I'll be more than happy to provide them to you, as soon as you provide us with those specific numerical predictions for the specific observations I've asked for, or you admit there isn't any, from EU/PU proponents. Deal?Originally Posted by Don J
Order of Kilopi
I'll be more than happy to provide them to you, as soon as you provide us with those specific numerical predictions for the specific observations I've asked for, or you admit there isn't any, from EU/PU proponents. Deal?
Established Member
I will do that as soon as you will find a source from the mainstream which is in agreement about a mechanism explaining the formation of these filaments.
Order of Kilopi
Your link doesn't work (you included the colon in the URL!), but that's OK (I found the paper anyway).
Do you know what a "random walk" is? Brownian motion? This source sums it up as "Random walk – the stochastic process formed by successive summation of independent, identically distributed random variables – is one of the most basic and well-studied topics in probability theory."
In the context of that paper, random walks are, well, random walks! Sorry, I'm not trying to be difficult, but first let's see how well you grasp the concept of random walks. Perhaps by checking what you understand of Brownian motion. I expect that once you get Brownian motion, the snippet from the paper you quoted will become clear.
Established Member
Thanks Neried I'll check that out. It sounded a little funny, "random walks" being used in an "excursion model" (sounded like my kind of excursion
Established Member
Don, have you ever read this one: http://astrophysics.fic.uni.lodz.pl/...pdf/10/002.pdf
It's Bennett's original 1934 paper on magnetically self-focussing streams (he revised it a couple of times, the latest I think in 1955). Point is, yes, it is a real phenomena, but given the state of astronomy today (of which he apparently had little real interest) I think he would be appalled to see his name thusly associated until measurable, quantitative evidence of the high voltages necessary for self-focussing are found out there. This is because he was a good scientist, and as such, not as emotionally invested in any individual idea, so much as the body of knowledge as a whole. Think about it
Order of Kilopi
Comment especially for Don J: If you are not prepared to put the time and effort in to understand how the science of astrophysics actually works, it's most unlikely you'll get much out of participating in the science-based parts of BAUT.
And understanding astrophysics requires, above all, that you acknowledge the primacy of observations, objective, independently verifiable, quantitative observations.
In some of your posts, you've mentioned Alfvén having predicted the filamentary nature of the ISM (interstellar medium) and IGM (inter-galactic medium)*. And when one reads the relevant Alfvén papers, one finds that he was talking in very general terms; specifically, Alfvén did not provide any quantitative descriptions - typical width and length, density enhancements, temperature decrements, etc, etc, etc. In that sense, what he did was no different than a physicist of a century ago saying that there are lots of things in space which will be visible in the infra-red, when we have the capability to make such observations, because they have temperatures greater than absolute zero. Or another predicting that there will likely be planets going round many of the stars we can see (other than our own Sun).
Or you can think of this the other way round: the ISM is composed of plasma, so any ISM filament observed must be composed of plasma. In other words, there is no way Alfvén could have been wrong^. Just like the hypothetical 19th century astronomer could not have been wrong when he predicted planets going round other stars. And this sort of stuff is so general, and so unhelpful in and of itself, it is hardly worth mentioning.
Where it - astrophysics - gets interesting is when specific objects are observed, where there are concrete models developed, from which testable hypotheses are derived.
Here the analogy would be if Alfvén predicted the galactic centre ISM feature called the Snake, based on a concrete model of pinches, current sources and sinks, etc. Just like the infrared emission from bright stars was predicted long before IRAS (Infrared Astronomy Satellite) was launched. No one got excited about IRAS confirming that the infrared emission from most stars was just as predicted, based on models of stellar atmospheres calibrated using optical data. What was exciting was the discovery that, for some stars, the quantitative infrared emission was not as the models predicted. Investigation of those stars followed, and today we know that Beta Pictoris (for example) is surrounded by a debris disk (and, possibly, a planet or two).
* exactly what you wrote is not all that important; the general idea is
^ other than by discovering no ISM filaments, which even Alfvén knew - or could have known - was impossible (ISM filaments had been observed well before Alfvén was born! e.g. NGC 2736)
Order of Kilopi
Let's face it Don, you can't produce any kind of numerical model and are just doing everything you can to avoid admitting that the EU/PU model can't provide an actual numerical model or a quantitative estimate to an OOM. This whole thread was about plasma science and what it predicted, not the mainstream? How about we get back to the OP and you answer the questions on EU/PU.
