz at the floor (offset >100 KHz from a 10 MHz carrier).
Thank you rq3, this is what I was suggesting, that vibration (or other mechanical distortion) could briefly alter the resonant frequency of the cavity and bring it close enough to resonance, momentarily, to allow it to lock to the oscillator.
Which raises the next question, does resonance lock within a waveguide, allowing sustain of a signal at a slightly different frequency to its natural frequency. And if so, to what extent does this alter Q from that of an otherwise identical waveguide whose natural frequency is perfectly tuned to its oscillator?
With a high Q piezo oscillator any mechanical stimulus will generate a voltage, due to the piezo properties. A Copper cavity will not generate a voltage when it is tapped. Some piezo materials can generate a very high voltage when flexed or stressed. You can see this happen the next time you press the red button on your Weber grill.
Very true, I'm not sure of a piezoelectric effect being generated from taping a frustum but it might tend to shake up the resonance a little if you think of the modes like jello in a mold and make the mode wiggle. Now what that would do is unknown. My goodness a tap is in the Hundreds of Hertz and the RF in in the Gigahertz.
Shell
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#3072
by
SteveD
on 23 Feb, 2016 05:48
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Gah, can't sleep.
Following up on my post from the other day, neither the photon rocket nor the doppler shift of light equations are exotic. Unless I am making an error in application the two equations are showing me that:
A. if I had a stationary structure that could:
B. Absorb all the photons emitted by a photon rocket acceleration from 100,000 m/s to 100,001 ms and
C. Capture all the kinetic energy from the photon rocket I would find that
D. The acceleration created an over unity of around 15 joules of energy
Since I don't believe in over unity I have to conclude that the equation are in error and that the device dumped 15 joules of energy somewhere.
That would mean that I would need a second wave, released at the same time as the first, and made up of something other than photons which would undergo a redshift to a stationary observer sufficient to lose 15 joules of energy.
If I posit a second wave made up of something other than light (perhaps gravity) generated by the emission of photons then I must consider the possibility that this wave is not absorbed and reflected when the photons in question are absorbed and reflected but instead continues onward in its direction of travel.
This would mean that a closed system with photons bouncing around inside it could "leak energy," become an open system.
But what happens when those photons undergo reflection? Have I misunderstood or botched the underlying equations or perhaps have fallen prey to the limits of Excel?
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#3073
by
Bob Woods
on 23 Feb, 2016 05:56
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You can see this happen the next time you press the red button on your Weber grill.
Zen, you may be a whiz in Physics, but if you push a button to char some meat you need to go back to school.
Wood, and carbonized wood fuel, is the only way to generate real flavor when transiting the B-B-Q frame of the universe.
I prefer old Mountain Oak and Mesquite. Finest kind...
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#3074
by
ThinkerX
on 23 Feb, 2016 06:29
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Gah, can't sleep.
Following up on my post from the other day, neither the photon rocket nor the doppler shift of light equations are exotic. Unless I am making an error in application the two equations are showing me that:
A. if I had a stationary structure that could:
B. Absorb all the photons emitted by a photon rocket acceleration from 100,000 m/s to 100,001 ms and
C. Capture all the kinetic energy from the photon rocket I would find that
D. The acceleration created an over unity of around 15 joules of energy
Since I don't believe in over unity I have to conclude that the equation are in error and that the device dumped 15 joules of energy somewhere.
That would mean that I would need a second wave, released at the same time as the first, and made up of something other than photons which would undergo a redshift to a stationary observer sufficient to lose 15 joules of energy.
If I posit a second wave made up of something other than light (perhaps gravity) generated by the emission of photons then I must consider the possibility that this wave is not absorbed and reflected when the photons in question are absorbed and reflected but instead continues onward in its direction of travel.
This would mean that a closed system with photons bouncing around inside it could "leak energy," become an open system.
But what happens when those photons undergo reflection? Have I misunderstood or botched the underlying equations or perhaps have fallen prey to the limits of Excel?
