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@berekuk
Created July 7, 2012 23:56
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mass(universe) = 3e52 kg # http://en.wikipedia.org/wiki/Observable_universe#Estimation_based_on_the_measured_stellar_density
mass(sun) = 2e30 kg
diameter(sun) = 1.3e6 km
radius(sun) = 6e5 km
orbit(earth) = 1.5e8 km
density(neutron star) = 4e14 * density(sun) # http://en.wikipedia.org/wiki/Neutron_star
mass(neutron star with the size of sun) = 2e30 * 4e14 = 8e44
mass(neutron star with the size of earth orbit) = (1.5e8 / 6e5)^3 * 8e44 = 1.2e52
orbit(mars) ~ 1.5 * orbit(earth)
mass(neutron star with the size of mars orbit) = 1.2 * 10^52 * 1.5**3 = 4.2e52 > mass(universe)
alternative direct method:
[neutron star density, kg/m3] 6e17 * [volume of sphere with the radius of mars orbit, km3] 5e25 * [convert m3 to km3] 1e9 = 3e52
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