The Best Time Travel Stories Don’t Change The Past
The Hulk was right, as it turns out.
The 1980s were weirdly rich with time travel movies. Everyone knows Back To The Future, Terminator, even Peggy Sue Got Married. But the best ones were the movies like The Final Countdown and Timerider, where they couldn’t change the past—no matter how hard they tried—because as it turns out, that’s probably how the universe actually works.
Bruce Banner tried to explain this in Avengers: Endgame. When you go back to the past, the present you just left becomes your past, and the past becomes your new present. But because it’s also your past, you can’t change anything in the present that you don’t already remember as the past.[1]
What he’s talking about is what’s called a Block Universe. One of the consequences of four-dimensional spacetime as Einstein describes it in his theories of relativity is that time is just a dimension, like length, width, and depth. To an observer standing outside our universe, the entire thing, past, present and future, is a single block of spacetime.
Think of it like a roller coaster. When you’re in one of the cars, you’re traveling along surprising twists and turns, and it feels like you’re going somewhere. But while every new section of track is novel to you, to someone standing—sensibly, I’m not big on roller coasters—on the ground, the entire structure exists as a piece. There are parts you haven’t gotten to yet, but they already exist. You’re just tracing a pre-existing pattern built into the structure.
Spacetime works the same way. The future is just as real as the past, and the flow of time is an illusion. As is free will. You still have to decide to get up and go to work every day, because the lack of free will doesn’t, alas, mean a lack of consequences, but that observer standing outside the universe knows you will go to work tomorrow. Because they can see it.
Which brings me back to time travel. My favorite time travel stories accept the idea of a block universe and posit that if you did travel back in time, you would find that no matter how hard you try to change things, you are part of what already happened—and you often end up causing the very thing you’re trying to prevent (while not an 80s movie, Twelve Monkeys was a great example of this).
Spoilers for movies that came out 40 years ago, but in The Final Countdown, the aircraft carrier USS Nimitz goes through a freak storm and finds itself west of Hawaii on December 6, 1941. A nuclear-powered aircraft carrier armed with F-14 Tomcats and A-6 Intruders could have demolished the Japanese fleet singlehandedly and prevented the attack on Pearl Harbor, and the crew has to decide if that’s the right thing to do, or if getting America into the war against the Nazis was more important.
In Timerider, Tremors star Fred Ward plays Lyle Swann, a dirt bike racer who cuts through a government experiment in the desert and finds himself in the old west. I won’t spoil too much, but the interactions he has there are a wonderful subversion of the grandfather paradox.
In both cases, the characters find themselves “on rails,” and any changes they make, like people left behind in 1941, turn out to be parts of the past that already happened. Physics tells us that while travel to the past may well be impossible, if it were accomplished this is exactly what we’d find. I think the reason we don’t see time tourists from the future is either that travel backwards turns out to be impossible after all, or it turns out to be of interest only to academics (paging Connie Willis) because the past is impossible to change, so there’s no profit in it.
To me, there’s something immensely satisfying about time travelers becoming instrumental in bringing about the history they tried to escape. It turns time travel from wish fulfillment into tragedy, irony, and cosmic engineering.
What about you? Do you prefer time travel stories where history can be rewritten, or the ones where the trap was already closed before anyone stepped into the machine? Drop a comment and let me know.
If you subscribe to the Many Worlds interpretation of quantum mechanics, you might be screaming, “what about the multiverse!” Yes, you can argue that you can make different choices in the past, but then your consciousness simply branches to follow the you in the new universe that choice spawns. There are great stories about that, too, like Dark Matter and most of the MCU, but that’s not what we’re focused on here.↩︎