1) The phenomenon known as "black holes" occurs when matter is crushed into an infinitely small space, creating a gravitational pull so strong that nothing can escape.

2) Marilyn Monroe, born Norma Jeane Mortenson, was an iconic American actress, model, and singer, known for her beauty, charisma, and tragic personal life.

3) The first bank in the world, Banca Monte dei Paschi di Siena, was established in Italy in 1472 and is still in operation today.

4) The name "Bluetooth" comes from the 10th-century Danish king, Harald Bluetooth, who united Denmark and Norway.