by Higgsy » Fri Mar 13, 2020 1:10 am
BeAChooser wrote: ↑Thu Mar 12, 2020 11:17 pm
Higgsy wrote: ↑Wed Mar 11, 2020 12:57 am
I have told you many times that I accept the existence of Birkeland currents, and braided filaments in the cosmic context, but that I do not do physics by looking at pretty pictures and making up stories.
First, what you actually, initially did was deny there were helically wound filaments in the photos I posted to you. Like this one
https://upload.wikimedia.org/wikipedia/ ... Nebula.jpg . You made comments like this: "You showed me images that
you interpreted as helically wound filaments." I read that to say you did not accept there were braided filaments in that image ... when they are clear as day. In fact, I then pointed out to you that the web page that image came from (
https://en.wikipedia.org/wiki/Veil_Nebula ) states: “When finely resolved, some parts of the image appear to be rope-like filaments.” Like I said back then, so not only does it mention “filaments” but calls them “rope-like”, which brings to mind the helically wound construction of an ordinary rope. You must have also missed the statement that another name for part of the Veil Nebula is the “Filamentary Nebula”. However, here you are now trying to pretend that wasn't ever your position ... so I guess we're making *some* progress.
...
Higgsy wrote: ↑Wed Mar 11, 2020 12:57 am
Several of the pretty pictures you presented have nothing to do with braided filaments produced by Birkeland currents. I explained why I thought that.
About that. You, for example, claimed that the Veil Nebula image above was from a Wikipedia page that “recites the standard explanation which is that they are not helically wound filaments (or filaments at all)”. But as I noted in my response to you, the page DOES NOT say that ... it says they are filaments and "rope-like" ... which is just another way of saying helically wound. So you were either illiterate or being dishonest in you're handwaving. As I think your current response here proves you continue to be, Higgsy.
I am going to address this question of the Veil Nebula because you have been misrepresenting my position on this egregiously and then I'm done with you. The Veil Nebula does not display braided filaments. Read my lips: the Veil Nebula
does not display braided filaments. The structures which you interpret as braided filaments are shock fronts in the expanding envelope of the supernova seen edge on. This is a perfect example of the problems with looking at pretty pictures and making up stories about them.
Then you claim that the Wikipedia page "says they are filaments and "rope-like" ... which is just another way of saying helically wound". But what does the Wikipedia page actually say?
Wikipedia wrote:When finely resolved, some parts of the nebula appear to be rope-like filaments. The standard explanation is that the shock waves are so thin, less than one part in 50,000 of the radius,[15] that the shell is visible only when viewed exactly edge-on, giving the shell the appearance of a filament. At the estimated distance of 2400 light-years, the nebula has a radius of 65 light-years (a diameter of 130 light-years). The thickness of each filament is 1/50,000th of the radius, or about 4 billion miles, roughly the distance from Earth to Pluto. Undulations in the surface of the shell lead to multiple filamentary images, which appear to be intertwined.
My emphasis.
For someone with reasonable reading comprehension, this means that although the edge of the shell
appears to be made up of rope-like filaments, it is in fact the edge of the undulating near-spherical shock-wave shell seen edge-on. I agree with that explanation because of the details of physics in supernova remnants. And you have the gall to accuse me of illiteracy and dishonesty, when it is you who have misrepresented or misunderstood the Wikipedia article.
Go here for a more detailed explanation:
https://www.spacetelescope.org/news/heic1520/
The same sort of misrepresentation is evident in the rest of your long post, (eg Andre explains in some physical and mathematical detail that the structures in his paper are produced by self-gravitation and the turbulent cascade).
Andre wrote:
"Since the mid 1990s, simulations of supersonic turbulence have consistently shown that gas is rapidly compressed into a hierarchy of sheets and filaments (e.g., Porteret al.,1994; V ́azquez-Semadeni,1994; Padoan et al.,2001).
Furthermore, when gravity is added into turbulence simulations, the denser gas undergoes gravitational collapse to form stars (e.g. Ostriker et al.,1999; Ballesteros-Paredeset al.,1999; Klessen and Burkert,2000;Bonnell et al.,2003;MacLow and Klessen,2004; Tilley and Pudritz,2004; Krumholz et al.,2007). There are many sources of supersonic turbulent motions in the ISM out of which molecular clouds can arise, i.e., galactic spiral shocks in which most giant molecular clouds form, supernovae, stellar winds from massive stars, expanding HII regions, radiation pressure, cosmic ray streaming, Kelvin-Helmholtz and Rayleigh-Taylor instabilities, gravitational instabilities, and bipolar outflows from regions of star formation (Elmegreen and Scalo,2004)...Simulations of turbulence often employ a spectrum of plane waves that are random in direction and phase. As is well known, the crossing of two planar shock wave fronts is a line - the filament (e.g.,Pudritz and Kevlahan,
2013)...Li et al. (2010) have shown that filaments are formed preferentially perpendicular to the
magnetic field lines in strongly magnetized turbulent clouds"
That was a present I gave you last time with lots of references for you to follow up to learn the relevant science. Have you? Apparently not. Who's stuck now asking me about the same pictures over and over again when I have already given you my explanation?
But I am done now.
