Neither the laws of physics nor a 30-year time difference will stop young Sheldon from appearing in his forbearer show, The Big Bang Theory. Before the long-running CBS sitcom goes off-air after the current season, Iain Armitage will appear as little Sheldon Cooper in a crossover event that’s being kept mostly secret for now. George Cooper Sr. (Lance Barber) and Georgie (Montana Jordan) will also somehow find their way to TBBT, according to The Hollywood Reporter, but it is not yet known if there will be some kind of wormhole or time-travel experiment that lands all three Young Sheldon characters in present-day Los Angeles — or if there will just be a pedestrian dream sequence or flashback scenario that throws them all together sometime this December.