In 1929, one of the most astounding discoveries ever made was published by the American astronomer Edwin Hubble. Using observations of distant galaxies, he showed that the Universe is expanding. Not only that, but it is doing so in a specific way, with galaxies racing away from each other at speeds that grow with their increasing distance from each other.
Now known as Hubble’s Law, his principles remain at the core of cosmology, allowing scientists to calculate the age of the Universe. Yet by rights it should really be known as Lemaître’s Law, after the Belgian priest, astronomer and academic who both predicted it and demonstrated its validity two years before the publication of Hubble’s work.
Originally trained in mathematics and astronomy, Georges Lemaître was an expert in the cosmic consequences of Einstein’s theory of gravity: General Relativity. In 1927, he published a paper showing that Einstein’s theory implied that the Universe could expand. He then used new observations of the distance and speed of galaxies to support his mind-boggling claim.
Published in a relatively obscure Belgian journal, Lemaître’s breakthrough was unknown to Hubble, who made the same discovery independently. Being more interested in science than glory, Lemaître declined to take a stand over priority, and so the law carries Hubble’s name today.