#### Rodal

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##### Re: EM Drive Developments
« Reply #2860 on: 11/02/2014 02:01 am »
Wouldn't thermoelastic waves from the small end also cause vibrations that would propagate throughout the device? The copper cone is not going to isolate the two ends. The interaction of vibrations from both ends should produce an interesting pattern.
The thermoelastic waves are quickly damped through dispersion (even in the absence of other forms of damping) and here they are also damped by the magnetic damping.
In most problems there is no such thing as "thermoelastic waves" because the inertial terms are entirely negligible in the great majority of  thermal problems.  Fourier's heat equation does not contain a second order time derivative.  The thermoelastic coupling with the inertial term is usually very negligible.  It only appears in very thin shells or plates.   That's why I asked for an independent assessment of the thickness of the copper before I presented this.  There would not be such a thing as a "thermoelastic wave" if the thickness would be 0.5 inch.  Even in this case it quickly becomes the steady state solution.  Yes, there is some participation from the smaller end, but I expect it to be smaller.
« Last Edit: 11/02/2014 02:07 am by Rodal »

#### zen-in

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##### Re: EM Drive Developments
« Reply #2861 on: 11/02/2014 02:40 am »
The coupling coefficient is non-trivial.  But calculating the Fourier non-dimensional time is trivial, so let's calculate the time for which the Fourier non-dimensional = 1, which is simply ((thickness)^2)/thermalDiffusivity

thermalDiffusivity = 1.11*10^(-4) m/s

so for thickness of copper = 1/8 in = 0.00318 m
hence time = 0.0908 s

so for thickness of copper = 1/16 in = 0.00159 m
hence time = 0.0227 s

so for thickness of copper = 0.022 in = 0.000559 m
hence time = 0.0028 s

So, the initial thermal effect on the copper thickness is clearly impulsive, from the point of view of the much slower response of the inverted torsional pendulum (with period ~ 4.5 s)

Great!  Look at the drumhead expansion of the big end .002" copper FRP w/ resistve heating from the Cu loss!

http://en.wikipedia.org/wiki/FR-4

I need to know the boundary conditions for the 0.002" copper.

Is the 0.002" copper a separate thin sheet of copper, or is the 0.002" copper thermally sprayed on the fiber-reinforced-polymer substrate and hence integrally bonded to it, or is the 0.002" copper adhered to the fiber-reinforced-polymer substrate ?

Can the 0.002" be easily peeled apart from the polymer composite substrate?
(Can one hold on to that 0.002" copper with pliers and peel it apart from the polymer composite substrate?

The single sided Copper FR4 used looks thicker than 1/16".   It may be 3/32" or 1/8" but the Copper is likely not any thicker than .020".   The Copper is heat bonded to the FR4 using a heat curing epoxy.  I base this assumption from my attempts to remove strips of Copper from PCBs.   The Copper has to heated up to about 700 F before trying to peel it off.
« Last Edit: 11/02/2014 02:42 am by zen-in »

#### ThinkerX

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##### Re: EM Drive Developments
« Reply #2862 on: 11/02/2014 04:14 am »
Am I to conclude from the last few posts the thrust produced by the Eagleworks EM drive is in fact a thermoelestic artefact?

#### RotoSequence

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##### Re: EM Drive Developments
« Reply #2863 on: 11/02/2014 04:30 am »
Am I to conclude from the last few posts the thrust produced by the Eagleworks EM drive is in fact a thermoelestic artefact?

We cannot say that. We can say that Rodal's hypothesis is that the Eagleworks EM drive is a thermoelectric artifact, that there is a distinct possibility that it is a thermoelectric artifact, and that Rodal in the process of demonstrating the likelihood of that cause with his analysis.
« Last Edit: 11/02/2014 04:31 am by RotoSequence »

#### frobnicat

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##### Re: EM Drive Developments
« Reply #2864 on: 11/02/2014 08:24 am »
Am I to conclude from the last few posts the thrust produced by the Eagleworks EM drive is in fact a thermoelestic artefact?

