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 A327854 Value of the critical density of the Universe in g/cm^3 multiplied by dimensionless scale factor h^(-2). 0
 1, 8, 7, 8 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET -28,2 COMMENTS The critical density is defined as p_c = 3*H^2/8*Pi*G, where H is the Hubble constant and G is the gravitational constant (A070058) (cf. ESA, Critical density). The critical density is the value of matter density that ensures the expansion of the Universe eventually halts, but the Universe does not recollapse in a "Big Crunch". This is often expressed via a density parameter Omega, defined as Omega = p/p_c, where p is the actual matter density of the Universe. Thus the Universe is "open", "flat" or "closed", depending on whether Omega < 1, Omega = 1 or Omega > 1. Observations suggest that the dark energy density Omega_Lambda and matter density Omega_m add to a value close to 1 (cf. Planck Collaboration, 2013). LINKS Table of n, a(n) for n=-28..-25. R. Aldrovandi, J. Gariel and G. Marcilhacy, On the pre-nucleosynthesis cosmological period, arXiv:gr-qc/0203079 [gr-qc], 2002. ESA, Cosmology - Critical density ESA, Cosmology - Open, flat or closed? NASA, What is the Ultimate Fate of the Universe? Planck Collaboration, Planck 2013 results. XVI. Cosmological parameters, arXiv:1303.5076 [astro.PH], 2014. M. Tanabashi et al. (Particle Data Group), Review of Particle Physics, Physical Review D, Vol. 98, No. 3, 030001 (2018). See p. 128, table 2.1. Wikipedia, Cosmological constant Wikipedia, Friedmann equations - Density parameter FORMULA Equals 3/(8 * Pi* (A217572 * A163103)^2 * A070058)/10^5. - Amiram Eldar, Sep 30 2019 EXAMPLE 1.87840(9) * 10^(-29) h^2 g cm^(-3), where h = 0.678(9) is a dimensionless scale factor (cf. Aldrovandi et al., 2002, p. 4) for the present day Hubble expansion rate H_0, which equals 100*h km s^(-1) Mpc^(-1) and where the digit in parentheses denotes the standard uncertainty (cf. Tanabashi et al., 2018, table 2.1). CROSSREFS Cf. A070058. Sequence in context: A342374 A319462 A086911 * A263179 A180311 A289913 Adjacent sequences: A327851 A327852 A327853 * A327855 A327856 A327857 KEYWORD nonn,cons,more AUTHOR Felix Fröhlich, Sep 28 2019 STATUS approved

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Last modified April 17 08:05 EDT 2024. Contains 371756 sequences. (Running on oeis4.)