The theory of the Big Bang as the beginning of our universe is almost universally accepted in contemporary popular consciousness. Astrophysicist Ethan Siegel, however, calls this “one of the greatest misconceptions of the universe”; indeed, evidence to the contrary has been fuelling theories for almost 40 years, and signs are emerging of a universe before the Big Bang.
The basic concept of a Big Bang was conceived by the astronomer and Catholic priest Georges Lemaître, who in the 1920s identified the expansion of the universe. From this observation he inferred a “primeval atom”, from which all time and space expanded. The discovery of the so-called Cosmic Microwave Background in 1964 by Arno Penzias and Bob Wilson confirmed Lemaître’s theory of an expanding universe, proving that the universe cools as time goes on.
Extrapolating backwards, the beginning of the universe was conceived as an infinitely dense, hot, and compact point— the origin of space and time. However, this may not be the case. In 1979, Alan Guth proposed that instead of beginning from an infinitely dense, hot state, the universe could have its origins in quite the opposite — a state with no matter or radiation at all, where all the energy was contained in the vacuum of space itself. This phase of the universe would have come to an end in the conversion of this energy into matter and radiation — what we think of as the Big Bang.
There is as yet no consensus as to how the universe began, or whether indeed it had a beginning at all. However, since Guth’s research up to the present day, astrophysicists have been working from the premise that we did not start with a bang after all.
Applicants for Physics ought to familiarise themselves with contemporary theories of the origins of our universe, as well as the history of the Big Bang theory. Students wishing to study Theology or Philosophy may wish to think about the implications of modern astrophysics on traditional arguments for the existence of God, such as Thomas Aquinas’ Cosmological Argument.