Question
Asked 16th Oct, 2018

What are the observational and practical evidences to support the fact that there exist strongly correlated astrophysical fluids in galaxies?

What are the observational and practical evidences to support the fact that there exist strongly correlated astrophysical fluids in galaxies?
Suggested reading materials are welcome.

Most recent answer

21st Oct, 2018
Daniel Pfenniger
University of Geneva
Dear Dwight:
I agree that ideally it is better to clearly define the used terms before discussion. But to avoid being lengthy one tends to omit this step, assuming the reader will know the meaning of the used terms.
Concerning the definition of a fluid in earthbound scientific/technical conditions, most of the fluids are collisional (but rarefied gas problems can yet be found in vacuum chambers and high altitude aerodynamics). In astrophysics one meets the most extreme fluids (for examples the ones like the interstellar medium having the highest dynamical ranges) so of course one has to stretch the semantic of the word "fluid" wrt to earthbound conditions.
The semantic of a word is determined by the community using it. So in such cases you could look at the scientific literature if you are unsure of the common definition.
The same for "correlation".
For myself I was unsure of your meaning of "Humpty Dumpty semantics" as it is strongly bound to the peculiar English culture to which I don't belong. A quick visit to Wikipedia answered my interrogation.

All Answers (6)

16th Oct, 2018
Dwight Hoxie
United States Geological Survey
Forgive me, but I do not understand what you mean by "astrophysical fluids". A fluid for me is a gas or liquid that possesses some internal coherence sufficient to maintain a macroscpic presence that can be touched and otherwise be recognized macroscopically. There are, apparently, clumps, currents and swirls of gaseous materials and dust in galaxies but at such low densities that I would be loath to call "fluids" in a macroscopic sense.
I also don't understand what you mean by "strongle correlated". Are we speaking of "fluid" currents that are maintaining shared motion separated by lightyears of distance under the galaxy's gravitational field?
My training was in astrophysics but the major part of my career was in the earth sciences so I likely am not up to date on developments in the physics of galaxies.
1 Recommendation
18th Oct, 2018
Daniel Pfenniger
University of Geneva
Look at any maps of the Milky Way in various wavelengths (radio, infrared, x-rays, ...) and you will see correlated structures, such as clumps, filaments, shells. All these structures can be understood as "fluids" in the sense that they follow conservation laws, and the mean free-paths of its ions, atoms, molecules, grains, ... is much shorter than the larger scale structure. In the extreme dense direction you find stars that are of course also fluid and correlated structures. In the large scale direction galaxies are composed of a special fluid where the particles are stars, where their mean-free path is much larger than the galaxy itself, but nonetheless form a so-called collisionless fluid. Some plasmas also are in this collisionless regime where ions are channelled by magnetic fields.
1 Recommendation
20th Oct, 2018
Dwight Hoxie
United States Geological Survey
Dear Daniel and P. K. Karmakar,
I sense that we are engaged here in Humpty Dumpty semantics - "When I chose a word it means exactly what I want it to mean, no more, no less" - applied to "fluids", "strongly correlated" and "fact". Any "fact" about galaxies clearly derives from observational evidence because observation is the only way we can gain any information about galaxies, whether near or far. As to the claim of there being "strongly correlated astrophysical fluids" in galaxies requiers a Humpty Dumpty definition of what is meant because the whole galaxy is one large internally correlated structure and if you include stars in your definition of an "astrophysical fluid", then the whole galaxy is a "correlated astrophysical fluid" (I dropped the modifier "highly") and the evidence supporting this "fact" is virtually every observation that has been made of the galaxy.
I gather, however, that the question really is concerned with the gas and dust components within the galaxy that accumulate in clumps, filaments, etc that are evidence for locally organized structures within the galaxy. Observational evidence for such structures abounds including many spectacular photos taken by the Hubble.
20th Oct, 2018
P.K. Karmakar
Tezpur University
We are thankful to each and everybody having participated in our joint discussion.
In addition, suggested materials for further reading are welcome.
21st Oct, 2018
Daniel Pfenniger
University of Geneva
Dear Dwight:
I agree that ideally it is better to clearly define the used terms before discussion. But to avoid being lengthy one tends to omit this step, assuming the reader will know the meaning of the used terms.
Concerning the definition of a fluid in earthbound scientific/technical conditions, most of the fluids are collisional (but rarefied gas problems can yet be found in vacuum chambers and high altitude aerodynamics). In astrophysics one meets the most extreme fluids (for examples the ones like the interstellar medium having the highest dynamical ranges) so of course one has to stretch the semantic of the word "fluid" wrt to earthbound conditions.
The semantic of a word is determined by the community using it. So in such cases you could look at the scientific literature if you are unsure of the common definition.
The same for "correlation".
For myself I was unsure of your meaning of "Humpty Dumpty semantics" as it is strongly bound to the peculiar English culture to which I don't belong. A quick visit to Wikipedia answered my interrogation.

