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#2260 by frobnicat on 18 Oct, 2014 23:32
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I have a question. Because these thruster cavities have very high Q don't they ring for a long time after the power is switched off? How long, because if the ringing is long enough shouldn't we see a tail off on the thrust trace shown in the various reports on the experiments?
What is the rule for diminishing stored power in the cavity once the power is switched off?
Of course if the thrust is due to Unruh waves, then thrust would stop instantly once the stored power dropped below a threshold.
Take a look at Shawyer's results.
There is thrust even after the power stops.
Time constant of a resonant EM wave decay for one dimensional cavity of length l : tau = Ql/c
Say Q=50000 l=.5m (give or take) -> 83µs
At 1.15ms after switch off, the energy is ringing at one millionth its initial value. I don't see this kind of millisecond temporal resolution in the charts so far. This is irrelevant.
There could be delay in the power off (DC or RF generator), there is certainly inertia in the mechanical balance, there could be delay in thermal effects. But as far as heavy mechanical balance time constants are concerned, photons switch off can be considered instantaneous until Q reaches at least 50000000
edit: or was it the half time rather than tau ? I have a doubt. Anyway, the above would stand correct by just replacing one millionth by around 1/700000 th
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#2261 by Rodal on 19 Oct, 2014 00:10
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Energy decay in a resonating cavity ~ Exp[ - omega * t / Q ] = Exp [ - t / τ]I have a question. Because these thruster cavities have very high Q don't they ring for a long time after the power is switched off? How long, because if the ringing is long enough shouldn't we see a tail off on the thrust trace shown in the various reports on the experiments?
What is the rule for diminishing stored power in the cavity once the power is switched off?
Of course if the thrust is due to Unruh waves, then thrust would stop instantly once the stored power dropped below a threshold.
Take a look at Shawyer's results.
There is thrust even after the power stops.
Time constant of a resonant EM wave decay for one dimensional cavity of length l : tau = Ql/c
Say Q=50000 l=.5m (give or take) -> 83µs
At 1.15ms after switch off, the energy is ringing at one millionth its initial value. I don't see this kind of millisecond temporal resolution in the charts so far. This is irrelevant.
There could be delay in the power off (DC or RF generator), there is certainly inertia in the mechanical balance, there could be delay in thermal effects. But as far as heavy mechanical balance time constants are concerned, photons switch off can be considered instantaneous until Q reaches at least 50000000
edit: or was it the half time rather than tau ? I have a doubt. Anyway, the above would stand correct by just replacing one millionth by around 1/700000 th
τ = Q/ omega = Q / (2 Pi f) = 50000 / (2 Pi 1.9 * 10 ^9 1/s) = 4 microseconds
τ is the time at which the amplitude is reduced to 1/e = 37% of its initial value. -
#2262 by frobnicat on 19 Oct, 2014 00:16
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Well everyone agrees that inertia is rooted in distant interactions with cosmos. Some say some interactions, others say just gravity. I say all, near and far. Why play favorites?
If by "rooted in distant interactions with cosmos" you mean some Machian principle, then I don't agree. Regardless of the role "Mach principle" have played for SR and GR genesis, this principle, in its various interpretations, is nonsense to me.
Is there a problem with inertia ? What is the problem with inertia ? Why would we need to implicate the whole cosmos when local phenomena can be explained in local fields on a small patch of curved spacetime with local coordinates in inertial frame ? Local vacuum can make a difference between inertial and non inertial trajectories (accelerated relative to free falling). There is no intrinsic local absolute 0 speed, but there is intrinsic local absolute 0 acceleration : does that make insurmountable theoretical problems, or fail at predicting some well proven experimental effects ? Does that have to be explained ?
I don't want to trigger a flow of scholarly answers here, just stating some astonishment.
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#2263 by Rodal on 19 Oct, 2014 00:26
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Well everyone agrees that inertia is rooted in distant interactions with cosmos. Some say some interactions, others say just gravity. I say all, near and far. Why play favorites?
If by "rooted in distant interactions with cosmos" you mean some Machian principle, then I don't agree. Regardless of the role "Mach principle" have played for SR and GR genesis, this principle, in its various interpretations, is nonsense to me.
