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Galactic Formation

  1. Jul 7, 2005 #1
    When will the Last Galaxy be created?..are the Newest (detected) Galaxies part of an ongoing process, or is there is definate Closure to their Existence/Creation. And are there more or 'less' Galaxies being created at this present epoch?..or was there a definate period of 'MASS-CREATION' (I mean this to be many, not aka..mass ), expansion and creation of Galaxies are part of a correlated function of an inflationary backreaction?

    This paper almost asks more questions of Stellar evolution:http://arxiv.org/abs/astro-ph/0507130

    than can be explained with current Big-Bang theory.
     
    Last edited: Jul 7, 2005
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  3. Jul 7, 2005 #2

    hellfire

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    As far as I understand it is usually assumed that new galaxies will not form today. Galaxies still grow and merge, but an initial process of star formation in a rotating disk is not expected to be observable in the present universe. However, my impression is that this must not be necessarily true, see: https://www.physicsforums.com/showthread.php?t=80024
     
  4. Jul 8, 2005 #3

    Chronos

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    There is evidence that galactic evolution is still in progress, albeit at a less frenzied pace than in the past. A link to consider:

    Evolution of galaxies in a changing Universe
    http://www.howcomyoucom.com/Universe/evolutionofgalax.htm
     
  5. Jul 11, 2005 #4

    Garth

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    The other interesting question is: "When did the first galaxies form?" and "How did that happen?"

    Garth
     
  6. Aug 5, 2005 #5
    i think the galaxies were formed in the early seconds of the universe, in the more dense regions.
     
  7. Aug 6, 2005 #6
    Well, it maybe possible for some type of galaxy to form today, but they would be far smaller seeing how little stars there are in the void between currently existing galaxies.
     
  8. Aug 6, 2005 #7

    Danger

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    Your time scale's a little off there, shaan. Matter didn't exist in the first few seconds. I think that stars took a few million years to form, although they might have been in general galactic positions when they did so. (Sorry, man... I'm just way too tired to go find the actual numbers.) It all depends upon where the density fluctuations were when matter began to condense out of the original energy state.
    I seems to me that small galaxies could still form in the future. There surely must be some rogue-star matter left over that isn't incorporated into current galaxies, even if the stars themselves have burned out. Also, most supernovae eject part of themselves so violently that it escapes the parent galaxy. If enough of that matter can congregate gravitationally, new stars can ignite. And if enough of them come into being in reasonable proximity to each other, then they might be gravitationally bound into a galaxy.
     
  9. Aug 16, 2005 #8
    scientists have found a galaxy that is only a billion years old wich means that galaxies are still bieng created
     
  10. Aug 16, 2005 #9
    So does this mean that the Big-Bang process is not that really important for the creation of Galaxies?..How can a Galaxy come into existence, away from the starting point of Big-Bang? :rolleyes:

    P.S does every Galaxy have its own, independent mini, BIG-BANG!
     
    Last edited: Aug 16, 2005
  11. Aug 16, 2005 #10

    SpaceTiger

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    In a sense, yes. The CDM paradigm suggests that galaxies are formed in a hierarchical fashion, meaning that smaller things (star clusters, gaseous overdensities, etc.) come together to form larger things, like galaxies. The initial formation is probably very brief on a cosmic scale, so much of what we now know as the galaxy probably came together within a short period of time (less than a billion years). The Big Bang itself is not the point at which galaxies are created, since the matter is much too hot and sparse to collapse gravitationally.
     
  12. Aug 16, 2005 #11
    I do agree with most of what you state, but I am more inclined to see the energy of BB as being a distribution point?..the appearence of Galaxies I believe are energy density related, and this energy is rather cold than hot, in the sense that Galaxies are 'hot' and thus must have evolved from regions of Cold Crunch Points(energy density ) of cyclic dynamic models?..the 'cold-matter', in colliding increases the thermal energy gradually over time, Stars can evolve thermally from a low-energy..up to a Fission-energy state..die off and wane back down to a thermally inert Neutron Phase?
     
  13. Aug 16, 2005 #12

    SpaceTiger

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    I'm not sure what you mean. Galaxies arise from the collapse of overdensities of matter. The initial spectrum of fluctuations in the universe was probably imprinted by inflation and these fluctuations could be viewed as the seeds of galaxy formation, but it's a bit of a stretch to say that galaxies formed when the fluctuations did. Besides, inflation occurred after the big bang, so it's not correct to say that the big bang itself caused the formation of fluctuations either.