Order of Kilopi
Of course, it didn't happen like that at all.
I recommend that you get hold of documents which Birkeland actually wrote, study them, and compare them with what we today understand about things like aurorae.See that little history about the establishment astronomy dispute against Birkeland the pionner of plasma cosmology who was later proven to be right....
Birkeland and the electromagnetic cosmology.
http://public.lanl.gov/alp/plasma/do...dCosmology.pdf
Some of his ideas were spot on, others vaguely OK in a general sense, and still others totally wide of the mark. That sort of thing happens to just about every scientist. Personally, I find it baffling that anyone would want to re-interpret a scientist's work as that of an oracle or seer.
Established Member
Told you Don, I am not going back through those papers. In my opinion they are awful. Lots of analogies, descriptions, assertions and so on. You don't seem to get it - I am a scientist, I publish and I review papers. I do not enjoy reading bad ones. We have given you problems with his models in this thread in response to your posting of these papers containing these models. I use the term model very loosely there.
You clearly will not accept our answers and keep switching what you demand to accept the mainstream answers. Not interested in playing that game. You have been given ample pointers to the information you are after but it always seems like it is not good enough.
I'm out.
Order of Kilopi
And if it's a good scientist, they'll be quite willing to admit to being wrong when shown to be by observations.
__________________________________________________
Reductionist and proud of it.
Being ignorant is not so much a shame, as being unwilling to learn. Benjamin Franklin
Chase after the truth like all hell and you'll free yourself, even though you never touch its coat tails. Clarence Darrow
A person who won't read has no advantage over one who can't read. Mark Twain
Established Member
The calculations you are asking for about to the Bennett pinch applied to space plasma start in page 17 at 3.4
http://public.lanl.gov/alp/plasma/do.../AdvancesI.pdf
Order of Kilopi
Sadly, in the case of Birkeland (and many another scientist too, of course), he didn't live long enough to see the advances in physics, and in observational capabilities, that could test most of his ideas. In terms of what was known at the time, his work was excellent8, and he actively sought to put his ideas through the wringer (so to speak) of empirical evidence.
What's sad is that EU/PC proponents - like Don J? - latch onto Birkeland's ideas and disrespect his science, particularly his devotion to quantitative, empirical methods and techniques.
* with some exceptions; for example, his idea that the rings of Saturn were self-luminous - rather than shining by reflected sunlight - was known to be inconsistent with direct observations of the rings (during ring-plane crossings), made as much as half a century before he published them. This has a general lesson which Peratt has, apparently, ignored: when you try to apply ideas from one field (laboratory plasma physics, say) to another (astronomy, say), you need to be extremely careful to understand the totality of what's known about a particular system before you write a paper claiming to model it accurately. For example, Peratt's papers on galaxy formation and the rotation curves of spirals are shockingly wrong, because - so it seems - he didn't bother to learn enough about the totality of observations of such galaxies.
Order of Kilopi
Not just your opinion; mine too. Some of those papers are truly appalling*.
This debating technique actually has a name, the Gish Gallop.You clearly will not accept our answers and keep switching what you demand to accept the mainstream answers.
* for example, see the comment in my last post re Peratt's on spiral galaxies
Order of Kilopi
Thanks for this.
You provided an excellent example of exactly the sort of error I mentioned, two posts ago!
On p103 (per page numbering of the paper itself), Peratt writes "By far the single largest plasmas detected in the Universe are those of double radio galaxies." (he then proceeds to provide values for the estimated ranges of various parameters of those plasmas).
In 1997 - when this paper was published - it was already well-known that:
a) rich clusters of galaxies are (nearly always) embedded in considerably larger plasmas (and indeed the double radio galaxies have the characteristic lobe shape due to interaction between the jets which produce these features and the surrounding rich cluster plasma)
b) every region of space, between galaxies, galaxy groups, and clusters of galaxies is filled with plasma.
Of course, at that point in the paper all he's doing is setting the scene; however, to make such a silly mistake, so easily fixed, really doesn't make you want to keep reading.