Is there a problem with inertia ? What is the problem with inertia ? Why would we need to implicate the whole cosmos when local phenomena can be explained in local fields on a small patch of curved spacetime with local coordinates in inertial frame ? Local vacuum can make a difference between inertial and non inertial trajectories (accelerated relative to free falling). There is no intrinsic local absolute 0 speed, but there is intrinsic local absolute 0 acceleration : does that make insurmountable theoretical problems, or fail at predicting some well proven experimental effects ? Does that have to be explained ?
I don't want to trigger a flow of scholarly answers here, just stating some astonishment.
Very well stated. But what if inertia can be explained by a local field that goes to some extent beyond the cavity and depends on the cavity shape?
For example, an object inside water has added inertia due to the water around it. And it is not due to viscosity.. It is due to the density of the fluid that the object is immersed in.
The inertia of an object immersed in water is greater than the inertia of an object in a vacuum. This is well known of course, and it affects the frequency of vibration of objects immersed in water. It is called "added mass" effect.
This added mass has nothing to do with distant interactions. It has nothing to do with distant water.
The added mass is a tensor (referred to as the induced mass tensor), it has components that dependon the direction of motion of the body. Some components of the added mass tensor have dimension of mass, but cross-components can have dimensions of mass × length and mass × length ^2.
Only for simple objects (like a sphere) one can easily compute the added mass.
For some other simple shapes, for example an airfoil inside water it is complicated. For a simple geometry one can use a Lagrangian to compute, for complicated geometries one has to do a numerical analysis. -
#2264 by frobnicat on 19 Oct, 2014 00:49
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.../...
Energy decay in a resonating cavity ~ Exp[ - omega * t / Q ] = Exp [ - t / τ]
Time constant of a resonant EM wave decay for one dimensional cavity of length l : tau = Ql/c
Say Q=50000 l=.5m (give or take) -> 83µs
.../...
τ = Q/ omega = Q / (2 Pi f) = 50000 / (2 Pi 1.9 * 10 ^9 1/s) = 4 microseconds
τ is the time at which the amplitude is reduced to 1/e = 37% of its initial value.
mm, I thought Q could be interpreted roughly as the mean number of times a photon bounces back and forth before being absorbed. This is not far off for fundamental mode but would be quite different for much higher harmonics. Maybe this is just a matter of definition, your definition τ = Q/ omega makes perfect sense. I'm all confused. Can you help clarify because I suspect also some poor understanding of what resonance really is :
At fixed f, a 1d cavity with mirrors at both ends of fixed 99% reflectivity will ring for a proportionally longer time if it is longer in size, no ? So if tau is to be proportional to Q, that we both agree, this would mean that longer cavity would have better Q ? That won't appear in you formula. Perplexum.
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#2265 by Rodal on 19 Oct, 2014 00:58
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.../...
Energy decay in a resonating cavity ~ Exp[ - omega * t / Q ] = Exp [ - t / τ]
Time constant of a resonant EM wave decay for one dimensional cavity of length l : tau = Ql/c
Say Q=50000 l=.5m (give or take) -> 83µs
.../...
τ = Q/ omega = Q / (2 Pi f) = 50000 / (2 Pi 1.9 * 10 ^9 1/s) = 4 microseconds
τ is the time at which the amplitude is reduced to 1/e = 37% of its initial value.
mm, I thought Q could be interpreted roughly as the mean number of time a photon bounces back and forth before being absorbed. This is not far off for fundamental mode but would be quite different for much higher harmonics. Maybe this is just a matter of definition, your definition τ = Q/ omega makes perfect sense. I'm all confused. Can you help clarify because I suspect also some poor understanding of what resonance really is :
At fixed f, a 1d cavity with mirrors at both ends of fixed 99% reflectivity will ring for a proportionally longer time if it is longer in size, no ? So if tau is to be proportional to Q, that we both agree, this would mean that longer cavity would have better Q ? That won't appear in you formula. Perplexum.
For a resonant cavity the dimensions of the cavity govern the frequency. I only wrote it that way because in the simplified McCulloch formula and in your almost-Infinite number of formulas program
we just used the microwave frequency.
