Stormbringer

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Re: EM Drive Developments
« Reply #3480 on: 11/30/2014 03:47 am »
Light does travel at different speeds in different mediums. When particles are emitted in fission underwater the speed of light slows such that the emitted particles exceed the speed for the medium and a blue glow called Cherenkov radiation results.
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aero

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Re: EM Drive Developments
« Reply #3481 on: 11/30/2014 04:13 pm »
@Mulleton & @Stormbringer,

That's good information but what I'm wondering about is simply this:
As the dielectric constant goes up, the resonate wave length of the RF increases so light takes more time to make the round trip in resonance. But the Cavity length does not increase nor does the air-filled length increase. So the trip time across the air-filled length stays constant with light speed=c. Now looking at the difference between dielectric constant of 1.76, and 4.2, the resonate distance increases by about 15% but the physical distance of course remains the same.

Note that quality factor, Q in all cases in the table is on the order of 10E+7 so I think that means that group velocity and phase velocity are nearly equal. How can the RF waves effectively travel 15% farther while slowing in the dielectric and traversing the same physical distance? I don't doubt that they do, just wonder how to interpret it using simplified geometry/math and English.
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Mulletron

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Re: EM Drive Developments
« Reply #3482 on: 11/30/2014 06:48 pm »
Ok so the refractive index of a material is the ratio of light speed in a medium wrt light speed in a vacuum. Quoting the Oracle by copy and paste, "For example, the refractive index of water is 1.33, meaning that light travels 1.33 times faster in a vacuum than it does in water."

You can calculate the refractive index by taking the sqrt erur. Relative permittivity isn't the same across the frequency spectrum, because absolute permittivity changes wrt frequency.

Quote
How can the RF waves effectively travel 15% farther while slowing in the dielectric and traversing the same physical distance?
Something doesn't seem right about that.

Quote
difference between dielectric constant of 1.76, and 4.2
That seems like an awfully large spread for a ~580mhz freq range.

http://users.tm.net/lapointe/Plastics.htm

So the relative permittivity stays the same within this frequency domain.

http://www.rfcafe.com/references/calculators/wavelength-frequency-calculator.htm
Now changing the relative permittivity of what's in there greatly changes the resonant frequency, of course, but that isn't what is going on. The same PE puck is being used, and it's relative permittivity remains pretty much constant over the frequencies in use.
« Last Edit: 11/30/2014 07:39 pm by Mulletron »
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Notsosureofit

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Re: EM Drive Developments
« Reply #3483 on: 11/30/2014 07:34 pm »
OK, second look (found one error so far) at the proposition that dispersion caused by an accelerating frame of reference implied an accelerating frame of reference caused by a dispersive cavity resonator to 1st order using massless, perfectly conducting cavity. Quickie calculation to rotate waveguide into doppler frame for acceleration g.

g = (X[subm,n])^2*(c/4*pi^2)*lambda^2*((1/a^2)-(1/b^2))

where a anb b are the end plate radii and the X are the Bessel function zeros.

X[subm,n] = m-th root of dJ[subn](x)/dx = 0

[1,0]=3.83, [1,1]=1.84, [1,2]=3.05, [2,0]=7.02, [2,1]=5.33, [2,2]=8.54, [3,0]=10.17, etc.

Lambda < cutoff wavelength.

Lambda is the free space wavelength c/f.

giving thrust per photon:

T = (X[subm,n])^2*(h/4*pi^2)*lambda*((1/a^2)-(1/b^2))

If the number of photons is power * Q / hf then I should be able to try some numbers (and possibly find more mistakes)

T = P*Q*(X[subm,n])^2*(c/4*pi^2)*lambda^2*((1/a^2)-(1/b^2))

Doesn't look too obvious, but we'll see what else I've missed.

Rodal

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Re: EM Drive Developments
« Reply #3484 on: 11/30/2014 07:55 pm »
OK, second look (found one error so far) at the proposition that dispersion caused by an accelerating frame of reference implied an accelerating frame of reference caused by a dispersive cavity resonator to 1st order using massless, perfectly conducting cavity. Quickie calculation to rotate waveguide into doppler frame for acceleration g.

g = (X[subm,n])^2*(c/4*pi^2)*lambda^2*((1/a^2)-(1/b^2))

where a anb b are the end plate radii and the X are the Bessel function zeros.

