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Minor Forum Reoganization

  1. Jan 30, 2006 #1
    GR&SR is moved to the Physics category

    "Atoms, Molecules, & Solids" becomes "Atomic, Solid State, & Computational Physics"

    "Nuclei & Particles" becomes "High Energy, Nuclear, & Particle Physics"

    "Strings, Branes, & LQG" becomes "Beyond the Standard Model"

    All threads in "Stellar Astrophysics" and "Celestial Mechanics" moved into "Astrophysics"

    Steller Astrophysics and Celestial Mechanics forums dropped and replaced with Astrophysics forum and Cosmology forum

    New forum breakdown:
     
  2. jcsd
  3. Jan 30, 2006 #2

    SpaceTiger

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    It's better. I think the line between astronomy and astrophysics is extremely fuzzy, but the important thing is that the SR&GR forums were moved. Only a fraction of the questions in that forum were astronomy-related and its gurus were mainly theoretical physicists, not astronomers or astrophysicists.

    It is true, however, that astrophysicists are particularly knowledgable about the cosmological applications of GR, so there will be some ambiguity in the forum assignment of those posts. I'll try to keep an eye on both forums, as will pervect and company, I'm sure.
     
  4. Jan 30, 2006 #3

    jtbell

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    What's the intended difference between "General Physics" and "Classical Physics?" Those forums aren't part of the re-org, but I've always been curious about this.
     
  5. Jan 30, 2006 #4

    PerennialII

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    .... have always wondered what is the purpose & scope of "general" physics overall? Misc simpler stuff, overall discussion about physics,...?
     
  6. Jan 30, 2006 #5
    Used for misc non technical banter.
     
  7. Jan 30, 2006 #6

    jtbell

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    Perhaps the "miscellaneous" nature of the General Physics forum would be more apparent if it were listed at the end of that section, rather than at the beginning? Then people would tend to scan down past the other forums first.

    Also, to me "General Physics" brings to mind an introductory college/university physics course, i.e. mainly classical physics.
     
  8. Jan 31, 2006 #7
    Much better! Great work!
     
  9. Jan 31, 2006 #8

    ZapperZ

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    At this stage, I'd be happy if the newbies could just not post homework-type questions in those two. I'm not terribly concerned if they can distinguish between "general physics" and "classical physics".

    Zz.
     
  10. Jan 31, 2006 #9

    saltydog

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    I'm just old. Palomar use to be a jewel. It's still all just Astronomy to me.:smile:
     
  11. Feb 2, 2006 #10

    Chronos

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    I agree that SR and classical physics belong together. GR is probably a better fit in the AC forum, since it has few applications outside that realm. On the other hand, explaining the difference might be a bigger headache than lumping them together.
     
  12. Feb 2, 2006 #11

    George Jones

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    While I agree that many of the applications of GR are in astronomy, astrophysics, and cosmology, I disagree very strongly with placing GR in the Astronomy and Cosmology section.

    GR is a fundamental part of physics as a whole, and, as such, GR belongs right where it has been placed - in the Physics section.

    My 2 cents. :smile:

    Regards,
    George
     
  13. Feb 2, 2006 #12

    Nereid

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    For now, the distinction - such as it is - is that Astrophysics threads should contain at least a modicum of the application of physics, to the understanding of the objects themselves (the Sun, planetary orbits, stars, the ISM, galaxies, etc).

    General Astronomy is more for the techniques (including those used by amateur astronomers), as well as planetary studies (maybe we'll have another re-alignment, what do readers think?), and general questions that aren't easily classified otherwise.

    What should we do with the stickies (at the top of the General Astronomy section)?
     
  14. Feb 3, 2006 #13

    Chronos

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    I think it's OK to leave them as is, or delete them and start fresh. They don't get enough traffic to merit the labor necessary to sort them out, IMO.
     
  15. Feb 3, 2006 #14

    SpaceTiger

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    It seems like the volume of posts that fit this description is very small and most of the things now in "General Astronomy" are a better fit to your first category. I'm not opposed to the current organization -- it will probably end up as a rough division between "advanced" and "intro" astronomy concepts -- but I think most of the posts in those two forums could be described as either astronomy or astrophysics.

