- Rubidium is a chemical element; it has symbol Rb and atomic number 37. It is a very soft, whitish-grey solid in the alkali metal group, similar to potassium and caesium. Rubidium is the first alkali metal in the group to have a density higher than water. On Earth, natural rubidium comprises two isotopes: 72% is a stable isotope 85Rb, and 28% is slightly radioactive 87Rb, with a half-life of 48.8 billion years – more than three times as long as the estimated age of the universe.
- Ferdinando de’ Medici, Grand Prince of Tuscany (Wikipedia)
Ferdinando de’ Medici (9 August 1663 – 31 October 1713) was the eldest son of Cosimo III de’ Medici, Grand Duke of Tuscany, and Marguerite Louise d’Orléans. Ferdinando was heir to the Grand Duchy of Tuscany, with the title Grand Prince, from his father’s accession in 1670 until his death in 1713. He is remembered today primarily as a patron of music. An excellent musician himself (sometimes called “the Orpheus of princes”), he attracted top musicians to Florence and thus made it an important musical center. Through his patronage of Bartolomeo Cristofori, Ferdinando made possible the invention of the piano.