Author Topic: EM Drive Developments Thread 1  (Read 765582 times)

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #880 on: 09/21/2014 11:38 PM »
Maintenant, on arrive à elle, j'étais sûr que ce nouveau développement de la technologie serait une catastrophe écologique d'une certaine sorte, combien de colibri de poussée de 80 tonnes à Saturne? Quant à la (soi-disant faux ...) proposition plus tard, vous pensez que les licornes ne sont pas suffisamment rare pour prendre un péage sur la diversité de leur population?

I am so NOT running this thru the translator.
Sometimes I just flat out don't get it.

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #881 on: 09/21/2014 11:43 PM »
Lei capisce ?



Sounds a mite gangsta.
Sometimes I just flat out don't get it.

Offline Rodal

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Re: EM Drive Developments
« Reply #882 on: 09/21/2014 11:51 PM »

Sounds a mite gangsta.

Mi scusi  :(

Offline Rodal

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Re: EM Drive Developments
« Reply #883 on: 09/22/2014 12:07 AM »
Yes, but are his papers publicly available and if so where ?

Sorry, didn't mean to sound picky.

OK. So there's a good chance I still have the '64 Sciama here somewhere, at least.

Here is Sciama's 1953 vintage (John's favorite year)  http://mnras.oxfordjournals.org/content/113/1/34.full.pdf

Offline Rodal

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Re: EM Drive Developments
« Reply #884 on: 09/22/2014 12:17 AM »
Interesting, note the 50KHz vs couple Gig.  Capacitive effect of dielectric surface to microwaves, check.

Virtual proton/positron creation is a strong function of photon energy (Hz).

The following does not check :

Virtual Pair production can only occur if the photons have an energy exceeding twice the rest energy of an electron (0.511 MeV rest energy, which doubled is --->1.022 MeV).

In 2008 the Titan laser aimed at a 1-millimeter-thick gold target was used to generate positron–electron pairs in large numbers. (No Titan laser near the NASA experiments)

[The Titan is a combined nanosecond-long pulse and ultrashort-pulse (subpicosecond) laser, with hundreds of joules of energy in each beam. This petawatt-class laser is used for a range of high-energy density physics experiments, including the science of fast ignition for inertial confinement fusion energy]
« Last Edit: 09/22/2014 01:16 AM by Rodal »

Offline Rodal

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Re: EM Drive Developments
« Reply #885 on: 09/22/2014 12:55 AM »
For 2 GHz I calculate the photon energy to be only 8x10^(-6) eV, good enough to heat food and drinks by exciting molecular rotations and vibrations, but not anywhere near good enough to produce electron/positron virtual particles.  Even X-Rays have photon energy of only 10^4 eV, so it looks like one needs wavelengths even smaller than 1 nanometer (need ~ picometer) to be able to produce virtual particles (we need 10^6 eV).

See:  http://en.wikipedia.org/wiki/Electronvolt#mediaviewer/File:Light_spectrum.svg

(Please check my math ...)

E= h c/λ =( ( 6.63x10^(-34) ) J s *( 3*10^8 m/s ) /(1.6x10^(-19) J/ eV)  ) /λ

where λ is the wavelength in meters
« Last Edit: 09/22/2014 01:22 AM by Rodal »

Offline Notsosureofit

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Re: EM Drive Developments
« Reply #886 on: 09/22/2014 02:25 AM »
"Pair production" can only occur if the photons have an energy exceeding twice the rest energy of an electron (0.511 MeV rest energy, which doubled is --->1.022 MeV).

Virtual pairs are never produced.  The question is can they carry momentum ?




