Ball lightning is a rare and unexplained phenomenon described as luminescent, spherical objects that vary from pea-sized to several meters in diameter. Though usually associated with thunderstorms, the observed phenomenon is reported to last considerably longer than the split-second flash of a lightning bolt, and is a phenomenon distinct from St. Elmo's fire.

Pyotr Leonidovich Kapitsa or Peter Kapitza was a leading Soviet physicist and Nobel laureate, whose research focused on low-temperature physics.