Lecture 5: Threshold 1—Origins of Big Bang Cosmology
Assuming that our part of the Universe was typical, Hubble’s discovery
suggested that the entire Universe was expanding. As Belgian astronomer
Georges Lemaître pointed out, this implied that in the distant past everything
in the Universe must have been crushed into a single, tiny, dense hot point,
a “primeval atom” as he called it. This meant that the entire Universe had a
history. These ideas solved the problems posed by an in¿ nite Universe, for
an expanding Universe had to be ¿ nite, containing ¿ nite amounts of light
and heat, and plenty of usable energy. The idea of an expanding Universe
also ¿ tted Einstein’s recently formulated general theory of relativity, which
appeared to show (though Einstein initially resisted this conclusion) that
the Universe must be either expanding or contracting. The name “big bang”
was coined by Fred Hoyle (1915–2001), who had worked with Gamow but
would become a ¿ erce critic of the theory. He used the label derisively in a
1950 radio broadcast.We have seen how, early in the 20th century, new evidence and new
arguments accumulating over several centuries generated a new model of
the Universe. This model suggested that the Universe had been created at a
speci¿ c date and had been expanding ever since. In other words, the Universe
had a history! ŶBryson, A Short History of Nearly Everything, chap. 8.
Christian, Maps of Time, chap. 1.Coles, Cosmology, chaps. 1, 4.Essential ReadingSupplementary Reading