Alan Guth. Portrait of Professor Alan Harvey Guth (born 1947), American cosmologist. Guth put forward the inflation hypothesis to explain the Big Bang at the creation of the Universe. During the Big Bang, the Universe is believed to have existed at a single point before expanding to form what we see today. First suggested in 1947, Guth modified the Big Bang theory in 1980 to include the effect of inflation in the first microsecond of the Universe's existence. This inflation theory claims that of the many chaotic states present, one expanded more rapidly to form the observable Universe. This theory explains why the Universe appears so uniform today. Photographed in 1996.