NASA and Government Discuss EU

[jjohnson]

If you are interested in whether Peratt "believes in" gravity or not, or uses it in simulations or not, the answer is clearly positive on both counts.

His Chapter 8 in Physics of the Plasma Universe is titled Particle-in-Cell Simulations of Cosmic Plasma. It proceeds with an interesting history of the development of this technique, and its application to plasma as well as gravity interactions. 8.7 Gravitation discusses the transition of plasma into stars, which involves the formation of dusty plasma, which subject's governing equations and applicability of including gravity in them based on grain size, etc are found in Appendix C.

His Figure 2.6, a chart of current in a Bennett pinch (z-pinch) of cylindrical geometry (i.e., a pinching Birkeland current (pair?) as a function of the number of particles N per unit length labels the regime of high particle density and relatively low current along the right hand side as "gravitationally balanced magnetic pressure". This is for a steady-state and rotationless condition, which is [probably, in my estimate] not always obtained in cosmic conditions, but nonetheless my point is that Peratt is neither ignorant nor dismissive of gravity interactions. He simply knows where to define regions where its importance is relevant and needs to be included, and where electrodynamic plasma processes are dominant. I would also observe that the dividing line between these two conditions likely is drawn differently by Peratt from that by many of those adhering to the standard model.

He comes from a background (IEEE; Los Alamos high energy labs) where the energy picture of the Universe is that it is almost completely in a plasma state of ionization. I can understand his bias. We all have evolved under different, rather more benign conditions that are a minority over the vast expanse of space. That helps explain the conventional bias.

Lightning is scary.

Jim

[Aardwolf]

Here's a couple of extracts, to give you an idea of where GR is being used:

The second version of the relativistic model based on S. Klioner approach has been implemented in GDAAS
[...]
In Spring 2004 S. Klioner and F. Mignard arranged a meeting with ESOC to discuss the mission requirements for the Gaia orbit tracking. This resulted into a very positive exchange whose results are reported in the Minutes of the 5th meeting of the RRFWG. Following this meeting S. Klioner has investigated the magnitude of the relativistic effect in the motion of Gaia on its Lissajous orbit in which it shows that according to the level of modelling differences between prediction can be larger than the 10 mm/s in velocity, well above the Gaia requirement.

Well this is the only one that relates to the orbit but as all orbits at Lagrangian points are in practice unstable, minor GR adjustments are entirely meaningless. Even their own mission operation overview here states;

"However, orbits about the L2 point are dynamically unstable; small departures from equilibrium grow exponentially overtime. Like ESA's Herschel and Planck missions, which also orbit about L2, Gaia will use its propulsion system to perform periodic orbit maintenance manoeuvres."

They are actively kept in these orbits, as all satellites are, and prove or confirm absolutely nothing about GR. A Newtonian approximation suffices and then they keep them exactly where they want them using propulsion systems.

[Nereid]

They are actively kept in these orbits, as all satellites are, and prove or confirm absolutely nothing about GR. A Newtonian approximation suffices and then they keep them exactly where they want them using propulsion systems.

Um, we seem to be engaged in a non-conversation.

You asked "What exactly are ESA scientists using GR instead of Newton for?", in respect to the planning for the GAIA mission.

I answered you by giving you some examples of what ESA scientists are using GR instead of Newton for, in respect to the planning for the GAIA mission.

Your response - the part that I quoted above - seems to have essentially nothing to do with your question.

What am I missing?

[Aardwolf]

They are actively kept in these orbits, as all satellites are, and prove or confirm absolutely nothing about GR. A Newtonian approximation suffices and then they keep them exactly where they want them using propulsion systems.

Um, we seem to be engaged in a non-conversation.

You asked "What exactly are ESA scientists using GR instead of Newton for?", in respect to the planning for the GAIA mission.

I answered you by giving you some examples of what ESA scientists are using GR instead of Newton for, in respect to the planning for the GAIA mission.

Your response - the part that I quoted above - seems to have essentially nothing to do with your question.

What am I missing?

You seem to miss lot. The question is whether it's deliberate...

The first quote relates to orbit mechanics and as the satellies are actively kept in place using propulsion systems they effectivly use neither Newton or GR.

The second seems to relate to time keeping which has nothing to do with Newtonian orbits.

So your comment about scientists using GR instead of Newton is entirely meaningless.