X[subm,n] = m-th root of dJ[subn](x)/dx = 0

[1,0]=3.83, [1,1]=1.84, [1,2]=3.05, [2,0]=7.02, [2,1]=5.33, [2,2]=8.54, [3,0]=10.17, etc.

Lambda < cutoff wavelength.

Lambda is the free space wavelength c/f.

giving thrust per photon:

T = (X[subm,n])^2*(h/4*pi^2)*lambda*((1/a^2)-(1/b^2))

If the number of photons is power * Q / hf then I should be able to try some numbers (and possibly find more mistakes)

T = P*Q*(X[subm,n])^2*(c/4*pi^2)*lambda^2*((1/a^2)-(1/b^2))

Doesn't look too obvious, but we'll see what else I've missed.

Kudos !

and a few

QUESTIONS:

1) What is the actual acceleration (formula used for acceleration and variables inside it)  of the accelerating frame of reference under your consideration?

2) Defining thrust force of a rocket to be in the same direction as the motion of the rocket, what is the direction of the thrust force according to your EM drive formula? Is it directed towards the small end or towards the large end?

3) For your formula, does it make a difference whether the cavity's mode is TE (outer circumferentially electric with an inner axial magnetic field) or TM (outer circumferentially magnetic with an inner axial electric field) ?

4) So the proposition that an accelerating frame of reference caused by a dispersive cavity resonator gives you a net thrust (as long as the ends have different diameter) proportional to Q even though there are no photons escaping the cavity?  What is the explanation for conservation of momentum? That one has to consider an open system because of the accelerating frame of reference?

PS: for the final equation giving the thrust as a function of the power input, Q, wavelength and radii:

T = P*Q*(X[subm,n])^2*(c/4*pi^2)*lambda^2*((1/a^2)-(1/b^2))

T =thrust force
P= power input
Q=quality factor
X[subm,n]=  m-th root of dJ[subn](x)/dx = 0 where J= Bessel function of the first kind
[1,0]=3.83, [1,1]=1.84, [1,2]=3.05, [2,0]=7.02, [2,1]=5.33, [2,2]=8.54, [3,0]=10.17, etc.
c= speed of light in the cavity inner medium
lambda=free space wavelength c/f such that lambda<cutoff wavelength
« Last Edit: 11/30/2014 08:30 pm by Rodal »

Mulletron

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Re: EM Drive Developments
« Reply #3485 on: 11/30/2014 08:33 pm »
Dispersion, like rainbow dispersion? Interesting.....

How does dispersion work with a CW spike operating in a single mode? I need to take a moment with a Twix.
« Last Edit: 11/30/2014 09:01 pm by Mulletron »
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Notsosureofit

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Re: EM Drive Developments
« Reply #3486 on: 11/30/2014 09:15 pm »
Dispersion, like rainbow dispersion? Interesting.....

How does dispersion work with a CW spike operating in a single mode? I need to take a moment with a Twix.

That is the question.

Mulletron

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Re: EM Drive Developments
« Reply #3487 on: 11/30/2014 09:17 pm »
Please forgive my ignorance. This is a new way of thinking for me. So do you mean dispersion due to doppler frequency shifting inside the cavity due to acceleration of the cavity? Maybe? Trying to grasp what you're saying is all.
« Last Edit: 11/30/2014 09:18 pm by Mulletron »
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Notsosureofit

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Re: EM Drive Developments
« Reply #3488 on: 11/30/2014 09:29 pm »
Please forgive my ignorance. This is a new way of thinking for me. So do you mean dispersion due to doppler frequency shifting inside the cavity due to acceleration of the cavity? Maybe? Trying to grasp what you're saying is all.

Exactly, I'm fishing around to see what the relationship is (if any) between a cavity w/ an asymmetric dispersion relation and the accelerated frame of reference that balances it via doppler shifts.

Pretty crude at the moment.

I just used the relation for a cylindrical wave guide to get those.  It would be nice to have the full vector dispersion for the cavity to start,  but    ,   time, time.

« Last Edit: 11/30/2014 09:50 pm by Notsosureofit »

Mulletron

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Re: EM Drive Developments
« Reply #3489 on: 11/30/2014 09:57 pm »
Given the permittivity and permeability of free space, I wonder how a spontaneously anisotropic vacuum could effect dispersion, eg vacuum dispersion.

The reason I'm saying this is linked to below. Seems like I have vacuum on the brain now days. It can do anything!
http://arxiv.org/abs/1302.6165

The other reason I'm saying that is because the acceleration thing doesn't "resonate"  with me because the cavity sitting on the bench isn't accelerating wrt any observers. But there are other ways to get dispersion besides acceleration induced doppler shifts.

« Last Edit: 11/30/2014 11:12 pm by Mulletron »
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IslandPlaya

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Re: EM Drive Developments
« Reply #3490 on: 11/30/2014 10:05 pm »
You are joking of course....
The lab setup is accelerating in most observers rf...

Rodal

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Re: EM Drive Developments
« Reply #3491 on: 11/30/2014 10:13 pm »
the cavity sitting on the bench isn't accelerating wrt any observers
It all depends on how small an acceleration one is considering, as astronomers need to subtract time-varying Doppler shifts due to Earth's changing velocities if they are interested in equal or smaller changes due to the actual motions of the stars.  For example,

1) the centripetal acceleration at the Equator is about 0.034 m/sec^2  (0.3% of the gravitational acceleration g).

2) The centripetal acceleration of the Earth around the Sun is 0.0059 m/sec^2 (0.06 % of the gravitational acceleration g).

3) The centripetal acceleration required for our  Sun and solar system to orbit the center of our galaxy is very  small: 1.9*(10^(-10)) m/sec^2.

« Last Edit: 12/01/2014 01:14 am by Rodal »

Mulletron

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Re: EM Drive Developments
« Reply #3492 on: 11/30/2014 10:35 pm »
So regardless of how dispersion comes about....dispersion is the key thing here though right? Or is the AFR the key thing here? I'm re-reading all of Notsosureofit's posts. Seeing a lot about AFRs there.
« Last Edit: 11/30/2014 10:55 pm by Mulletron »
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Notsosureofit

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Re: EM Drive Developments
« Reply #3493 on: 12/01/2014 12:01 am »
But there are other ways to get dispersion besides acceleration induced doppler shifts.

Yes, you might expect to see some from the energy loss while the NASA cavity is loading the spring, or from Shawyers rotating rig.  Any non-linearity.

Rodal

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Re: EM Drive Developments
« Reply #3494 on: 12/01/2014 02:20 am »
the cavity sitting on the bench isn't accelerating wrt any observers
It all depends on how small an acceleration one is considering, as astronomers need to subtract time-varying Doppler shifts due to Earth's changing velocities if they are interested in equal or smaller changes due to the actual motions of the stars.  For example,

1) the centripetal acceleration at the Equator is about 0.034 m/sec^2  (0.3% of the gravitational acceleration g).

2) The centripetal acceleration of the Earth around the Sun is 0.0059 m/sec^2 (0.06 % of the gravitational acceleration g).

3) The centripetal acceleration required for our  Sun and solar system to orbit the center of our galaxy is very  small: 1.9*(10^(-10)) m/sec^2.

And what is the acceleration measured by NASA Eagleworks?

acceleration = 55 microNewtons / mass

say that the mass was 20 lbm, then the acceleration was:

acceleration = (55*10^(-6) kg m / sec^2) / (20 lbm * 0.453592 kg / lbm) = 6 * 10^(-6) m/sec^2

= 0.00018 of the Earth's centripetal acceleration at the Equator
= 0.0010 of the centripetal acceleration of the Earth around the Sun
= 32000 times  the centripetal acceleration required for our  Sun and solar system to orbit
the center of our galaxy

In other words, the acceleration measured by NASA is less than 1/5000 times the  Earth's centripetal acceleration at the Equator, and 1/1000 times the  Earth's centripetal acceleration around the Sun , so with respect to an observer at the pole the EM Drive at NASA was already accelerating "sitting at the table" and the tiny acceleration measured by NASA Eagleworks was an insignificant change in acceleration compared to its pre-existing centripetal acceleration due to the Earth's rotating around its own axis.

This is what we are dealing with here: an experiment at NASA Eagleworks where only 2.6 watts of input power was applied to obtain a tiny force of only 55 microNewtons: an acceleration so small that even the centripetal acceleration of the Earth around the Sun is larger than it.
« Last Edit: 12/01/2014 02:33 am by Rodal »

Mulletron

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Re: EM Drive Developments
« Reply #3495 on: 12/01/2014 02:40 am »
Quote
the cavity sitting on the bench isn't accelerating wrt any observers

Well I concede it is accelerating wrt observers after you turn it on. Gotta look at cause and effect here.

That was a good analysis. I wish you could run your math wizardry on my "unpossible" post from yesterday.

