Georges Lemaître was an astronomer and professor of physics who is thought to be the first to have theorised that the universe is expanding.
His theory was observationally confirmed soon afterwards by Edwin Hubble in what is now known as Hubble’s Law.
Lemaître is also credited with proposing what has now become known as the Big Bang theory – which says that the observable universe began with an explosion of a single particle. He called his “hypothesis of the primaeval atom” or the “Cosmic Egg”.
He was the first to derive what is now known as Hubble’s law and made the first estimation of what is now called the Hubble constant, which he published in 1927, two years before Hubble’s article.
In Honor of his contributions, Google is celebrating the 124th birthday of Georges Lemaître with nice Space themed Doodle.