Did the universe have a beginning?

That time, that place

A Belgian Catholic priest and a physicist, who had served as an artillery officer in the First World War.

In 1927 he solved Einstein's equations for an expanding universe and predicted that a galaxy's recession speed is proportional to its distance — two years before Hubble. The paper appeared in French in a minor Belgian journal and was barely read.

Why this question

Einstein, meeting him, is said to have remarked that his calculations were correct but his physics was abominable.

Lemaître pushed further still. If the universe is expanding, what happens when you run time backward?

What was found

Everything converges to a point. The universe had a beginning.

He called it the primeval atom.

Many physicists were uncomfortable with the conclusion; it sounded like a creation myth. Fred Hoyle, mocking it on the radio, called it a big bang, and the name stuck. Hoyle himself backed a steady-state universe with no beginning and no end.

Lemaître drew extra suspicion for being a priest — surely religious motives were driving him. Yet when the Pope prepared to declare the theory proof of Genesis, Lemaître asked him not to. Science and faith, he held, cannot serve as grounds for each other.