Instead of a rectangular waveguide with open ends we have a rectangular waveguide terminated at both ends by conducting walls which makes it a resonant cavity. Instead of having a wave propagating axially in a waveguide, we have to meet the boundary conditions at both ends which entails equal forward- and backward-propagating waves that form a standing wave. Unlike rectangular waveguides with open ends that propagate any frequency above cut-off, cavity resonators operate only at specific resonant frequencies (in order to match all boundary conditions).
It is clear that the tested EM Drives had high Q. For NASA Eagleworks we have the S22 plot showing resonance vs. frequency. Therefore the EM Drives were not waveguides but resonant cavities: they must have had both ends made of highly conducting copper, and the inside surfaces must have been highly polished copper (in order to have high Q).
For a perfectly-conducting hollow rectangular "box" of dimensions of width w, height h, and length d, where
d ≥w≥h, filled with a medium characterized by permittivity ε, permeability μ and electrical conductivity σ, the lowest resonant frequency ω is "101" mode. The boundary conditions dictate that the oscillating electric field's x component to disappear on the y-z walls, the y component to disappear on the x-z walls and the z component to disappear on the x-y walls. Since boundary conditions can not be met unless at least two of the quantum numbers m, n, and p are non-zero, the lowest resonant frequency is associated with the two longest dimensions, d and w. It is given by (where c=speed of light in a vacuum only when the interior cavity is tested in a vacuum of course )
ω = Pi c Sqrt[ (1/w)^2 + (1/d)^2 ] (radians / second)
Some people here are still very interested in the dielectric. In a dielectric, the speed of light is lower of course, so let's allow for the case where the medium is a dielectric, for generality:
c = 1/ Sqrt[με]
In general the permittivity ε, permeability μ and electrical conductivity σ can be complex, frequency dependent, and anisotropic functions of field direction. They can also be functions of density, temperature, field strength, and other quantities (they can depend on the electric field and the magnetic field).
ω = Pi Sqrt[ ((1/w)^2 + (1/d)^2)/(με) ] (radians / second)
Assuming Q >>1.
The electric-energy/dissipation density ratio everywhere is ε/2σ. The stored electric and magnetic energy are equal. Therefore the total energy stored is two times the average electric energy stored.
Q = ω (total energy stored) / (power dissipated) = ω ε / σ
Q = Pi Sqrt[ ((1/w)^2 + (1/d)^2)/(με) ] ε / σ
so really the time constant ends up being given simply by the medium properties: the permittivity divided by the electrical conductivity:
τ = Q/ ω = ε / σ
This is for the case in which all losses are produced by the medium (air or vacuum).
for air at 20 deg C
ε = 1.00058986 * 8.8541878176 * 10^(-12) Farad / meter
= 8.859410 * 10^(-12) Farad / meter
σ = 3*10^(-15) Siemens / meter to 8*10^(-15) Siemens / meter
Therefore the longest possible time constants are:
Minimum τ = ε / σ =( 8.859410 * 10^(-12) )/( 8*10^(-15) ) seconds
= 1107 seconds = 18 minutes
Maximum τ = ε / σ =( 8.859410 * 10^(-12) )/( 3*10^(-15) ) seconds
= 2953 seconds = 49 minutes
c (air) = 299705000 m/s
w (Shawyer Demonstrator) ~ Sqrt[0.28*0.1679] = 0.217 m
d (Shawyer Demonstrator) = 0.345 m
ω = Pi (299705000) Sqrt[ (1/0.217)^2 + (1/0.345)^2 ]
= 5.126 GHz
f = ω / (2 Pi) = 0.816 GHz
NOTE: Neither Shawyer, nor NASA Eagleworks operated the EM Drive at this lowest fundamental mode, and this calculation is for a rectangular box cavity, instead of a truncated cone.
