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Bancor
2007-Nov-02, 04:19 PM
Yesterday I discussed with a friend of mine (ATM enthusiast) the news about a new model of star formation I found here (http://www.space.com/scienceastronomy/071031-star-collapse.html).

He insisted that this wasn't a new model at all, as it was already developed by Alfvén and Arrhenius in their 1975 book published by NASA (http://history.nasa.gov/SP-345/sp345.htm), and successively summarized in another 1984 Alfvén's paper (http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1984SSRv...39...65A&data_type=PDF_H IGH&whole_paper=YES&type=PRINTER&filetype=.pdf).

Reading this last paper, which moves from interstellar clouds but mainly applies to the evolution of the Solar System, I have to admit that my friend's claims don't seem so unfounded; nevertheless I think it strange indeed that the researchers hadn't cited these preceding papers, if consistent with their new model.

So, could anyone help me to find the differences, if any, hence the reason why Alfvén-Arrhenius model wasn't cited (in the press-release, at last)?

Thanks everybody.

antoniseb
2007-Nov-02, 04:24 PM
could anyone help me to find the differences, if any, hence the reason why Alfvén-Arrhenius model wasn't cited (in the press-release, at last)?

It looks to me more like the AA paper from 1975 was about the formation of the planets, whereas the recent article you linked to is about the formation of the Sun. Both involve electricity and magnetism, but they aren't talking about the same thing at all.

Spaceman Spiff
2007-Nov-02, 05:33 PM
Gravity is still in charge.

The magnetic structures that co-form with the accretion disk around the protostar act to allow angular momentum to leak out of the system, increasing the efficiency of the accretion of more matter.

Bancor
2007-Nov-02, 06:23 PM
It looks to me more like the AA paper from 1975 was about the formation of the planets, whereas the recent article you linked to is about the formation of the Sun. Both involve electricity and magnetism, but they aren't talking about the same thing at all.

Thanks for your prompt reply, antoniseb.

Unfortunately, your answer couldn't change the level I was able to reach myself; so I need some more clarification in order to get rid of my friend's conviction that the "new" model isn't new at all.

In fact, I was aware of the different cosmic frameworks pertaining to the two models, but the doubt raised about these statements:

from Space.com press-release

(excerpts)
"Some of this rotation energy, called angular momentum, must be dissipated before the star can contract completely. How this happens, though, is unknown."
(...)
"Hence, there needs to be a mechanism present which removes this angular momentum."
(...)
"A new model by Chrysostomou and colleagues suggests excess material and energy are borne away from the protostar along helical magnetic field lines that surround the star. This stellar exodus carries away enough angular momentum to allow the spinning cloud to undergo the final phase of collapse necessary to become a star."
(...)
"The presence of ionized particles in the cloud will effectively drag the field around with it, thereby twisting it up," Chrysostomou told SPACE.com."


whereas my friend insisted on those statements, from 1984 Alfvén's paper, qualitatively comparable, according to him:


(excerpts; italics in the original)
- page 71: "The theory of interstellar clouds should be treated as an extrapolation of magnetospheric research (...)
"As a reasonable guess as to what a future model of the formation and evolutiuon of interstellar clouds should be, we may suggest the following:
(a) Electric currents in 'void' interstellar pace assist gravitation in collecting matter by the pinch effect, so the interstellar clouds are formed.
(b) These develop under the combined action of mechanical and electromagnetic forces. (...) Still, a network of filamentary currents may be decisive to the evolutiuon of the clouds. It is correct to treat the evolution of an interstellar cloud indipendent of its surroundings only if there is no current connecting it with the surroundings.(...)
(...)
- page 73: "(a) The transfer of angular momentum from the central body to the surrounding plasma. The transferred angular momentum is now found in the orbital moment of the secondary bodies. There is a rather obvious candidate for this process, viz. the auroral current system, which is known to transfer angular momentum between a rotating central body and a surrounding plasma."

This was the reason why I asked for an help, if possible.

Thanks.

antoniseb
2007-Nov-02, 06:27 PM
The transferred angular momentum is now found in the orbital moment of the secondary bodies. There is a rather obvious candidate for this process, viz. the auroral current system, which is known to transfer angular momentum between a rotating central body and a surrounding plasma.
Alfven is talking about transferring angular momentum to the planets, and the new paper is talking about transferring it out of the system via high speed jets.

Bancor
2007-Nov-02, 06:52 PM
Alfven is talking about transferring angular momentum to the planets, and the new paper is talking about transferring it out of the system via high speed jets.

Your answers are deadly concise and cathegoric; I finally realise that this is the very way to defeat ATMers. Many thanks.

Anyway, my friend insisted that the conclusions of Chrysostomou's (et al.) paper state literally:

Finally, given that the combination of a rotating disk and a helical magnetic field structure would naturally launch material into the outflow with a significant toroidal component, angular momentum will be carried away from the central accreting system thus preventing centrifugal forces from stopping the collapse and allowing low angular momentum material to be accreted onto the protostar.
and this, in his view, equals Alfvén's statement about the formation of the Solar System from an interstellar cloud, so about the formation of a star, namely our Sun.

If so, the question remains open.
Regards.

John Mendenhall
2007-Nov-02, 08:52 PM
Your answers are deadly concise and cathegoric; I finally realise that this is the very way to defeat ATMers. Many thanks.



"Enlighten" is probably better than "defeat".

John Mendenhall
2007-Nov-02, 09:07 PM
Alfven is talking about transferring angular momentum to the planets, and the new paper is talking about transferring it out of the system via high speed jets.

To the extent that both propose coupling angular momentum out through the magnetic fields, they are the same. However, what they are coupling it to is quite different, Alfven to planetary bodies and these folks to plasma. I guess 1) That their idea is different enough to not reference Alfven. 2) We see lots of jets. 3) I don't know of any observations of transfer of angular momentum from stars to planets via auroral coupling.

Certainly we on Earth would be a prime candidate for #3. Is their any supporting research?

Nereid
2007-Nov-02, 09:27 PM
To the extent that both propose coupling angular momentum out through the magnetic fields, they are the same. However, what they are coupling it to is quite different, Alfven to planetary bodies and these folks to plasma. I guess 1) That their idea is different enough to not reference Alfven. 2) We see lots of jets. 3) I don't know of any observations of transfer of angular momentum from stars to planets via auroral coupling.

Certainly we on Earth would be a prime candidate for #3. Is their any supporting research?

Consider this: the Earth is just as subject to the Poynting-Robertson effect (http://en.wikipedia.org/wiki/Poynting-Robertson_effect) and the Yarkovsky effect (http://en.wikipedia.org/wiki/Yarkovsky_effect) as any dust mote or small asteroid ... yet the Earth's motion (wrt the solar system barycentre) can be modelled without including either, and (AFAIK) there are no deltas (observed minus predicted) greater than observational uncertainty.

Can we thus conclude that neither effect is real?

antoniseb
2007-Nov-03, 01:37 PM
Your answers are deadly concise and cathegoric; I finally realise that this is the very way to defeat ATMers. Many thanks.
Many thanks, this is high praise. Though I would like to point out that my aim is not so much to defeat them. As JM points out enlightening them is good too, but I also want to keep myself open to seeing the wheat in their chaff. It is pretty easy to reject ATM ideas before you really understand them. Many ATM ideas are really just junk thrown up be people who either reject some aspect of the mainstream family of ideas for some philosophical idea (such as how could the universe spring from nothing?), and others because they misunderstand something about the mainstream model. Some are working on different ways to explain mainstream observations, and we have to question these other ways to see if they can fit all the observations, or to know where their model still has uncertainty, but understanding their model helps give depth to my understanding of the mainstream model, and the science that got us to this model. And as the ATM guys frequently point out, there is a small chance that the mainstream model may be overturned by new observations, and they are frequently on the lookout for the strange and different. That's pretty cool, and not something I want to defeat.

I can't speak for everyone, but I think one reason that a lot of us try to ask questions that seem to poke holes in the ATM ideas, and hope for fairly reasoned and quick replies is because we want to separate the possible alternatives from the broken ideas as quickly as possible. This is usually frustrating for an ATM supporter who thinks he's on to something big, but it is worth doing for both sides.

Bancor
2007-Nov-03, 02:13 PM
Thanks everyone, you gave me some good hints about the way to correctly appreciate the differences between the recently proposed model of star formation and the Alfen's one, proposed many years ago when our knowledge of cosmic processes was undoubtedly much less accurate than nowadays.

To antoniseb I owe an explanation for my use of the term "defeat": I was mistaken, and it would be better the much more "evangelic" term proposed by John_Mendenhall: enlighten.
Anyway, here we aren't discussing a case as those you related to (junk ideas, misunderstandigs, and so on), but the contents of a paper published many years ago and seemingly predictive of what other researchers seem to have found nowadays.

Actually, it isn't so easy to "enlighten" a skeptic ATMer; in fact, my friend answered the argument about the different reference framework of the two models, telling me that probably that Alfvén's paper wasn't attentively read by those who based on those differences for rejecting a possible "right of primogeniture" by Alfvén.

As he pointed out, it's true that Alfvén's work deals with the evolution of the Solar System, but nevertheless it moves primarily from the evolution of interstellar clouds, so the clouds where a star formation may be triggered.
References for this may be found in one of the excerpts I posted beforehand (see ref. 'page 71').

WRT John_Mendenhall's guess about the reasons why Chrysostomou's method is quite different, I was told to read again Alfvén's Chapter 2.5 (page 75), where he says (italics in the original):

Plasma effects were of considerable importance for the evolutionary history of the solar system from the formation and evolution of cosmic clouds to the formation of the Sun and a surrounding solar nebula.
(a) In the solar nebula the plasma effects were of decisive importance in two respects: (1) they tranferred angular momentum from the Sun to the plasma (...), and (2) the critical velocity produced the band structure of the solar system. (...)
(b) After the plasma phase of the solar nebula came the plasma planetesimal transition (...)
(c) The mass of matter in the planetesimal state increased slowly, until the planetesimals began to aggregate to planets (...) Plasma processes are of negligible importance for these processes.

This would demonstrate that Alfvén worked primarily on interstellar clouds, as does seem to do Chrysostomou and his collaborators, and that he was well aware of the differences between the state of dusty plasma and the planetesimal one (and its evolution to planets).
Since, according to Alfvén, in these last phases plasma processes have no effect, maybe that the question posed by John_Mendenhall about the possibility to observe a transfer of angular momentum from stars to planets couldn't be applicable.

Kind salutations.

01101001
2007-Nov-03, 03:54 PM
As he pointed out, it's true that Alfvén's work deals with the evolution of the Solar System, but nevertheless it moves primarily from the evolution of interstellar clouds, so the clouds where a star formation may be triggered.

