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Unformatted text preview: 300 Mpc cube ~ 100000 galaxies Universe has about 125-150 galaxies Two assumptions: 1) Universe is smooth 2) The same in every direction Universe has no center Olberss Paradox If universe is infinite with uniform density, the sky should be bright-Universe is not infinite because it has finite age-Universe changes with time According to Hubbles law, at one point galaxies were on top of each other. T = d/v = 1/H0 If H0 = 100 km/sec/Mpc Then t = 10^10 years The Big Bang-Big Bang was not explosion in an empty universe-Big Bang is the entire universe exploding-Everything happened at the same time If we look back we see back in time...
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