Those longest possible time constants correspond to these highest possible Q's achievable in air:
Q = (5.126*10^9)*1107 to (5.126*10^9)*2953
= 5.67*10^12 to 1.51*10^13
Of course, in practice, the Q's were much lower ~ 4 * 10^5, or 7 orders of magnitude lower. Therefore the time constants were also 7 orders of magnitude lower than those computed above (time constant in microseconds rather than minutes). What limited the Q's (and therefore the time constant) are the losses on the internal copper surface, which was not a perfect conductor.
These calculations are interesting to show what Q's are theoretically possible with a superconductor cavity, as apparently Shawyer is working on.
Also, therefore, the time constant is different in the dielectric.
And by the way, that formula also reminds me, did you allow formulas of the type
Sqrt[ (1/w)^2 + (1/d)^2 ]
in your program?
If not, you should in the next iteration... -
#2266 by frobnicat on 19 Oct, 2014 01:54
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.../...
For example, an object inside water has added inertia due to the water around it. And it is not due to viscosity.. It is due to the density of the fluid that the object is immersed in.
The inertia of an object immersed in water is greater than the inertia of an object in a vacuum. This is well known of course, and it affects the frequency of vibration of objects immersed in water. It is called "added mass" effect.
This added mass has nothing to do with distant interactions. It has nothing to do with distant water.
The added mass is a tensor (referred to as the induced mass tensor), it has components that depend on the direction of motion of the body. Some components of the added mass tensor have dimension of mass, but cross-components can have dimensions of mass × length and mass × length ^2.
Only for simple objects (like a sphere) one can easily compute the added mass.
For some other simple shapes, for example an airfoil inside water it is complicated. For a simple geometry one can use a Lagrangian to compute, for complicated geometries one has to do a numerical analysis.
Excellent analogy dr Rodal. So excellent we must be all the more careful in extrapolating from it.
Let's take superfluid helium to get rid of viscosity (superfluid helium comes cheap in thought experiments).
All right then, does the added mass tensor have something to say different when going on the same axis but on opposite directions ? If it is used to analyse vibrations I guess it is a linearised (or nth order ?) form that is correct only for small moves around, not for moves fast and big enough to generate turbulent flows. Correct ? So for instance, an horizontal plate would have a huge added mass in vertical direction and small in horizontal directions, but not a different mass whether it goes up or down. In this limit of small or slow movements, a cone of vertical axis would also see the same added mass, whether going up or down, in spite of its asymmetry. Correct ?
So in this formalism something can have a different "mass" depending on its position, but it can't have a different mass depending on it going to or leaving a position. The push heavy pull light analogy don't hold for slow moves. It can hold for fast moves but then I'm not sure this still makes sense to see the asymmetric resistance to changes of speed as changes of mass : basically it is a propeller and medium has to be modelled as a separate mass, not as an added mass to the propeller blades.
Or else, move medium boundary or gradient : lower position of sphere from air into liquid, lower liquid surface so that sphere is no longer immersed, raise sphere, raise liquid, start again. Push heavy, pull light. Ok, but that is quite a work to do (energy to give) in the moving medium, compared to what can be harnessed by the sphere.
For me this is not a problem of how a property like mass can depend on position, but how it can depend on velocity (back and forth) unless the "field" that changes the property is itself dynamic (at great energetic cost).
And resonance is not a magic answer to "recycle" the dynamic of "mass altering" field : say we have a bucket of water excited at resonant frequency, fundamental mode. At the centre of the bucket, the surface of water goes up and down periodically. A sphere is put at such height as to be periodically immersed and emerged(?), slightly raised when out of water, slightly lowered when in water. This can be interesting for the sphere to push heavy and pull light, but someone has to pay the power bill, resonance or not.
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#2267 by Rodal on 19 Oct, 2014 02:14
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.../...
For example, an object inside water has added inertia due to the water around it. And it is not due to viscosity.. It is due to the density of the fluid that the object is immersed in.
The inertia of an object immersed in water is greater than the inertia of an object in a vacuum. This is well known of course, and it affects the frequency of vibration of objects immersed in water. It is called "added mass" effect.
This added mass has nothing to do with distant interactions. It has nothing to do with distant water.
The added mass is a tensor (referred to as the induced mass tensor), it has components that depend on the direction of motion of the body. Some components of the added mass tensor have dimension of mass, but cross-components can have dimensions of mass × length and mass × length ^2.