    You'll find it easier to communicate if you stick with standard terms rather than trying to create your own. Despite how it may seem in the scientific community, the purpose of jargon is to make communication faster, not more obscure.
     
  14. Aug 16, 2005 #13
    What "matter" are you talking about?..is this "matter" radiative?..does it emit Light?..is it a cloud of Gas?..Dust?..Zero-Point-Energy?

    What is its Qualative makeup, in standard terms?

    Now I'm confused, first you state in thread:The CDM paradigm suggests that galaxies are formed in a hierarchical fashion, meaning that smaller things (star clusters, gaseous overdensities, etc.) ..you appear to be contradicting yourself on a scale comparable to the Vacuum Selection principle, you state :
    [The initial formation is probably very brief on a cosmic scale, so much of what we now know as the galaxy probably came together within a short period of time (less than a billion years). The Big Bang itself is not the point at which galaxies are created, since the matter is much too hot and sparse to collapse gravitationally.]

    Emphisis on: since the matter is much too hot and sparse to collapse gravitationally.

    Call me obscure..but that seems to be a Dynamically excessive outline for gobblygook :yuck: sorry!..but care to explain how a extremly hot collection of matter can be close enough to be "Dense", just based on simple thermodynamics, hot things are more energetic and do not 'collect'..until they cool down....over a long..long time, which in the early Universe is on a Micro Scale, when compeared to the Universe today, we are talking about the same Universe?..one that was small..and expands at every point to a bigger area?

    http://www.sdss.org/news/releases/20050111.yardstick.html

    What you appear to be confusing me with is a Universe in Expansion, and Contraction similtaineous?

    Correct me if Iam wrong, please use definate standard models, a Tiny Dense Expanding Hot Big-Bang, OR an enormous Cold Contracting Crunch. thanks for the interesting response's.

    P.S another yardstick:https://www.physicsforums.com/archive/t-68345_Physics_of_Dark_Matter_(theory).html
     
    Last edited: Aug 16, 2005
  15. Aug 16, 2005 #14

    SpaceTiger

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    As far as we know right now, the universe is composed of baryonic matter (which does emit light) and dark matter (which doesn't, for the most part). Both of these are found in galaxies. The identity of the latter is still unknown, but the baryonic matter includes everything from ambient gas to stars to planets which, again, are all found in galaxies. Virtually every known type of matter that exists today can be found in a galaxy.


    I'm afraid I don't see where you're confused. Immediately after the initial "Big Bang", galaxies simply do not exist. A billion or so years later, they do. The reason they don't exist in the beginning is, as I said, that the gas is too hot and sparse to collapse into bound gravitational entities.


    Again, the fluctuations of density in the universe were initially created by quantum fluctuations during the inflationary epoch. If you're asking why the matter didn't then undergo diffusion and smooth out, it's because the universe was expanding and the timescale for diffusion was much larger than the hubble time (approximately the time it takes for the universe to double its size). Thus, the fluctuations remained.


    That's correct, the universe is indeed expanding. As a result, it's also getting colder. As conditions change, different processes occur. Galaxy formation could only occur at certain times during the universe's evolution.


    The universe at large can expand while certain components of it collapse. For example, if you look at the galaxies within a cluster, they will exhibit motions that are primarily influenced by the gravity of the matter in the cluster, but if you look the relative motion of one galaxy cluster to another, they will almost certainly be moving away from one another. The expansion of the universe is only noticable on very large scales.


    Everything I'm saying is within the context of the standard model, with an expanding universe including dark matter and dark energy. The eventual fate of the universe is still uncertain, but for this discussion, we only need to know that it has been expanding up to this point in time.

    I mean no offense when I say that your language is difficult to understand. Rather, I'm just trying to find a common ground for communication. I realize that you're not familiar with all of the standard astro jargon, but it is self-consistent and can be found in other sources (and I'm of course happy to explain any of it). However, if you use jargon that isn't standard (including terms you made up), then there's no way for anyone to understand you other than to guess at their meaning. If you're confused about something, it's best to state your confusion in simple terms. Some of the most difficult problems in science could be explained to a five-year-old, so there's no shame in speaking in ordinary terms.
     
  16. Aug 17, 2005 #15
    the big bang is irrelevant for galaxies, its matter that matter. First a hallow of dark matter is formed that drag normal matter to it by gravity and after a while stars have been formed and begin shining. but to become any bigger the hierarchical formation is needed
     
  17. Aug 23, 2005 #16
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