1) The smallest unit of time is known as a zeptosecond, which is equal to one trillionth of one billionth of a second.

2) Dwayne "The Rock" Johnson is an American actor, producer, and former professional wrestler. He has become one of the highest-paid actors in Hollywood, known for his roles in films such as the "Fast & Furious" franchise, "Jumanji," and "Moana."

3) The concept of gravity was famously described by Sir Isaac Newton after an apple fell on his head.

4) The Southern Ocean surrounds Antarctica and is the coldest and least-visited ocean.