Concerning section 3.4: yes, Peratt does develop a model of a particular configuration of plasma. Yes, he does write "Phenomena of this general type also exist on a cosmic scale and lead to a bunching of currents and magnetic fields to filaments. This bunching is usually accompanied by the accumulation of matter, and it may explain the observational fact that cosmic matter exhibits an abundance of filamentary structures."
But does he cite any evidence? For example, work done - by him or others - on applying that (or a similar) model to actual astronomical observations? No. He simply asserts it.
If you spend enough time reading astrophysics papers, Don J, you'll come across an abundance of beautiful, theory-based models. You'll also discover that a great many of them go nowhere, in that they are rarely cited, and no one is working on them any more. Do you know why this happens*? Do you know what's missing*? Evidence that what the models predict matches what astronomers see, quantitatively.
* usually
Established Member
Yes ,there is evidence that -the description of a mechanism and model prediction- made by Peratt about the formation of these filaments match what astronomers see.
You have even provided a paper about that.The area is filled by filaments and star forming system associated to the filaments in an aera where there is strong magnetic field and dense plasma source .Read what Peratt is decribing in page 17 (pdf page notation) at 3.4 and read your paper .The author of your paper dont even know why this is happening since Peratt describe why there is accretion of matter and star formation in that aera...
http://arxiv.org/abs/astro-ph/0308008
Edited it is at page 17 starting at 3.4 on Peratt paper
http://public.lanl.gov/alp/plasma/do.../AdvancesI.pdf
Last edited by Don J; 2012-Apr-18 at 09:13 PM. Reason: Wording and clarity
Order of Kilopi
We seem to have a breakdown in communication, Don J.Yes ,there is evidence that -the description of a mechanism and model prediction- made by Peratt about the formation of these filaments match what astronomers see.
You have even provided a paper about that.The area is filled by filaments and star forming system associated to the filaments in an aera where there is strong magnetic field and dense plasma source .Read what Peratt is decribing in page 17 (pdf page notation) at 3.4 and read your paper .The author of your paper dont even know why this is happening since Peratt describe why there is accretion of matter and star formation in that aera...
http://arxiv.org/abs/astro-ph/0308008
Edited it is at page 17 starting at 3.4 on Peratt paper
http://public.lanl.gov/alp/plasma/do.../AdvancesI.pdf
Peratt did not cite any evidence - as in quantitative astronomical observations - that his (Section 3.4) model matches what's observed. He certainly did not cite Yusef-Zadeh.
F. Yusef-Zadeh does not cite Peratt, does not mention Bennett pinches, and so on.
The model (mechanism) which F. Yusef-Zadeh discusses, in that paper, is "an extension of a model originally proposed by Rosner and Bodo (1996), who suggested that energetic nonthermal particles are produced in a terminal shock of mass-losing stars".
So, how did you manage to conclude the "author of your paper dont even know why this is happening since Peratt describe why there is accretion of matter and star formation in that aera"?
Did you arrive at that conclusion based solely on a qualitative understanding of "strong magnetic field and dense plasma source" (etc)?
Or did you estimate a likely range of values for various parameters in the equations in Peratt's section 3.4, plug them in, turn the handle, transform them to observables, compare the results with the quantitative data reported in the literature, that sort of thing?
If you've done the latter, why not write up your work, as a paper, and submit it to ApJ (or some other suitable journal)?
If you've done the former, please say so; it would greatly facilitate communication.
Order of Kilopi
Yeah, Don, a mainstream astrophysicist, using MHD along with other models. We've been over that many times. Mainstream scientists use MHD, tusenfem is one of them. Peratt is no where near providing anything closer to specific predictions and your link doesn't provide any kind of non-thermal prediction, or anything to do with the situation in Yusef-Zadeh paper.
But, there is nothing from the EU/PU people, using Peratt's equations. All that data in Yusef-Zadehis freely available on the internet, yet the EU/PU people can't seem to provide specific numerical models for the specific observations in the paper. Somehow, it's the mainstream people who do the work, using MHD along with other models.
Yeah, and Peratt's specific numerical calculations that are applicable to the masses and star formation rates in the center of the galaxy are, where? Not just some equations in some book, the calculations themselves.