Similar questions and discussions

Is is ethically acceptable for editors to just yank your article from the review process without providing a single reason?
Question
40 answers
  • Marco PereiraMarco Pereira
The offended paper is here:
This is a rhetorical question since, in my mind, that is utterly non-acceptable.
I say that while accepting the reality that it takes time to write a few paragraphs in a rejection letter.
That said, it might take years to polish the arguments contained in a paper.
In my case, it took 16 years.
My issue is that, on purpose, I chose to tackle the Big Bang Theory first. It is the weakest model in the whole Physics. There are "Crisis in Cosmology" articles written by everyone and their cats. There is Hubble Tension, S8 tension... Missing Dark Matter, Early Galaxy Formation Conundrum...
Not to mention the lack of any evidence of a False Vacuum, Inflaton Field or Inflaton Particle, etc, etc.
My theory starts with a new model for matter, where matter is made of shapeshifting deformations of the metric (so, it is not Mass Deforms Metric, but modulated metric is mass).
It cannot be simpler. It allows the Universe to have just space, deformed space and time - the simplest possible model.
Occam's Razor will tell you that this model should be part of the conversation.
The Universe starts from a Heisenberg-Dictated Metric Hyperspherical Fluctuation, which after partial recombination is left with an Inner Dilation Layer (IDL) and the Outermost Contraction Layer (OCL).
As one would expect OCL breaks apart when it starts to move, pushed by the IDL. This process has a physical analogy in the Prince Rupert Drop
SO, the model is disappointly simple. No metrics, nothing for you to polish... just a simple model that explains EVERYTHING.
It also debunks General Relativity (Einstein's equations do not describe the Universe expansion). And replicates all Einstein's successes, while providing simpler explanations (instead of time dilation, we have the weakening of forces with absolute velocity).
What about ABSOLUTE VELOCITY? Well, we all know we can define absolute velocity using the CMB. Period. So, absolute velocity (and the breakdown of Relativity) shouldn't be a surprise.
So, my theory also challenges the current Cosmic Distance Ladder and in doing so (using an epoch-dependent law of Gravitation), it parameterless predicts the distances using just the redshifts. The predictions are attached.
So, in doing so, it attacks Dark Matter and Dark Energy and all the sordid interests behind them. I say sordid in the sense that I believe that all these entrenched interests are at play in this summary rejection of my work.
Why would I say that? There is a simple reason. If an editor (and all the other editors) don't bother to justify their actions, one is left with nothing to do other than speculate on the WHY.
Why is it ok for preprint repositories to block my already published work?? That is happening (and happened during the last 16 years) at the Los Alamos Archives.
Why would it be ethical for an editor not to write a single paragraph pointing to an specific scientific reason for yanking a paper out of the review process?
How calous these people can be with respect to Science and Mankind's Future? Science is the key to the Future. It shouldn't be at the mercy of unconfessable motivations.

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