As the brave crew of the Enterprise are returning to Earth on a Klingon Bird of Prey to stand
trial for the events of the previous movie,
Spock determines that
Earth’s demise is imminent unless they can return to 1986 and retrieve a humpback whale
(which they proceed to do).
I saw this in the theater with Deb Baker and Jon Shultis during
a winter trip to Pittsburgh for a small computer science education conference.
— Michael Main
McCoy: You realize that by giving him the formula you’re
altering the future.
Scotty: Why? How do we know he
didn’t invent the thing?