Final answer:
The cosmic inflation theory explains the rapid expansion of the universe shortly after the Big Bang. It suggests that the universe increased in size significantly during this period, leading to the flatness and uniformity observed today.
Step-by-step explanation:
The cosmic inflation theory suggests that shortly after the Big Bang, the universe underwent a period of rapid expansion known as inflation. This rapid expansion, which occurred within the first 10-35 seconds of the universe's existence, is hypothesized to explain the flatness and uniformity of the cosmos today. The inflationary universe model proposes that the universe increased in size by a factor of about 10^50 times more than predicted by standard Big Bang models.