Short answers, pulled from the story.
John Lennon wrote the lyrics to Tomorrow Never Knows in January 1966. He drew these words from a book titled The Psychedelic Experience: A Manual Based on the Tibetan Book of the Dead authored by Timothy Leary, Richard Alpert, and Ralph Metzner.
Recording sessions for Revolver began at 8 pm on the 6th of April 1966 in Studio Three at EMI Studios. Geoff Emerick served as the recording engineer during this process.
The song relies heavily on a high volume C drone played on a tambura instrument with George Harrison introducing Indian musical elements. Engineers achieved a swirling effect by running Lennon's vocal through a Leslie speaker cabinet and using thirty tape loops created by technicians.
Initial reception included harsh criticism from publications like NME and Record Mirror which described the track as nonsense or gibberish. Despite this backlash Pitchfork ranked the track at number 19 on its list of The 200 Greatest Songs of the 1960s and Rolling Stone placed it at number 18 on their list of the 100 greatest Beatles songs.
Jimi Hendrix, Frank Zappa, and The Chemical Brothers used similar extreme tape-speed manipulation or referenced the song in their work. John Foxx of Ultravox cited the song as containing almost everything he wanted to investigate for the rest of his life while DJ Spooky stated the use of tape collage makes it one of the first tracks to use sampling really successfully.
The song appeared as the fifth episode of the third season of The Beatles Cartoon on the 14th of October 1967 and served as the soundtrack to Bruce Conner's film Looking for Mushrooms in 1967. It was also licensed for the 1997 James Bond film Tomorrow Never Dies and the Mad Men episode Lady Lazarus with rights costing producers around $250,000.