    For me, it doesn't matter all that much how it's organized. If this organization makes it easier for the moderators, then it's all good.
     
  16. Feb 3, 2006 #15

    Astronuc

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    OK - good reorganization.

    However, where would a thread on Plasma Physics go?

    I would like to start one with Resources on Plamsa Physics, which could include applications to astronomical/cosmological objects as well as fusion/magnetoplasmadynamic systems.

    e.g. - http://www.plasmaphysics.org.uk/

    http://plasma-gate.weizmann.ac.il/PlasmaI.html

    http://www.ipp.mpg.de/~Wolfgang.Suttrop/ppcfsites.html [Broken]

    http://wwwppd.nrl.navy.mil/ [Broken]

    http://www.imperial.ac.uk/research/plasma/ [Broken]

    Some of these might go under Nuclear Energy however.
     
    Last edited by a moderator: May 2, 2017
  17. Feb 4, 2006 #16

    vanesch

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    Good question. A priori, plasma physics is classical physics (electrodynamics, thermodynamics, transport equations,... all that). Of course, plasma physics has different applications (astrophysics, nuclear physics...).
    I would suggest that if the main topic is the physics of plasmas, that this belongs in classical physics. If you want to concentrate on a specific application, and you just use plasma physics for it, then pick the forum for the application. If you really don't know and you want to talk about everything at once :smile: , go to general physics.
     
  18. Feb 4, 2006 #17

    Astronuc

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    I was thinking Classical Physics would be appropriate for Plasma Physics topics, but I prefer other opinions.

    I was also thinking last night about the fact that stellar (star) plasmas are much denser than those in interstellar space and on earth, so Astrophysics would be appropriate for stellar and interstellar plasmas, while Classical Physics would be approriate for the rarefied plasmas we deal with on earth.
     
    Last edited: Feb 4, 2006
  19. Feb 4, 2006 #18

    Nereid

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    While I like the idea of putting it in astrophysics (no prizes for guessing why), for the same reasons that Relativity (especially General) belongs with 'Physics' and not 'Astro{insert your favourite ending here}', plasma physics lives with Physics. I'm with vanesch - it's primarily Classical.

    By all means, point interested folk to Astrophysics and High Energy, Nuclear, and Particle Physics (I note that the first link in Astronuc's post has a strong astrophysics bent.)

    If you'd like to start some threads, in Astrophysics, on the application of plasma physics to this field Astronuc, that would be a most welcome and much appreciated contribution.
     
  20. Feb 4, 2006 #19

    selfAdjoint

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    Wouldn't this suggest a general rule? If the topic is physics qua physics, then it should go in the appropriate physics forum. But if it's physics qua application to something else, then it should go in the something else forum.

    A thought for future upgrades would be to have easier crosslinks between threads in different fora. Isn't that that the world wide web was invented for?
     
  21. Feb 4, 2006 #20

    Astronuc

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    Thanks. I will discuss this with Space Tiger.

    The reason I asked was that another PF member asked me about Astrophysics/Physics and Space Exploration, and I was trying to think of
    areas of overlap, and the two things that came to mind were orbital mechanics and space craft propuslion, particularly EM and MPD systems. I found that first link while searching "Plasma Physics", and I was looking for a place to post it. I checked all the subforums and didn't see one that looked right, although I thought Classical Physics seem the best based on "Electrodynamics, & Thermodynamics".
     
  22. Feb 5, 2006 #21

    SpaceTiger

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    But isn't the big question just what we mean by "physics qua physics"? Plasma physics is not the study of fundamental physics, but rather the application of fundamental physics (mostly classical and non-relativistic quantum) to some system. Sometimes that system is within the realm of astronomy (as in stellar fusion and accretion disks) and sometimes it's related to something else (as in controlled nuclear fusion). Sometimes those other applications are called "physics" and sometimes they aren't -- and the reasons for their classification are often just historical.