If you're going to continue to be carrying your friend's arguments here, and I presume carrying back the reponses of BAUT members, why don't you escape the thankless middle-man job and get your friend to become a BAUT member and make the claims directly? Wouldn't it be less cumbersome?

Bancor
2007-Nov-03, 04:31 PM
If you're going to continue to be carrying your friend's arguments here, and I presume carrying back the reponses of BAUT members, why don't you escape the thankless middle-man job and get your friend to become a BAUT member and make the claims directly? Wouldn't it be less cumbersome?

You're right, and would you know how many times I recommended him... but he's timid and moreover he doesn't know English language (well, I must confess that I translated for him to Italian language some Alfvén's papers, as this one we are discussing), so I've no escape but to bear the middle-man role.
For me it isn't a cumbersome job at all, since I'm pleased to discuss here on the board, and moreover I may improve my rather limited knowledge of English language too: "pigliare due piccioni con una fava" we say in Italy (I seem it's "To get two birds with a stone" in English).

I'm sorry if this situation is cumbersome for you; the best way would be to give a "killer answer" to his questions, but if it cannot be so, tell me and I'll stop immediately (he'll resign himself to accept the Word, at last!).

Regards.

Bancor
2007-Nov-04, 11:31 AM
I was warned by a forum member that my asking the question on behalf of my friend was a break of forum rules, #7 in particular, which prohibits the "Second and third part posting".

It wasn't my intention to break these rules, nor my question was a sort of workaround in order to promote ATM ideas.
In fact, I would like to say that I don't think Alfvén's 1984 paper be so ATM, as -if anyone reads it forgetting for a while the name of the writer- it doesn't question any of the fundamental statements about gravity and correlated forces and theories.
Moreover, in this occasion I asked only to discuss if his paper did envisage, at that time, the same mechanism now proposed by Chrysostomou and colleagues in the paper published in November issue of the journal Nature, which may be found here (http://arxiv.org/abs/0710.5927).

Anyway, as I don't want to be the middle-man, nor the puppet, for anyone, I stop my posting here, and if the Mods think it better to close the thread, I will agree with their decision.

Regards and apologies to everyone; I'll be more careful in the future, I promise.

antoniseb
2007-Nov-04, 11:46 AM
Anyway, as I don't want to be the middle-man, nor the puppet, for anyone, I stop my posting here, and if the Mods think it better to close the thread, I will agree with their decision.

There are several situations that the posting-for-a-friend covers, and the worst is a variation on sock-puppetry. In the current situation, I think you have been in the gray area of what this rule does and doesn't cover, so no harm has been done, you are not in trouble, and you may continue being the translator for your friend.

Bancor
2007-Nov-04, 01:28 PM
There are several situations that the posting-for-a-friend covers, and the worst is a variation on sock-puppetry. In the current situation, I think you have been in the gray area of what this rule does and doesn't cover, so no harm has been done, you are not in trouble, and you may continue being the translator for your friend.

Many thanks to have trusted me; as I found myself in the gray area, unfortunately, I deem it better not to insist, however, since my will is to keep my reputation and not to lose it because of some miswriting (due to my erratic English language).

Obviously, I'll greet any further answer on this question.

Thanks again.

iantresman
2007-Nov-08, 07:03 PM
Alfven is talking about transferring angular momentum to the planets, and the new paper is talking about transferring it out of the system via high speed jets.

In Alfvén's paper cited above, Cosmogony as an extrapolation of magnetospheric research (http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1984SSRv...39...65A&db_key=AST) (1984), there is a section already mentioned by Bancor 2.4 Basic Processes in Evolution of Solar Nebula (p.73), which discusses:


"(a) The transfer of angular momentum from the central body to the surrounding plasma. The transferred angular momentum is now found in the orbital moment of the secondary bodies. There is a rather obvious candidate for this process, viz., the auroral current system, which is known to transfer angular momentum between a rotating central body and a surrounding plasma"
Isn't this the analogous bit with the other article (http://www.space.com/scienceastronomy/071031-star-collapse.html) (full article (http://arxiv.org/abs/0710.5927)) mentioned by Bancor. Alfvén notes that the angular momentum is lost to the surrounding plasma ... a known mechanism which removes this angular momentum electromagnetically?

Bancor
2007-Nov-09, 03:01 PM
In Alfvén's paper cited above, Cosmogony as an extrapolation of magnetospheric research (http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1984SSRv...39...65A&db_key=AST) (1984), there is a section already mentioned by Bancor 2.4 Basic Processes in Evolution of Solar Nebula (p.73), which discusses:


"(a) The transfer of angular momentum from the central body to the surrounding plasma. The transferred angular momentum is now found in the orbital moment of the secondary bodies. There is a rather obvious candidate for this process, viz., the auroral current system, which is known to transfer angular momentum between a rotating central body and a surrounding plasma"
Isn't this the analogous bit with the other article (http://www.space.com/scienceastronomy/071031-star-collapse.html) (full article (http://arxiv.org/abs/0710.5927)) mentioned by Bancor. Alfvén notes that the angular momentum is lost to the surrounding plasma ... a known mechanism which removes this angular momentum electromagnetically?

Thank you for your confirmation of the very essence of the question I posed, which stays unanswered however.
In fact, when I tried to ask some more in the aim to get a reply, whatever might it be, I gained only a (politely private) warning that I was unduly breaking a forum rule (which forbids "third part posting), besides disguising an ATM idea promotion.
I took note and stopped posting, as it wasn't my intention to polemize on an higly subjective argument, though it seemed pretty pretextuous even if absolutely correct with regard to the observance of forum rules.

Now that you return on the argument, I venture again, on my name this time, to ask the question (absolutely NOT ATM, if it's regarded bona fide): didn't Alfvén predict over thirty years ago what now is envisaged by Chrysostomou's team paper?
Deny and reject it at all, I don't matter as I want to know, but please not on the basis that Alfvén's work applied to Sun and Planets, as the excerpt aforementioned by iantresman (and reported in my previous #4 post too), looks clear enough on this issue (and it's still clearer if one reads the whole paper).

Salutations.

Nereid
2007-Nov-09, 03:59 PM
Thank you for your confirmation of the very essence of the question I posed, which stays unanswered however.
In fact, when I tried to ask some more in the aim to get a reply, whatever might it be, I gained only a (politely private) warning that I was unduly breaking a forum rule (which forbids "third part posting), besides disguising an ATM idea promotion.
I took note and stopped posting, as it wasn't my intention to polemize on an higly subjective argument, though it seemed pretty pretextuous even if absolutely correct with regard to the observance of forum rules.

Now that you return on the argument, I venture again, on my name this time, to ask the question (absolutely NOT ATM, if it's regarded bona fide): didn't Alfvén predict over thirty years ago what now is envisaged by Chrysostomou's team paper?
Deny and reject it at all, I don't matter as I want to know, but please not on the basis that Alfvén's work applied to Sun and Planets, as the excerpt aforementioned by iantresman (and reported in my previous #4 post too), looks clear enough on this issue (and it's still clearer if one reads the whole paper).

Salutations.For starters, the key part of the Chrysostomou et al paper is not available in the arXiv preprint*, so commenting in detail is not possible without access to the Nature paper.

Second, the 1984 Alfvén paper is only marginally related to the Chrysostomou et al one, if only because the (observed) phenomena that are the scope of the respective papers are quite different (Alfvén looks at Saturn's rings, for example, while Chrysostomou et al look at YSO jet polarisation).

However, the two classes of model Chrysostomou et al mention are X-wind models and disk-wind models, both of which "appeal to the magneto-hydrodynamic (MHD) interaction of the magnetic field with the accreting gas in some form or another", and "In each [class of model], material is lifted and centrifugally accelerated along magnetic field lines (rather like ‘beads on a wire’)."

One would need to read Chrysostomou et al's sources 6 and 7 in some detail to be sure, but my impression is that the key physical mechanisms in these models are quite different than those in Alfvén's 1984 paper. Further, neither source cites the Alfvén 1984 paper, and none of the citations to that 1984 paper seems to be relevant to any of the references in 6 or 7. While this is far from a certain measure, it is a pretty clear indication that the Chrysostomou et al model owes nothing to Alfvén's 1984 paper.

Of course, one could say that Alfvén developed MHD and that the Chrysostomou et al model incorporates MHD, ergo the latter is the former's intellectual heir. While that may be true, it is also seriously misleading.

And so to Bancor's question ("didn't Alfvén predict over thirty years ago what now is envisaged by Chrysostomou's team paper?"): from what I have read in the relevant papers so far, no, not in any meaningful sense. In fact, one can make a stronger statement: the mechanisms in Alfvén's 1984 paper seem to be unable to account for at least one salient, observed, feature of YSOs - the jets.

*"Output from a successful model (see Supplementary Information", and "Supplementary Information accompanies the paper on www.nature.com/nature"

iantresman
2007-Nov-09, 04:31 PM
Now that you return on the argument, I venture again, on my name this time, to ask the question (absolutely NOT ATM, if it's regarded bona fide): didn't Alfvén predict over thirty years ago what now is envisaged by Chrysostomou's team paper?
Deny and reject it at all, I don't matter as I want to know, but please not on the basis that Alfvén's work applied to Sun and Planets, as the excerpt aforementioned by iantresman (and reported in my previous #4 post too), looks clear enough on this issue (and it's still clearer if one reads the whole paper).

The best person to decide, is you. There will be others that agree with you, and others that don't.

On the one hand, I don't think Alfvén has specifically said in one sentences, that "during star formation, angular momentum is lost via jets". On the other hand, he did mention that stars acting as a unipolar inductor, loose angular momentum to the surrounding plasma.

As early as 1958, Alfvén had written that: It is possible that the [solar] magnetic field transfers momentum from the sun to its environment." ("Interplanetary Magnetic Field" (1958) (Abstract and full text (http://adsabs.harvard.edu/abs/1958IAUS....6..284A))).

I guess this is magnetic breaking which Professor of the History of Science, Stephen G. Brush (http://www.punsterproductions.com/~sciencehistory/), has already credited Alfvén with predicting correctly [ref (http://adsabs.harvard.edu/abs/1992ITPS...20..577B)]

Nereid
2007-Nov-09, 04:44 PM
The best person to decide, is you. There will be others that agree with you, and others that don't.

On the one hand, I don't think Alfvén has specifically said in one sentences, that "during star formation, angular momentum is lost via jets". On the other hand, he did mention that stars acting as a unipolar inductor, loose angular momentum to the surrounding plasma.

As early as 1958, Alfvén had written that: It is possible that the [solar] magnetic field transfers momentum from the sun to its environment." ("Interplanetary Magnetic Field" (1958) (Abstract and full text (http://adsabs.harvard.edu/abs/1958IAUS....6..284A))).