We cannot say that. We can say that Rodal's hypothesis is that the Eagleworks EM drive is a thermoelectric artifact, that there is a distinct possibility that it is a thermoelectric artifact, and that Rodal in the process of demonstrating the likelihood of that cause with his analysis.

There are a number of things going on, some are probably negligible in magnitude (relative to the "signal") and others are not. Luckily we have balance beam's end displacement vs time graphs and there is a lot of information in that. Beyond what we have to complain about, rightly so (as the controversial nature of such experiments needs more instrumental details than casual measures, not less), that should nevertheless be put to the credit of the experimenters team of "anomalous thrust...".

Some of the effects unaccounted for by Brady et al might have very clear temporal signatures in those graphs, making it possible to confirm such effects even with wide error bars on parameters (obviously, the less uncertainty in the parameters the better, but since we have to guess a lot...) by reaching conclusions "in the ballpark" for magnitudes and in qualitative agreement with time aspects (rises/falls aspects, time constants...). Such "rough fits" if they show in the graphs the same parameter dependence as the models (between Brady a b c have different parameters, would the models "predict" the way results change ?) would be a strong indication in favor of such classical spurious effect(s) being the source of the reported "thrust" pulses.

At the moment we have one visually convincing reconstruction of the "thrust vs time" as a simple 2 parameter curve model, which shows that a big part (say between 30% to 50%) of the thrust pulses magnitude is not instantaneous. There is a delay of typical time 5s between the power on of the thruster and this part of the measured thrust, and the same delay is also showing in the decay at power off. As convincing as "real EMdrive theories" can go, none of them (I think) ever could explain such delay. The time constants of electromagnetic energy filling the cavity are more in the ten of µs at most (making it "instantaneous").

I have my idea about the slow rising/falling part as a warm jet of air, heated inside the cavity, dilating and leaking asymmetrically. A number of details must be evaluated, including PCBs elasticity, anisotropies in dissipated power inside the cavities walls, air humidity... only to know what is relevant and what is not, and make correct simplifying assumptions for the "simulations". I won't have much spare time in the coming weeks, don't expect a definite answer from me (on this specific hypothesis of warm air jet) before a month or so. Please be patient. One thing is for sure : it can roughly amounts for both the magnitude and sustained (for 30s or so) of the "slow" component.

Dr Rodal has his idea about how thermoelastic effects could explain the fast rising/decaying part, that might not be that instantaneous but just fast enough. "Brady c" could serve as a confirmation as the fast part is less convincingly instantaneous in this case.
« Last Edit: 11/02/2014 08:27 am by frobnicat »

#### Mulletron

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##### Re: EM Drive Developments
« Reply #2865 on: 11/02/2014 08:29 am »
A [Date Acquired: Oct 30, 2014] paper co-authored by Dr. White presented at the Institution of Electrical and Electronic Engineers: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140013174.pdf where he discusses short trips to the Jovian and Saturnian moons and "uncovers an energy paradox" (see Appendix A)  .

Quote from: White et al
It is not the intent here to detail the theory or engineering of quantum vacuum plasma thrusters (Q-Thrusters). Rather, an overview of the foundational physics and laboratory findings are given.
Q-Thrusters attempt to use the properties of the “quantum vacuum” to propel a spacecraft. Quantum Electrodynamics (QED) predicts that the quantum vacuum (the lowest state of the electromagnetic field) is not empty, but rather a sea of virtual particles and photons that pop into and out of existence stemming from the Heisenberg uncertainty principle.
A number of approaches to utilize this quantum vacuum to transfer momentum from a spacecraft to the vacuum have been synopsized in [1].
A Q-Thruster uses the same principles as conventional plasma thrusters, namely magnetohydrodynamics, where plasma is exposed to crossed electric and magnetic fields which induce a drift of the entire plasma in a direction orthogonal to the applied fields. The difference arises in that a Q-Thruster uses quantum vacuum fluctuations as the “propellant” source, eliminating the need for conventional on-board propellant. A discussion of spacecraft “conservation of energy” is given in Appendix A. Recent laboratory test results [2] indicate the expected thrust-to-power ratio for flight applications could be in the 0.4 – 4.0 N/kWe range, which is one to two orders of magnitude greater than current operational electric thrusters. This combination of characteristics – relatively high specific thrust combined with essentially zero on-board propellant requirement - suggest space mission performance levels significantly exceeding current capabilities.

