How did a test of gold's purity revolutionize the world 2500 years ago and lead to the atomic bomb? Standardizing precious metal in coins stimulated trade from Greece to Persia, causing the construction of a huge commercial center and library at Alexandria. This wealth of nautical knowledge aided navigators 14 centuries later. Mariners discovered that the compass's magnetized needle did not point directly north. Investigations into the nature of magnetism led to the discovery of electricity, radar and to the atomic bomb.
