“Measurement of the Electric Current in a Kpc-Scale Jet”
Kronberg, Philipp P.; Lovelace, Richard V. E.; Lapenta, Giovanni; Colgate, Stirling A.
I'm sure the EUers will be all over this, claiming that it means mainstream science is finally coming around to their ideas. But if they actually read the original paper, and not just the press-releases, they would discover that they were wrong (again)...
The introduction of the paper reveals that this work is actually based on a model for galactic jets that dates back to 1976 with work by Roger Blandford (Accretion disc electrodynamics - A model for double radio sources) and independently by Lovelace (Dynamo model of double radio sources), one of the co-authors of the current paper.
The model relies on the jets of plasma being collimated by a magnetic field and particle flows driven by an electric field created by an accreting black hole. The model has been studied heavily since first proposed by Lovelace and Blandford. The electromagnetic properties of the jet are determined through the rotation measure (RM) of the Faraday Effect (wikipedia). Through this method, they obtained an electron density of 1.4e-5 electrons/cc and a current of 3.8e17 amps directed away from the galactic nucleus.
I suspect EUers will want to compare this result with the Alfven galaxy model, but there may be a problem with that. The earliest reference I can find where Alfven suggested something similar is in a few paragraphs in a paper from 1977:
Electric currents in cosmic plasmas by Hannes Alfven.
Alfven describes a galaxy central radio source as a unipolar inductor, but the description is very qualitative. There is not even a single numerical estimate of currents expected or the visible flux.
Alfven went into a little more detail in 1978 with
Double Radio Sources and the New Approach to Cosmical Plasma Physics by Hannes Alfven
providing at least a graphic, but still no way to estimate the luminosity and other characteristics one could expect to measure from Alfven's proposed galaxy configuration. An examination of the citation lists for both of Alfven's papers reveals no citations for either Blandford or Lovelace. Two years after the fact, Alfven was not acknowledging others who not only preceded his effort, but developed the model in far more detail.
When you look at the contributions made by others prior to Alfven, one begins to realize that Alfven's work described little that wasn't already known. The only aspect of the model that could be considered as a contribution by Alfven could be recognizing the need for a return circuit in the 1977 paper. However, I regard the rigor of the 'return circuit' questionable. MHD simulation volumes are generally modeled as closed systems so the same flows have to return full circle, but the intergalactic medium (IGM) is not a closed system. Charge imbalances can be remedied by charges flowing back towards the galactic center from the IGM, but nothing requires them to be the same particles emitted in original the jets of the galaxy, just that the quantities are sufficient to balance the charge.
Probably the greatest deficiency of Alfven's papers is that while Alfven describes the central engine as a unipolar inductor, there is NO information on how such a structure could be built in Nature. Alfven's central source is a black box with no way to even estimate its power capabilities. For all intents and purposes, Alfven's unipolar inductor could've been a machine built by alien civilizations in all these radio galaxies.
Meanwhile, mainstream astronomy had an object that fit the bill for creating a unipolar inductor (AKA a homopolar generator, Wikipedia): an accreting black hole. The theory had sufficient mathematical development that one could develop testable predictions with it. Accreting plasma around a black hole forms a highly conducting layer just outside the event horizon, making a near perfect conductor that couples to magnetic field generated by the differentially rotating accretion disk. This idea is also related to work by Blandford and Znajek (Electromagnetic extraction of energy from Kerr black holes). Black holes have also been treated as resistors and rotors in circuit elements in a number of configurations (see Black Holes: The Membrane Paradigm, 1986, and related papers by Kip Thorne).
It is ironic that objects EU supporters most deny exist (black holes & neutron stars) are the best known producers of large electric fields in the cosmos.
Problems for Electric Universe
- Alfven was NOT the first to propose this configuration for radio galaxies. He made, at best, only very minor contributions to the model, and nothing that contributed to testing the model against actual observations.
- The Blandford & Lovelace model, like Alfven's model, is inconsistent with Peratt model because the current seen is strictly a product of the galaxy's central engine, and not due an external source. See (Scott Rebuttal. II. The Peratt Galaxy Model vs. the Cosmic Microwave Background, Still no electric currents powering the galaxies...).
- Perhaps the greatest problem it makes for EU is that it demonstrates that we can measure extragalactic currents. This means the EU whines about undetectable 'dark currents' are moot.
- In Blandford (1976), the author even notes that his proposed configuration “therefore acts as a unipolar inductor, generating an electric field, E, in the inertial frame.” It demonstrates that astronomers have long considered the effects of electric fields and currents in the cosmos, in spite of EU denials.