[quote=BeAChooser post_id=1409 time=1584055078 user_id=29858]
[quote=Higgsy post_id=1351 time=1583888269 user_id=30122]
I have told you many times that I accept the existence of Birkeland currents, and braided filaments in the cosmic context, but that I do not do physics by looking at pretty pictures and making up stories.
[/quote]
First, what you actually, initially did was deny there were helically wound filaments in the photos I posted to you. Like this one [url]https://upload.wikimedia.org/wikipedia/commons/1/1d/Revisiting_the_Veil_Nebula.jpg[/url] . You made comments like this: "You showed me images that [i]you[/i] interpreted as helically wound filaments." I read that to say you did not accept there were braided filaments in that image ... when they are clear as day. In fact, I then pointed out to you that the web page that image came from ( https://en.wikipedia.org/wiki/Veil_Nebula ) states: “When finely resolved, some parts of the image appear to be rope-like filaments.” Like I said back then, so not only does it mention “filaments” but calls them “rope-like”, which brings to mind the helically wound construction of an ordinary rope. You must have also missed the statement that another name for part of the Veil Nebula is the “Filamentary Nebula”. However, here you are now trying to pretend that wasn't ever your position ... so I guess we're making *some* progress.
...
[quote=Higgsy post_id=1351 time=1583888269 user_id=30122]
Several of the pretty pictures you presented have nothing to do with braided filaments produced by Birkeland currents. I explained why I thought that.
[/quote]
About that. You, for example, claimed that the Veil Nebula image above was from a Wikipedia page that “recites the standard explanation which is that they are not helically wound filaments (or filaments at all)”. But as I noted in my response to you, the page DOES NOT say that ... it says they are filaments and "rope-like" ... which is just another way of saying helically wound. So you were either illiterate or being dishonest in you're handwaving. As I think your current response here proves you continue to be, Higgsy.[/quote]
I am going to address this question of the Veil Nebula because you have been misrepresenting my position on this egregiously and then I'm done with you. The Veil Nebula does not display braided filaments. Read my lips: the Veil Nebula[b] does not display[/b] braided filaments. The structures which you interpret as braided filaments are shock fronts in the expanding envelope of the supernova seen edge on. This is a perfect example of the problems with looking at pretty pictures and making up stories about them.
Then you claim that the Wikipedia page "says they are filaments and "rope-like" ... which is just another way of saying helically wound". But what does the Wikipedia page actually say?
[quote=Wikipedia]When finely resolved, some parts of the nebula [b][i]appear [/i][/b]to be rope-like filaments. The standard explanation is that the shock waves are so thin, less than one part in 50,000 of the radius,[15] that the shell is visible only when viewed exactly edge-on, giving the shell the [b][i]appearance [/i][/b]of a filament. At the estimated distance of 2400 light-years, the nebula has a radius of 65 light-years (a diameter of 130 light-years). The thickness of each filament is 1/50,000th of the radius, or about 4 billion miles, roughly the distance from Earth to Pluto. Undulations in the surface of the shell lead to multiple filamentary images, which appear to be intertwined. [/quote]My emphasis.
For someone with reasonable reading comprehension, this means that although the edge of the shell [i]appears [/i]to be made up of rope-like filaments, it is in fact the edge of the undulating near-spherical shock-wave shell seen edge-on. I agree with that explanation because of the details of physics in supernova remnants. And you have the gall to accuse me of illiteracy and dishonesty, when it is you who have misrepresented or misunderstood the Wikipedia article.
Go here for a more detailed explanation: https://www.spacetelescope.org/news/heic1520/
The same sort of misrepresentation is evident in the rest of your long post, (eg Andre explains in some physical and mathematical detail that the structures in his paper are produced by self-gravitation and the turbulent cascade).
[quote=Andre]
"Since the mid 1990s, simulations of supersonic turbulence have consistently shown that gas is rapidly compressed into a hierarchy of sheets and filaments (e.g., Porteret al.,1994; V ́azquez-Semadeni,1994; Padoan et al.,2001).
Furthermore, when gravity is added into turbulence simulations, the denser gas undergoes gravitational collapse to form stars (e.g. Ostriker et al.,1999; Ballesteros-Paredeset al.,1999; Klessen and Burkert,2000;Bonnell et al.,2003;MacLow and Klessen,2004; Tilley and Pudritz,2004; Krumholz et al.,2007). There are many sources of supersonic turbulent motions in the ISM out of which molecular clouds can arise, i.e., galactic spiral shocks in which most giant molecular clouds form, supernovae, stellar winds from massive stars, expanding HII regions, radiation pressure, cosmic ray streaming, Kelvin-Helmholtz and Rayleigh-Taylor instabilities, gravitational instabilities, and bipolar outflows from regions of star formation (Elmegreen and Scalo,2004)...Simulations of turbulence often employ a spectrum of plane waves that are random in direction and phase. As is well known, the crossing of two planar shock wave fronts is a line - the filament (e.g.,Pudritz and Kevlahan,
2013)...Li et al. (2010) have shown that filaments are formed preferentially perpendicular to the
magnetic field lines in strongly magnetized turbulent clouds"[/quote]That was a present I gave you last time with lots of references for you to follow up to learn the relevant science. Have you? Apparently not. Who's stuck now asking me about the same pictures over and over again when I have already given you my explanation?
But I am done now.