Escape velocity
“To infinity and beyond”, may be the catchphrase of Buzz Lightyear (one of the Toy Story heros) but why would someone, or something, need to get to infinity in the first place? Well, one reason could be in order to completely escape the clutches of a gravitational field, and that means travelling at escape velocity. Gravitational fields extend to infinity, so for Buzz to truly escape one, he really would need to...