While I was researching & assembling this post, Nereid pointed me to this on the Thunderbolts site:
Universe's Highest Electric Current Found
Funny, it appears some thunderbolt forum members actually read the paper, but I have yet to see any acknowledgement of how long ago this model was actually proposed.
Posts
14 comments:
Indeed, there have been numerous papers on "the cosmic battery" and other proposed accretion generated electric currents. The thing to note is of course that large scale currents are detected in the first place.
Then riddle me this: aren't one of the main argument against the Electric Universe, that electric currents can't exist over stellar or galactic distances due to 'Debye shielding'? How come this is not an issue in the discussed paper (and related ones)?
To Siggy_G:
Odd, I only find you advocating Debye screening as a mechanism to block radiation emission.
As I noted in these posts, I suspect Debye screening can't operate in cases where electrons and ions have significantly different velocities. Debye screening is defined in a thermal plasma. If any significant screening operates in non-thermal plasmas, it is not called Debye screening and I have yet to find evidence of this issue in the literature.
See posts below and the comments:
Electric Universe: Everything I needed to know about science I learned from watching Star Trek?
Charge Separation in Space
Electric Universe: Real Plasma Physicists Use Mathematical Models!
That's interesting – and agreeing that Debye screening don't seem to apply in scenarios where electron and ions velocities are significantly different.
Also, the particles on the far side of a system don't neccesarily need to be driven by the direct electric field of a central net charge. The particles' travel aren't linear or one dimentional all the way through, like considered within the Debye screening formula. I believe that in a dynamic and sparse scenario like within astrophysical plasma, numerous and turbulent "local" electric fields can occur increasingly along the path towards the central net charge. (This would be due to temporary and regional inbalances in electrons or positive ions in a filamentary structure). In average, this constitutes a global and radial electric field for the system, but it is not neccesarily this one vector the particles follow at any given time throughout the system. That's another reason why I don't think Debye screening applies in interstellar and intergalactic scenarios as they may in higher density plasmas, where the mean free path is way shorter.
Siggy_G,
It's nice to have interesting thoughts.
And if you're really into this sort of thing, I do not doubt you could write the most fascinating of science fiction short stories.
But if you are seriously interested in science (astrophysics in this case), don't you think you need to roll up your sleeves and start doing some real work?
Alternatively, if you genuinely believe you have discovered an alternative path to making sense of the universe, one that involves a radical re-writing of the foundations of the relevant parts of science (physics, in this case), why are you fussing around with trivia like this?
Nereid
(Discard this comment if it already went through earlier on)
Nereid,
I'll see what I can manage - I haven't attempted to write or submit any actual papers yet, but it would sure be interesting to have a go; including some simulation approaches.
If you by 'trivia like this' mean 'forum and comment field activity', then my intentions and interests are probably not much different than yours or Tom's.
If you mean 'bringing up insignificant issues', I'd say Debye screening is one of several important topics, because it is one of the reasons many people dismiss electric currents existing over steller or galactic distances. Yet, they are detected, but with a gravity-only field interpretation. There's nothing radical about the physics in my description above. It is quite basic; there will be electric cirquitries between regions of one net charge and regions of the opposite net charge. The question is if there is data that can be interpreted towards verifying the described scenario - or not. If so, it would also indicate that the interplanetary medium can allow circuitries between the heliopause and the Sun, dispite a radial and outward emission of particles within the medium (those particles travel outwards due to thermal escape velocities from the corona, and would only regionally be affected by electric fields, like described above. The electric field is according to Scott/Thornhill thought to be relatively weak along most of that distance, with references to plasma discharge and voltage graphs).
Siggy_G,
If all you do is apply textbook plasma physics to astronomical observations, what would make your results different from any of the thousands (yes, thousands!) who have already done exactly this?
Alternatively, if you genuinely believe that Talbott, Thornhill, et al. are onto something - with their 'qualitative science' and their permanent promise that paradigm-shifting *quantitative* papers are just "a few months' away" - you would surely be wasting your time to bring your grasp of textbook plasma physics up to PhD level, wouldn't you?
Nereid
Nereid,
Can't the "thousands of contributors" point be said about any field in science? The difference lies in interpretation of observations and application of theory - and perhaps a revision of consensus notions.
There surely aren't thousands of contributors like H. Alfven, A.Peratt, C.G. Felthammer, A. Brynjolfson and D.Scott. Over stellar and galactic distances, gravity is the only applied field (and point of view) by the remaining thousands of contributors, it appears. I'm not so sure that gives fruitful output in the long run. I also wonder if such a constraint is in line with textbook methodology... (when other factors can't be ruled out)
To Siggy_G,
Have you already forgotten the original post above?
