The idea that, in the first split-second after the Big Bang, the universe underwent a fantastically fast (exponential) expansion driven by the vacuum of empty space. The theory was developed by Alan Guth in the early 1980s to explain certain problems and inconsistencies with the basic Big Bang theory, such as those related to the large-scale structure of the features of the universe, the “horizon problem”, the “flatness problem” and the “magnetic monopole problem”.