1. Would the formation of 1r+ or 1r0 have occurred for a longer time from creation by thermal interactions in the early universe? What is the difference in mean temperatures for their thresholds of formation?
2. Calculate the temperature of the universe when photons can no longer disassociate deuterons. Use the mean value of the distribution.
3. Determine the temperature of the universe when it had cooled enough that photons no longer disassoci- ate the hydrogen atom. Use the mean value of the distribution.