Think I got it. At least half of it.

Quoting from Appendix A,"Consider what an inertial observer that is at rest relative to the background radiation would see when considering a spacecraft in our solar system that undergoes a Δ𝑣 of 1 km/s.."

This inertial observer is an artificially contrived situation, so in reality no paradox could exist. It exists on paper. But if one were to create this inertial observer, they would have to expend energy to decelerate the observer from 371km/s to 0km/s wrt the CMB.

This reminds me of a solar system simulator I used to play with a LOT called Celestia. It allowed you to completely stop your motion wrt everything else, and you could see the planets flying at you at enormous speeds. In reality, completely stopping your motion wrt the universe would cost a lot of energy.

The two orders of magnitude too much change in kinetic energy change at the end......still processing.....

So I calculated a loss of 33,648,680,000,000 joules of kinetic energy. The spacecraft gained 1km/s velocity but lost 540kg of mass. So I agree with his change in kinetic energy, even though he didn't state it was a loss of kinetic energy. I get three more zeros in my calcs, so I'm tera not giga on everything. But my math matches him where he got 33,649Gj.

As far as the disparity between energy provided by the power source and change in kinetic energy of the system, 174Gj vs 33,649Gj, he didn't show his work. He just says, "The example spacecraft for our scenario will be a 10,000 kg spacecraft with a power system that provides 10 kWe of power. The electric propulsion system for this example spacecraft will be modeled as Hall-thruster-like with thrust to power of 0.056 N/kWe and a specific impulse of 1838 s. This spacecraft will take 17,370,579 seconds or 201 days to change the velocity of the spacecraft by 1 km/s, and will consume 540 kg of propellant. The amount of energy provided by the power source over this time frame is 174 Gigajoules."

I can only guess he didn't take into account the fact that the craft is losing mass every second it is thrusting, while providing the same constant energy from the power source. Or he is not separating frames of reference, from galactic vs universe.

I think the problem lies in his calc of specific impulse, using the earthly 9.8m/s^2 and atmospheric conditions, which is fine for a rocket on earth, but not when you're out in space. He didn't state whether his specific impulse calcs were sea level or vacuum. It looks like sea level to me.

So he got the thrust velocity wrong. I think he forgot that specific impulse is calculated using the propellant's weight, not mass, and in space that propellant is weightless, yet still has mass. So he has to calculate things differently.

I can tell you that from here:
http://www.strout.net/info/science/delta-v/intro.html
I get the correct result of delta V. See the discussion.

This is why I don't do math.
« Last Edit: 11/02/2014 09:06 am by Mulletron »
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#### frobnicat

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##### Re: EM Drive Developments
« Reply #2866 on: 11/02/2014 10:01 am »
A [Date Acquired: Oct 30, 2014] paper co-authored by Dr. White presented at the Institution of Electrical and Electronic Engineers: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140013174.pdf where he discusses short trips to the Jovian and Saturnian moons and "uncovers an energy paradox" (see Appendix A)  .

Quote from: Joosten & White
.../... the point of this paragraph is to identify that the paradox can be created for any spacecraft using conventional propulsion as well as advanced propulsion.
That ends the appendix A that "addresses" the apparent "issue" of energy conservation. There is no issue : energy conservation is broken every time we fly a rocket. Ok. Let's proceed to more interesting stuff...

Only...

Propellantless

before
O---->    +energy to spend

after
O----->

Action/reaction rocket

before

oo---->   + energy to spend

after
o-->        o----->
expelled

So in the later case, when taking into account the mass_energy of masses, there is energy conservation overall (in any inertial frame). In the former case there is no such conservation as soon as you choose an inertial frame where speed above some threshold.

Said otherwise, in any given arbitrary inertial frame, for the classical rocket to give practical power at constant rate (pushing at constant speed) you have to replenish both energy & reaction mass from the said frame, can't have more energy than you put in. For the propellantless rocket, with thrust/power better than 1/c, then you just have to replenish in energy, and energy is light enough to be communicated from a "rest frame" to the rocket at lower cost than you get back from the rocket pushing.

