Where Andy Weir's Science Fiction Breaks Physics

There's a particular kind of writer who will memorize the exact wavelengths where CO2 absorbs infrared radiation just to get one throwaway line right in a novel about alien algae eating the sun. Andy Weir is that writer. And in a recent conversation with physicist Brian Keating, he explained exactly where he draws the line between rigorous science and necessary fiction—and why that line matters.

The answer involves neutrinos, quantum mechanics, and a philosophy about handwaving that's more interesting than most science fiction.

The Quantum Level Is Where Reality Ends

Weir's approach to writing hard science fiction sounds almost masochistic. For Project Hail Mary, his latest novel about a teacher-turned-astronaut trying to save Earth from an interstellar threat, he researched down to wavelengths and particle physics before allowing himself a single violation of known physics.

"I want to minimize the violations to physics that I have to do," Weir told Keating. "In the case of Project Hail Mary, you have to go all the way down to the quantum level, literally, before you find where I was handwaving."

The specific handwave involves neutrinos—those ghost particles that pass through matter so readily that trillions are moving through your body right now without interaction. In Weir's novel, they become a method for storing energy. The physics of neutrino annihilation? Real. The property where neutrinos serve as their own antiparticle? Real. The infrared photons that would result from their collision? Real, down to the specific wavelength.

The part where you can actually store neutrinos long enough to use them as a battery? That's the fiction.

"You can use neutrinos to store mass," Weir explained. "The problem is you can't store neutrinos. And so that's the part that I made up."

It's a remarkably contained violation—one that requires understanding the actual physics deeply enough to know exactly where the impossibility begins. This isn't a writer who gives his spacecraft a convenient warp drive and moves on. This is someone who goes down the rabbit hole until he hits bedrock, then drills exactly far enough to fit his story through.

The Credibility Budget

What Weir is managing, whether he'd frame it this way or not, is credibility. Every science fiction writer has a credibility budget with scientifically literate readers. Violate physics casually—invent a reactionless drive, ignore conservation of momentum, have sound in space—and you spend that budget fast. But earn trust through rigorous attention to detail everywhere else, and readers will follow you into the one place where you need them to suspend disbelief.

"I spend too much time and effort going further down the rabbit hole than I need to," Weir admitted, "where I could have just handwaved much earlier and nobody would have objected."

But that's the point. The exhaustive research isn't really about the neutrinos. It's about everything around the neutrinos—the orbital mechanics, the spectroscopy, the thermodynamics—being so accurate that when you finally encounter the impossible thing, you trust it belongs there. You trust the writer knows where reality ends and necessity begins.

Keating, who teaches cosmology at UC San Diego and apparently assigns The Martian as required reading, pressed on this balance. How do you know when you've gone too far?

"I never really think I've gone too far because I kind of, if anything, I spend too much time and effort going further down the rabbit hole than I need to," Weir said.

The Pandemic Coincidence

One thing Weir didn't plan: writing a novel about global cooperation against an existential threat right before a pandemic. He finished Project Hail Mary before COVID-19 emerged, making the parallels between his fictional crisis and our real one pure coincidence.

But the pandemic changed how he sees his own premise. "I would say more plausible," Weir said, when asked if COVID made his scenario of worldwide scientific mobilization seem more or less believable. "It kind of validates my beliefs that we can pretty much come together pretty significantly as a species to fight a common enemy."

The caveat matters, though. In Project Hail Mary, the threat is truly global—no individual nation can protect just its citizens. COVID allowed for fragmented responses. The novel's crisis is more like climate change, except faster and with no room for denial. Everyone dies if the problem isn't solved. That changes the math on cooperation.

"Obviously we weren't perfect about it," Weir said of humanity's pandemic response. "There was some sloppiness there." The understatement is very him.

The Amateur Question

Amateur astronomers play a role in Project Hail Mary, which prompted a digression into where amateurs still matter in science. Astronomy is one of the few fields where non-professionals contribute real research—variable star observations, binary star data, the kind of patient monitoring work that doesn't require billion-dollar instruments.

Weir himself is an amateur-turned-professional, a programmer who wrote The Martian as a serial blog before it became a phenomenon. He sees the pattern elsewhere: 3D printing advanced because amateurs with home kits worked out the kinks. Open-source software often outpaces corporate development. Art movements start with unknown artists in cheap studios.

"You can be a quote-unquote amateur and really have an effect on the field," Weir noted.

There's something optimistic in that framing, especially from someone whose own trajectory proves it. The credentialed institutions matter, but the boundaries are more porous than they appear. You don't need permission to figure things out.

What Gets Left Out

Weir is adamant about what doesn't go into his stories: messages, morals, meanings beyond the immediate plot. Project Hail Mary isn't about climate change, even though alien algae dimming the sun has obvious resonances. It's not about pandemic response, despite the global mobilization narrative. It's about a teacher who wakes up in space and has to science his way out of trouble.

"I never have any sort of meaning or message or moral in my stories," Weir said.

Whether that's entirely true is debatable—any story about ingenuity, resourcefulness, and scientific problem-solving under pressure is making an argument about what matters. But Weir's point stands: he's not using aliens as metaphors. The algae isn't standing in for capitalism or hubris or anything else. It's just algae that happens to eat solar energy, and that's enough.

That restraint might be what makes his fiction feel scientific rather than science-flavored. Real science doesn't come pre-loaded with meanings. It's just phenomena you're trying to understand. The meaning is something humans add later, and Weir trusts his readers to do that work themselves.

The movie adaptation is coming, which will require translating all that technical specificity into visual storytelling. But for now, the novel exists as this strange artifact: fiction that goes down to the quantum level before permitting itself a single lie, written by someone who could have cut corners much earlier but chose not to.

Because the corners are the whole point.

—Nadia Marchetti, Unexplained Phenomena Correspondent