[Nereid]

You seem to miss lot. The question is whether it's deliberate...

It's not.

The first quote relates to orbit mechanics and as the satellies are actively kept in place using propulsion systems they effectivly use neither Newton or GR.

The second seems to relate to time keeping which has nothing to do with Newtonian orbits.

So your comment about scientists using GR instead of Newton is entirely meaningless.

Here's the small number of words I wrote, in a post earlier in this thread, which seems to have sparked your questions: "Somewhat analogous perhaps to the ESA doing their mission planning, implementation, and management using Newtonian gravity rather than GR".

Perhaps you read into this "orbit mechanics", and "Newtonian orbits"; perhaps you assumed the only thing I was referring to was "orbit mechanics", and "Newtonian orbits"?

Let me assure you that I did not have only these in mind! Mission planning (and implementation, management, etc) involves a great deal more than just "orbit mechanics", and "Newtonian orbits"; use of one theory of gravity or another can enter into the planning (etc) in many more ways than just these ... as I showed (for GAIA).

I hope that clarifies any misunderstandings you may have had.

[Aardwolf]

You seem to miss lot. The question is whether it's deliberate...

It's not.

The first quote relates to orbit mechanics and as the satellies are actively kept in place using propulsion systems they effectivly use neither Newton or GR.

The second seems to relate to time keeping which has nothing to do with Newtonian orbits.

So your comment about scientists using GR instead of Newton is entirely meaningless.

Here's the small number of words I wrote, in a post earlier in this thread, which seems to have sparked your questions: "Somewhat analogous perhaps to the ESA doing their mission planning, implementation, and management using Newtonian gravity rather than GR".

Perhaps you read into this "orbit mechanics", and "Newtonian orbits"; perhaps you assumed the only thing I was referring to was "orbit mechanics", and "Newtonian orbits"?

Let me assure you that I did not have only these in mind! Mission planning (and implementation, management, etc) involves a great deal more than just "orbit mechanics", and "Newtonian orbits"; use of one theory of gravity or another can enter into the planning (etc) in many more ways than just these ... as I showed (for GAIA).

I hope that clarifies any misunderstandings you may have had.

I'm afraid you're the one with the misunderstandings.

Your quote that you refer to states "...using Newtonian gravity rather than GR". I have been refering to the quote where you stated "ESA scientists will use GR instead of Newton (e.g. GAIA)".

So what exactly were you refering to because the two abstracts you provided didn't show any scientists using GR instead of Newton. And if not orbit mechanics then what? Alchemy formula?

[Goldminer]

The answer resides in the fact that when plasmas carrying oppositely directed magnetic field lines are brought together, a strong current sheet is established, in the presence of which even a vanishingly small amount of resistivity in a small volume can become important, allowing plasma diffusion and, thus, magnetic reconnection to occur.

To which

The point is that there is no Magnetic Disconnection in the first place. What part of dipole don't you understand?

The point being: Magnetic field lines automatically terminate in either a North or South pole, one on each end of the "magnetic lines." It would take a whole 'nother magnet with its two poles being brought together in order to cause "magnetic reconnection to occur;" and that would be only if they were opposite poles. Like poles repel, remember? So where is all the pent up "magnetic energy?" It is more likely the completion of a high amperage/voltage electrical current, short circuiting and creating the magnetism.

[mharratsc]

Nereid quoting PPPL wrote:
The answer resides in the fact that when plasmas carrying oppositely directed magnetic field lines are brought together, a strong current sheet is established, in the presence of which even a vanishingly small amount of resistivity in a small volume can become important, allowing plasma diffusion and, thus, magnetic reconnection to occur.

I think that I'd mentioned in regards to this very quote was that they were describing a field-aligned current (or Birkeland current). Solrey went to some length providing links to the dielectric properties of plasma in these current sheets, and how they can break down (even explode) releasing the power stored in the entire circuit across the boundary where the double-layer broke down... which is what I think they are referring to in the whole 'reconnection' thing.

It really does seem to me that they put the cart before the horse in their explanations... they see something 'connecting' which releases energy, rather than a breakdown of an existing circuit. I truly do not see how they can continue to operate from this explanation when so many experiments point to the contrary. :\ Sigh...

[Goldminer]

When first discovered, the truth seems always stranger than previously held beliefs.