There’s no future in time travel.

By Jeff Boortz, edited and edited for clarity by ChatGPT.

I’m not a physicist, but I recently fell down a rabbit hole of time-travel movies: Back to the Future, The Umbrella Academy, Everything Everywhere All At Once, and Frequently Asked Questions About Time Travel. And while Hollywood’s portrayal of time travel is entertaining, it left me wondering: what really defines a moment in time, and could we ever return to one?

The short answer: no. Not in the way movies would have us believe. Because, as I’ve come to see it, time isn’t something we move through—it’s something we create by moving.

Time Is Movement

Imagine trying to return to a specific moment, say 02:56 GMT on July 21, 1969—the instant Neil Armstrong set foot on the moon. That moment wasn’t just defined by Neil’s footprint in lunar dust. It was defined by everything—the position of every particle in the universe, from the lunar surface to a protestor in Haight Ashbury to the stars in the sky. To revisit that moment would require every particle in the universe to return to exactly where it was at that time.

But there’s a problem: everything is in constant motion. Not just people and planets, but the very particles that make up our bodies and the world around us. Their motion and changing relationships are what give rise to the perception of time. No movement? No time.

There Is No “Back”

If we wanted to return to a past moment, we’d have to reverse the vector of motion for every single particle in the universe. They would need to move, precisely and simultaneously, in the opposite direction to the one they’re currently on. And even if we could manage that miraculous reversal, it wouldn’t instantly send us back to 1969. It would take just as long to get there—55 years of reversed movement—because all motion is still forward motion.

Even worse: along the way, the particles in your brain responsible for your current memories would “unencode” as you moved backward. By the time you arrived in 1969, you wouldn’t remember your journey or even know you had come from the future. From your perspective, you’d simply be living in the present—because that’s all consciousness ever experiences.

Time Without Space Is Nonsense

Pop culture tends to forget that time is married to space. They’re a package deal: space-time. If you were to somehow leap back to 1955 in a DeLorean, as Marty McFly does, you’d find yourself in the vacuum of space. Earth wouldn’t be in the same location it was thirty years later. In fact, it would be millions of miles away. Without accounting for the motion of the Earth, Sun, galaxy, and universe, your trip through time would be a trip out of existence.

And don’t forget: the universe is expanding. To return to a moment in the past, space itself would have to contract at exactly the inverse rate of its previous expansion—a feat requiring godlike precision and control over the cosmos.

The Illusion of Time Machines

Our fascination with time travel hinges on the assumption that time is a dimension we can slide along like space. But that’s a misreading of Einstein’s insight. Time is more like a story unfolding from the interactions of moving matter. It’s emergent. Directional. Entropic.

Time travel, as depicted in film, would require not just an impossible rearrangement of matter, but a betrayal of thermodynamics and causality. Even the popular notion of multiple timelines—where every decision spawns a new universe—would demand infinite copies of all particles in existence, which violates fundamental laws of conservation.

A New Understanding

In the end, we don’t travel through time. We generate it by moving through space, moment to moment. The future is what we predict based on our current trajectory, and the past is a record of where we’ve been—nothing more.

Time isn’t a highway we can U-turn on. It’s a shadow cast by motion—a by-product of change.

And that, to me, is even more fascinating than a DeLorean with a flux capacitor.

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