The Epstein Drive: Why The Expanse Makes Me Love the Future—and Feel Impatient With the Present

Some science-fiction ideas are entertaining thought experiments. Others quietly rewire how you think the future should work.

Cast of The Expanse television show

The Epstein Drive belongs firmly in the second category.

The first time I encountered it in The Expanse, something clicked almost immediately. It wasn’t flashy like warp drive or mystical like hyperspace. It wasn’t framed as magic or destiny. Instead, it felt like an inevitable technological step—something humanity would eventually build once it became sufficiently serious about space.

And that’s exactly why it’s so frustrating.

Because once you accept the logic of the Epstein Drive, it becomes very difficult to look at the current state of space propulsion without feeling disappointed. We live in a world where computing power explodes year after year, artificial intelligence accelerates at an astonishing pace, and materials science routinely produces breakthroughs. Yet when it comes to traveling between planets, we are still crawling along on trajectories that take most of a year to complete.

Once you’ve imagined a better way, seven months to Mars starts to feel absurd.

A Drive That Changes Everything

In the universe of The Expanse, the Epstein Drive is a fusion-powered engine capable of sustained, efficient, high thrust over long periods of time. Ships accelerate continuously—often at fractions of Earth’s gravity—for days or weeks. At the midpoint of a journey, they flip around and burn in the opposite direction, decelerating smoothly until arrival.

This simple capability reshapes the entire solar system.

Instead of distant worlds reachable only through carefully timed orbital transfers, planets and moons become meaningfully connected. Trade becomes viable. Political power shifts. Cultures evolve in response to proximity rather than isolation. Space stops being an occasional destination and starts feeling like a place people actually live.

What makes the Epstein Drive so compelling is that it doesn’t violate physics. There’s no faster-than-light travel, no reactionless thrust, no hand-waving away of momentum or conservation laws. The drive obeys Newton and Einstein just fine. It merely assumes that humanity has solved a handful of extraordinarily difficult engineering problems—and then explores what happens next.

That restraint is why it feels real.

Hard Science Fiction Done Right

The novels, written by James S. A. Corey, are deeply respectful of real physics. Acceleration matters. Orbits matter. Time delays matter. Space is big, hostile, and unforgiving.

When the Epstein Drive is introduced, it isn’t treated as a miracle. It’s treated as a disruptive breakthrough—one that arrives suddenly, destabilizes existing power structures, and leaves humanity scrambling to adapt. That reaction feels authentic, because it mirrors how transformative technologies have behaved throughout history.

Steam power didn’t just improve transportation; it rewrote economies. Electricity didn’t just light homes; it reshaped society. The internet didn’t just connect computers; it altered politics, culture, and warfare.

The Epstein Drive fits comfortably into that lineage. It’s not just an engine—it’s the keystone that turns humanity into a truly interplanetary civilization.

Why the Epstein Drive Feels Plausible

The uncomfortable truth is that the Epstein Drive isn’t built on fantasy physics. At its core, it resembles a concept aerospace engineers have discussed for decades: the fusion torch drive.

Fusion offers an extraordinary energy density. Unlike chemical reactions, nuclear fusion converts a measurable fraction of mass directly into energy. If that energy could be harnessed efficiently and directed as exhaust, it would allow exhaust velocities far beyond anything we use today.

Exhaust velocity is the heart of propulsion. Higher exhaust velocity means more momentum change per unit of fuel. It means you can keep accelerating without carrying impossibly large propellant tanks. It means sustained thrust stops being a dream and starts becoming a design goal.

In other words, the Epstein Drive doesn’t require new laws of physics. It requires that we become exceptionally good at using the ones we already understand.

Where Reality Pushes Back

So why don’t we have anything like it?

Because space propulsion is merciless, and the Epstein Drive neatly sidesteps the three hardest constraints engineers face.

• The first is heat. Any engine powerful enough to accelerate a spacecraft at a constant fraction of Earth gravity would generate staggering amounts of waste heat. In space, heat can only be removed by radiation, and radiation is astonishingly inefficient. A real Epstein-class engine would require massive radiators—structures far larger than the ships depicted in the series.
• The second constraint is power density. Sustained acceleration demands an enormous and continuous power output from a system that must remain compact and lightweight. Fusion theoretically offers this, but in practice we haven’t even achieved a stable, net-positive fusion power plant on Earth yet. Miniaturizing one for spaceflight remains a monumental challenge.
• The third limitation is materials. A functioning fusion torch would expose nearby structures to intense radiation, extreme temperatures, and violent plasma flows. The materials required to survive those conditions for months at a time—while remaining light enough to launch—do not yet exist.

None of these problems are impossible. They’re simply very, very hard.

Why Propulsion Feels Stuck in Time

What makes this gap especially frustrating is how stagnant propulsion feels compared to other technologies.

Chemical rockets are refined descendants of mid-20th-century designs. They’re powerful, but their burns last minutes. After that, spacecraft coast along paths dictated almost entirely by gravity.

Electric propulsion, such as ion engines, is genuinely impressive. These engines can run for years, accumulating enormous total velocity change. But their thrust is so low that acceleration is almost imperceptible. They are perfect for robotic missions and completely impractical for rapid human travel.

Nuclear thermal propulsion improves efficiency, but only briefly. Nuclear electric propulsion shows promise, but acceleration remains modest.

We know how to go fast, and we know how to go efficiently—but doing both at once remains frustratingly out of reach.

Could the Epstein Drive Ever Exist?

Despite all this, I don’t think the Epstein Drive is pure fantasy.

To build something truly Epstein-like, we don’t need a single miracle. We need sustained progress across several domains. Fusion power must become reliable and practical. Heat rejection systems must improve dramatically. Materials science must deliver structures capable of surviving extreme environments.

Organizations like NASA already study advanced propulsion concepts seriously. The distance between those efforts and the Epstein Drive is large—but it’s a gap of scale and engineering, not imagination or physics.

The Cost We Rarely Acknowledge

There’s no avoiding the uncomfortable truth: an Epstein-class propulsion system would be staggeringly expensive.

We’re talking about investments measured in hundreds of billions of dollars over decades. Entire industries would need to be built. Safety frameworks would need to be rewritten. Failure would need to be tolerated.

But history shows we’re capable of that level of commitment. We’ve done it for nuclear technology, spaceflight, and global communications. The barrier isn’t feasibility—it’s priority.

Right now, fast interplanetary travel simply isn’t something we’ve collectively decided to pursue with urgency.

Why The Expanse Endures

What makes The Expanse so powerful isn’t that the Epstein Drive solves everything. It doesn’t end conflict. It doesn’t eliminate inequality. It doesn’t fix human nature.

It just removes distance as an excuse.

Once distance no longer protects us from ourselves, all our familiar problems scale up to the solar system. Politics, exploitation, cultural friction—they all follow us outward. That honesty is what makes the series feel so grounded.

And perhaps that’s why the Epstein Drive resonates so deeply. It’s not a fantasy of perfection. It’s a challenge—a reminder that the universe didn’t impose a speed limit on us. We did.

Until that changes, I’ll keep rereading the books, imagining flip-and-burn trajectories, and wondering why it still takes seven months to reach a planet that’s practically next door.