Perpetual motion of the first kind possible in the propellantles case, not in the classical action/reaction case. Not the same thing. Period.
« Last Edit: 11/02/2014 10:02 am by frobnicat »

#### Mulletron

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##### Re: EM Drive Developments
« Reply #2867 on: 11/02/2014 10:32 am »
A [Date Acquired: Oct 30, 2014] paper co-authored by Dr. White presented at the Institution of Electrical and Electronic Engineers: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140013174.pdf where he discusses short trips to the Jovian and Saturnian moons and "uncovers an energy paradox" (see Appendix A)  .

Quote from: Joosten & White
.../... the point of this paragraph is to identify that the paradox can be created for any spacecraft using conventional propulsion as well as advanced propulsion.
That ends the appendix A that "addresses" the apparent "issue" of energy conservation. There is no issue : energy conservation is broken every time we fly a rocket. Ok. Let's proceed to more interesting stuff...

Only...

Propellantless

before
O---->    +energy to spend

after
O----->

Action/reaction rocket

before

oo---->   + energy to spend

after
o-->        o----->
expelled

So in the later case, when taking into account the mass_energy of masses, there is energy conservation overall (in any inertial frame). In the former case there is no such conservation as soon as you choose an inertial frame where speed above some threshold.

Said otherwise, in any given arbitrary inertial frame, for the classical rocket to give practical power at constant rate (pushing at constant speed) you have to replenish both energy & reaction mass from the said frame, can't have more energy than you put in. For the propellantless rocket, with thrust/power better than 1/c, then you just have to replenish in energy, and energy is light enough to be communicated from a "rest frame" to the rocket at lower cost than you get back from the rocket pushing.

Perpetual motion of the first kind possible in the propellantles case, not in the classical action/reaction case. Not the same thing. Period.

I'm not seeing it that way. A Hall thruster is not propellant less. He never used the word propellant less to describe the paradox. I see a false paradox, which was created by bad methodology and bad math.

Now considering a true Q-thruster, which is propellant less. The ship could never be expected to accelerate past a velocity greater than the energy provided by the propulsion system. Even with constant acceleration. Acceleration is constant until max velocity is reached; at some point the kinetic energy of the craft and the energy provided by the propulsion system output would be equal. The propulsion system isn't a perpetual motion machine and has physical limits on amount of power that can be provided, thus ensuring the craft doesn't zoom away towards infinity, violating conservation of energy.

The universe itself provides the rest of the speed limit. C.

Advanced propulsion does not equal propellant less propulsion. Advanced propulsion is ion thrusters and similar junk to Nasa. This is the parlance they go by.

Breakthrough propulsion is propellant less propulsion.
« Last Edit: 11/02/2014 02:16 pm by Mulletron »
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#### Mulletron

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##### Re: EM Drive Developments
« Reply #2868 on: 11/02/2014 10:48 am »
Ok first we're gonna draw little mustaches on our electrons, then use them to interact with the QV through the dielectric:

http://www.quantumdiaries.org/2011/06/19/helicity-chirality-mass-and-the-higgs/
http://physics.unl.edu/~tgay/content/CPE.html

Still looking for a way past the "one way check valve" that allows the QV to interact with me, but doesn't allow me to interact with the QV.

Probably a dead end since the Higgs is spin 0, but interesting nonetheless.
Seriously this is good stuff.

« Last Edit: 11/02/2014 10:56 am by Mulletron »
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#### frobnicat

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##### Re: EM Drive Developments
« Reply #2869 on: 11/02/2014 11:12 am »

I'm not seeing it that way. A Hall thruster is not propellant less. He never used the word propellant less to describe the paradox. I see a false paradox, which was created by bad methodology and bad math.

Advanced propulsion does not equal propellant less propulsion.

"One of the issues to consider for a constant thrust system is the matter of conservation of energy."
You can't have constant thrust with action/reaction scheme, because there can be a constant expelled mass flow for only so long. So for me this is broadly "we are talking about propellantless propulsion". And indeed any such propellantless scheme has an issue of energy conservation. In the terminology of this appendix, the Hall thruster is conventional, the EMdrive (propellantless whatever) is advanced.

