In November last year, the paper “The Large N Limit of Superconformal Field Theories and Supergravity” by Juan Maldacena had its 20th anniversary. It is by now the most cited physics paper of all time. In it, Juan Maldacena discovered the Ads/CFT-correspondence, that is as far as I understand it (and I don’t) is a duality between certain quantum field theories (without gravity) and certain spaces (anti-de Sitter spaces) that do contain gravity. Unfortunately, though, these spaces don’t describe our universe since AdS-spaces are universes with a negative cosmological constant while our universe has a small positive one. However, a lot of interesting insights came out of this (and it made Stephen Hawking concede his famous bet with John Preskill about whether information is lost or not in a black hole).
Here is a nice twitter thread celebrating the AdS/CFT-correspondence: