March 20, 2026

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How accurate is the science in Project Hail Mary?

This science-fiction movie plays with quantum physics, space travel, astrobiology and mass-to-energy conversion

By Emma Gometz edited by Lee Billings

Ryan Gosling plays Dr. Ryland Grace in Project Hail Mary.

The much-anticipated sci-fi film Project Hail Mary is out in theaters today. In it, light-eating alien microbes sap the sun’s energy, threatening life on Earth with extinction. To find a solution, an unlikely hero—a middle school teacher played by Ryan Gosling—is sent on a one-way mission to the star Tau Ceti and encounters an otherworldly sidekick nicknamed Rocky along the way.

The premise is fantastical, but the concepts that inspired the story are real—and not as implausible as you might think.

Andy Weir, author of the eponymous book that inspired the movie, carefully researched the physics, astronomy and biology that drives the plot, and he even consulted on set to preserve scientific accuracy while actors ad-libbed during scenes.

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“Actors are very much part of the creative process, [but] sometimes the science on what they say would be wrong,” Weir says. “And so I’d go over to the directors, and then they’d say, ‘Oh, okay, well, let’s try that again, but this time say nanograms instead of milligrams.’”

In that spirit, Scientific American spoke with Weir, as well as an astrobiologist, a physicist and a couple of astronauts about the real-life science that inspired this work of cinematic fiction.

How do the film’s “Astrophage” work?

The film’s premise is that alien microbes called Astrophage (roughly translated from ancient Greek as “star eater”) colonize the sun and travel between our star and Venus to breed. As the population of star-hugging Astrophage grows, it dims the sun’s light, jeopardizing life on Earth.

Microbes could make a sun-Venus round trip with the right amount of power, but the journey would demand different amounts of it in each direction, says Chad Orzel, a physicist at Union College. “From the sun to Venus wouldn’t be that hard because there’s already a steady flux of [solar] particles going in that direction,” he says. The return trip “would require a bit more effort” to counteract solar wind, however.

Weir’s way of dealing with this problem, he says, was to imagine Astrophage as able to absorb neutrinos, so-called ghost particles that don’t tend to interact with other matter. A neutrino can slip untouched right through a light-year’s worth of lead, for instance, and every second tens of billions of them pass through every cubic centimeter of Earth—and through you, dear reader. Most of these neutrinos come from the sun, which is constantly spewing them out as it shines. But these ghost particles do carry mass (and thus energy via Albert Einstein’s handy equation E = mc2). If Astrophage could use the sun’s energy to create neutrinos within their cell membranes (the “science” gets very hand-wavy here), Weir mused, perhaps they could use the particles as propellant. Astrophage could convert most of the neutrinos’ mass back into energy (or, really, infrared light) that they would then directionally beam out to produce thrust.

Ryan Gosling as Dr. Ryland Grace in Project Hail Mary.

This (imaginary) process would be efficient and powerful. In the film, Astrophage make up the fuel that powers the Hail Mary, the ship that takes Gosling’s character to Tau Ceti.

“The idea is out there,” Orzel says. “If you want to completely convert matter into energy, the way you usually go about that is by combining it with an equal amount of antimatter. [But] there just isn’t that much antimatter running around.”

Are Tau Ceti, 40 Eridani and the planet Adrian real places in the universe?

Yes, these places really exist, though Adrian is a fictional name. Tau Ceti is a star about 12 light-years away from Earth, and 40 Eridani, the Astrophage-plagued star system that Rocky is from, is about 16 light-years away from Earth. Adrian, the Tau Ceti world that the characters visit, really exists in astronomers’ exoplanet catalogs as Tau Ceti e (although we know very little about it).

In the grand scheme of things, these places are not all that far apart. Using nearby stars that are similar to ours in the story, Weir sa

How accurate is the science in Project Hail Mary? | Scientific American