Veritasium explains black holes, white holes and wormholes

Cited in black hole threads as an approachable introduction to Penrose diagrams and what happens inside a black hole.

Veritasium explores what general relativity says about black holes, white holes and wormholes, with help from physicists Geraint Lewis and Juan Maldacena. It introduces Penrose diagrams and the idea that other universes may be implied.