    I would advise against Astronuc posting solely in the astro forum, since the majority of plasma physicists are not working on astronomical applications. However, it's not obvious to me that it fits nicely into any other single forum either. If Astronuc wants to put in the effort and the mods don't mind, I would think multiple posts (tailored the field in question) would be most appropriate. Alternatively, since there are separate plasma physics departments in many universities, I don't think it would be crazy to give it its own forum.
     
    Last edited: Feb 5, 2006
  23. Feb 6, 2006 #22

    vanesch

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    Well, I think the policy here is not to have too many fora, and only create a new one when the flux of specific posts on the topic justifies it. As such, I'd say that everything that would go in the specific "plasma physics" forum, can now go very well in the "classical physics" forum. If it then turns out that, say, 30% of the classical physics posts are plasma physics topics, it might be justified to create its own forum - but I think Greg is a bit reluctant to create miriads of fora just for the sake of reflecting the organizational chart of a science faculty. And as such, the creation of a plasma physics forum would not solve the dilemma between posting on astrophysics, or in plasma!

    Nevertheless, I think the separation is quite clear: if you talk about the specific physics of plasmas (the different types of waves you can have, certain transport phenomena etc...), and its application is secondary, then it belongs in the classical physics forum (and later, eventually, in the plasma physics forum/subforum whatever). If you talk of a specific physical phenomenon in the frame of, say, an accretion disk, and you have to address specific aspects of plasma physics for that, it should be in the astro forum. If it is related to, say, etching of surfaces or something, it would be appropriate in the atoms, molecules... forum.
     
  24. Feb 6, 2006 #23

    Astronuc

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    Ah, I see that there is perhaps a slight misunderstanding. I was not looking to start a new forum. Rather, I just needed to know which of the current fora in which to place topics on plasma physics. Thanks all for the input!

    I propose, putting plasma physics topics under Classical Physics, and perhaps the subtitle/descriptor "Mechanics, Electrodynamics, & Thermodynamics" can be altered to include Plasmas or Plasma Physics. Plasmas, at least on earth are not really high energy - the particle energies are in the keV to low MeV range.

    Also, for Plasma Physics topics concerning stars and cosmological objects, I would propose to place them in the Astrophysics forum.
     
  25. Feb 6, 2006 #24

    SpaceTiger

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    I can't really agree that the distinction is as clear as you're saying. There are many phenomena that occur only in the ISM or accretion disks, so you're more likely to find an expert on them in the astro forum. One can categorize based on whether or not the OP is trying to apply the physics to a particular larger system, but that seems to me a superficial detail in comparison to the relevant concepts. I understand that moderation is hard and we can't realistically expect every post to be properly placed, but when possible, I think we should be trying to reach the audience with the maximum expertise.


    I know, Astronuc, I was just suggesting it as a possibility. If it doesn't come up specifically in very many posts, then I agree that we shouldn't make an extra forum. If it does become a frequent subject of discussion, however, I think it's a very reasonable division.
     
  26. Feb 6, 2006 #25

    Astronuc

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    Cool! I see we are already having a discussion on various aspects or nuances of Plasma Physics. :biggrin:

    Something else that occurred to me just now, based on Space Tiger's comment "There are many phenomena that occur only in the ISM or accretion disks, . . . " is that on earth, the plasmas tend to be pretty clean, i.e. not much in the way of higher Z materials than H, He, Li or such. This is because we like to avoid energy losses due to cyclotron and brehm├čtrahlung radiation. Fusion plasmas are really limited to D, T and maybe He-3 and byproducts. Propulsion plasmas might include Li, but still, losses due to the aforementioned effects are still undesirable.

    On the other hand, in ISM and accretion disks, one can have heavier ions, of C, N, O, etc. Topics in Plasma Physics involving these clearly belong in the Astrophysics section.

    I also have some material on MHD applications, but in general, those are low temperature plasma applications.

    Geez, like I don't have enough to do already. :biggrin: :tongue2:
     
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