Established Member
Do you mean non-thermal prediction or production ?
Yah know Yusef-Zabehi model is only one model who claim that the strong magnetic field (s) in the center of the Galaxy do not play a role about the formation of these filaments ,there are other model in the mainstream who say exactly the contrary
and other claiming that it is caused by the decomposition of old O star....
and other described
at 7 from page 4
http://arxiv.org/abs/astro-ph/0308008
Yes, lots of equation but still no consensus about who in the mainstream will pop up with the real solution about a mechanism explaining the formation of these filaments.
So until one of these papers wins the lottery all these "sounding" equations are just good as a brain gymnastic for theorician physisits.
Last edited by Don J; 2012-Apr-19 at 03:00 AM. Reason: Typos
Established Member
No, no, no, What I say is that if you apply the mechanism provided by Peratt on page 17 starting at 3.4 you will have the real solution for explaining these filaments which are non-thermal...without the need for all these sounding but innapropriate equation provided in Yusef-Zadeh paper. Note that If the Yusef-Zadeh paper wins the lottery in the mainstream as to -which one among these competitive and conflictual papers solve the problem - about the formation of these filaments, i will revise my comment.!We seem to have a breakdown in communication, Don J.
Peratt did not cite any evidence - as in quantitative astronomical observations - that his (Section 3.4) model matches what's observed. He certainly did not cite Yusef-Zadeh.
F. Yusef-Zadeh does not cite Peratt, does not mention Bennett pinches, and so on.
The model (mechanism) which F. Yusef-Zadeh discusses, in that paper, is "an extension of a model originally proposed by Rosner and Bodo (1996), who suggested that energetic nonthermal particles are produced in a terminal shock of mass-losing stars".
So, how did you manage to conclude the "author of your paper dont even know why this is happening since Peratt describe why there is accretion of matter and star formation in that aera"?
Did you arrive at that conclusion based solely on a qualitative understanding of "strong magnetic field and dense plasma source" (etc)?
Or did you estimate a likely range of values for various parameters in the equations in Peratt's section 3.4, plug them in, turn the handle, transform them to observables, compare the results with the quantitative data reported in the literature, that sort of thing?
If you've done the latter, why not write up your work, as a paper, and submit it to ApJ (or some other suitable journal)?
If you've done the former, please say so; it would greatly facilitate communication.
http://public.lanl.gov/alp/plasma/do.../AdvancesI.pdf
Last edited by Don J; 2012-Apr-19 at 03:16 AM. Reason: Typos and clarity
Order of Kilopi
A specific non-thermal numerical prediction, from Peratt's model, based on the mass and the types of stars seen in the galactic center. Along with the shape and strength of the magnetic field, since you didn't answer this question before. And how exactly do the stars in the galactic center affect the shape and strength of the magnetic field, according to Perat?.
What you keep ignoring, is that the various mainstream papers are consistent with the observations. You haven't provided any papers, that use only the formulas from Peratt, that are consistent with the observations in Yusef-Zabehi's paper, or any other paper we've provided for you. Which means the models in the mainstream papers, showing the calculations specific to the observations in each of the papers, are possibly valid. It doesn't matter that there are other possible models, those are consistent also. In the case of Peratt's model you haven't presented any calculations that are numerically consistent with the specific observations in any of the papers. Which means Peratt's model is not valid. So, you can complain all you want to about what you think isn't a consensus, but until you show us some calculations using Peratt's model, and then compare the answers from those calculations numerically to the observations from each of the papers, Peratt's model isn't consistent with the observations, which means it fails to match observations.
Actually, no. You don't seem to understand how science works. Those physicists are using what each of them thinks is the best data, to develop their model. If new data or observations show up, that contradict the model, then either their model, or the data they used is wrong. In which case, they have to change either the data or model. Other physicists my come up with another model, or believe other data is more appropriate. As long as the data is consistent with observations, the model is still possibly valid. A model is only valid if it's numerical predictions are consistent with observations. Of course, a model has to make specific numerical predictions before it can be considered valid. To bad we don't have a example for Peratt's model.