I wonder...didn't Doctor Rodal's calculations from the sadly incomplete MEEP runs show something like this?
And would over unity on that scale amount to EM Drive 'thrust?'
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#3075
by
SeeShells
on 23 Feb, 2016 09:20
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Nice work shell...not to rain on a parade, but thought I read somewhere that the alum cooling fins were also called yokes. It may be nothing, but this term implies it might impact resonance or directivity. anxious to see if u notice any output freq or level variance. I view them as grounded cooling fins only btw.
Thanks! Great question!
I will let you know if there is any significant frequency changes. I used these references.
http://www.ets-lindgren.com/pdf/emctd_1293_weibler.pdf
http://hyperphysics.phy-astr.gsu.edu/hbase/tables/magprop.html
I suspect I'll see a small shift but considering the thickness of the copper walls and the thin aluminum sheets used on the magnetron it should be very little. I'm looking to stabelize the magnetron over longer runs and a slight center frequency shift I can work with in my tuning scheme.
Shell
rfmwguy,
Steve, I'm with you and can't sleep.
Dave, I had to get up and pull out the image I'd downloaded months ago to satisfy the earworm you stuck in my head about the yoke and was it indeed the area around the surface of the copper on the magnetron tube where the aluminum heat fins wrapped?
It's the structure of the steel frame around the magnetron not the structure of the aluminum heat sink radiator. This makes more sense now that it's considered the yoke.
I truly need to finish my coco and crawl back into bed.
Shell
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#3076
by
rfmwguy
on 23 Feb, 2016 12:13
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A lot of us emdrive types are gadget minded and we've discussed gravity and magnetism at length...so to keep us all in a clever mood, here's a gravity and magnetism demo that would make a fun science project for our kids and grandkids. Think gravity, mass and em:
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#3077
by
rfmwguy
on 23 Feb, 2016 12:22
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Nice work shell...not to rain on a parade, but thought I read somewhere that the alum cooling fins were also called yokes. It may be nothing, but this term implies it might impact resonance or directivity. anxious to see if u notice any output freq or level variance. I view them as grounded cooling fins only btw.
Thanks! Great question!
I will let you know if there is any significant frequency changes. I used these references.
http://www.ets-lindgren.com/pdf/emctd_1293_weibler.pdf
http://hyperphysics.phy-astr.gsu.edu/hbase/tables/magprop.html
I suspect I'll see a small shift but considering the thickness of the copper walls and the thin aluminum sheets used on the magnetron it should be very little. I'm looking to stabelize the magnetron over longer runs and a slight center frequency shift I can work with in my tuning scheme.
Shell
rfmwguy,
Steve, I'm with you and can't sleep.
Dave, I had to get up and pull out the image I'd downloaded months ago to satisfy the earworm you stuck in my head about the yoke and was it indeed the area around the surface of the copper on the magnetron tube where the aluminum heat fins wrapped?
It's the structure of the steel frame around the magnetron not the structure of the aluminum heat sink radiator. This makes more sense now that it's considered the yoke.
I truly need to finish my coco and crawl back into bed.
Shell
Sorry shell...didn't mean to earworm you
. Yes, that's the pic I recall, outer box is magnetic yoke. You should be fine with copper tubing. Smart engineering, as always...
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#3078
by
Mulletron
on 23 Feb, 2016 12:51
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There's a ton of fake free energy machines on YouTube. Magnets don't do work and gravity is a conservative field.
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#3079
by
rfmwguy
on 23 Feb, 2016 13:00
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There's a ton of fake free energy machines on YouTube. Magnets don't do work and gravity is a conservative field.
This one is just a clever under unity gadget, not a perpetual motion machine as some would claim. Friction and magnetic field weakening eventually stops the toy, but think its useful to spark a kids imagination. I used to be a judge at annual science fairs at my kids school...have a soft spot for gadgetry I guess.
