Einstein had already become world- famous when a young ex-lawyer, returning from the First World War,started work at the Mount Wilson Observatory in California.Using the most high-powered telescope of the time,he began the long slow process of exploring our galaxy.Edwin Huble was about to make astronomy's greatest breakthrough of the century.He discovered nebulae which were in fact galaxies like our won, millions of light years away from us, which proved that the universe was vastly larger than had previously been thought. Then,Hubble proved that the universe
is actually expanding, and that the futher away galaxies are, the faster they move. In 1929,another far-reaching finding was made by the son of a Scottish shepherd. Before he went on holiday, Alexander Fleming left a dish with bacteria in it near the window of his laboratory.When he came back, he was just about to throw the dish away when he noticed something our of the ordinary. He double-checked and saw a blue mould in the dish around which the bacteria had been destroyed. This blue moud was in fact the natural form of pencicillin which Fleming realized was an effective way of killing bacteria.