I see another spectacularly failed attempt at addressing the intrinsic issue with energy conservation of propellantless schemes, as bad as Shawyer's. Any serious physicist/engineer reading this appendix A will immediately see the plain absurdity of the argument, one way or another. This is not serious.

Propellantless scheme with better than 1/c thrust/power : either the ship taps into some energy source outside of it, or it is on its own energy and it uses tachyons. http://forum.nasaspaceflight.com/index.php?topic=29276.msg1275281#msg1275281
A classical action/reaction scheme needs neither energy source exterior to ship nor tachyons to be energy conservative. The expelled mass that's used to get better than 1/c thrust/mass had to be accelerated at the given speed first is another way to see it, this kinetic energy of expelled mass (at the moment it is expelled) is sacrificed as well as the energy taken to give it velocity relative to ship's frame.
« Last Edit: 11/02/2014 11:32 am by frobnicat »

#### Rodal

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##### Re: EM Drive Developments
« Reply #2870 on: 11/02/2014 11:23 am »

I'm not seeing it that way. A Hall thruster is not propellant less. He never used the word propellant less to describe the paradox. I see a false paradox, which was created by bad methodology and bad math.

Advanced propulsion does not equal propellant less propulsion.

"One of the issues to consider for a constant thrust system is the matter of conservation of energy."
You can't have constant thrust with action/reaction scheme, because there can be a constant expelled mass flow for only so long. So for me this is broadly "we are talking about propellantless propulsion". And indeed any such propellantless scheme has an issue of energy conservation. In the terminology of this appendix, the Hall thruster is conventional, the EMdrive (propellantless whatever) is advanced.

I see another spectacularly failed attempt at addressing the intrinsic issue with energy conservation of propellantless schemes, as bad as Shawyer's. Any serious physicist/engineer reading this appendix A will immediately see the plain absurdity of the argument, one way or another. This is not serious.

What is most perplexing is that this report follows the "Anomalous..." Brady experiment report.  It continues to insist on explaining the experimental results as being the result of the Quantum Vacuum of electron-positron virtual particles acting like a plasma that can be modeled with magnetohydrodynamics.  It has not backed down at all from that claim, which remains entirely unsupported: it does not add any support to it.  It takes for granted that these microwave propellant less thrusters work based on the Quantum Vacuum, it does not address the criticisms from the scientific community (except energy conservation by now creating a paradox questioning energy conservation ?) that has been raised against those claims and continues to build on this unsupported claim by further discussion of trips to the Jovian and Saturnian moons.

I would have expected instead to address the criticisms about the Quantum Vacuum hypothesis and to further analyze the tests and to comment on future tests.

I would have expected an effort to analyze the anomalous experimental results instead of trips to Enceladus with a propellant-less drive that has never been shown to operate in flight.
« Last Edit: 11/02/2014 11:51 am by Rodal »

#### Mulletron

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##### Re: EM Drive Developments
« Reply #2871 on: 11/02/2014 11:38 am »

I'm not seeing it that way. A Hall thruster is not propellant less. He never used the word propellant less to describe the paradox. I see a false paradox, which was created by bad methodology and bad math.

Advanced propulsion does not equal propellant less propulsion.

"One of the issues to consider for a constant thrust system is the matter of conservation of energy."
You can't have constant thrust with action/reaction scheme, because there can be a constant expelled mass flow for only so long. So for me this is broadly "we are talking about propellantless propulsion". And indeed any such propellantless scheme has an issue of energy conservation. In the terminology of this appendix, the Hall thruster is conventional, the EMdrive (propellantless whatever) is advanced.

I see another spectacularly failed attempt at addressing the intrinsic issue with energy conservation of propellantless schemes, as bad as Shawyer's. Any serious physicist/engineer reading this appendix A will immediately see the plain absurdity of the argument, one way or another. This is not serious.

