How Time Travel Happens In Star Trek IV: The Voyage Home
In Star Trek IV: The Voyage Home, time travel is achieved through some pretty strenuous circumstances. A vessel attempting to travel through time needs to calculate an exact slingshot orbit around the Sun, while speeding at close to Warp Factor 10. This is pretty hard no matter what ship you’re using, but it’s even harder when the only craft available is a rickety Klingon Bird of Prey. Time travel also requires a lot of energy, as the Dilithum Crystals of said vessel need a recharge through some nuclear energy stolen from the a naval vessel, coincidentally named the Enterprise, in 1986. When the conditions are right, one hell of an LDS trip awaits, as traveling in time apparently involves rudimentary CGI likenesses of all the participants as they travel through the time stream. Seriously, it’s weird, even for Star Trek.
Article source: https://www.cinemablend.com/news/2551874/how-star-trek-ivs-time-travel-works