Not only did Alfven not develop the radio source model to a testable level as much as others, but I've yet to find evidence that he published the idea prior to others! Alfven has received recognition in many areas of astrophysics, but here's a case where he was a weak 'me too'.
Alfven & Falthammar (and probably Peratt as well) know that the Sun is not electrically powered, so why invoke them as EU supporters? Page 14-15 of Alfven & Falthammar's "Cosmical Electrodynamics" (1963) presents a very simple analysis of why the Sun can't support a significant net charge.
Don Scott's "On the Sun's Electric Field" uses an electrostatic field, despite Thornhill's claims of it's invalidity(ref1, ref2). What's up with that? More on Scott's 'model' in a future post.
Siggy_G,
"If all you do is apply textbook plasma physics to astronomical observations, what would make your results different from any of the thousands (yes, thousands!) who have already done exactly this?" - that's me.
"Can't the "thousands of contributors" point be said about any field in science? The difference lies in interpretation of observations and application of theory - and perhaps a revision of consensus notions." - that's you.
If that's what you want, or intend, to do, then go for it. When you think you've got some sound results, write them up and publish them; in the meantime, why are you wasting your time posting comments to this blog?
"There surely aren't thousands of contributors like H. Alfven, A.Peratt, C.G. Felthammer, A. Brynjolfson and D.Scott. " - you again.
The first three no longer write (publish papers) in this area, as far as I know. While there have been some who've done limited work on the approaches they used, none of it has gone anywhere. Certainly, none of the hundreds (thousands?) of members of the TB forum seem to have actually published anything along these lines (what a waste; imagine if only a small fraction of the person-years' of effort that's gone into writing material for that forum had been devoted to taking Alfvén's work further!)
The last two have published - using the word in a very broad sense - nothing of value, with respect to the application of plasma physics, have they? In this respect, there certainly are thousands like them.
For the rest, the only thing I'd add to what Tom already wrote is this: you seem rather unfamiliar with what's in standard astrophysics textbooks (perhaps it's time for you to start looking for a university programme that offers an appropriate PhD track?).
Nereid
Tom,
My response (in reply to Nereid's) was about mentioned contributors that have researched the effect of large scale electric currents and EM fields is cosmic plasmas (which in any case is a basis for the Electric Universe). I don't see you refuting that the majority only considers gravity fields in cosmic scenarios.
You're right, Alfven (and Perrat) didn't consider an Electric Sun, only its surrounding electrodynamic effects. The extension of Alfven's (and Perrat's) notions are mainly put forward by Thornhill and Scott. Looking forward to your future post. Ps: Scott mentions in his third assumption in your linked paper that electrostatics isn't sufficient.
Here's a paper from 2010 that considers a net charge of stars: http://www.prespacetime.com/index.php/pst/article/view/93/89 Personally, I suspect that the actual scenario of stellar cirquitry is even more complex than this (such as the surface having spikes of charge and not an even one).
Nereid,
I refered to what research is about in general - different approaches for applying theory (hereby textbook plasma physics) to data/observations. In some cases that may include or result in a revision of consensus notions. Two researchers can have completelly different approaches, look for different mechanics and hence stipulate different scenarios. Especially if one uses a 'mass and gas' approach and the other a plasma process approach. Alfven and Peratt's papers are examples of different approaches from the norm in astrophyscs. So, that is why 'my results' could be different from 'the thousands of others'.
To Siggy_G,
Actually, an electrostatic approach gets you further than you might think. In a configuration where free electrons & ions aren't moving together (as in a quasi-neutral plasma such as the solar wind), you will ALWAYS get regions of net charge.
i=ion, e=electron, velocity & density
current density = idensity*ivelocity - edensity*evelocity
charge density = idensity-edensity
evelocity & ivelocity will be different in any configuration driven by an electric field and will vary along the field. If the total current is constant, the charge density will change along the path, in the case of the Scott model as a radial charge distribution. Langmuir & Blodgett first explored this problem in the 1920s and got much further than Scott.
"Alfven and Peratt's papers are examples of different approaches from the norm in astrophyscs." - Siggy_G.
Neither of these guys' results, using this different approach, went anywhere, did they?
"So, that is why 'my results' could be different from 'the thousands of others'."
I "could" become the next Secretary General of the UN ... but I certainly won't if all I do is sit around and write comments on various blogs and in discussion fora.
When may we expect to read your first results, in a paper that meets the minimum standards for acceptance in an astrophysics journal?
Nereid
My my! What started out was a discussion into electric currents in space has degenerated into a pissing contest. On to another site where real issues can be explored. This site is too hostile and full of "I went to such and such university", etc. It reminds me of the time I spent working in the federal government as an engineer...too much nonsense and too many pissing contests....
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