Propellantless scheme with better than 1/c thrust/power : either the ship taps into some energy source outside of it, or it is on its own energy and it uses tachyons. http://forum.nasaspaceflight.com/index.php?topic=29276.msg1275281#msg1275281
A classical action/reaction scheme needs neither energy source exterior to ship nor tachyons to be energy conservative. The expelled mass that's used to get better than 1/c thrust/mass had to be accelerated at the given speed first is another way to see it, this kinetic energy of expelled mass (at the moment it is expelled) is sacrificed as well as the energy taken to give it velocity relative to ship's frame.
Ok I'm getting ya. The energy budget (right term? meaning it stores well and doesn't take up a huge volume/and is easier to refuel..solar sails, batteries, reactors....)of a propellantless system is fantastic but they aren't perpetual motion machines. They run out of juice and need recharging just as a classical action/reaction rocket runs out of fuel and needs topped off. Tomato/tomaaato. I don't see any paradox.
« Last Edit: 11/02/2014 11:42 am by Mulletron »
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#### Rodal

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##### Re: EM Drive Developments
« Reply #2872 on: 11/02/2014 11:42 am »

Great!  Look at the drumhead expansion of the big end .002" copper FRP w/ resistve heating from the Cu loss!

http://en.wikipedia.org/wiki/FR-4

I need to know the boundary conditions for the 0.002" copper.

Is the 0.002" copper a separate thin sheet of copper, or is the 0.002" copper thermally sprayed on the fiber-reinforced-polymer substrate and hence integrally bonded to it, or is the 0.002" copper adhered to the fiber-reinforced-polymer substrate ?

Can the 0.002" be easily peeled apart from the polymer composite substrate?
(Can one hold on to that 0.002" copper with pliers and peel it apart from the polymer composite substrate?

The single sided Copper FR4 used looks thicker than 1/16".   It may be 3/32" or 1/8" but the Copper is likely not any thicker than .020".   The Copper is heat bonded to the FR4 using a heat curing epoxy.  I base this assumption from my attempts to remove strips of Copper from PCBs.   The Copper has to heated up to about 700 F before trying to peel it off.

See:  http://forum.nasaspaceflight.com/index.php?topic=29276.msg1279402#msg1279402

Quote from: Notsosureofit
For what it's worth, I measure the FRP board at 0.060" and the copper cladding at 0.002". (the stuff I have here anyway)
« Last Edit: 11/02/2014 11:48 am by Rodal »

#### Mulletron

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##### Re: EM Drive Developments
« Reply #2873 on: 11/02/2014 11:56 am »
The QV thrust scenario is the only method available to justify measuring thrust from an otherwise sealed rf cavity and still say that momentum was conserved. Now people can argue that the QV doesn't exist or it is magic or whatever, but they are wrong on both counts. Magic doesn't exist and the QV does. Every field has a ground state and that is the QV. Not even worth trying to defend that the QV exists because the literature is rich and deep enough and goes all the way back to the Lamb Shift up to the present day. Did I mention that MiHsC has Casimir right in the name? Casimir and the QV are two peas in a pod. An all pervasive field is not such a leap, as the scalar Higgs field is a prime example of an all pervasive field and one of its associated excitation particles, the Higgs Boson has been confirmed. Even the Higgs field itself has a vacuum component, aka the vev of the Higgs field.

http://gravityandlevity.wordpress.com/2013/04/24/the-lamb-shift/

It is a clear as this: Those who believe that empty copper cans are exhibiting thrust are being fooled by artifact effects.

Is anybody here still on board with Quantum Thrusters?

On a separate note, why do the Pioneer probes get to lose inertial mass as they fly away from the solar system, but photons get to gain inertial mass (which they can't anyway, but lets pretend they can) by the same rationale?
http://arxiv.org/abs/astro-ph/0612599

Solution. Since you can't modify the inertial mass of light because photons are massless and speed invariant, look at what else is in the cavity which has mass and is not speed invariant. The STUFF in the cavity. The air and the dielectric. The stuff in the cavity is enjoying much less interaction with the outside world thanks to being surrounded by a copper can blocking that interaction, which means if we're going to modify the inertia of anything (which the possibility of doing so is debatable, but I and others support that we can) we should focus on that stuff instead. Not the light. We can't mess with light and not get laughed at. We can't mess with the invariant mass of massive particles and its associated invariant inertial mass, but if MiHsC holds true, we can mess with the remainder inertia, modified by interaction...Unruh, EM, whatever....if such remainder exists. I hold that such a remainder does exist due to what I've learned about superfluids and meta materials.

« Last Edit: 11/02/2014 01:52 pm by Mulletron »
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#### MikeMcCulloch

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##### Re: EM Drive Developments
« Reply #2874 on: 11/02/2014 02:45 pm »
I'd just like to clear up a couple of misunderstandings. To answer your red text: the Pioneer probes lose inertia according to MiHsC since they're moving out to lower accelerations, see longer Unruh waves, so a greater proportion of those waves are disallowed by the Hubble horizon. In the emdrive the difference is that the horizon itself changes from end to end. Both predictions are consistent with MiHsC, given the assumptions made. As for photons, special relativity (and experiment) say they have inertial mass. It is their rest mass that's zero. So it is logical and consistent to try and apply MiHsC to them. Can this be done in a way that still satisfies all the experiments performed to date? I don't know, but I'm curious about it..

#### Mulletron

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##### Re: EM Drive Developments
« Reply #2875 on: 11/02/2014 03:22 pm »
I'd just like to clear up a couple of misunderstandings. To answer your red text: the Pioneer probes lose inertia according to MiHsC since they're moving out to lower accelerations, see longer Unruh waves, so a greater proportion of those waves are disallowed by the Hubble horizon. In the emdrive the difference is that the horizon itself changes from end to end. Both predictions are consistent with MiHsC, given the assumptions made. As for photons, special relativity (and experiment) say they have inertial mass. It is their rest mass that's zero. So it is logical and consistent to try and apply MiHsC to them. Can this be done in a way that still satisfies all the experiments performed to date? I don't know, but I'm curious about it..

Sir thank you and I will think hard about what you are saying about the inside of the emdrive.

But please see above where I said, "you can't modify the inertial mass of light because photons are massless and speed invariant." The issue is about applying MiHsC to a constant. Modifying a constant. Not whether or not photons have inertial mass.

Indeed light changes direction by gravitational effects and is red shifted by similar effects, showing signs of inertia like behavior due to the momentum which photons carry, the underlying behavior of light remains the same and isn't subject to modification; the fundamental constant of C remains the same and cannot be modified.
« Last Edit: 11/02/2014 03:57 pm by Mulletron »
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#### Rodal

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##### Re: EM Drive Developments
« Reply #2876 on: 11/02/2014 04:12 pm »
I'd just like to clear up a couple of misunderstandings. To answer your red text: the Pioneer probes lose inertia according to MiHsC since they're moving out to lower accelerations, see longer Unruh waves, so a greater proportion of those waves are disallowed by the Hubble horizon. In the emdrive the difference is that the horizon itself changes from end to end. Both predictions are consistent with MiHsC, given the assumptions made. As for photons, special relativity (and experiment) say they have inertial mass. It is their rest mass that's zero. So it is logical and consistent to try and apply MiHsC to them. Can this be done in a way that still satisfies all the experiments performed to date? I don't know, but I'm curious about it..

Confining myself here only to the specific discussion (and not to MiHsC) of the statement that "photons are speed invariant."  This statement is incorrect in general and contrary to what I was taught at MIT.  It is well known that light travels at different speed in different media:  Experiments show, that single photons travel through glass at the group velocity of light, which can be quite different from the speed of light in vacuum.
It is classical (Newtonian corpuscular theory) mechanics that demands that the momentum of the photons be greater in water than in air, but  measurements show that the opposite relationship holds for their velocity.

The view that photons are particles whose speed is invariant in any media and under all conditions is contradicted also by these recent experiments revealing a new state made possible with photons:

http://www.princeton.edu/engineering/news/archive/?id=13459
https://journals.aps.org/prx/pdf/10.1103/PhysRevX.4.031043

I think that there is a confusion in the statement between the constant "c" (that of course, indeed, is an invariant constant) from  General Relativity and the quantum description of photons in Quantum Mechanics.