Only for simple objects (like a sphere) one can easily compute the added mass.
For some other simple shapes, for example an airfoil inside water it is complicated. For a simple geometry one can use a Lagrangian to compute, for complicated geometries one has to do a numerical analysis.
Excellent analogy dr Rodal. So excellent we must be all the more careful in extrapolating from it.
Let's take superfluid helium to get rid of viscosity (superfluid helium comes cheap in thought experiments).
All right then, does the added mass tensor have something to say different when going on the same axis but on opposite directions ? If it is used to analyse vibrations I guess it is a linearised (or nth order ?) form that is correct only for small moves around, not for moves fast and big enough to generate turbulent flows. Correct ? So for instance, an horizontal plate would have a huge added mass in vertical direction and small in horizontal directions, but not a different mass whether it goes up or down. In this limit of small or slow movements, a cone of vertical axis would also see the same added mass, whether going up or down, in spite of its asymmetry. Correct ?
So in this formalism something can have a different "mass" depending on its position, but it can't have a different mass depending on it going to or leaving a position. The push heavy pull light analogy don't hold for slow moves. It can hold for fast moves but then I'm not sure this still makes sense to see the asymmetric resistance to changes of speed as changes of mass : basically it is a propeller and medium has to be modelled as a separate mass, not as an added mass to the propeller blades.
Or else, move medium boundary or gradient : lower position of sphere from air into liquid, lower liquid surface so that sphere is no longer immersed, raise sphere, raise liquid, start again. Push heavy, pull light. Ok, but that is quite a work to do (energy to give) in the moving medium, compared to what can be harnessed by the sphere.
For me this is not a problem of how a property like mass can depend on position, but how it can depend on velocity (back and forth) unless the "field" that changes the property is itself dynamic (at great energetic cost).
And resonance is not a magic answer to "recycle" the dynamic of "mass altering" field : say we have a bucket of water excited at resonant frequency, fundamental mode. At the centre of the bucket, the surface of water goes up and down periodically. A sphere is put at such height as to be periodically immersed and emerged(?), slightly raised when out of water, slightly lowered when in water. This can be interesting for the sphere to push heavy and pull light, but someone has to pay the power bill, resonance or not.
I remember that a cone positioned in water such that the point of the cone is in the highest position (think of a conehead ) and the base of the cone is in the lowest position, although it is symmetric fore and aft, when accelerated, the added mass (which in this case has to be calculated numerically and it is not trivial ) is such as to produce a tipping moment on the cone. If you accelerate the center of mass of the cone, the pointy top of the cone will tip forward in the direction of the acceleration. So the added mass inertia will act as a horizontal force located below the base of the cone (a horizontal force applied as if the cone would virtually extend into the water).
Now, as you said we should be very careful, because if there is something funny going on, no measurements have been performed with these EM Drives linearly accelerating. In all the measurements the EM Drives are rotating. So perhaps in free space the EM Drive will rotate
EDIT: Also, when a symmetric body is near a solid wall, its added mass facing the wall is actually larger than its added mass facing the opposite side, so the presence of a wall on one side makes the added mass asymmetric.
This is interesting because in general a mass matrix must be symmetric for a closed system. But the fluid makes the added mass an open system and hence being close to the wall on one side produces an asymmetry that would not be present in a mass closed system. -
#2268 by frobnicat on 19 Oct, 2014 02:18
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And by the way, that formula also reminds me, did you allow formulas of the type
Sqrt[ (1/w)^2 + (1/d)^2 ]
in your program?
If not, you should in the next iteration...[/b]
d not in summary table : length not used so far
sqrt((1/a)^2+(1/b)^2) not explicitly allowed, but (a^-2 + b^-2)^1 and all other terms either -2 0 or 2 allowed, which is equivalent as far as other terms aren't quadratic (excluding only exoticas like F=a²/b² PQL/c sqrt(1/a²+1/b²))
good night dr Rodal
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#2269 by Mulletron on 19 Oct, 2014 06:55
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Well everyone agrees that inertia is rooted in distant interactions with cosmos. Some say some interactions, others say just gravity. I say all, near and far. Why play favorites?
