Georges Lemaitre was the first to propose an expanding universe.
By Kiona N. Smith
Today’s Google Doodle celebrates the 124th birthday of Georges Lemaître, the astronomer and physicist who first proposed the idea of an expanding universe which began with the event we now call the Big Bang.
Lemaître was born on July 17, 1894. During World War I, he served in the Belgian Army as an artillery officer, and like many veterans, he pursued further education after the war. He obtained a doctorate in physics in 1920, and three years later, he began working toward a second doctorate, in astronomy, the same year he was ordained as a Catholic priest.
In 1927, Lemaître (by then an ordained priest who held two doctorates and a Belgian War Cross with palms) was working as a lecturer at the Catholic University of Leuven when he published a paper entitled “A homogenous Universe of constant mass and growing radius accounting for the radial velocity of extragalactic nebulae.” Based on Einstein’s theory of General Relativity, the paper proposed an expanding universe, rather than a stable one. It was the first time anyone had outlined the idea that light from objects in deep space is shifted toward the red end of the spectrum because the Doppler Effect stretches the wavelength of light from sources moving away from us. In other words, far-away objects in space are getting farther away; the universe is expanding. Today, we know this as Hubble’s Law, but it was Lemaître who published the basic idea first.
But Lemaître hadn’t yet described the model of the universe we now accept today. For one thing, he described the universe expanding from a static starting point – not the cataclysmic cosmic explosion of the Big Bang. That didn’t come along until 1931, when Lemaître published a paper in the journal Nature, describing the universe’s beginning from “the Primeval Atom” or even more poetically “the Cosmic Egg exploding at the moment of the creation.” Astronomer Fred Hoyle, one of the model’s most respected and outspoken critics, later gave it the name we recognize today: Big Bang.
Twenty years later, Lemaître – a Catholic priest, teaching and researching at a Catholic university – spoke out when Pope Pius XII declared that the Big Bang offered scientific proof of the Christian account of cosmology. Lemaitre, though personally devout, felt that scientific theory neither supported nor conflicted with religious belief; for Lemaître , the two ways of understanding the universe could coexist but shouldn’t be directly combined. In fact, Lemaître worked with the papal science adviser to persuade Pius XII to stop making official declarations about cosmology and creation.
Lemaître lived just long enough to see the discovery of the Cosmic Microwave Background, the faint electromagnetic radiation left over from the earliest phase of the universe, which provided strong evidence supporting his theory. He died on June 20, 1966.