I guess this is magnetic breaking which Professor of the History of Science, Stephen G. Brush (http://www.punsterproductions.com/~sciencehistory/), has already credited Alfvén with predicting correctly [ref (http://adsabs.harvard.edu/abs/1992ITPS...20..577B)]
Perhaps our posts crossed, iantresman.

In any case, to re-state what I wrote, if you look at the actual mechanisms in each of the two papers Bancor mentions (and, specifically, the extract of the Alfvén one you posted above), it would seem they have little to do with one another; specifically, "the auroral current system" does not seem to be used in the Chrysostomou et al paper, in any form at all.

While it is no doubt interesting, the much broader, and more general, topic of 'magnetic breaking' is well beyond the scope of Bancor's questions.

iantresman
2007-Nov-09, 04:46 PM
And so to Bancor's question ("didn't Alfvén predict over thirty years ago what now is envisaged by Chrysostomou's team paper?"): from what I have read in the relevant papers so far, no, not in any meaningful sense. In fact, one can make a stronger statement: the mechanisms in Alfvén's 1984 paper seem to be unable to account for at least one salient, observed, feature of YSOs - the jets.
Beams are an integral part of Alfvén theory, and further detailed in Anthony L. Peratt's paper, "Evolution of the plasma universe. I - Double radio galaxies, quasars, and extragalactic jets (http://adsabs.harvard.edu/abs/1986ITPS...14..639P)", IEEE Transactions on Plasma Science (ISSN 0093-3813), vol. PS-14, Dec. 1986, p. 639-660. (Full text (http://plasmascience.net/tpu/downloadsCosmo/Peratt86TPS-I.pdf), PDF) (peer reviewed in a mainstream journal and includes math!)

iantresman
2007-Nov-09, 04:48 PM
In any case, to re-state what I wrote, if you look at the actual mechanisms in each of the two papers Bancor mentions (and, specifically, the extract of the Alfvén one you posted above), it would seem they have little to do with one another; specifically, "the auroral current system" does not seem to be used in the Chrysostomou et al paper, in any form at all.

While it is no doubt interesting, the much broader, and more general, topic of 'magnetic breaking' is well beyond the scope of Bancor's questions.

Correct, the devil is in the detail; I think there are sufficient similarities, but the details show the differences in approach.

Nereid
2007-Nov-09, 05:09 PM
Beams are an integral part of Alfvén theory, and further detailed in Anthony L. Peratt's paper, "Evolution of the plasma universe. I - Double radio galaxies, quasars, and extragalactic jets (http://adsabs.harvard.edu/abs/1986ITPS...14..639P)", IEEE Transactions on Plasma Science (ISSN 0093-3813), vol. PS-14, Dec. 1986, p. 639-660. (Full text (http://plasmascience.net/tpu/downloadsCosmo/Peratt86TPS-I.pdf), PDF) (peer reviewed in a mainstream journal and includes math!)That may be so.

However, I very much doubt that the jet mechanism(s) in the Chrysostomou et al paper paper have anything to do with the Peratt ones*.

But, I could be quite wrong; can you show that these two are related, iantresman? I mean other than that there are magnetic fields involved in both ...

*which, incidentally, rather badly fail to account for the wealth of detailed observational results published after 1986; IOW, the Peratt jet mechanism seems to be inconsistent with good (astronomical) observational results, at least for quasars etc. This illustrates rather nicely the point I made elsewhere (http://www.bautforum.com/1102028-post168.html): one reason why you don't see many references to Alfvén or Peratt papers on specifics is that there's apparently no observational basis for them in the enormous wealth of high quality results obtained in the last decade or so.

VanderL
2007-Nov-10, 11:02 AM
That may be so.

However, I very much doubt that the jet mechanism(s) in the Chrysostomou et al paper paper have anything to do with the Peratt ones*.

But, I could be quite wrong; can you show that these two are related, iantresman? I mean other than that there are magnetic fields involved in both ...

There is a similarity in the (helical) shape of the magnetic fields in both models. Of course there are also differences, Chrysostomou's model has mechanical twisting of the magnetic field to account for the helicity, Alfvén's model relies on Birkeland currents. Maybe that's why Alfvén isn't referenced, or maybe Chrysostomou isn't familiar with Alfvén's work or simply doesn't want to acknowledge it for whatever reasons.


*which, incidentally, rather badly fail to account for the wealth of detailed observational results published after 1986;

You rather badly fail to convince me that indeed Peratt's paper "rather badly fails to account for the wealth of detailed observational results published after 1986".


IOW, the Peratt jet mechanism seems to be inconsistent with good (astronomical) observational results, at least for quasars etc.

Seems? I don't see how you can say this, because all astrophysical jets are shaped by magnetic fields and the latest data show many (if not all) of them to have this helical structure. There is nothing inconsistent that I can see.


This illustrates rather nicely the point I made elsewhere (http://www.bautforum.com/1102028-post168.html): one reason why you don't see many references to Alfvén or Peratt papers on specifics is that there's apparently no observational basis for them in the enormous wealth of high quality results obtained in the last decade or so.

Indeed you don't see many references to Alfvén or Peratt, but your inference that this is because there's "apparently no observational basis for them" is simply your interpretation, it could just as well mean the authors are not familiar with their work.

Cheers.

Bancor
2007-Nov-10, 03:27 PM
The discussion gets very interesting and adds so much to my knowledge on this issue; so, before all, many thanks to Nereid, iantresman and VanderL.

Perhaps you already know my approach to standard cosmology as a bit skeptic amateur, certainly not scientifically learned to discuss the specific issues of a research paper, but nevertheless willing to know some more than the news in a press-release.
So, my reference to the contents of Alfven's thought aimed to be a bit, even though a simple bit, more accurate than the usual popular scientific reviews reader.

In this, whereas I have to thank iantresman for having pointed out some papers I didn't yet know, and VanderL for clarifying some aspects of the issue, I much appreciate Nereid's attention and explanations too, which I have to discuss under some aspects, anyhow:

(...) the 1984 Alfvén paper is only marginally related to the Chrysostomou et al one, if only because the (observed) phenomena that are the scope of the respective papers are quite different (Alfvén looks at Saturn's rings, for example, while Chrysostomou et al look at YSO jet polarisation)
That's the issue I referred to in my last post: gases and jets versus Sun and Planets (solid and heavy bodies), so nothing to share.
May I repeat that it wouldn't be so?
Of course Alfvén work may be rejected at all (I posed the question just to know of this eventuality), but this wouldn't be the reason, as:
(a) Alfvén clearly predicts the "...transfer [of] angular momentum between a rotating central body and a surrounding plasma".
(b) Chrysostomou et al. paper (in its freely readable part, at least) moves from "gases", "molecular clouds", "grains" and "material ... accelerated along magnetic field lines" to conclude that "...angular momentum will be carried away from the central accreting system (...) allowing low angular momentum material to be accreted onto the protostar".
(c) provided that Alfvén referred to a "...transfer [of] angular momentum between a rotating central body and a surrounding plasma", may the difference lay only in the fact that, in the nowadays paper, the word "plasma" is accurately avoided?


(...) Further, neither source cites the Alfvén 1984 paper (...) it is a pretty clear indication that the Chrysostomou et al model owes nothing to Alfvén's 1984 paper.
Apart from a vague taste of petitio principii (AKA begging the question) of the statement, would anyone wonder at this? Provided the general rebuttal of Alfvén's cosmological research, who will be so rash to cite his ancient contributions in a refereed paper? (In this, I try to be a bit more explicit than VanderL about the "...whatever reasons" why Chrysostomou may have choosed not to acknowledge former Alfvén's work).


(...) specifically, "the auroral current system" does not seem to be used in the Chrysostomou et al paper, in any form at all. (...)
He didn't use the term "plasma" and we would really expect he might refer to "the auroral current system", alias "Birkeland currents"? Why would he commit suicide?


(...) one reason why you don't see many references to Alfvén or Peratt papers on specifics is that there's apparently no observational basis for them in the enormous wealth of high quality results obtained in the last decade or so.
I totally agree, here; that's just one reason; many others may stay behind a simple benign neglect, however.

To conclude, I would like you take note that, IMHO at least, this is NOT an ATM discussion, nor a whatsoever ATM claim, as we are debating only on the possible prediction in a former paper of the mechanism now proposed in a mainstream hypothesis on stars formation process.

Regards.

Nereid
2007-Nov-10, 04:16 PM
The discussion gets very interesting and adds so much to my knowledge on this issue; so, before all, many thanks to Nereid, iantresman and VanderL.

Perhaps you already know my approach to standard cosmology as a bit skeptic amateur, certainly not scientifically learned to discuss the specific issues of a research paper, but nevertheless willing to know some more than the news in a press-release.
So, my reference to the contents of Alfven's thought aimed to be a bit, even though a simple bit, more accurate than the usual popular scientific reviews reader.

In this, whereas I have to thank iantresman for having pointed out some papers I didn't yet know, and VanderL for clarifying some aspects of the issue, I much appreciate Nereid's attention and explanations too, which I have to discuss under some aspects, anyhow:

(...) the 1984 Alfvén paper is only marginally related to the Chrysostomou et al one, if only because the (observed) phenomena that are the scope of the respective papers are quite different (Alfvén looks at Saturn's rings, for example, while Chrysostomou et al look at YSO jet polarisation)
That's the issue I referred to in my last post: gases and jets versus Sun and Planets (solid and heavy bodies), so nothing to share.
May I repeat that it wouldn't be so?
Of course Alfvén work may be rejected at all (I posed the question just to know of this eventuality), but this wouldn't be the reason, as:
(a) Alfvén clearly predicts the "...transfer [of] angular momentum between a rotating central body and a surrounding plasma".
(b) Chrysostomou et al. paper (in its freely readable part, at least) moves from "gases", "molecular clouds", "grains" and "material ... accelerated along magnetic field lines" to conclude that "...angular momentum will be carried away from the central accreting system (...) allowing low angular momentum material to be accreted onto the protostar".
(c) provided that Alfvén referred to a "...transfer [of] angular momentum between a rotating central body and a surrounding plasma", may the difference lay only in the fact that, in the nowadays paper, the word "plasma" is accurately avoided?

[snip]I've been wondering how best to explain this, without trying to compress a four year university course into < 500 words.

Let's bring in this too:

[snip]

But, I could be quite wrong; can you show that these two are related, iantresman? I mean other than that there are magnetic fields involved in both ...
There is a similarity in the (helical) shape of the magnetic fields in both models.
IIRC, economics is your field of professional expertise Bancor, so I'll try an analogy from that field*.

Suppose there are two papers on the causes of the recent turmoil in the (global) financial markets, one presenting a model based on a failure of central banks' regulatory roles, and the other on a systemic failure of global financial institutions' risk models. From reading the (non-technical) parts of each, or from reading articles in the Economist magazine, you may find many similarities between the papers' models - links between SIVs and risk, for example, or the role of ratings agencies.

