Etiqueta: space

cosmic inventory
The Cosmic Inventory

In ancient Greece, Empedocles stated that everything was made up of only four elements: water, fire, earth and air. It was undoubtedly the first attempt to describe the content of our universe. Over a hundred years later, Aristotle added a fifth element: ether or quintessence, which formed the stars, while the other four were the constituents of terrestrial substances.