The Primeval Atom Hypothesis
Georges Lemaître · 1931
"A Belgian priest-physicist proposed, years before Hubble's data was fully digested, that the universe began from a single, extremely dense 'primeval atom' that has been expanding and cooling ever since — the first real formulation of what became the Big Bang theory."
The Big Bang wasn't Hubble's idea. In 1927, a Catholic priest who also held a physics doctorate proposed the universe expanded from an initial dense state — before most physicists, including Einstein at first, took it seriously.
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Hubble's Law and the Expanding Universe
"Distant galaxies are receding from us at speeds proportional to their distance — the first hard observational evidence that the universe itself is expanding, which run backward in time implies it began from a single point."