One of the running gags in the Back to the Future movies is the Hollywood equivalent of a closed timelike curve – in which a time traveler brings an innovation back from the future and invents it in the past, so that it exists in the future. For example, there’s Michael J. Fox as Marty McFly, doing the “Johnny B. Goode” duckwalk that inspires Chuck Berry’s signature move, 30 years earlier in 1955.
This week marks the flip side of that record: In Back to the Future Part 2, Marty travels ahead from 1985 to Oct. 21, 2015 – and brings back glimpses of a weird future world where flying robots roam the skies and the Cubs are contenders. It’s one thing to talk about which technologies the movie got right (fingerprint recognition) or wrong (dog-walking drones). But what’s really interesting are the technologies that arguably take a page from the “BTTF” script and close the time loop, just in time for Marty’s arrival.