Multiversal success and failure.  Success?   Star Trek TOS episode "Mirror, Mirror," and the 2017 Starz series, "Counterpart."  Failure?  It pains Driftglass to say it, but Robert Heinlein's "The Number of the Beast" is well-known as a massive fail in the multiverse and just plain science fiction novel genre.  (The Heinlein novel has some sexual situations that are discussed in this episode.)  And you can hear Patton Oswalt's magnificent Parks and Rec filibuster concerning "multiverses" here. More at sciencefictionuniversity.com. Support the show at  paypal.me/proleftpodcast or patreon.com/proleftpod, and thank you! Support the show