If Peratt's model is so good, why hasn't someone, somewhere shown that, Peratt's model can be numerically consistent with the observations? With all those EU/PU types that think the model is valid, why can't they provide the calculations showing the model is numerically consistent with the observations? Since you think the model is so good, why don't you show us how Peratt's model can be numerically consistent with the observations?
What Yusef-Zabehi did in his paper was to develop his model, showed the calculations he did, and then compared his answers numerically to the observations. Where are the equivalent numerical comparison for Peratt's model?
Order of Kilopi
(colour added)
But how do you know that, by application of stuff in Section 3.4, the result will be the appearance of filaments which match the actual astronomical observations*?
My impression is that you believe it to be so, but have no basis - other than your belief - for your conclusion.
Specifically, you have not done the work necessary to estimate the observables, and you have not read any paper in which such work is reported.
Is my assessment correct? If not, please correct it.
(bold added)Note that If the Yusef-Zadeh paper wins the lottery in the mainstream as to -which one among these competitive and conflictual papers solve the problem - about the formation of these filaments, i will revise my comment.!
How will you know which one "solves the problem"?
What are your criteria for assessing the validity of quantitative models proposed by various people?
My impression - so far - is that if it's a model developed by Peratt it must be correct; if by anyone else, it may, or may not ... depending on whether it agrees with any or Peratt's models.
Is my impression correct? If not, please correct it.
* to within the estimated uncertainties
Established Member
Please tell me if I'm reading the Yusef-Zadeh paper (http://arxiv.org/pdf/astro-ph/0308008v1.pdf) correctly. Basically he's saying that "the nonthermal emission from the Galactic center filaments originates from the shocked region of the colliding stellar winds of young clusters or young stellar binary systems in star forming regions." In other words, filaments are the result of mass shedding stars, rather than the cause of those stars?
Order of Kilopi
Yes.
With the usual caveats.
Established Member
Here the problem
(Excerpts from Yusef-Zadeh paper)
7.A number of NRFs ie(Birkeland Currents)...appear to be located in the vicinity of star forming regions.
In the OP you have presented the filamentary feature (Birkeland Currents)NRF discovered by Vershurr which obviously are not formed - from the shocked region of the colliding stellar winds of young clusters or young stellar binary systems in star forming regions."Theoretically, it has been challenging to understand the nature of these filaments that resemble extragalactic radio jets but are not accompanied with any obvious source of acceleration of charged particles to high energy relativistic energies.
So, i want to know by the mainstream representative Neired ,Tensor, or Shaula how these filaments ie Birkeland currents(NRF) discovered by Vershurr are explained using the Yusef-Zadeh paper ?
Order of Kilopi
You're doing it again, Don J.
You seem to have equated "NRFs" with "Birkeland Currents" (yes?), but have done so (apparently) for no reason other than that you believe them to be the same.
Putting this another way, there is no evidence - as in objective, independently verifiable, quantitative evidence - for your belief.
Huh?In the OP you have presented the filamentary feature discovered by Vershurr which obviously are not formed - from the shocked region of the colliding stellar winds of young clusters or young stellar binary systems in star forming regions."Theoretically, it has been challenging to understand the nature of these filaments that resemble extragalactic radio jets but are not accompanied with any obvious source of acceleration of charged particles to high energy relativistic energies.
So, i want to know by the mainstream representative Neired ,Tensor, or Shaula how these filaments ie Birkeland currents discovered by Vershurr are explained using the Yusef-Zadeh paper ?
First, are any of the filamentary features covered in the Yusef-Zadeh ones which Verschuur* discovered?
Second, what evidence - as in objective, independently verifiable, quantitative evidence - is there that the filamentary features which Verschuur did discover are "Birkeland currents"?
Third, why do you expect that any of the filamentary features which Verschuur discovered should, or could, be explained by the mechanism/model explored in the Yusef-Zadeh paper?
* Could you please try to spell his name correctly? I'd also like you to try a bit harder to spell my name correctly too. Thanks.
Established Member
I think YZ mentions it here Don:
Which does sound alot like a pinch effect...interesting...btw i'm still looking for the "more detailed account". This one also:Another characteristic of a number of NRFs is that their brightness peak in the middle of the filaments. This peak emission does not appear to be in the vicinity of the stellar clusters responsible for their supply of relativistic particles. In the context of this model, we believe the deviation of the orientation of the magnetic fields is likely to be responsible for an increase in the brightness of the filaments...A change in the orientation of the magnetic field, as has been observed in a number prominent NRFs, suggests that there are internal oblique shocks re-accelerating partilces to relativistic energies in midpoints where synchrotron emissivity is enhanced (a more detailed account of this picture will be given elsewhere).