« Last Edit: 09/22/2014 02:37 AM by Notsosureofit »

Offline Rodal

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Re: EM Drive Developments
« Reply #887 on: 09/22/2014 02:31 AM »
So, it is even much more unlikely (by a factor of 10^(-11) compared to 10^(-2)) for the microwave to produce virtual particle electron/positron pairs than for the PTFE  dielectric resonator to produce real electrons by field emission.  And no, if electrons are indeed released by the PTFE dielectric, they are not going to disappear into the quantum vacuum because to do that they would need to get annihilated by real positrons (it is practically impossible for any real positron to show up in the microwave cavity -much more improbable than for a virtual electron-positron pair to show up).
« Last Edit: 09/22/2014 02:38 AM by Rodal »

Offline 93143

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Re: EM Drive Developments
« Reply #888 on: 09/22/2014 02:42 AM »
The Mach effect... was derived from a simplified form of general relativity

1) Woodward's derivation uses a flat Minkowski space.  In that sense he does not use Einstein's General Relativity.  He uses Special Relativity (and says so in a number of places). There is no curvature of space in Woodward's derivation.  There is no covariant, contravariant or mixed tensors. No Riemannian geometry.
Gravity is given "ab initio" (unlike Einstein's General Relativity where gravity is a result of curving of space by massive objects), yet goes on to postulate transient mass effects due in most part to most distant objects.  The justification appears to be isotropy of spacetime and local flatness of spacetime.

2) He uses the [rest energy/volume] relationship to [rest density] Eo=rho c^2 sometimes here and sometimes there.

3) I have not found Woodward's transient mass effect equations in any paper by Sciama.  He apparently uses some results from Sciama's 1953 paper and goes on from there.

Okay, I simplified a bit.

It is true, and should be understood, that Sciama-type Machian inertia (which is derived from a vector theory of gravity that turned out to be a simplified form of GR) is separate from Woodward's "Mach effect" theory (which was derived from Sciama's theory).

But the main point I was trying to get across is that as far as I know neither of these theories requires us to abandon any accepted physics, since (a) they are derived within the framework of accepted physics, and (b) the phenomenon they explain currently has no commonly-accepted physical explanation.

Offline aero

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Re: EM Drive Developments
« Reply #889 on: 09/22/2014 04:28 AM »
"Pair production" can only occur if the photons have an energy exceeding twice the rest energy of an electron (0.511 MeV rest energy, which doubled is --->1.022 MeV).
As I understand, that is correct but I also understand that this pair is a real electron and a real antielectron (positron). And when they self annihilate they produce real energy. Not what we are seeing.
Quote
Virtual pairs are never produced.  The question is can they carry momentum ?
Not produced in any way that we know of. They appear from the quantum vacuum and disappear into it. I believe they do so leaving no trace of their passing. The fly in that ointment is that the electron is real as I understand it while the positron is not but to reach that conclusion I go back to the 1930's as the theory was developed. Point is, virtual electron/positron pairs do not leave an energy trace when they annihilate. Hence virtual, but the electron is real else why bother developing the theory in the first place?
Retired, working interesting problems

Offline Rodal

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Re: EM Drive Developments
« Reply #890 on: 09/22/2014 11:43 AM »
"Pair production" can only occur if the photons have an energy exceeding twice the rest energy of an electron (0.511 MeV rest energy, which doubled is --->1.022 MeV).
As I understand, that is correct but I also understand that this pair is a real electron and a real antielectron (positron). And when they self annihilate they produce real energy. Not what we are seeing.
Quote
Virtual pairs are never produced.  The question is can they carry momentum ?
Not produced in any way that we know of. They appear from the quantum vacuum and disappear into it. I believe they do so leaving no trace of their passing. The fly in that ointment is that the electron is real as I understand it while the positron is not but to reach that conclusion I go back to the 1930's as the theory was developed. Point is, virtual electron/positron pairs do not leave an energy trace when they annihilate. Hence virtual, but the electron is real else why bother developing the theory in the first place?
See http://profmattstrassler.com/articles-and-posts/particle-physics-basics/virtual-particles-what-are-they/

<<Virtual particles, [this means the virtual electron as well as the virtual positron] which are what appear in the loop in that diagram, are not particles.  They are not nice ripples, but more general disturbances.  And only particles have the expected relation between their energy, momentum and mass; the more general disturbances do not satisfy these relations.  So your intuition is simply misled by misreading the diagram.  Instead, one has to do a real computation of the effect of these disturbances.  In the case of the photon, it turns out the effect of this process on the photon mass is exactly zero.>>
« Last Edit: 09/22/2014 11:48 AM by Rodal »

