Were it not for WingNut Films’ machine assisted learning tech, Peter Jackson’s 2021 The Beatles: Get Back Disney Plus docuseries might not exist the way it does today, and that very same artificial intelligence that made that project possible is why the music group’s final song will soon be available to the public for the first time. Earlier this year, Paul McCartney teased that the same tech Jackson used to de-mix and isolate all of the Beatles’ speaking voices in old footage had also made it possible to recover John Lennon’s vocals from an old cassette of “Now and Then” — an unfinished track recorded as a demo back in the 1970s. Today, the group announced that, after decades of lying in wait, “Now and Then” is finally being released as...