How plausible is ‘Project Hail Mary’? Experts have thoughts

“The stars weren’t big enough,” Mark Popinchalk said. “Stars are really big.”

Popinchalk, a postdoctoral fellow at the American Museum of Natural History in New York, was voicing a quibble with “Project Hail Mary,” the sci-fi blockbuster. Starring Ryan Gosling as Ryland Grace, a reluctant astronaut, it follows a desperate mission to save the human race, through perilous interstellar travel and some nifty microbiology experiments.

The film has inspired online argument about everything from its cheery vision of international cooperation to Grace’s rumpled, cardigan-friendly style. But much of the debate has centered on the film’s science.

In some ways, this is silly. “Project Hail Mary” is a work of science fiction, emphasis on the fiction. And while it’s possible to get caught up in the wattage of a lightsaber or the precise speed a warp drive allows, such speculation is extraneous to the stories. But this movie is based on a novel by Andy Weir (“The Martian”), who writes hard science fiction, which blends imagined tales with fact, or at least plausibility. As Weir said recently, scientific accuracy is his “whole shtick.”

So discussions of the science of “Project Hail Mary” aren’t exactly ancillary. Armchair physicists and even some actual physicists have powered countless online threads with questions around interstellar travel, alien life and why Grace, who has a doctorate in microbiology, can’t seem to balance a centrifuge.

The film, like the book, relies on a premise that a microbe called astrophage, a fictional space mold, has entered our solar system, absorbing enough of the sun’s light to send Earth into an ice age. It has also attacked other suns, imperiling other planets. Jillian Bellovary, a scientist who directs the masters program in astrophysics at the CUNY Graduate Center, dismissed this crisis.

“Nothing can siphon the sun’s light away,” she said. “It’s a cute idea, OK, but that is not a thing.” This was also Popinchalk’s chief complaint, that the sun and similar stars are so massive that it would take a phenomenal amount of microbes to affect their light. Other scientific grumbles: that xenon, a noble gas, could transform into a pliant solid; that microbes can not only survive but even thrive in the vacuum of space; that the microbes would somehow power interstellar travel.

“It is very squishy,” Charlotte Olsen, an astrophysicist at the New York City College of Technology who specializes in galaxy formation, said of that idea. But Olsen didn’t mind the squish, in part because the film was accurate in many other ways, including its depiction of the silence of space, the physics of a spacewalk, the work of rotational gravity or a moment when Rocky, the alien engineer who befriends Grace, calls out the lameness of naming a planet Tau Ceti e.

“It’s true, astronomers are not good at naming things,” Popinchalk said. “That’s an actual astronomy thing.”

Many of the seemingly implausible ideas of “Project Hail Mary” have some basis in fact. There’s precedent for a dangerous calculation error and for the use of light emission to power spacecraft. Scientists have even been able to crystallize xenon, though they can’t yet manipulate it in the ways Rocky can. And if the idea that astrophage might harm the sun stretches credulity, a lack of light has plunged Earth into ecological crisis. Just ask a dinosaur. (Some Reddit wags have joked that the book’s great lapse is the insistence that Grace might walk from the Neutral Buoyancy Laboratory to the Mission Control Center in the Houston heat.)

“I didn’t get too upset at any of the scenes,” Bellovary said. “I was never like, ‘Oh, my God, that’s so wrong. That never actually happens.’ A pretty good score for science.”

What might delight scientists most is the depiction of scientific thought. While “Project Hail Mary” has its share of explosions and catastrophes, it’s the thinking that’s thrilling. Grace and Rocky must come together, with tools and whiteboards, craft and ingenuity, to solve a seemingly insoluble problem. They make mistakes, but they learn from those mistakes and from each other.

“Getting things wrong is really important in science, and that’s not something that people who aren’t scientists really know,” Bellovary said.

The film also shows the importance of cooperation. Grace bounced out of academia after his thesis was mocked, suggesting that he doesn’t work well with others. But in Rocky, a faceless, adorable life form, Grace finds a colleague.

“One of the core things that scientists do is collaborate,” Olsen said. “My take is that he learns to become a scientist because he learns how to collaborate.”

Before the mission, Grace worked as a middle school science teacher. (Could he pilot a spacecraft without proper training? That’s another detail the movie fudges.) Bridget Ierace, a high school science teacher and science communicator, thinks her students could learn a lot from the film.

“It shows the people behind the science,” she said. “It shows that scientists make mistakes and have emotions and that there are different things that drive them.” That’s not necessarily a lesson in physics or microbiology, but it’s still a good one.