To what extent is it then reasonable to conclude that one model is the intellectual heir of the other?

I don't know; however, I guess that a professional economist would shake her head at the naďveté of such an approach, and would, if pressed, stress the need to study the actual models themselves, in their full technical detail, before any such conclusion could be drawn.

From a history and philosophy of economics perspective, I guess that showing the influence of ideas would involve, at least, an analysis of (historical) papers and conference presentations (more later).

I'll comment on the rest of your post later Bancor.

*Please excuse the inevitable mis-statements and misunderstandings here; clearly, I have very limited understanding of economics.

Bancor
2007-Nov-10, 06:19 PM
Very well, Nereid, let's talk of economics (warning: I'm not a "professional economist", though I studied economics; my professional experience as a bank manager who dealt with credit & loans, information technology and internal auditing departments, may help in this case however).
And please, do not apologise for your limited understanding of economics, otherwise what had I to say, for my even more limited knowledge of astronomy (and my lame English)?

You ask to what extent it is reasonable to conclude that, in the present turmoil (a pretty euphemism indeed) in the financial markets, the "failure of central banks' regulatory role" model may be regarded as the intellectual heir of the "systemic failure of financial institutions' risk model" one (or vice-versa).

Here I have to say that, whereas on reading an economic magazine it's possible that a layman reader might even find some similarities (surely, those you underlined are the best candidates), he would more probably identify two different wicked responsibles for the crisis: central banks and financial institutions, each of whom charged with its proper "criminal action" to its own interest.
And this not to speak of cental banks' and financial insitutions' reciprocal points of view, obviously more sharply oriented to one's own advantage.

So, in this example, the naďveté is just the "independent model" approach; in actually, an independent professional economist (not so many in charge nowadays, however) hadn't no reason to shake his/her head, as he/she would think that the two models are neither independent, nor each other heirs, rather sons of a twinning; and the mother is the free market dogma.

You may find some interesting discussions on this argument in many online newspapers, but I seem that this recent Guardian article (http://politics.guardian.co.uk/columnist/story/0,,2205122,00.html), written by a formerly convinced liberal (i.e. monetarist "ŕ la Milton Friedman") journalist might suffice.

Moreover, if you don't fear to read against the mainstream economics, you may take some book by John Kenneth Galbraith; amongst them, try to read "The Affluent Society" (1958), or "The Great Crash 1929" (1955), and you'll find some hints on how we came to our present financial turmoil through an epoch of "financial euphoria" (from another Galbraith's book title).

Might some Alfvén intuitions be bound to a similar destiny?

See you later, Nereid, it's a pleasure to discuss with you.

Nereid
2007-Nov-11, 01:06 AM
Very well, Nereid, let's talk of economics (warning: I'm not a "professional economist", though I studied economics; my professional experience as a bank manager who dealt with credit & loans, information technology and internal auditing departments, may help in this case however).
And please, do not apologise for your limited understanding of economics, otherwise what had I to say, for my even more limited knowledge of astronomy (and my lame English)?

You ask to what extent it is reasonable to conclude that, in the present turmoil (a pretty euphemism indeed) in the financial markets, the "failure of central banks' regulatory role" model may be regarded as the intellectual heir of the "systemic failure of financial institutions' risk model" one (or vice-versa).

Here I have to say that, whereas on reading an economic magazine it's possible that a layman reader might even find some similarities (surely, those you underlined are the best candidates), he would more probably identify two different wicked responsibles for the crisis: central banks and financial institutions, each of whom charged with its proper "criminal action" to its own interest.
And this not to speak of cental banks' and financial insitutions' reciprocal points of view, obviously more sharply oriented to one's own advantage.

So, in this example, the naďveté is just the "independent model" approach; in actually, an independent professional economist (not so many in charge nowadays, however) hadn't no reason to shake his/her head, as he/she would think that the two models are neither independent, nor each other heirs, rather sons of a twinning; and the mother is the free market dogma.

You may find some interesting discussions on this argument in many online newspapers, but I seem that this recent Guardian article (http://politics.guardian.co.uk/columnist/story/0,,2205122,00.html), written by a formerly convinced liberal (i.e. monetarist "ŕ la Milton Friedman") journalist might suffice.

Moreover, if you don't fear to read against the mainstream economics, you may take some book by John Kenneth Galbraith; amongst them, try to read "The Affluent Society" (1958), or "The Great Crash 1929" (1955), and you'll find some hints on how we came to our present financial turmoil through an epoch of "financial euphoria" (from another Galbraith's book title).

Might some Alfvén intuitions be bound to a similar destiny?

See you later, Nereid, it's a pleasure to discuss with you.Well, it seems pretty clear that my attempt to explain via analogy didn't work.

Back to the straight-forward approach then, up one level.

What you are asking* is, at one level up, what method(s) should be used to evaluate statements concerning similarities between two specific models, with the specific hypothesis to be tested something like {insert hypothesis here}.

So far, the methods which have been put on the table include:

-> searching for strings of words which can be shown to be very similar (or not) in the two models

-> comparing the (technical, equation-filled) details of the respective models

-> evaluating perceptions of, or extrapolations of, the respective models in terms of their applicability to {insert modifier here} questions (that may, or may not, be pertinent)

-> comparing the explicitly stated scopes of the two models.

What I have been trying to say - unsuccessfully so far, it seems - is that the first and third methods are at best unreliable (and at worst downright dangerous), and that the second and fourth are the most direct and reliable.

So how to proceed?

Of course it is always possible to mine the two papers and come up with a list like Bancor's^ (or the much shorter one of VanderL: "There is a similarity in the (helical) shape of the magnetic fields in both models"), and to some extent such lists are to be expected!

But in terms of how contemporary astrophysics and space science are done (the avowed scope of BAUT), what more is there to say beyond noting that these are methods neither used nor part of such science (not least because they are so unreliable and subjective)?

Of course, shifting the scope to one of HPS (the history and philosophy of science) gives us the opportunity to examine these methods in a different light ... (to be continued).

*And what iantresman and VanderL, separately, are asserting

^ "(a) Alfvén clearly predicts the "...transfer [of] angular momentum between a rotating central body and a surrounding plasma".
(b) Chrysostomou et al. paper (in its freely readable part, at least) moves from "gases", "molecular clouds", "grains" and "material ... accelerated along magnetic field lines" to conclude that "...angular momentum will be carried away from the central accreting system (...) allowing low angular momentum material to be accreted onto the protostar".
(c) provided that Alfvén referred to a "...transfer [of] angular momentum between a rotating central body and a surrounding plasma", may the difference lay only in the fact that, in the nowadays paper, the word "plasma" is accurately avoided?"

Nereid
2007-Nov-11, 01:37 AM
(continued, as promised)
[snip]
(...) Further, neither source cites the Alfvén 1984 paper (...) it is a pretty clear indication that the Chrysostomou et al model owes nothing to Alfvén's 1984 paper.
Apart from a vague taste of petitio principii (AKA begging the question) of the statement, would anyone wonder at this? Provided the general rebuttal of Alfvén's cosmological research, who will be so rash to cite his ancient contributions in a refereed paper? (In this, I try to be a bit more explicit than VanderL about the "...whatever reasons" why Chrysostomou may have choosed not to acknowledge former Alfvén's work).

(...) specifically, "the auroral current system" does not seem to be used in the Chrysostomou et al paper, in any form at all. (...)
He didn't use the term "plasma" and we would really expect he might refer to "the auroral current system", alias "Birkeland currents"? Why would he commit suicide?

[snip]
First we must acknowledge that the people who write papers which are published in the relevant astronomy (etc) peer-reviewed journals are ordinary human beings, in many ways no different from you and I, our family members, friends, associates, neighbours, etc - some are arrogant, some humble; some headstrong, some meek; some egotistical, some introverted; some will take pride in skating as close to the edge of acceptable behaviour as possible, some will bend over backwards to be fair and be seen to be fair; ...

Second, within the bounds of the diversity of human character, let me simply state that to fail to acknowledge a clearly demonstrable, direct, pertinent intellectual debt (or precedent, or ...) - by citing a paper previously published in a relevant peer-reviewed journal - is unacceptable. Worse, for those who do so when the relevant paper has a still living, still scientifically active Nobel laureate as an author is risky in the extreme, and it is doubly risky for the reviewers who fail to counsel the foolhardy (or naive) author, and triply risky for the editors of the publication who persistently fail their editorial responsibilities.

Third, of course mistakes are sometimes made, corrections are not always published, databases such as ADS not always accurate or complete, ....

---------------- end of preamble ------------

For all kinds of all too human reasons, it may not be possible to trace a direct line of intellectual debt (shall we say) from Chrysostomou et al (2007) to Alfvén's (1984), via citations and references.

However, I expect that a failure to find such a trail of citations and references is much more likely due to an absence of any such intellectual debt than any combination of fear, spite, clumsiness, over-work, dishonesty, etc that the part of your post I am quoting seems to imply.

But there's no need to go to such lengths! A direct, objective, and very straight-forward test can be done by anyone who has the full Chrysostomou et al (2007) Nature paper and the Alfvén 1984 one - just compare the two models at the equation (and explicit scope) level!

May I suggest that if you wish to continue with the idea that Chrysostomou et al would be "commit[ing] suicide" by "refer[ing] to "the auroral current system", alias "Birkeland currents"" you should start a new thread in BAUT's Conspiracy Theories section (http://www.bautforum.com/conspiracy-theories/)?

