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Thread: The Universe is the Same, Everywhere We Look. Even More than Cosmologists Predicted

  1. #1
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    The Universe is the Same, Everywhere We Look. Even More than Cosmologists Predicted

    The Universe is about 10% smoother than we expect, and astronomers aren't entirely sure why.
    The post The Universe is the Same, Everywhere We Look. Even More than Cosmologists Predicted appeared first on Universe Today.


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  2. #2
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    Quote Originally Posted by Fraser View Post
    The Universe is about 10% smoother than we expect, and astronomers aren't entirely sure why.
    The post The Universe is the Same, Everywhere We Look. Even More than Cosmologists Predicted appeared first on Universe Today.


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    "A difference of opinion makes a horse race" One of my favorite quotes, of origin unknown, in that it reminds us that we can be very confident of a result, or at least a line of thinking, and suddenly a new result throws a monkey wrench into the works, and some hard thinking is required. Such is the case, here.
    A recent paper, by Lior Shamir, indicates that the SDSS and PAN-STARRS galaxy surveys show a surprising difference in the frequency of clockwise, (cc), and counterclockwise ( ccw), spins of galaxies depending upon both redshift and direction of viewing. The author over-rides earlier results which used some untrained observors, and after comparing about 64,000 galaxies in one survey, and about 33,000 galaxies in the other, with two different telescopes, negating systemic error, that the result is correct at between 5 and 8 sigma. The latter result occurs when making a data cut for some of the nearby galaxies.
    That means the article above has a difference of opinion to deal with.
    Many years ago, in spring of 2008, Marc Kamionkowski ( California Tech then, Johns Hopkins now) spoke on cosmology at MIT, and I asked after the talk whether there was any evidence for a parity effect in the universe, Big Bang at all. He has done some parity checks since and should be intrigued as it removes the contention of the first article....that the universe is uniform at all scales. Not so with spins of spiral galaxies, it depends on how far back in time one is looking, and, in which direction. New horse race.
    pete

    SEE:https://arxiv.org/abs/2007.16116
    Last edited by trinitree88; 2020-Aug-05 at 02:20 AM. Reason: artificial int. Spelling errors...

  3. #3
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    Quote Originally Posted by trinitree88 View Post
    "A difference of opinion makes a horse race" One of my favorite quotes, of origin unknown, in that it reminds us that we can be very confident of a result, or at least a line of thinking, and suddenly a new result throws a monkey wrench into the works, and some hard thinking is required. Such is the case, here. ...
    The papers look to be not in conflict.
    KiDS-1000 Cosmology: Multi-probe weak gravitational lensing and spectroscopic galaxy clustering constraints is about the distribution of galaxies, i.e. whether the Universe is homogeneous and isotropic.
    Patterns of galaxy spin directions in SDSS and Pan-STARRS show parity violation and multipoles is an interesting paper about the distribution of galaxy spin directions. The main result is that they confirm previous studies without possible biases by use of manual analysis or machine learning. Their conclusion lists a couple of standard models explaining the spin anisotropy and possible candidates explaining the analogous anisotropy of the CMB.

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