Offline frobnicat

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Re: EM Drive Developments
« Reply #891 on: 09/22/2014 12:17 PM »
Yes this article by Matt Strassler is very good at explaining things, and the loooong comments section is worthwhile too as he answers with great patience and pedagogy a lot of more or less obvious questions asked by people not trained to QFT when confronted to those concepts.
Virtual particles can't propagate, that is precisely what makes them virtual. Only field disturbances that reach a certain level of "punch" (the level of quanta) can propagate on their own away from their source on an independent trajectory, contrary to virtual disturbances that always are "linked" to a real source. If I understand well what's explained.

Aero, I have the feeling you want to treat positrons differently from electrons. A (real, not "virtual") positron is as real as an electron, as real as a particle can get, to the point of giving dermatitis (or worse) if you really want to hold that reality in your hand (Beta+ decay radioactive source for instance). The fact that the anti-electron is "moving backward in time" is just a mathematical way of stating that the equations are identical (almost ? perfectly ?) upon time-charge-parity inversion as explained in this thread :
Quote
Identifying a positron as a backwards in time electron, is an elegant interpretation that exhibits in the Feynman diagrams the CPT symmetry they must obey.

What I am saying is : the statement: "positrons are backward going electrons" is a convenient and accurate mathematical representation for calculation purposes. "As if". There has not been an indication, not even a tiny one, that in nature as we study it experimentally anything goes backwards in time, as we define time in the laboratory .

So positrons are not causing havoc in causality or usual arrow of time, they have no reason to be less real than electrons, they are symmetrical solutions to the same field as the electron field (if I understand correctly). Sorry if I misunderstood what I thought you were implying.
« Last Edit: 09/22/2014 12:22 PM by frobnicat »

Offline Rodal

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Re: EM Drive Developments
« Reply #892 on: 09/22/2014 01:10 PM »
Lawrence Livermore National Laboratory in California has used a short, ultra-intense laser to irradiate a millimetre-thick gold target and produce more than 100 billion (very real ) positronshttp://www.nbcnews.com/id/27998860/#.VCAfKvk7s0s

But again, it takes a very powerful (petawatt-class)  ultrashort-pulse (subpicosecond) laser to produce real positrons. 

Real positrons (or electrons) will not pop out of the quantum vacuum on their own in a microwave cavity like Cannae's or the Frustum tested at NASA.

One needs wavelengths  ~ picometer (frequencies 10^(11) times higher than microwave frequencies) to be able to produce real positrons or real electrons from photons (we need 10^6 eV).

As JohnFornaro said, very appropriately, alchemists in the Middle Ages thought that they could turn lead into gold by conventional chemistry.  They couldn't.  It turns out that one needs orders of magnitude higher energy (a particle accelerator) to turn lead into gold.  Similarly, it takes much higher energy (and frequency) to produce positrons (or electrons) from photons, a microwave won't do it.
« Last Edit: 09/22/2014 01:56 PM by Rodal »

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #893 on: 09/22/2014 01:49 PM »
...JohnFornato...

You say Fornato.  I say Fornaro.

But hey.
Sometimes I just flat out don't get it.

Offline Rodal

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Re: EM Drive Developments
« Reply #894 on: 09/22/2014 01:58 PM »
...JohnFornato...

You say Fornato.  I say Fornaro.

But hey.
The "t" is next to the "r" in the keyboard and it was early in the morning...But hey, it's much easier to fix this than to turn lead into gold.   It's fixed now  :)
« Last Edit: 09/22/2014 01:59 PM by Rodal »

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #895 on: 09/22/2014 02:01 PM »
There is no distinction between the cavity's interior and the (copper ?) metal wall in the COMSOL finite element analysis display of the Electric Field, so my reading of this is that the metal wall was modeled as a Boundary Condition for the field.


2. If the [metal walls are modelled as a] boundary condition as Rodal suggests, then what difference does it make what you make the truncated conical frusturm thingy out of?

....
6. The usual rejoinder.

It makes just as much difference as for example when you model the end supports of a beam made with material modulus Ea supported inside another material with modulus Eb at both ends:

blah, blah, blah...

Lei capisce ?

It's all in how one models the Boundary Conditions.  Maxwell's equations are differential equations, and to solve them one needs to satisfy Boundary Conditions, just as when one solves a beam equation.

That's what I'm getting at, my gangsta godfadda.  What I took the above conversation to mean was that the results (all those Roy G. Biv color schemes) cannot be well understood without knowing the boundary conditions.  Since there was "no distinction" between the cavity interor and the metal wall, you assume (which is what your "reading" of that is) that there must be a boundary condition defined somewhere.  That boundary condition is not specified, and would differ significantly on whether the boundary's various modulii were based on copper or compressed hummingbird wings.

Ergo, (ipso fatso being my preferred translation, BTW) there are limited conclusions which can be drawn from the FEA display of the electric field.

Non?
Sometimes I just flat out don't get it.

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #896 on: 09/22/2014 02:02 PM »
It's fixed now

What???  You changed the Akashic record?
Sometimes I just flat out don't get it.

Offline Rodal

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Re: EM Drive Developments
« Reply #897 on: 09/22/2014 02:17 PM »
There is no distinction between the cavity's interior and the (copper ?) metal wall in the COMSOL finite element analysis display of the Electric Field, so my reading of this is that the metal wall was modeled as a Boundary Condition for the field.


2. If the [metal walls are modelled as a] boundary condition as Rodal suggests, then what difference does it make what you make the truncated conical frusturm thingy out of?

....
6. The usual rejoinder.

It makes just as much difference as for example when you model the end supports of a beam made with material modulus Ea supported inside another material with modulus Eb at both ends:

blah, blah, blah...

Lei capisce ?

It's all in how one models the Boundary Conditions.  Maxwell's equations are differential equations, and to solve them one needs to satisfy Boundary Conditions, just as when one solves a beam equation.

That's what I'm getting at, my gangsta godfadda.  What I took the above conversation to mean was that the results (all those Roy G. Biv color schemes) cannot be well understood without knowing the boundary conditions.  Since there was "no distinction" between the cavity interor and the metal wall, you assume (which is what your "reading" of that is) that there must be a boundary condition defined somewhere.  That boundary condition is not specified, and would differ significantly on whether the boundary's various modulii were based on copper or compressed hummingbird wings.

Ergo, (ipso fatso being my preferred translation, BTW) there are limited conclusions which can be drawn from the FEA display of the electric field.

Non?

Well, yeah, kernosabe, there is a certain amount of hypothetical trust (for review purposes) involved in any discussion of reported results.

Having said that, you asked me to go ahead with calculations on the inverted pendulum parasitic modes, where I have even less information (I would need to know the dimensions of the devices and the supports, to calculate the moments of inertia).  What d'ya think?
« Last Edit: 09/22/2014 03:04 PM by Rodal »

Offline Rodal

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Re: EM Drive Developments
« Reply #898 on: 09/22/2014 02:21 PM »
It's fixed now

What???  You changed the Akashic record?

<<In theosophy and anthroposophy, the akashic records (from akasha, the Sanskrit word for 'sky' 'space' or 'æther') are a compendium of mystical knowledge supposedly encoded in a non-physical plane of existence known as the astral plane. There is no scientific evidence for the Akashic records.>>

Never heard of Akashic  records before.  Great! You taught me something new today, kernosabe    :)
« Last Edit: 09/22/2014 02:28 PM by Rodal »

Offline aceshigh

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Re: EM Drive Developments
« Reply #899 on: 09/22/2014 02:48 PM »
hey Dr Rodal, regarding the derivation of Woodward's Mach Effect, I asked GiThruster at TalkPolywell

Quote from: GiThruster
I would just recommend the book. If Dr. Rodal wants to be placed on Woodward's general reading list where he can have a dialog on this issue, have him send me a note to this effect with a couple sentences of his background and interest and I'll forward this to Jim.

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