(to be continued)

Realitly
2007-Nov-11, 02:24 AM
Author:

Andrea Ciardi
(Observatoire de Paris)

Collimated, powerful jets are found in a large variety of astrophysical objects, ranging from those associated with proto-stars to galactic jets powered by black-holes. A frequent element found in many evolutionary jet models is the presence, at least in some regions, of a dominant toroidal field responsible for accelerating and confining the plasma to narrow channels which transport angular momentum and energy away from the source. In this context we present 3D MHD simulations of scaled laboratory experiments that not only reproduce the important physical processes thought to exist in the astrophysical systems but also provide new insights into the formation, evolution and stability of magnetically produced jets. The laboratory jets are produced using radial wire arrays driven by a 1 MA current pulse. The general outflow structure of a magnetic tower comprises an expanding magnetic cavity, largely collimated by the pressure of an extended plasma background medium, and a magnetically confined jet which forms within the magnetic cavity itself. A shell of swept-up shocked plasma surrounds the cavity. Although this structure is intrinsically transient and instabilities in the jet and disruption of the magnetic cavity ultimately lead to its break-up, a well collimated, radiatively cooled, ``clumpy'' jet still emerges from the system; notably such morphology is reminiscent of that observed in many astrophysical jets. We also investigate the effects on the laboratory jets of poloidal fields and rotation, which are thought to stabilize the jets observed in space. In collaboration with S. V. Lebedev, A. Frank, E. G. Blackman, D. J. Ampleford, C. A. Jennings, J. P. Chittenden, S. N. Bland, S. C. Bott, G. N. Hall, F. A. Suzuki Vidal, and A. Marocchino.

tp://meetings.aps.org/Meeting/DPP06/Event/52446


Author:

Setthivoine You
(California Institute of Technology)

This talk presents experimental observations, first reported by You, Yun, Bellan in PRL (art. 045002, 2005), strongly supporting the ``MHD pump-collimation'' model proposed by Bellan in Phys.~Plasmas (vol. 10, p.1999, 2003). Collimated, plasma-filled, magnetic flux tubes are observed over a tremendous range of scales. In laboratory plasmas, on the surface of the Sun, or jetting out of galactic cores, these flux tubes are extremely collimated, with cross-sections that do not vary much along the length of the tube even in the absence of external magnetic fields or any significant ambient medium pressure. Furthermore, these flux tubes are not in static equilibrium but exhibit strong plasma flows on a rapid time-scale compared to their overall motion within their surroundings. The Caltech experiment simulates magnetically-driven astrophysical jets at the laboratory scale by imposing boundary conditions analogous to astrophysical jet boundary conditions and with plasma dimensionless numbers comparable to numerical MHD simulations. Observations show a distinct sequence of events. The initial flux tubes flare out into the large vacuum, because the magnetic field weakens away from the source. As electrical current flows, the flux tubes become denser and more collimated while sucking plasma from gas sources at the system boundary, effectively acting like a magnetohydrodynamic pump. These flux tubes then merge together into a single column which jets out into the vacuum. The jet continues the same pumping process, to become even denser and more collimated, until either the electrical current or the supply of particles stop. The strong plasma flow convects frozen-in magnetic flux to regions of weaker magnetic field at the end of the tube, and as the flow stagnates there, magnetic flux piles up, pinching the tube into a collimated filament.

ttp://meetings.aps.org/Meeting/DPP06/Event/52021


Neried wrote:
So how to proceed?

Of course it is always possible to mine the two papers and come up with a list like Bancor's^ (or the much shorter one of VanderL: "There is a similarity in the (helical) shape of the magnetic fields in both models"), and to some extent such lists are to be expected!

But in terms of how contemporary astrophysics and space science are done (the avowed scope of BAUT), what more is there to say beyond noting that these are methods neither used nor part of such science (not least because they are so unreliable and subjective)?


antoniseb
Quote:
The transferred angular momentum is now found in the orbital moment of the secondary bodies. There is a rather obvious candidate for this process, viz. the auroral current system, which is known to transfer angular momentum between a rotating central body and a surrounding plasma.

Alfven is talking about transferring angular momentum to the planets, and the new paper is talking about transferring it out of the system via high speed jets.

So do these two pending papers have any bearing on this thread wrt angular momentum transferral Neried, Antinoseb?

Maybe something else to add wrt the list below


Of course Alfvén work may be rejected at all (I posed the question just to know of this eventuality), but this wouldn't be the reason, as:
(a) Alfvén clearly predicts the "...transfer [of] angular momentum between a rotating central body and a surrounding plasma".
(b) Chrysostomou et al. paper (in its freely readable part, at least) moves from "gases", "molecular clouds", "grains" and "material ... accelerated along magnetic field lines" to conclude that "...angular momentum will be carried away from the central accreting system (...) allowing low angular momentum material to be accreted onto the protostar".
(c) provided that Alfvén referred to a "...transfer [of] angular momentum between a rotating central body and a surrounding plasma", may the difference lay only in the fact that, in the nowadays paper, the word "plasma" is accurately avoided?

Wrt (b) allowing low angular momentum material to be accreted onto the protostar" do we need material to be accreted onto the protostar when MHD pump-collimation (Marklund convection) will do the job more consistently than some random collapse of a molecular cloud due to gravity.

A though it maybe outside the scope of the OP, but the UT story on Black Holes Linked to Cosmic Rays may also have a casual link?


Astronomers now know that cosmic rays don't come from all regions of the sky, but they're shot out from actively feeding supermassive black holes.

The exact process that creates the cosmic rays isn't fully understood, but astronomers think that the environment around an active supermassive black hole is ferocious, to say the least. Powerful magnetic fields are generated, which can act like natural particle accelerators, pushing protons to energy levels much higher than anything physicists could recreate with our technology.

These magnetic fields seem pretty prevalent through out this discussion, maybe there something in it?

And so far nothing is ATM, correct?

Neverfly
2007-Nov-11, 02:25 AM
http://www.bautforum.com/astronomy/66835-scientists-link-mysterious-highest-energy-cosmic-rays-violent-black-holes.html

ETA: currently two threads on that particular topic- One started by Fraser in UT.

Nereid
2007-Nov-11, 03:22 AM
Welcome to BAUT, Realitly! :)


Author:

Andrea Ciardi
(Observatoire de Paris)

Collimated, powerful jets are found in a large variety of astrophysical objects, ranging from those associated with proto-stars to galactic jets powered by black-holes. A frequent element found in many evolutionary jet models is the presence, at least in some regions, of a dominant toroidal field responsible for accelerating and confining the plasma to narrow channels which transport angular momentum and energy away from the source. In this context we present 3D MHD simulations of scaled laboratory experiments that not only reproduce the important physical processes thought to exist in the astrophysical systems but also provide new insights into the formation, evolution and stability of magnetically produced jets. The laboratory jets are produced using radial wire arrays driven by a 1 MA current pulse. The general outflow structure of a magnetic tower comprises an expanding magnetic cavity, largely collimated by the pressure of an extended plasma background medium, and a magnetically confined jet which forms within the magnetic cavity itself. A shell of swept-up shocked plasma surrounds the cavity. Although this structure is intrinsically transient and instabilities in the jet and disruption of the magnetic cavity ultimately lead to its break-up, a well collimated, radiatively cooled, ``clumpy'' jet still emerges from the system; notably such morphology is reminiscent of that observed in many astrophysical jets. We also investigate the effects on the laboratory jets of poloidal fields and rotation, which are thought to stabilize the jets observed in space. In collaboration with S. V. Lebedev, A. Frank, E. G. Blackman, D. J. Ampleford, C. A. Jennings, J. P. Chittenden, S. N. Bland, S. C. Bott, G. N. Hall, F. A. Suzuki Vidal, and A. Marocchino.
tp://meetings.aps.org/Meeting/DPP06/Event/52446

[snip]

Neried wrote:
So how to proceed?

Of course it is always possible to mine the two papers and come up with a list like Bancor's^ (or the much shorter one of VanderL: "There is a similarity in the (helical) shape of the magnetic fields in both models"), and to some extent such lists are to be expected!

But in terms of how contemporary astrophysics and space science are done (the avowed scope of BAUT), what more is there to say beyond noting that these are methods neither used nor part of such science (not least because they are so unreliable and subjective)?
antoniseb
Quote:
The transferred angular momentum is now found in the orbital moment of the secondary bodies. There is a rather obvious candidate for this process, viz. the auroral current system, which is known to transfer angular momentum between a rotating central body and a surrounding plasma.

Alfven is talking about transferring angular momentum to the planets, and the new paper is talking about transferring it out of the system via high speed jets.

So do these two pending papers have any bearing on this thread wrt angular momentum transferral Neried, Antinoseb?

[snip]Yes ... at least in the sense that one can - objectively, using ADS - trace the references relevant to YSO jets, polarisation, etc back to 1984 (and earlier), and determine - objectively - what the direct intellectual influence of Alfvén's 1984 paper was on these two 2006 APS meeting presentations.

For the first, my preliminary findings are as follows:

* the Ciardi et al. paper (2007) (http://adsabs.harvard.edu/abs/2007PhPl...14e6501C) has 54 references, of which the most pertinent would seem to be Shu et al (1994) (http://adsabs.harvard.edu/abs/1994ApJ...429..781S)^, which has been cited a massive 542 times!

* the Shu et al. paper has 92 references; of those with publication dates of 1984 or later, the most pertinent may be Edwards et al. (1993) (http://adsabs.harvard.edu/abs/1993AJ....106..372E)^^, which has been cited a mere 231 times

* no paper at all with Alfvén as an author seems to be referenced, let alone his 1984 paper (cited by Bancor); specifically, neither Ciardi et al. (2007), nor Shu et al. (1994), nor Edwards et al. (1993) reference any Alfvén paper.

So, in a very narrow sense (the chain of papers referenced by, and cited by, Ciardi et al. (2007)), it would seem that we can answer Bancor's question - interpreted narrowly - in the negative; Alfvén's 1984 paper had no apparent influence on the development of contemporary astrophysical models of YSOs, their accretion disks, associated bipolar jets, etc, etc, etc.

FWIW, "some random collapse of a molecular cloud due to gravity" seems to hint at a very persistent misconception, namely that modern astrophysics is concerned solely with gravitation (with a few atomic and nuclear transitions thrown in to add some colour perhaps). I would encourage you to spend some time researching the extent to which this persistent misconception has been addressed, in BAUT; the threads started by long-time BAUT member tusenfem (http://www.bautforum.com/search.php?searchid=954824) might be a good place to start such research.

^"Magnetocentrifugally driven flows from young stars and disks. 1: A generalized model"

^^"Angular momentum regulation in low-mass young stars surrounded by accretion disks"

Bancor
2007-Nov-11, 06:08 AM
Ah, Nereid, in your domain you're unbeatable indeed!

What might I reply, to such a perfect examination of methodology and philosophy of science?

Others will reply and object, in case, to your intransigent defense of the Established Order (and indeed, I see they do).

On my part let me say only that history of science is plenty of examples of similar situations, and so many are due to those human behaviours you justly blamed as unacceptable.
But so goes the world, and no wonder if this happens.

Si parva licet componere magnis, let's glance at Aristarchus of Samos and we may find the case of a precursor who had to wait more, much more, than a millennium before his intuition was renowned (whereas in his times he risked to be indicted for impiety).
Was his misfortune due to lack of math and technical, equation-filled details of his model? Maybe, nevertheless he was right and his opponents wrong.
Had the history of science, and mankind progress, moved faster if his intuition hadn't encountered, four centuries later, the giant Ptolemy?

As to your suggestion in post #30, be sure: I don't like conspiracy theories, and what I aimed to discuss is much more related to what I just said about Aristarchus.

