Thanks to the miracle of time travel – well, okay, the relatively less magical miracle of a newly discovered VHS tape – tonight’s new episode features Sheldon encountering his youthful alter ego. In other words, Old Sheldon meets Young Sheldon… but since the elder Sheldon is only watching on videotape, there’s no time paradox to worry about. And that’s just the sort of thing that would concern Sheldon greatly, at any age.