Assuming that hydrogen fusion requires the Universe to have a temperature of T ≥ 107 K (as measured by the CMB), determine the redshift at which the fusion of hydrogen into helium was just possible as the Universe expanded and cooled.
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Assuming that hydrogen fusion requires the Universe to have a temperature of T ≥ 107 K (as measured by the CMB), determine the redshift at which the fusion of hydrogen into helium was just possible as the Universe expanded and cooled.
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- What would be the critical density of matter in the universe if the value of the Hubble constant were (a) 40 km/sec/ Mpc? (b) 90 km/sec/Mpc?TRUE OR FALSE: Current mass estimates and deceleration rates tell us that our universe is closedBy what factor would the critical density of the universe today change if the Hubble constant today measured at 5 times greater than what we previously thought?
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