Which two isotopes are compared in radiocarbon dating

Preoccupied with change, he declared that fire is the central element of the universe, and he postulated a world with no beginning and no end...Pythagoras - Greek philosopher and mathematician; held that numbers were basic to matter; the Pythagorean Theorem is named for his geometric formulation; developed atomic theory; students of his philosophy emphasized geometrical form as a basic property of atoms; developed mathematical relationships which led to musical harmony.Issac Newton - English mathematician and scientist; developed theory of matter; first to demonstrate the color components of white light with a prism and the reconstruction of these colors into white light with a second prism; researched the optical characteristics of chemical substances; studied gravitation and motion; developed the law of gravitation.Ole Christensen Roemer - Denmark; was the first to show that the velocity of light is finite.Phillippus Aureolus Paracelsus (Theophrastus Bombast von Hohemheim) - Swiss physician; controversial figure in medicine and alchemy; promoted the production of chemical medicines for illnesses of the human body; saw the human body as a chemical system monitored by spiritual alchemists; developed many medical remedies; developed theoretical chemistry through sets of metal experiments which produced salt solutions; added salt to mercury and sulphur as components of metals.Georg Bauer - "Agricola" - German educator, city official, and physician Georgius Agricola (Latinized for of George Bauer) is best known as the author of De re metallica (1556), a treatise on mining and metallurgy.

This, coupled with Epicurus' teachings concerning pleasure, led to public criticism of the school as a scene of debauchery. Johann Gutenberg - a craftsman from Mainz, Germany.He printed the 42-line Gutenberg Bible (c.1455) but in the end he lost a suit from one of his creditors, who confiscated the type for the Bible. Aided by Konrad Humery, he was able to set up another press, but little is known of his work thereafter.The impact of printing was enormous - it led to an almost instant mass production of books and truly initiated the information age.Love and hate were considered principles of attraction and repulsion that alternately dominated the universe in a recurring cycle.