1) In Norse mythology, the World Tree, known as Yggdrasil, is a massive ash tree that connects the nine realms of existence. It is considered the center of the cosmos and serves as a conduit between different realms, including Asgard (realm of the gods), Midgard (realm of humans), and Helheim (realm of the dead).

2) Cyclones play a vital role in Earth's climate system by redistributing heat and moisture, maintaining global temperature patterns, and influencing weather patterns.

3) The first successful mass-produced personal computer, the IBM PC, was introduced in 1981 and played a significant role in popularizing the use of computers in homes and offices.

4) The speed of light is approximately 299,792,458 meters per second.