If by "rooted in distant interactions with cosmos" you mean some Machian principle, then I don't agree. Regardless of the role "Mach principle" have played for SR and GR genesis, this principle, in its various interpretations, is nonsense to me.
Is there a problem with inertia ? What is the problem with inertia ? Why would we need to implicate the whole cosmos when local phenomena can be explained in local fields on a small patch of curved spacetime with local coordinates in inertial frame ? Local vacuum can make a difference between inertial and non inertial trajectories (accelerated relative to free falling). There is no intrinsic local absolute 0 speed, but there is intrinsic local absolute 0 acceleration : does that make insurmountable theoretical problems, or fail at predicting some well proven experimental effects ? Does that have to be explained ?
I don't want to trigger a flow of scholarly answers here, just stating some astonishment.
Yep I'm on board with you. That's why I said, "I say all, near and far. Why play favorites?"
I am disagreeing with "everybody" and all that Machian business regarding distant interactions. It is clear that inertia is dependent on all interactions at all distances, near and far.
Mach simply wasn't as informed about the universe as we are now. We have the benefit of new data.
I keep restating the same things over and over here on this forum.
I've been trying for weeks to put this business of photons experiencing Unruh radiation business to bed. This all happened because of a fundamental mis-attribution of Unruh waves (all possible waves in the vacuum, and the relationship between what modes fit and what modes don't fit, eg. casimir effect) and Unruh radiation (black body radiation felt by accelerating massive objects). Photons can't and don't and won't ever experience Unruh radiation. They can't accelerate. They don't accelerate. They don't have mass. If you want to play with ideas about Unruh radiation, switch to accelerating electrons instead.
TMI on Unruh:
http://www.powershow.com/view1/596fe-ZDc1Z/Radiation_from_Accelerated_Observers_powerpoint_ppt_presentation
The other thing I've been trying to drive home is that the momentum of a photon in an EM field (static or dynamic) doesn't just slam into things and impart linear momentum. The conditions where this is happening is what is important. Solar sails work because they are open to the universe. The devil is in the details. I put references up over and over again attesting to this, with lots of math which is what people love. An EM wave is an AC signal, which oscillates above and below 0, each cycle is 180degrees out of phase. There is no net linear momentum that can be obtained from this. An AC signal pushes for half, and pulls for the other half. The field lines inside the EMdrive are all wrapped up onto themselves, and the device is a giant loop inside. Any radiation pressure you would hope to get can't be used because the walls of the device are connected to all the other walls of the device. EM waves rotate along the axis of travel. This angular momentum is all you get to play with in a closed system.
The final thing I've been trying to drive home is that in a closed system, such as inside the emdrive cavity, all the field lines flow in continuous circles, even the poynting vector is two counter rotating oscillating circles, which diminishes with Q. No useful work can be derived from that either. All the momentum inside emdrive is angular momentum. There is no way to extract linear momentum.
The devil is in the details, and you can't push the I believe button ever, not even once.
This method isn't going to work.
There is clear data from the Nasa paper (dielectric importance/thrust not scaling with Q) and new insights mentioned above that is being ignored in favor of pet theories based off of faulty assumptions. Respectfully.
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#2270 by ThinkerX on 19 Oct, 2014 08:29
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Are we working our way back to Doctor Whites 'virtual particle becoming 'real' for millisecond' premise? (Hope I stated that correctly.)
Or does that still involve too many major violations of physics for serious consideration?
A thought that's crossed my mind a few times these last few pages. Maybe this device 'hitches a ride' on space time expansion?
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#2271 by Mulletron on 19 Oct, 2014 12:50
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For anyone who's interested, this video will cut through all the complexity and explain the origin of conservation laws and their relation to the geometry and symmetry of spacetime. This is directly related to emdrive, the shape of the cavity, and whether the anomalous thrust is a result of heat, magnetic influence, or dielectric thrust, something else, or all, wrt the principle of least action. This is intended to help out those who don't necessarily do science on a regular basis, or don't work in sci tech.