Regards.

antoniseb
2007-Nov-11, 12:06 PM
Had the history of science, and mankind progress, moved faster if his intuition hadn't encountered, four centuries later, the giant Ptolemy?
Ptolemy (or more rightly Hipparcos) did something that Aristarchus did not, which is create tables that pretty accurately predicted the locations of the planets. He also recorded clearly how those tables were constructed. Aristarchus' intuition, however correct, did not seem to have been expressed numerically, and for many centuries was not useful in the advancement of science. When Kepler published the New Copernican Astronomy, it was really the first time it mattered what revolved around what. I don't think that Ptolemy slowed the advancement of astronomy. I think his work was critical to astronomical understanding not being forever lost in the dark ages.

Bancor
2007-Nov-11, 04:37 PM
Ptolemy (or more rightly Hipparcos) did something that Aristarchus did not, which is create tables that pretty accurately predicted the locations of the planets. He also recorded clearly how those tables were constructed. Aristarchus' intuition, however correct, did not seem to have been expressed numerically, and for many centuries was not useful in the advancement of science. When Kepler published the New Copernican Astronomy, it was really the first time it mattered what revolved around what. I don't think that Ptolemy slowed the advancement of astronomy. I think his work was critical to astronomical understanding not being forever lost in the dark ages.

I asked, you answered; many thanks, antoniseb!

I cannot but agree that Hipparchus created the bases on which Ptolemy constructed his geocentric system three centuries later, but may we ask ourselves what if his tables of the motions of Sun and Planets were applied to the former Aristarchus' intuition three centuries before Ptolemy's work?

Ptolemy stands, I said, as a giant in the history of astronomy, but are we sure that astronomical understanding hadn't gained from Aristarchus model anything more than the progress (progress?) it got from fifteen centuries of geocentrism?
And when Kepler published his New Copernican Astronomy, no doubt on his scientific greatness, but didn't he apply, after all, the nineteen-centuries-old Aristarchus' intuition?

Anyhow, the creed that only "numerically expressed" ideas are worth to be considered is, IMHO, the very drama of nowadays science; no doubt that math is important, even crucial, but it wouldn't obscurate the talent of (scientifical) intuition, especially in the cosmological domain.

Unfortunately it isn't so, now, and to confront the strength of this conviction is an uneven struggle indeed.
Contro la forza, la ragion non vale (might be translated: might is right) is an old Italian saying, forever true as all sayings in all languages.

Kind salutations.

antoniseb
2007-Nov-11, 07:09 PM
...when Kepler published his New Copernican Astronomy, no doubt on his scientific greatness, but didn't he apply, after all, the nineteen-centuries-old Aristarchus' intuition? ...

I don't really think so. Copernicus still used epicycles to explain the non-circular movements. Kepler's advance was to finally find an explanation that didn't require the epicycles (which in my understanding existed because the geometry of circles was MUCH easier to compute than any alternative, and not because Copernicus believed they were physical). Kepler may have been aware of Aristarchus, but he was also aware of Nicolas of Cusa, Nicole Oresme, and Johannes Scotus, and others known for expressing non-geocentric views. The thing that made Kepler's work stick was that it was useful in better predicting the location of Mars in the sky than any previous model. If he owes something substantial intellectually, it is to Tycho Brahe for his careful measurements, and to mathematicians who had recently developed easier ways to use logarithms to compute tedious complex math functions. The Sun being at the center was a necessity.

Bancor
2007-Nov-11, 11:05 PM
I don't really think so. Copernicus still used epicycles to explain the non-circular movements. Kepler's advance was to finally find an explanation that didn't require the epicycles (which in my understanding existed because the geometry of circles was MUCH easier to compute than any alternative, and not because Copernicus believed they were physical). Kepler may have been aware of Aristarchus, but he was also aware of Nicolas of Cusa, Nicole Oresme, and Johannes Scotus, and others known for expressing non-geocentric views. The thing that made Kepler's work stick was that it was useful in better predicting the location of Mars in the sky than any previous model. If he owes something substantial intellectually, it is to Tycho Brahe for his careful measurements, and to mathematicians who had recently developed easier ways to use logarithms to compute tedious complex math functions. The Sun being at the center was a necessity.

I have no reason to object to your learned historyc dissertation: your knowledge is here so far greater than mine.

Hence, I should conclude that Aristarchus was nothing more than a visionary, who didn't contribute anything useful to science and astronomy, since he didn't use math (or, at least, he didn't take the trouble to make measurements: in his times, Greece was plenty of astronomical instruments, in fact); and, when these measurements were done (one century later), had to pass three more centuries before than someone other interpreted them in accordance with the then conventional wisdom, in so carving a niche for himself in the history of science cathedral; this one was wrong but it doesn't matter: the intuition of the precursor had to be forgotten, and now I know that it has to be dismissed even if it's so clear that he was right and some other was wrong.
A sort of soft damnatio memorić.

It's good to know how stuff works in science, however.
Let's keep on this way...

antoniseb
2007-Nov-11, 11:13 PM
...Aristarchus was nothing more than a visionary, who didn't contribute anything useful to science and astronomy, since he didn't use math (or, at least, he didn't take the trouble to make measurements: in his times, Greece was plenty of astronomical instruments, in fact)...

We know of Aristarchus from mention of him in Plato, and not from any writings of his own. I think that the reason that Hipparchos was much more influential was that he produced a tangible and useful result (the ability to accurately predict the positions of planets and the Sun).

BTW, there were plenty of accurate instruments from the time of Aristarchus, which we know about from their use in surveying. Recall that Aristarchus was more than a century after Pythagorus.

Nereid
2007-Nov-12, 01:08 AM
Ah, Nereid, in your domain you're unbeatable indeed!

What might I reply, to such a perfect examination of methodology and philosophy of science?

Others will reply and object, in case, to your intransigent defense of the Established Order (and indeed, I see they do).
You've lost me I'm afraid Bancor; what I have written is not intended, primarily, as "defense of the Established Order", but simply as an answer (or set of answers) to your questions (and, tangentially, assertions by other BAUT members) ... within the explicitly stated framework and scope of BAUT's Q&A section.

If you - and other BAUT members reading along - feel that your questions have been so answered, good; if not, then by all means ask further!

On my part let me say only that history of science is plenty of examples of similar situations, and so many are due to those human behaviours you justly blamed as unacceptable.
But so goes the world, and no wonder if this happens.
Perhaps, in some ways, 'twas ever thus.

But surely in a great many ways things are very different these last decade or three?

I mean, already in English you can get a Master in Astronomy degree, over the internet (http://www.bautforum.com/off-topic-babbling/66831-toseek-bad-master.html); perhaps within a few years you can get one in Chinese, French, Spanish and even Arabic too?

In times of yore, access to raw astronomical data, other than that which you took yourself, was difficult if not downright impossible; yet today almost all the high quality modern observations are available over the internet (albeit often after a proprietary period of a year or so), and vast amounts of historical data too (or will be soon: for example DASCH is “Digital Access to a Sky Century at Harvard”, the effort to digitize approximately 500,000 astronomical plates in the Harvard College Observatory collection (http://www.aavso.org/aavso/meetings/fall07present/los.pdf)). Not only does your humble PC have the computing power to do in a second or less what would have taken astronomers a century ago a lifetime to do, but the techniques to do analyses can also be learned over the interet, and if your needs require the computing power of some significant fraction of the world's PCs, then that too is available (http://boinc.berkeley.edu/).

In such a world, your friend can easily research those ATM ideas to almost any depth she chooses, at a marginal cost of nothing more than time and (perhaps) a few euros for the extra electricity.

(I think I'll stop here).

Si parva licet componere magnis, let's glance at Aristarchus of Samos and we may find the case of a precursor who had to wait more, much more, than a millennium before his intuition was renowned (whereas in his times he risked to be indicted for impiety).
Was his misfortune due to lack of math and technical, equation-filled details of his model? Maybe, nevertheless he was right and his opponents wrong.
Had the history of science, and mankind progress, moved faster if his intuition hadn't encountered, four centuries later, the giant Ptolemy?

As to your suggestion in post #30, be sure: I don't like conspiracy theories, and what I aimed to discuss is much more related to what I just said about Aristarchus.

Regards.
If I may roll in a response to your later post as well here:
I asked, you answered; many thanks, antoniseb!

I cannot but agree that Hipparchus created the bases on which Ptolemy constructed his geocentric system three centuries later, but may we ask ourselves what if his tables of the motions of Sun and Planets were applied to the former Aristarchus' intuition three centuries before Ptolemy's work?

Ptolemy stands, I said, as a giant in the history of astronomy, but are we sure that astronomical understanding hadn't gained from Aristarchus model anything more than the progress (progress?) it got from fifteen centuries of geocentrism?
And when Kepler published his New Copernican Astronomy, no doubt on his scientific greatness, but didn't he apply, after all, the nineteen-centuries-old Aristarchus' intuition?

Anyhow, the creed that only "numerically expressed" ideas are worth to be considered is, IMHO, the very drama of nowadays science; no doubt that math is important, even crucial, but it wouldn't obscurate the talent of (scientifical) intuition, especially in the cosmological domain.

Unfortunately it isn't so, now, and to confront the strength of this conviction is an uneven struggle indeed.
Contro la forza, la ragion non vale (might be translated: might is right) is an old Italian saying, forever true as all sayings in all languages.

Kind salutations.
First, without the (subsequent) ""numerically expressed" ideas" (and the numerical testing of them), how would anyone ever know how good Aristarchus' intuition was?

Second, how many dozen, hundred, thousand or even million intuitions, by (ancient) intellectual giants in (today's) Central and South America, China, India, Iran, even Australia do we no longer even mention in our astronomy textbooks? Or, to say the same thing in another way, isn't a high regard for "Aristarchus' intuition" simply a crass example of confirmation bias?

Third, if you read books by those who've done their share of contributing mightily to astronomy, physics, and cosmology, I think you'll find that 'intuition' is very much alive and well, and playing a key role in discovery. However, I think you'll also find that it's very much a two-way street wrt math etc; for example, without a great deal of math under one's belt, the flow of insightful intuitions is very poor indeed.

I have the impression that there's a much deeper question hovering in the background, having to do with disquiet over the role of quantitative methods in modern cosmology ...

Nereid
2007-Nov-12, 01:21 AM
That may be so.

However, I very much doubt that the jet mechanism(s) in the Chrysostomou et al paper paper have anything to do with the Peratt ones*.

But, I could be quite wrong; can you show that these two are related, iantresman? I mean other than that there are magnetic fields involved in both ...There is a similarity in the (helical) shape of the magnetic fields in both models. Of course there are also differences, Chrysostomou's model has mechanical twisting of the magnetic field to account for the helicity, Alfvén's model relies on Birkeland currents. Maybe that's why Alfvén isn't referenced, or maybe Chrysostomou isn't familiar with Alfvén's work or simply doesn't want to acknowledge it for whatever reasons.

*which, incidentally, rather badly fail to account for the wealth of detailed observational results published after 1986;
You rather badly fail to convince me that indeed Peratt's paper "rather badly fails to account for the wealth of detailed observational results published after 1986".

