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

I Preferred axis in cosmology

  1. Apr 20, 2016 #1

    wolram

    User Avatar
    Gold Member

    Is there a preferred axis in cosmology, if there is what is the origin?

    arXiv:1604.05484 [pdf, other]
    Preferred axis in cosmology
    Wen Zhao, Larissa Santos
    Comments: 21 pages, 9 figures, 8 tables, invited review
    Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)

    The foundation of modern cosmology relies on the so-called cosmological principle which states an homogeneous and isotropic distribution of matter in the universe on large scales. However, recent observations, such as the temperature anisotropy of the cosmic microwave background (CMB) radiation, the motion of galaxies in the universe, the polarization of quasars and the acceleration of the cosmic expansion, indicate preferred directions in the sky. If these directions have a cosmological origin, the cosmological principle would be violated, and modern cosmology should be reconsidered. In this paper, by considering the preferred axis in the CMB parity violation, we find that it coincides with the preferred axes in CMB quadrupole and CMB octopole, and they all align with the direction of the CMB kinematic dipole. In addition, the preferred directions in the velocity flows, quasar alignment, anisotropy of the cosmic acceleration, the handedness of spiral galaxies, and the angular distribution of the fine-structure constant are also claimed to be aligned with the CMB kinematic dipole. Since CMB dipole was confirmed to be caused by the motion of our local group of galaxies relative to the reference frame of the CMB, the coincidence of all these preferred directions hints that these anomalies have a common origin, which is not cosmological or due to a gravitational effect. The systematical or contaminative errors in observation or in data analysis, which can be directly related to the motion of our local group of galaxies, can play an important role in explaining the anomalies
     
  2. jcsd
  3. Apr 20, 2016 #2

    DrSteve

    User Avatar
    Gold Member

    A preferred axis would violate the assumptions underlying GR of a homogeneous and isotropic (on a sufficiently large scale) universe. Yet GR does not necessarily describe the universe we actually live in.

    However, the authors conclude that there likely isn't a preferred axis "Since CMB dipole was confirmed to be caused by the motion of our local group of galaxies relative to the reference frame of the CMB, the coincidence of all these preferred directions hints that these anomalies have a common origin, which is not cosmological or due to a gravitational effect. "
     
  4. Apr 20, 2016 #3

    phinds

    User Avatar
    Gold Member
    2016 Award

    What do you suppose they could possibly mean by the "angular distribution of the fine-structure constant" ??? How does a dimensionless constant have an "angular distribution"?
     
  5. Apr 20, 2016 #4
    The fine structure constant can be estimated from cosmic observations no? So look at the estimated value as a function of position in the sky? At least that was my interpretation, but I'm just a layman...
     
  6. Apr 20, 2016 #5

    phinds

    User Avatar
    Gold Member
    2016 Award

    I think you need to look up the definition of the fine structure constant.

    EDIT: hm ... I find that there may be more to the fine structure constant than I realized. I thought it was a simple ratio of factors in charged particle interactions and could not vary with position but that seems to be either debatable or wrong.
     
    Last edited: Apr 20, 2016
  7. Apr 20, 2016 #6
    Fair enough.

    FWIW the reference given is http://arxiv.org/abs/1008.3907 which seems to talk about [itex]\Delta\alpha / \alpha[/itex] and how it varies.
     
  8. Apr 20, 2016 #7

    phinds

    User Avatar
    Gold Member
    2016 Award

    My edit must have crossed this post in the ether :smile:
     
  9. Apr 20, 2016 #8

    PeterDonis

    User Avatar
    2016 Award

    Staff: Mentor

    "Somewhat debatable" would best describe our current state of knowledge. Our best current theories predict that it is a constant, at least within our observable universe; but there are some observations which suggest it might vary. But it's only a suggestion, and AFAIK nobody has come up with a theoretical framework that predicts it should vary.
     
  10. Apr 20, 2016 #9

    phinds

    User Avatar
    Gold Member
    2016 Award

    Thanks Peter.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Preferred axis in cosmology
Loading...