Big Bang is a past horizon, though in practice our view is also limited by the opacity of the universe at early times. So our view cannot extend further backward in time, though the horizon recedes in space. If the expansion of the universe continues to accelerate, there is a future horizon as well. English astronomer Fred Hoyle is credited with coining the term "Big Bang" during a 1949 BBC radio broadcast, saying: "These theories were based on the hypothesis that all the matter in the universe was created in one big bang at a particular time in the remote past." It
Big Bang (book) of the Big Bang theory, the book tells the personal stories of the people who played a part in advancing it, both by hypothesis and by experiment. These include Einstein, for his General Relativity, Friedmann for first discovering that this theory led to an expanding universe, Lemaître who concluded independently of Friedman discovered an expanding universe, and then that the theory must lead to an initial event of creation, which is the Big Bang theory we know today, Hubble for observing that the universe expanded, thereby confirming Friedman and Lemaître, Gamow, Alpher, Herman, Ryle, Penzias and Wilson, among many others.