IOW, the Peratt jet mechanism seems to be inconsistent with good (astronomical) observational results, at least for quasars etc.
Seems? I don't see how you can say this, because all astrophysical jets are shaped by magnetic fields and the latest data show many (if not all) of them to have this helical structure. There is nothing inconsistent that I can see.

This illustrates rather nicely the point I made elsewhere: one reason why you don't see many references to Alfvén or Peratt papers on specifics is that there's apparently no observational basis for them in the enormous wealth of high quality results obtained in the last decade or so.
Indeed you don't see many references to Alfvén or Peratt, but your inference that this is because there's "apparently no observational basis for them" is simply your interpretation, it could just as well mean the authors are not familiar with their work.

Cheers.If you'd like to start a new Q&A thread, specifically on the Peratt jet ('beam') paper which iantresman cited, please do so.

If you do, I would be glad to present an investigation of the modern astrophysics papers on mechanisms relevant to the astronomical jets within the scope of that Peratt paper, similar to the one I presented in response to Realitly's post, and incorporating elements from my responses to Bancor's excellent posts.

Bancor
2007-Nov-12, 06:14 AM
We know of Aristarchus from mention of him in Plato, and not from any writings of his own. I think that the reason that Hipparchos was much more influential was that he produced a tangible and useful result (the ability to accurately predict the positions of planets and the Sun).

BTW, there were plenty of accurate instruments from the time of Aristarchus, which we know about from their use in surveying. Recall that Aristarchus was more than a century after Pythagorus.

I knew it slightly different:
- it was Archimedes (contemporary of Aristarchus) to give us an excerpt of his writing, and more later Plutarchus to refer of his eliocentric theory;
- we do have one writing by Aristarchus, which survived to our time, and it's that where he explains his method for the calculation of the distance of the Sun: right method and wrong result, owing to the difficulties of measurement (recall that Aristarchus was more than a century before Hypparchus);
- Aristarchus is currently named, in many astronomy commentaries, as a "Copernicus precursor". Maybe it's not the case on this board; I cannot understand why, but I content myself to have known of this.

Let's keep on this way...

Bancor
2007-Nov-12, 06:29 AM
Well, Nereid,
your arguments are all sound and rational, how could I oppose them without being (and not only being considered) "out of reality"?

You moved correctly within the forum rules, of course; it was only my (partisan) interpretation to imagine that you played the part of the "orthodoxy defender".

But let me say that this discussion about the Aristarchus role as eliocentric theory precursor, and the attermpts to deny and dismiss this role, seems a bit surreal and pretty biased.

But I don't want to criticize anyone: omnia munda mundis, to insist with latin wisdom.

Greetings.

VanderL
2007-Nov-12, 02:28 PM
If you'd like to start a new Q&A thread, specifically on the Peratt jet ('beam') paper which iantresman cited, please do so.

If you do, I would be glad to present an investigation of the modern astrophysics papers on mechanisms relevant to the astronomical jets within the scope of that Peratt paper, similar to the one I presented in response to Realitly's post, and incorporating elements from my responses to Bancor's excellent posts.

Why not in this thread, I think looking at the alternative/earlier model mentioned by Bancor is also part of the question. In the OP Bancor actually asked 2 questions:

1. Why isn't Alfvén, or his model referenced.
2. What are the differences (if any) between Alfvén's and the new model.

Question 1 cannot really be answered conclusively, although some good reasons have been mentioned. What I see in your citation analysis is that both Alfvén and Peratt are not referenced in this research area. And in the citation study I did (finding citations in ADS is easy), both authors are hardly referenced at all. Maybe not significant, but in the Chrysostomou paper, more than a third of the references are from their own group.

Question 2 is of course the crux of the matter, this question is what prompted me (and possibly Ian Tresman too), to try and argue that indeed the models do have similarities. Maybe not enough to be referenced, but the helical structures in Herbig-Haro jets have been studied by many other people, including some that do reference Peratt and Alfvén (P. Carlqvist et al. for example). I think it is obvious that the 2 models are different, one is trying to reconcile the magnetic field structure with an energy source that depends on gravity. The other is trying to show that the structure is a diagnostic of large scale electric currents. The interesting part is that these jet structures need magnetic fields and in that respect both models agree.

The additional point I was trying to make to you Nereid, is that you indicated that one of the reasons Alfvén (or Peratt) was never referenced by the authors of the new model is that Alfvén's model is inconsistent with observations made after Alfvén published his model. I'm merely opposing this claim; unless you show exactly what is inconsistent (or provide references to papers that specifically address this point) you shouldn't make such statements.

Cheers.

Nereid
2007-Nov-12, 02:40 PM
Well, Nereid,
your arguments are all sound and rational, how could I oppose them without being (and not only being considered) "out of reality"?

You moved correctly within the forum rules, of course; it was only my (partisan) interpretation to imagine that you played the part of the "orthodoxy defender".

But let me say that this discussion about the Aristarchus role as eliocentric theory precursor, and the attermpts to deny and dismiss this role, seems a bit surreal and pretty biased.

But I don't want to criticize anyone: omnia munda mundis, to insist with latin wisdom.

Greetings.Hi Bancor,

Perhaps what I have written, re Aristarchus' role, isn't as clear as it should be; let me try again.

It seems the path from Aristarchus' intuition to today's (or the Renaissance's) cosmology is pretty unambiguous, in terms of the history of ideas. And in terms of the origins of today's (or the Renaissance's) cosmology, as ideas, it is also pretty unambiguous that the contributions of (ancient) intellectual giants in (today's) Central and South America, China, India, Iran, even Australia are minimal or marginal (at best).

However, that isn't the point I was trying to make.

At the risk of a second failure, I'd like to use an analogy ... this time one from the bush of life*.

Think of Aristarchus' intuition as a 'cosmology meme' (a meme can be thought of as the cultural information counterpart of a gene). That particular meme has survived; thousands, possibly millions, of others haven't. Further, some, possibly many, of the ones which didn't survive may have been very similar to Aristarchus' intuition. For all we know, some genius who lived, 20,000 years ago, in what today we call the Araluen Valley (in NSW in Australia), had an intuition with much the same central idea as Aristarchus' intuition ... but that meme didn't even survive the author's death, much less get written down in a language many today can still read. The equivalent of paleontology for memes is quite rudimentary, and relies heavily on written records, especially for memes a thousand or more years old

Where it starts to get interesting, from the perspective of the history and philosophy of science, is the extent to which Aristarchus supported his intuition with observational evidence, the extent to which he considered possible tests of the intuition, and so on. And that, of course, somewhat lowers the height of the pedestal on which Aristarchus' intuition - as intuition alone - seems to have been placed.

ETA: I note that you yourself have already written that Aristarchus seems to have done considerably more than have had a mere intuition (my bold): "we do have one writing by Aristarchus, which survived to our time, and it's that where he explains his method for the calculation of the distance of the Sun: right method and wrong result, owing to the difficulties of measurement (recall that Aristarchus was more than a century before Hypparchus)"

* To paraphrase Stephen Jay Gould (http://brembs.net/gould.html).

Nereid
2007-Nov-12, 05:19 PM
If you'd like to start a new Q&A thread, specifically on the Peratt jet ('beam') paper which iantresman cited, please do so.

If you do, I would be glad to present an investigation of the modern astrophysics papers on mechanisms relevant to the astronomical jets within the scope of that Peratt paper, similar to the one I presented in response to Realitly's post, and incorporating elements from my responses to Bancor's excellent posts.Why not in this thread, I think looking at the alternative/earlier model mentioned by Bancor is also part of the question. In the OP Bancor actually asked 2 questions:

1. Why isn't Alfvén, or his model referenced.
2. What are the differences (if any) between Alfvén's and the new model.

Question 1 cannot really be answered conclusively, although some good reasons have been mentioned. What I see in your citation analysis is that both Alfvén and Peratt are not referenced in this research area. And in the citation study I did (finding citations in ADS is easy), both authors are hardly referenced at all. Maybe not significant, but in the Chrysostomou paper, more than a third of the references are from their own group.
It's actually relatively straight-forward to see why 'the Chrysostomou paper', and the prior chain of citations, does not include Alfvén's 1984 (or the model presented therein): the two models are quite different.

Question 2 is of course the crux of the matter, this question is what prompted me (and possibly Ian Tresman too), to try and argue that indeed the models do have similarities. Maybe not enough to be referenced, but the helical structures in Herbig-Haro jets have been studied by many other people, including some that do reference Peratt and Alfvén (P. Carlqvist et al. for example). I think it is obvious that the 2 models are different, one is trying to reconcile the magnetic field structure with an energy source that depends on gravity. The other is trying to show that the structure is a diagnostic of large scale electric currents. The interesting part is that these jet structures need magnetic fields and in that respect both models agree.(my bold)

If that's so, then it's a very good reason why the Chrysostomou paper, and its chain of references, does not include such Peratt or Alfvén papers!

It would also explain the curious fact that, apparently, such Peratt or Alfvén papers do not include any of the older (than 1984, or 1986, say) references found in the Chrysostomou paper, and its chain of references - there is a deep intellectual divide.

If so, then I must thank you for pointing this out; it will allow me - and other BAUT readers - to more comprehensively and robustly address questions about Alfvén's contributions to modern astronomy and cosmology.

The additional point I was trying to make to you Nereid, is that you indicated that one of the reasons Alfvén (or Peratt) was never referenced by the authors of the new model is that Alfvén's model is inconsistent with observations made after Alfvén published his model. I'm merely opposing this claim; unless you show exactly what is inconsistent (or provide references to papers that specifically address this point) you shouldn't make such statements.

Cheers.Good point.

I'll address this in more detail later, but I want to note that the footnote* in my earlier post on this is, indeed, poorly worded.

*Here it is again; note that it refers to the (extra-galactic) jet ('beams' in iantresman's post) mechanisms presented in a 1986 paper by Peratt: "which, incidentally, rather badly fail to account for the wealth of detailed observational results published after 1986; IOW, the Peratt jet mechanism seems to be inconsistent with good (astronomical) observational results, at least for quasars etc. This illustrates rather nicely the point I made elsewhere: one reason why you don't see many references to Alfvén or Peratt papers on specifics is that there's apparently no observational basis for them in the enormous wealth of high quality results obtained in the last decade or so."

Bancor
2007-Nov-12, 05:30 PM
Dear Nereid,
it seems that we are bound to not understand each other, even in questions that, let's say in confidence, wouldn't be worth spending more than a word.

Anyway, could you please explain me the reason why, while many, and many, and many more astronomy and history textbooks depict Aristarchus as a precursor (better, the first precursor) of eliocentrism, you and your esteemed colleague antoniseb are grasping at straws in the aim to denegate the evidence?

