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Cosmic Dynamics - Cosmological Constant

  1. May 20, 2014 #1
    Suppose the energy density of the cosmological constant is equal to the present critical density ε[itex]\Lambda[/itex] = ε[itex]c,0[/itex] = 5200 MeV m-3. What is the total energy of the cosmological constant within a sphere 1 AU in radius?

    My answer:
    ε[itex]\Lambda[/itex] = ET / V
    ET = ε[itex]\Lambda[/itex] * V = (8.33 * 10-10 J)*4∏/3*(1.5*1011m3)3 = 1.2*1035 J

    What is the rest energy of the Sun ?

    My answer:
    E = (2*1030kg)(3*108 m/s)2 ≈ 1.8*1047 J

    Comparing these two numbers, do you expect the cosmological constant to have a significant effect on the motion of planets within the solar system?

    My answer:
    Esolar ≈ (1.5*1022)*ET

    So the total amount of energy from the Sun is much much greater than the total energy of the cosmological constant within a sphere of 1 AU radius.

    According to Einstein, mass/energy curves spaces around it. Thus, the immense curvature of space by the sun will control the motion of the planets.
  2. jcsd
  3. May 20, 2014 #2


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    Science Advisor

    You've made an error in the first line. ET should be about ((10^11)^3)*10^(-10) = 10^23, not 10^35.
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