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Steady-State Universe and Matter Creation

  1. Apr 6, 2009 #1
    1. The problem statement, all variables and given/known data
    Estimate the rate of continuous creation required to keep the density of the universe constant at 10-29 g/cm3
    Assume Hubble's constant Ho=70 km/s/Mpc

    2. Relevant equations
    I'm not sure if these are relevant, but for spherical shells: dV=4*(pi)*r2dr and N=4*(pi)*r2ndr, where N is the total number of particles in the shell and n is the density (#/unit volume)
    Hubble's law: v=Hd or dr/dt=H*r

    3. The attempt at a solution
    So, given the mass of a proton, the density is approximately 6*109 protons/km3.
    I also converted Hubble's constant to 2.2*109 km/year/Mpc.
    I'm kind of stuck after that... I feel like there should be some easy way to figure out how much a volume changes per year, but that depends on how many Mpc away we are.
    I feel like there's some simple equation that I'm missing...
  2. jcsd
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