The Alternative Factor

TOS Season 1 Episode 27
Air Date: March 30th, 1967

This episode was probably the worse writing wise in the season. The Enterprise arrives in a system and are scanning a planet that appears void of life. Then the Enterprise is rocked. Spock determines that the cause was the universe had "wink" out of existence for a second. There were reports from Starfleet that the effect had occurred across the whole galaxy, but not as strong.

When they check the planet again, it turns out it was the origin of the "wink" and now there is a life form on the planet. When they get to the planet they find a humanoid named Lazarus. Lazarus claimed there is a being on the planet that threatens to destroy the universe and that he needs dilithium crystals to stop him.

It turns out that after a bunch of deceptions and Lazarus acting like he has two personalities, Kirk finds out that there are two Lazarus. One from an alternate dimension made completely of antimatter. The other Lazarus claims that if the two meet, they would destroy both universes, unless they met in the doorway between dimensions. So Kirk sends his Lazarus into the doorway and the antimatter Lazarus holds him there while Kirk destroys the doorway effectively leaving both Lazarus stuck for eternity.