Cosmology

Georges Lemaître was a devout priest and a brilliant physicist who found Hubble’s Law in theory two years before Hubble did in practice. He took Einstein’s equations of general relativity and showed that they had a solution in which the universe expands, with the speed of expansion increasing as time goes on – just as Hubble had observed in

The Latin word nebula means ‘mist’, and originally a nebula was any sort of misty patch in the sky. Today it is more precise, referring to an interstellar cloud of dust and gas; and we shall see in a moment why the name evolved. An issue that came to the fore around 1920 was the question of the nature

The story of the development of the idea of the Big Bang has two separate strands, and we have to switch back and fore between them. The one strand is the observational work of astronomers, developing techniques to measure the distance of stars and galaxies – and also their relative speed. The discovery – published by Edwin Hubble in