time-travel-3
Explanation
The Joke
A child asks their father if it's possible to go back in time and meet your own grandfather. The dad says he keeps time-traveling and introducing himself, but his grandfather never seems to believe it and keeps wandering off. Another character suggests that if they have a time machine, they could do something grander — like preventing wars or crossing the Atlantic. The dad responds that he's "down to just killing random people who annoy me, and also I keep on existing." In the final panel, the characters discuss: "Wait, you have a time machine and you don't want yours? Give it to me!" and the dad replies that once he succeeds, he'll never have been born at all, so none of it will have mattered.
The Humor
The comic takes the classic "grandfather paradox" of time travel and makes it personal and absurd. Instead of a philosophical thought experiment, the father is literally trying to meet his own grandfather, with comically mundane results — the grandfather just ignores him and wanders off. The joke escalates when it becomes clear the dad isn't trying to have a heartwarming family reunion; the implication leans toward the darker version of the grandfather paradox (would you go back and kill your own grandfather?), but treated with casual indifference rather than dramatic weight.
The humor also comes from the contrast between having access to a time machine — one of the most powerful devices imaginable — and using it for petty, self-destructive, or pointless purposes.
Broader Context
Time travel paradoxes are a recurring theme in SMBC, and Weinersmith enjoys exploring them not through rigorous physics but through the lens of human pettiness and poor decision-making. The grandfather paradox is one of the most well-known thought experiments in physics and philosophy, and this comic deflates it by showing that actual humans would probably use time travel for trivial or self-sabotaging reasons.