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Calculation mass of a finite universe

  1. May 31, 2013 #1
    Over the past few months, I researched how to validate the mass of ordinary matter in the universe assuming a finite volume. Three of my previous posts involved issues related to this question. Generally, the number E56 grams is quoted but without assumptions or calculations. I used one technique extrapolating from the number of stars. A second approach was based on critical density.
    For the Star Extrapolation approach the key inputs were:
    Number of stars (E22), Hubble Telescope and literature
    Percent of ordinary matter in stars (5.9%), Comic Energy Inventory
    For Critical Density calculation the key inputs were:
    Hubble constant (67.15 km/sec/Mpc), ESA - Planck
    Radius of universe (46.7 billion light years), Astronomy Magazine
    Percent of ordinary matter in all matter (4.8 %), ESA – Planck
    Mass extrapolated from number of stars = 1.70 x E56 gm
    Mass calculated from density = 1.46 x E56 gm
    Because “ballpark” assumptions were used, this close result is a coincidence, for example, 3 x 1022 stars would extrapolate to three times more mass in the first calculation.
    Conclusion - The ballpark number of E56 gm for the mass of ordinary matter is a reasonable approximation.
    If you want to view an 8 minute video showing the calculations go to:
    Jim J
    Last edited by a moderator: Sep 25, 2014
  2. jcsd
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