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The age of the univverse is CALCULATED!

Discussion in 'JF Chit-Chat' started by Nzowa Godat, Oct 6, 2011.

  1. Nzowa Godat

    Nzowa Godat JF-Expert Member

    Oct 6, 2011
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    The ΛCDM model is based on
    six parameters: physical
    baryon density, physical dark
    matter density, dark energy
    density, scalar spectral index,
    curvature fluctuation
    amplitude and reionization
    optical depth. From these the
    other model values, including
    the Hubble constant and age of
    the universe, can be derived.
    Parameter values listed below
    are from the Seven-Year
    Wilkinson Microwave
    Anisotropy Probe
    (WMAP) temperature and
    polarization observations.[2]
    These include estimates based
    on data from Baryon Acoustic
    Oscillations[3] and Type Ia
    supernova luminosity/time
    dilation measurements.[4]
    Implications of the data for
    cosmological models are
    discussed in Komatsu et al. [5]
    and Spergel et al.[6]
    Age of the universe
    km s−1Mpc−1
    Hubble constant
    Physical baryon density
    Physical dark matter density
    Baryon density
    Dark matter density
    Dark energy density
    , k0 =
    Curvature fluctuation
    Fluctuation amplitude at 8h
    −1 Mpc
    Scalar spectral index
    Redshift at decoupling
    Age at decoupling
    Reionization optical depth
    Redshift of reionization
    The "physical baryon density"
    Ωbh2 differs from the "baryon
    density" Ωb in that the baryon
    density gives the fraction of
    the critical density made up of
    baryons (the critical density is
    the total density of matter/
    energy needed for the
    universe to be spatially flat,
    with measurements indicating
    that the actual total density
    Ω tot is very close if not equal
    to this value, see below), while
    the physical baryon density is
    equal to the baryon density
    multiplied by the square of the
    reduced Hubble constant h,[7]
    where h is related to the
    Hubble constant H 0 by the
    equation H0 = 100 h (km/s)/
    Mpc.[8] Likewise for the
    difference between "physical
    dark matter density" and
    "dark matter density".
    Extended models
    Possible extensions of the
    simplest ΛCDM model are to
    allow quintessence rather than
    a cosmological constant. In this
    case, the equation of state of
    dark energy is allowed to
    differ from −1. Cosmic
    inflation predicts tensor
    fluctuations ( gravitational
    waves). Their amplitude is
    parameterized by the tensor-
    to-scalar ratio, which is
    determined by the energy
    scale of inflation. Other
    modifications allow for spatial
    curvature (Ω tot may be
    different from 1), hot dark
    matter in the form of
    neutrinos, or a running
    spectral index, which are
    generally viewed as
    inconsistent with cosmic
    Allowing these parameters will
    generally increase the errors
    in the parameters quoted
    above, and may also shift the
    observed values somewhat.
    Total density
    Equation of state
    < 0.24, k0 = 0.002Mpc&#8722;1
    Tensor-to-scalar ratio
    d ns / d ln k
    , k0 =
    Running of the spectral index
    < 0.0062
    Physical neutrino density
    < 0.58 eV (2&#963;)
    Neutrino mass
  2. hashycool

    hashycool JF-Expert Member

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  3. Nyani Ngabu

    Nyani Ngabu Platinum Member

    Oct 6, 2011
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  4. ndyoko

    ndyoko JF-Expert Member

    Oct 6, 2011
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    hivi, mwehu ujamjuaje wakuu?
  5. FaizaFoxy

    FaizaFoxy JF-Expert Member

    Oct 6, 2011
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    And the answer is?
  6. Zagazaga

    Zagazaga JF-Expert Member

    Oct 6, 2011
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    duuuuuu..... imagine ndo pepa hilo....lazima utoke na yai. nimesoma kufika mwisho sikumbuki nianzia wapi. mwe...
  7. Mama Mdogo

    Mama Mdogo JF-Expert Member

    Oct 6, 2011
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    Haya ndiyo matatizo ya cut and paste, hata huyo aliyeleta mda (Nzowa Godat) huenda hata hajui kipi ni kipi. Haya yetu macho na masikio, haya mambo ebu tuwaachie hao ma-astro physcists waliokubuhu, yaani, Carl Sagan, Edwine Hubble, Stephen Hawking, Tadashi Nakajima, Albert Einstein, Isaac Newton etc.
  8. feis buku

    feis buku JF-Expert Member

    Oct 7, 2011
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    Njia panda!