“The Visitor” is episode three of season four of Star Trek: Deep Space Nine.
This episode opens with an old man, who turns out to be an elderly Jake Sisko (Tony Todd), answering the door to a visitor. The young woman is an aspiring writer, who loves his work, and wants to know why he stopped writing. So he tells her the story.
When Jake was 18, he want with his father to the Gamma Quadrant. There was an accident, a discharge from the warp core, and his father was atomised. Several months later, Jake has a vision of the elder Sisko, which he thinks was a dream. Then, it happens again, and he is able to touch him.
It’s determined that Captain Sisko is out of time, in what is assumed to be a pocket of subspace. When the attempt to keep him here fails, Jake goes on with his life. Then his father appears again, and the cycle of appearances is determined. Jake devotes his life to trying to bring his father back, an attempt which takes the rest of his life.
The crew of the station appear with makeup to make them appear older. This is still not very effective.