Is it a personal point of honour? Well, I resign myself willingly.
Is it an issue that I unwisely linked to an unseemly name? Well, it isn't my problem and I cannot do anything to solve it: I only asked a question.

Your reconstruction of the case via the sumptuous analogy "from the bush of life" (BTW, I didn't know Gould, but I'll read his article with much interest) is quite fascinating; I seem it might be discussed, however, on the basis that Aristarchus historic condition (i.e. notoriety of his works and scientific activity) was, and stays, much different from your hypothetical prehistoric man of the Araluen Valley, who has nothing to share with the real question we are debating.

And this appears, to me at least, even more true when I read your post scriptum, where you acknowledge this evident difference by saying

I note that you yourself have already written that Aristarchus seems to have done considerably more than have had a mere intuition (my bold): "we do have one writing by Aristarchus, which survived to our time, and it's that where he explains his method for the calculation of the distance of the Sun: right method and wrong result, owing to the difficulties of measurement (recall that Aristarchus was more than a century before Hypparchus)"
In fact, as you wrote immediately beforehand that

Where it starts to get interesting, from the perspective of the history and philosophy of science, is the extent to which Aristarchus supported his intuition with observational evidence, the extent to which he considered possible tests of the intuition, and so on. And that, of course, somewhat lowers the height of the pedestal on which Aristarchus' intuition - as intuition alone - seems to have been placed.
it's hard indeed to reconcile all this with your steady dismissal of the role Aristarchus played in eliocentrism pioneering.
It's not a question of pedestals, and if you didn't know (but I don't think so), now you know that it wasn't only an intuition, child of a survived "cosmogical meme" flying from Araluen Valley.

Greetings.

antoniseb
2007-Nov-12, 05:40 PM
Anyway, could you please explain me the reason why, while many, and many, and many more astronomy and history textbooks depict Aristarchus as a precursor (better, the first precursor) of eliocentrism, you and your esteemed colleague antoniseb are grasping at straws in the aim to denegate the evidence?

You started this off talking about how Aristarchus' work was crushed by mainstream scientists (Ptolemy 400 years later), and suggested that if so much effort hadn't gone into Ptolemy's work, that the science of astronomy might have advanced faster. Our point is not that Aristarchus was nothing, but rather that his work did little to advance astronomy. How many times does Copernicus reference Aristarchus in De Revolutionibus? or Kepler reference him in the New Copernican Astronomy? It strikes me that you are the one grasping at straws.

Bancor
2007-Nov-12, 09:27 PM
You started this off talking about how Aristarchus' work was crushed by mainstream scientists (Ptolemy 400 years later), and suggested that if so much effort hadn't gone into Ptolemy's work, that the science of astronomy might have advanced faster. Our point is not that Aristarchus was nothing, but rather that his work did little to advance astronomy. How many times does Copernicus reference Aristarchus in De Revolutionibus? or Kepler reference him in the New Copernican Astronomy? It strikes me that you are the one grasping at straws.

May I suggest we all re-read our posts? It would be useful to better understand our reciprocal statements.

Be as it be, I note that the answer ever stands the same: math and references; references and math.
No other: the merit of the question is worth nothing. And it's me that grasps at straws, indeed.

I surrender.
Regards.

Gillianren
2007-Nov-13, 12:27 AM
I, for one, am lousy at math. However, I still know that, without it, you don't really have science. Even if all you have is measurements, those measurements are part of math. If you don't have it, your idea can't really be used for anything.

Bancor
2007-Nov-13, 05:57 AM
I, for one, am lousy at math. However, I still know that, without it, you don't really have science. Even if all you have is measurements, those measurements are part of math. If you don't have it, your idea can't really be used for anything.

I never denegated the importance of mathematics in science, and I confirmed my point of view on this in post #36.

And, from the only writing attributed to Aristarchus survived to our times, we know that he indeed applied math (of his time) to astronomy (better, to cosmogony, as he determined the distance of the Sun).
We don't know, because his work didn't survive the centuries, if and how he applied math to derive eliocentric theory (from his original intuition, as we don't know of anyone who did this before), but, provided what we know for sure about his works, you may agree that it seems a lot difficult that he hadn't based and supported with (his time) math this intuition.

And when I'm told that Aristarchus eliocentrism did little or nothing to advance astronomy, basing on the fact that neither Copernicus nor Kepler (nineteen centuries later, let's remember this) did reference him in their so important works, I have to grasp at straws indeed, not to precipitate in the logical abyss open by this preposterous statement.
As, if Aristarchus eliocentric theory stayed buried for fifteen centuries under the heavy sands of (religious) geocentric desert, how can we pretend that it could contribute to science progress in astronomy? And, even if it were known by our Renaissance eliocentric heroes, do you really think that they had cited it, "heretical" and damned as it was for centuries and centuries, adding fuel to the great fire they had lit?
Let's remember that the stake was well in fashion, at that times.

Anyway, my question was different: I asked how could have been bettered the evolution of astronomy if Aristarchus theory weren't buried under Ptolemy geocentric system, whose authority served so well the then raising religious system.
And in my turn I might respond asking how much work did geocentrism, during its fifteen-century-old domination, to advance astronomy.

But I'm abundantly OT, so I stop here.

Gillianren
2007-Nov-13, 08:12 AM
I realize English is not your first language, but the word you're looking for is "heliocentric."

As has been said before, a lot of determining who matters in the history of a scientific idea is who is influenced by it. We can acknowledge--we do acknowledge--those who we know had correct ideas that were ignored for hundreds of years. (Gregor Mendel's paper on genes, as a side note, sat unread on Darwin's desk, holding back the progress of biology by decades, since no one else really read it, either.) However, certain people are not truly part of the genealogy, if you will, of science, simply because their ideas were discovered or rediscovered too late.

Bancor
2007-Nov-13, 06:49 PM
I realize English is not your first language, but the word you're looking for is "heliocentric."
You're right, I stand corrected. And this was a simple orthography error, so I wonder how many syntax and grammar errors had you all to bear on reading my posts! Thanks once more for your patience.


As has been said before, a lot of determining who matters in the history of a scientific idea is who is influenced by it. We can acknowledge--we do acknowledge--those who we know had correct ideas that were ignored for hundreds of years. (Gregor Mendel's paper on genes, as a side note, sat unread on Darwin's desk, holding back the progress of biology by decades, since no one else really read it, either.) However, certain people are not truly part of the genealogy, if you will, of science, simply because their ideas were discovered or rediscovered too late.
On these bases, I totally agree with you.
In fact - if we would read more attentively the thread - this was the subtle understatement of the discussion: that one may have had a good scientific intuition in the past, he may have developed it by means of theoretical and mathematical studies, he may have even published it, and nevertheless his work sat unread (or it got dismissed) on someone other's desk for a (too) long time.

No question, no scandal: so goes the world, as I just said beforehand.
Nonetheless, to remember the lesson learned by history may help.

Thanks again and best regards.

Nereid
2007-Nov-18, 01:13 AM
[snip]
The additional point I was trying to make to you Nereid, is that you indicated that one of the reasons Alfvén (or Peratt) was never referenced by the authors of the new model is that Alfvén's model is inconsistent with observations made after Alfvén published his model. I'm merely opposing this claim; unless you show exactly what is inconsistent (or provide references to papers that specifically address this point) you shouldn't make such statements.

Cheers.
Good point.

I'll address this in more detail later, but I want to note that the footnote* in my earlier post on this is, indeed, poorly worded.

*Here it is again; note that it refers to the (extra-galactic) jet ('beams' in iantresman's post) mechanisms presented in a 1986 paper by Peratt: "which, incidentally, rather badly fail to account for the wealth of detailed observational results published after 1986; IOW, the Peratt jet mechanism seems to be inconsistent with good (astronomical) observational results, at least for quasars etc. This illustrates rather nicely the point I made elsewhere: one reason why you don't see many references to Alfvén or Peratt papers on specifics is that there's apparently no observational basis for them in the enormous wealth of high quality results obtained in the last decade or so."I've run out of time, but here's where I got up to:

* only Peratt cited the 1986 paper iantresman mentioned, and even he did not add much in terms of claims of the match between his model and observations; the last paper with anything substantive seems to have been over a decade ago

* no one else seems to have published a paper using Peratt's model of extra-galactic jets

* Peratt has published many papers, on topics other than his model of extra-galactic jets, since 1986 (and indeed since 1997).

Perhaps I missed some key (recent) papers, on the match between Peratt's model of extra-galactic jets and astronomical observations?

iantresman
2007-Nov-18, 01:09 PM
* only Peratt cited the 1986 paper iantresman mentioned, and even he did not add much in terms of claims of the match between his model and observations; the last paper with anything substantive seems to have been over a decade ago

* no one else seems to have published a paper using Peratt's model of extra-galactic jets
If you're referring to Peratt's paper I mentioned in this post (http://www.bautforum.com/questions-answers/66583-new-spin-how-stars-born.html#post1108854), then the ADS database shows citations (http://adsabs.harvard.edu/cgi-bin/nph-ref_query?bibcode=1986ITPS...14..639P&amp;refs=CITATIO NS&amp;db_key=AST) not only from Peratt himself, but also from W. H. Bostick, Eric J. Lerner, Daniel R. Wells et al, N. A. Salingaros, Torsten Neubert et al, O. Buneman et al, Per Carlqvist et al, Nikos A. Salingaros, Boris A. Trubnikov, Cynthia Kolb Whitney, and D. D Ryutov (to name but ten).

The idea that extragalactic jets can be modelled as plasma beams, is not Peratt's alone. See for example:

Borovsky, J. E., "Double layers and plasma-wave resistivity in extragalactic jets - Cavity formation and radio-wave emission (http://adsabs.harvard.edu/abs/1987LPB.....5..169B)" (NASA, Conference on Double Layers in Plasmas, Huntsville, AL, Mar. 1986) Laser and Particle Beams (ISSN 0263-0346), vol. 5, May 1987, pt. 2, p. 169-175. NASA Record (http://ntrs.nasa.gov/search.jsp?R=553678&id=5&qs=Ntt%3DDouble%252BLayers%252Bin%252BPlasmas%26Nt k%3Dall%26Ntx%3Dmode%2520matchall%26N%3D0%26Ns%3DH arvestDate%257c1) | Full text (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19870013880_1987013880.pdf) PDF (p.307)

Peratt has published other papers on the same subject which have also been cited by others. For example:

"The role of particle beams and electrical currents in the plasma universe (http://adsabs.harvard.edu/abs/1988LPB.....6..471P)" (1986) Laser and Particle Beams (ISSN 0263-0346), vol. 6, Aug. 1988, p. 471-491. (Full text (http://plasmascience.net/tpu/downloads/Peratt_RolePartBeams.pdf), PDF)