There were a couple of other things he said which also got my attention with regard to binaries (remember Peratt predicted alot of them)In addition, the Snake is unusual in that it shows a gradient in spectral index at the location of the kinks
I feel like I'm reading a mirror image of EU/PU here...kinda wildIf indeed thermal X-rays are the result of colliding winds, previous studies of 30 Doradus support the idea that the binary fraction in a young compact cluster is extremely high (Portegies Zwart, Pooley and Lewin 2002).
The colliding wind model of synchrotron emission was confirmed by Dougherty and Williams (2000), who showed evidence that most nonthermal WR systems are binaries.
Established Member
Ho! so you are saying that Vershurr Nonthermal Radio Filaments are not the same that the Nonthermal Radio Filaments Yusef-Zadeh describe in his paper .... how do you explain that they share something in common ie these filaments that resemble extragalactic radio jets but are not accompanied with any obvious source of acceleration of charged particles to high energy relativistic energies.
1 Aug 2003
arXiv:astro-ph/0308008v1
The Origin of the Galactic Center Nonthermal Radio Filaments
Theoretically, it has been challenging to understand the nature of these filaments that resemble extragalactic radio jets but are not accompanied with any obvious source of acceleration of charged particles to high energy relativistic energies.
Order of Kilopi
He did?
I must have missed that; where - in the primary source material - did Peratt predict a lot of binary stars?
Yeah.I feel like I'm reading a mirror image of EU/PU here...kinda wildIf indeed thermal X-rays are the result of colliding winds, previous studies of 30 Doradus support the idea that the binary fraction in a young compact cluster is extremely high (Portegies Zwart, Pooley and Lewin 2002).
The colliding wind model of synchrotron emission was confirmed by Dougherty and Williams (2000), who showed evidence that most nonthermal WR systems are binaries.
Except for the quantitative details.
But hey, who cares about the quantitative details, right?
I mean, your average human being needs to breath oxygen to survive (for more than a few minutes, perhaps an hour), right? So as long as they breath in 10 oxygen molecules per second, they'll be fine, until they need to drink some water (i.e. about a week) won't they?
Established Member
Sorry Nereid I was mis-remembering this from earlier in the thread
* very few galaxies have double nuclei (as they all must, per the Peratt model)
Order of Kilopi
No.
I am not saying that.
All I did was to ask three questions.
This is what I wrote (I've added bold); please read it again. Carefully. Once you've done that, if you have any questions about what I actually wrote, I'll be more than happy to try to answer them for you.
First, are any of the filamentary features covered in the Yusef-Zadeh ones which Verschuur* discovered?
Second, what evidence - as in objective, independently verifiable, quantitative evidence - is there that the filamentary features which Verschuur did discover are "Birkeland currents"?
Third, why do you expect that any of the filamentary features which Verschuur discovered should, or could, be explained by the mechanism/model explored in the Yusef-Zadeh paper?
A soap bubble shares something in common with a planet. They are both (approximately) spherical in shape.... how do you explain that they share something in commonthese filaments that resemble extragalactic radio jets but are not accompanied with any obvious source of acceleration of charged particles to high energy relativistic energies.
1 Aug 2003
arXiv:astro-ph/0308008v1
The Origin of the Galactic Center Nonthermal Radio Filaments
A salamander shares something in common with a dog. They are both animals, the active genes in their DNA has more in common than not, etc.
Mercury shares something in common with Vesta (the asteroid). They both have craters, mountains, a solid surface, orbit the Sun, etc.
Yet: the underlying reason why a spherical soap bubble is not a spherical planet is that surface tension is not the same as gravity.
(I think you can fill in the rest for yourself).
Earlier I said "I infer that you may have a, um, strange idea of the nature of astrophysics ..." This tendency of yours to (apparently) conflate similarity of appearance with commonality of cause is a good example, wouldn't you say?
Posting Permissions
Reply With Quote