Here's what I'm looking at:

So Molly is an electron in the dielectric, Chris and Jim are a bunch of random vacuum fluctuations. Will and Richard Grieco (not shown  ) are photons of the RF EM waves. Will and Richard Grieco only dance when "What is Love" is playing when RF is turned on. The dance club is a new place called Copper Conical Frustum. The idea here is to get Chris to dance harder than Jim. I want Molly to dance across the room. Instead of being buffeted in the middle, like what usually happens over at The China Club.

http://www.nasa.gov/centers/glenn/technology/warp/possible.html
"It has also been suggested by Millis that any asymmetric interactions with the vacuum energy might provide a propulsion effect."
#vacuum polarization #zitterbewegung
Disclaimer: I promise I wasn't tanked while writing this analogy. Just trying to communicate a concept in a hilarious thought provoking way.
« Last Edit: 12/01/2014 09:04 am by Mulletron »
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Rodal

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Re: EM Drive Developments
« Reply #3496 on: 12/01/2014 01:17 pm »
Quote
the cavity sitting on the bench isn't accelerating wrt any observers

Well I concede it is accelerating wrt observers after you turn it on. Gotta look at cause and effect here.

That was a good analysis. I wish you could run your math wizardry on my "unpossible" post from yesterday.

Here's what I'm looking at:

So Molly is an electron in the dielectric, Chris and Jim are a bunch of random vacuum fluctuations. Will and Richard Grieco (not shown  ) are photons of the RF EM waves. Will and Richard Grieco only dance when "What is Love" is playing when RF is turned on. The dance club is a new place called Copper Conical Frustum. The idea here is to get Chris to dance harder than Jim. I want Molly to dance across the room. Instead of being buffeted in the middle, like what usually happens over at The China Club.

http://www.nasa.gov/centers/glenn/technology/warp/possible.html
"It has also been suggested by Millis that any asymmetric interactions with the vacuum energy might provide a propulsion effect."
#vacuum polarization #zitterbewegung
Disclaimer: I promise I wasn't tanked while writing this analogy. Just trying to communicate a concept in a hilarious thought provoking way.

Direction-biased random walks:
http://demonstrations.wolfram.com/DistributionsInDirectionBiasedRandomWalk/

Biased random walks:

« Last Edit: 12/01/2014 01:38 pm by Rodal »

Notsosureofit

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Re: EM Drive Developments
« Reply #3497 on: 12/02/2014 11:50 am »
Found dumb error, update by weekend, thanks for patience

Notsosureofit

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Re: EM Drive Developments
« Reply #3498 on: 12/02/2014 08:36 pm »
OK, third time is the charm (same error only twice) on the proposition that dispersion caused by an accelerating frame of reference implied an accelerating frame of reference caused by a dispersive cavity resonator to 1st order using massless, perfectly conducting cavity. Quickie calculation to rotate waveguide into doppler frame for acceleration g.

g = (X[subm,n])^2*(c/4*pi^2)*lambda^2*((1/a^2)-(1/b^2))

where a anb b are the end plate radii and the X are the Bessel function zeros.

X[subm,n] = m-th root of dJ[subn](x)/dx = 0

[1,0]=3.83, [1,1]=1.84, [1,2]=3.05, [2,0]=7.02, [2,1]=5.33, [2,2]=8.54, [3,0]=10.17, etc.

Lambda < cutoff wavelength.

Lambda is the free space wavelength c/f.

giving thrust per photon:

T = (X[subm,n])^2*(h/4*pi^2)*lambda*((1/a^2)-(1/b^2))

If the number of photons is power * Q / hf then I should be able to try some numbers.

T = P*Q*(X[subm,n])^2*(1/c*4*pi^2)*lambda^2*((1/a^2)-(1/b^2))

TM211 T=9.84e-5 vs 9.12e-5 P=16.9 Q=7320
TM211 T=2.39e-4 vs 5.01e-5 P=16.7 Q=18100
TE012 T=1.32e-4 vs 5.54e-5 P=2.6  Q=22000

Close enough for gummint work ?

So if you have the dispersion relation for any cavity, can you now directly calculate Thrust (force ?) as GR ??

Edit: Does it also mean, as in the acoustic case, that you can optimize the cavity shape ?
« Last Edit: 12/02/2014 10:19 pm by Notsosureofit »

IslandPlaya

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Re: EM Drive Developments
« Reply #3499 on: 12/02/2014 10:39 pm »
I like this without checking... I trust you.

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