General Relativity does not deal with individual photons.  Photons are described by Quantum Mechanics.
« Last Edit: 11/02/2014 04:47 pm by Rodal »

#### Mulletron

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##### Re: EM Drive Developments
« Reply #2877 on: 11/02/2014 04:18 pm »
I'd just like to clear up a couple of misunderstandings. To answer your red text: the Pioneer probes lose inertia according to MiHsC since they're moving out to lower accelerations, see longer Unruh waves, so a greater proportion of those waves are disallowed by the Hubble horizon. In the emdrive the difference is that the horizon itself changes from end to end. Both predictions are consistent with MiHsC, given the assumptions made. As for photons, special relativity (and experiment) say they have inertial mass. It is their rest mass that's zero. So it is logical and consistent to try and apply MiHsC to them. Can this be done in a way that still satisfies all the experiments performed to date? I don't know, but I'm curious about it..

Confining myself here only to the specific discussion (and not to MiHsC) of the statement that "photons are speed invariant."  This statement is incorrect in general and contrary to what I was taught at MIT.  It is well known that light travels at different speed in different media:  Experiments show, that single photons travel through glass at the group velocity of light, which can be quite different from the speed of light in vacuum.
It is classical (Newtonian) mechanics that demands that the momentum of the photons be greater in water than in air, but  measurements show that the opposite relationship holds for their velocity.

The view that photons are particles whose speed is invariant in any media and under all conditions is contradicted also by these recent experiments revealing a new state made possible with photons:

http://www.princeton.edu/engineering/news/archive/?id=13459
https://journals.aps.org/prx/pdf/10.1103/PhysRevX.4.031043

I think that there is a confusion in the statement between the constant "c" (that of course, indeed, is an invariant constant) from  General Relativity and the quantum description of photons in Quantum Mechanics.

General Relativity does not deal with quantum particles like photons.  Particles like photons are described by Quantum Mechanics.

Group and phase velocity of light aren't the speed of light. They can even exceed the speed of light. Group and phase velocity change quite frequently depending on the medium light is in and transferring to/from.

Need I remind you that inside of a medium, most of that space is vacuum. The apparent slowing of light is simply the absorption and emission of light/photons when it encounters atoms. That does not change the speed of light. C is a constant. It is no coincidence that the invariance of c is linked to causality. As violating that constant would also violate cause and effect.
« Last Edit: 11/02/2014 05:12 pm by Mulletron »
And I can feel the change in the wind right now - Rod Stewart

#### Rodal

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##### Re: EM Drive Developments
« Reply #2878 on: 11/02/2014 09:40 pm »
The following shows, for the torsional inverted pendulum at NASA Eagleworks, that harmonic forcing functions with small enough period (= high enough frequency) are undistinguishable (due to the pendulum response) from a rectangular impulse forcing function

See http://forum.nasaspaceflight.com/index.php?topic=29276.msg1281244#msg1281244

The time for which the Fourier non-dimensional = 1,  is simply ((thickness)^2)/thermalDiffusivity

thermalDiffusivity = 1.11*10^(-4) m/s

so for thickness of copper = 1/8 in = 0.00318 m
hence time = 0.0908 s

One can see below the forcing function with a period 0.0908 s (equal to the Fourier non-dimensional time for a copper sheet 1/8 in) gives a response which is indistinguishable from a rectangular impulse.

For the torsional inverted pendulum at NASA Eagleworks, any period of vibration smaller than 0.2 seconds has a response which is unrecognizable from a rectangular impulse.

FORCING FUNCTION = 2 ((Sin[Pi* t/tau])^2) is the square of a sinusoid
« Last Edit: 11/03/2014 10:21 pm by Rodal »

#### hop

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##### Re: EM Drive Developments
« Reply #2879 on: 11/02/2014 10:59 pm »
On a separate note, why do the Pioneer probes get to lose inertial mass as they fly away from the solar system, ...
The so called "Pioneer anomaly" is very well explained by very ordinary physics: http://arxiv.org/abs/1204.2507

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