1) Kim Kardashian West is an American media personality, businesswoman, and socialite. She gained fame through reality television show "Keeping Up with the Kardashians" and has built a successful brand empire encompassing fashion, beauty, and other ventures.

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

3) The recent advancements in space exploration include missions to Mars by various space agencies, such as NASA's Perseverance rover landing on Mars in 2021, aiming to explore the planet's geology and search for signs of past microbial life.

4) In Norse mythology, Valhalla is a majestic hall located in Asgard, the realm of the gods. It is the afterlife destination for brave warriors who die in battle, where they are greeted by the Valkyries and engage in feasting, drinking, and preparing for the final battle of Ragnarok.