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#2272 by JohnFornaro on 19 Oct, 2014 13:07
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8, 12, 16
You give them the material before the test and they still get the answer wrong.MassMESS # 1 illustrated first.MassMESS #2 Illustrated second.
Well, tanks (instead of thanks) for fix'n that sideways picture
That happened within seconds of posting. R U stalking me? -
#2273 by JohnFornaro on 19 Oct, 2014 13:08
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I don't want to trigger a flow of scholarly answers here, just stating some astonishment.
How about wisecracks? -
#2274 by JohnFornaro on 19 Oct, 2014 13:13
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There is no intrinsic local absolute 0 speed, but there is intrinsic local absolute 0 acceleration ...
And why not? It would be a jiggly wiggly atom seemingly zipping around somewhere in the universe. Finding it would be problematical.
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#2275 by JohnFornaro on 19 Oct, 2014 13:15
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Very well stated. But what if inertia can be explained by a local field that goes to some extent beyond the cavity and depends on the cavity shape?
Primitive man want know what side of equation term "what if?" go on. -
#2276 by JohnFornaro on 19 Oct, 2014 13:20
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So in this formalism something can have a different "mass" depending on its position, but it can't have a different mass depending on it going to or leaving a position. The push heavy pull light analogy don't hold for slow moves. It can hold for fast moves but then I'm not sure this still makes sense to see the asymmetric resistance to changes of speed as changes of mass : basically it is a propeller and medium has to be modelled as a separate mass, not as an added mass to the propeller blades.
Back to the ether, I see. -
#2277 by Rodal on 19 Oct, 2014 13:31
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You say potato I say potato,So in this formalism something can have a different "mass" depending on its position, but it can't have a different mass depending on it going to or leaving a position. The push heavy pull light analogy don't hold for slow moves. It can hold for fast moves but then I'm not sure this still makes sense to see the asymmetric resistance to changes of speed as changes of mass : basically it is a propeller and medium has to be modelled as a separate mass, not as an added mass to the propeller blades.
Back to the ether, I see.SometimesI just flat out don't get it
you say tomato I say tomato,
you say Noether and I say either
you say ether and I say neither
either, ether, Noether, neither
you eat potato and I eat potato
tomato, tomato, potato, potato
you say after and I say laughter
you say ether, I say aether
ether, aether, Noether, neither...
let's call the whole thing off... -
#2278 by JohnFornaro on 19 Oct, 2014 13:37
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Well everyone agrees that inertia is rooted in distant interactions with cosmos. Some say some interactions, others say just gravity. I say all, near and far. Why play favorites?
If by "rooted in distant interactions with cosmos" you mean some Machian principle, then I don't agree. Regardless of the role "Mach principle" have played for SR and GR genesis, this principle, in its various interpretations, is nonsense to me.
... I don't want to trigger a flow of scholarly answers here, just stating some astonishment.
Yep I'm on board with you. That's why I said, "I say all, near and far. Why play favorites?"
I am disagreeing with "everybody" and all that Machian business regarding distant interactions. It is clear that inertia is dependent on all interactions at all distances, near and far.
Mach simply wasn't as informed about the universe as we are now. We have the benefit of new data.
Ja. The same can be said of Maxwell's equations too; but they are still valid to this day. Just personally, I have an intuition that Mach may have been on tosomething, but that's just an intuition.
I keep restating the same things over and over here on this forum.Quote from: MulletronI've been trying for weeks to put this business of photons experiencing Unruh radiation business to bed. ...
Good doctor been mucho patient with primitive man, but primitive man still not seeing connection between group velocity and momentum of mass, among other things.Quote from: MulletronThe other thing I've been trying to drive home is that the momentum of a photon in an EM field ... doesn't just slam into things and impart linear momentum. ... angular momentum is all you get to play with in a closed system.
Me think you right.Quote from: MulletronThe final thing I've been trying to drive home is that ... there is no way to extract linear momentum. ...
The devil is in the details, and you can't push the I believe button ever, not even once.
Me still want believe in ether. -
#2279 by JohnFornaro on 19 Oct, 2014 13:38
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What? Emmy Noether? So she already doesn't believe?????????????????
we just used the microwave frequency.