(a) When the universe was a mere 10^-4 s old, the temperature was about 10^13 K. What is the probability that two average protons could fuse in this opening split second?
(b) Ages later when the universe was 1s old, the temperature fell to only 10^10. What is the probability that two average protons could fuse in this second?
(c) Compare these probabilities to the likelyhood of being struck by lightning in a given year.