Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

First cosmology computer simulations

  1. Jan 27, 2015 #1
    I understand that the first cosmological computer simulations

    Did not have DM

    Only gas dynamics on expanding grids

    And, that those sims produced no structure of any kind

    No LSS

    Only vast expanses of nearly uniform space plasma

    Devoid of any clumps

    Essentially reminiscent of the real actual voids

    Which fill about 3/4ths of the volume of space

    So simply stated, the first earliest computer simulations

    Accurately reproduced VOIDS ...
    In some sense they were 75% accurate...

    But they never produced the large scale STRUCTURE

    Particularly important to people upon this planet?

    Hence the motivation for " something extra" ( people inserted DM ) to cause clumping into galaxies and clusters etc??
  2. jcsd
  3. Jan 27, 2015 #2


    User Avatar
    2017 Award

    Staff: Mentor

    The concept of dark matter is older than the first proper simulations, and it was based on galaxy rotation curves, not on cosmology and structure formation.

    Sure, if you have some type of matter you cannot see you want to check if simulations work out without this type - and as you see, they do not. With dark matter, they work out nicely.
  4. Jan 28, 2015 #3
    Fritz Zwickey and Vera Rubin?

    they noticed that unseen mass seems to "plague" the matter we see ( bright stars ), in the sense of being near and amidst and around "light matter" ( as it were )

    like nemesis planets or stars orbiting beyond Pluto, or something like that ( please see link below )

    As for the VOIDS ( only ) they are well described by the first simulations...

    perhaps implying that we can claim the voids to be "well understood"...

    i.e. no DM, only huge regions of diffuse space plasma?
  5. Jan 28, 2015 #4
  6. Jan 28, 2015 #5
  7. Jan 28, 2015 #6


    User Avatar
    Science Advisor
    Gold Member

    It sounds like you are making a case against DM based on cherry picked popular sources. That doesn't impress.
  8. Jan 28, 2015 #7
    say again?

    is it true, that nobody ever argues, for the presence of DM, out in the VOIDS comprising deep intergalactic space ( size scale ~100 Mpc or something like that ) ?

    no DM in voids is non-controversial, yes? To be distinguished from the ~25% of space harboring LSS?
  9. Jan 28, 2015 #8


    User Avatar
    Science Advisor
    Gold Member

    DM is generally considered the 'scaffolding' upon which structures are formed. Have you seen the cosmic web portrayals based on Herschel space observatory, or 2df galaxy redshift surveys? Given dark matter is only detectable, at present, based on gravitational effects, and since voids are, by definition, matter deficient, it is understandably difficult to assess dark matter distribution in such regions.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook