1) The word "music" contains two vowels: U and I.

2) Celtic mythology encompasses the folklore and legends of the Celtic peoples across Europe, particularly in regions like Ireland, Scotland, and Wales. It features deities like Morrigan, Cernunnos, and Brigid, and delves into themes of nature, magic, and the heroic exploits of legendary figures like Cu Chulainn.

3) The "Star Wars" franchise, created by George Lucas, has become a global phenomenon with numerous films, TV shows, books, and merchandise.

4) 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.