"Kugelblitz" normally refers to "ball lightning", but what I only recently discovered is that astronomers also use the term for a special (and so far theoretical) kind of black hole - a black hole made of light!
Einstein's famous formula for mass and energy tells us the precise relationship between mass and energy, and so what can be calculated using mass can also be calculated using light.
If a black hole can be formed due to massive amounts of mass, then it can also be formed due to even more massive amounts of energy in the form of light.
Original open collaboration version from Paploviante:
https://soundcloud.com/paploviante-and-friends/black-hole-paploviante-open-collab
