A man awakes in some kind of lab, his body riddled with tubes and wires. Nearby, a robot asks him what two plus two is. He can’t remember his name, where he is, or how he got here. At least he knows two plus two is four.
Actually, he knows a lot more than that. Walking around the lab, he finds a test tube and a stopwatch. Using the stopwatch to time how long it takes for the test tube to fall to the floor, he calculates that the gravity is stronger than on Earth. He reasons he must be in outer space. Some more tests reveal he’s not just in space but another solar system — one several light-years away from Earth, further than any human or space probe has ever ventured.
Gradually, his returning memories fill in the gaps. He is Ryland Grace. He’s an expert on speculative astrobiology, turned junior high school science teacher. He’s on a spaceship headed for the star Tau Ceti, and he’s part of a last-ditch, one-chance mission to save humanity from an extinction event.
This is the start of Project Hail Mary, a 2021 science fiction novel by software engineer turned bestselling author Andy Weir. Weir burst onto the sci-fi scene with his first book, The Martian, a tale about an astronaut stranded on the Red Planet. If you aren’t familiar with the book, you may be familiar with its critically acclaimed 2015 film adaptation starring Matt Damon.
Project Hail Mary has now been given the silver-screen treatment, too. Directed by Phil Lord and Christopher Miller, the duo behind The Lego Movie and Spider-Man: Into the Spider-Verse, and with Ryan Gosling in the lead role, Project Hail Mary has received critical praise for its humor and heart. But it’s the science that steals the show.
See, the novel is what is called “hard science fiction,” a category of the genre that’s particularly concerned with technical detail and scientific accuracy. In Dune or Star Wars, two examples of “soft science fiction,” you don’t learn how many of the futuristic devices, vehicles, and weapons actually work. The characters press a button, and the machines do whatever the plot needs them to. Even when you do learn how they work, descriptions of kyber crystals and psychedelic space travel are no more scientifically accurate than tales of dragons or rings to rule them all.
Not so in Project Hail Mary. Where Luke Skywalker and Paul Atreides face off against Sith Lords and giant sand worms, Grace struggles with fuel conservation, equipment sterilization, and atmospheric pressure. To some readers, these topics may sound boring, but in the right hands, hard science fiction can prove as gripping and immersive as the best stories in any genre.
In many ways, Weir tells Big Think in an email interview, the challenge of writing hard sci-fi isn’t too dissimilar from teaching a high school science class. Whether you’re trying to tell an engaging story or inspire rowdy teens, you’re wrestling with the same question: How do I make this stuff interesting to people who aren’t fellow nerds?
Down to a science
You’d think the trickiest part of writing hard science fiction would be explaining the science. Too much explanation, and your story risks reading like a textbook. Too little, and only graduate students will be able to follow along. It’s a balancing act — not in the least because it requires equal doses of scientific knowledge and creative writing skills — but Weir isn’t too worried about the exposition in his novels. The way he sees it, it’s not about what you say but how you say it.
“I’ve found that the audience will forgive any amount of exposition as long as you make them laugh while learning it,” he tells Big Think.
This is certainly true in Project Hail Mary, where Grace delivers the scientific know-how as if he were teaching his students. Befitting the “cool” teacher vibe, he knows how to hold your attention: His delivery is animated, his passion for science infectious, and his humor a mix of snarky and corny — if occasionally cringeworthy — that can’t help but grow on you. Whatever the day’s lesson, Grace finds a way to make it absorbing.
A greater challenge for the hard sci-fi writer is perhaps the demand for logical consistency. In soft sci-fi, authors can bend or outright ignore the laws of physics and other sciences so long as it serves the story. Hard science fiction doesn’t often afford that luxury. In this category, accuracy is sacred and the rules, once established, are unbreakable. For such stories to work, each contradiction has to be hammered out, variables accounted for, and plot holes filled and covered with grass.
For instance, a potential plot hole Weir needed to address in Project Hail Mary was the absence of artificial intelligence. He knew he didn’t want to put an AI on Grace’s spaceship because, if he did, Grace wouldn’t need to solve any problems. He could just ask the computer and wait for the answers. Still, Weir couldn’t leave this absence unaddressed. We live in a world with AI already; why wouldn’t the characters in his sci-fi story have access to the tech? The justification he eventually came up with is simple but convincing: The organizers of Grace’s mission decide to use only tried-and-tested technology; AI, a relatively new development, was deemed too hazardous.
Soft sci-fi writing also tends to start with a story and invent the necessary science as it goes; for hard sci-fi, it’s often the other way around. In Weir’s case, the seed that would sprout into Project Hail Mary wasn’t Grace’s character or mission. It was the technology powering his spaceship.
It all starts with the science. Everything works around that.
“I wanted humanity to have a mass-conversion fuel,” Weir says, referring to a type of fuel that would theoretically allow for interstellar space travel. “And not in a thousand years, but right now. A mad scientist inventing it seemed like too much of a stretch. I considered the fuel coming from a crashed alien ship, but then how would we make more of it? Finally, I thought of fuel in the form of an organism we could breed and harvest.”
With this central concept established, each new plot point flowed from the previous one — not unlike how an unsolved mathematical equation already contains its own solution. “I asked myself, ‘Why would a life-form like this evolve?’” The question led him to the idea of Astrophage: a kind of space mold that feeds on stars, powering them down and causing climate disaster on Earth-like planets.
But while Weir will play with his own scientific inventions, he tries to keep them to a minimum. This helps ensure his stories remain logically consistent. “Once you start making up physics,” he explains, “you have to make up more when edge cases come up. In Project Hail Mary, you really have to drill down to the quantum level to find violations of the laws of physics.”
As a result of this commitment, these stories tend to take on a life of their own. What happens next will be dictated as much by the author’s understanding of the scientific concepts they have chosen to explore as by their imaginations.
Grace is sent to Tau Ceti because it’s the only star in the observable Universe not infected by Astrophage. Why is Tau Ceti not infected? Because it’s home to Astrophage’s natural predator: amoeba-like organisms Grace dubs “Taumoeba.” Why did Taumoeba not spread across the galaxy along with Astrophage? Because it, unlike Astrophage, the species cannot survive in atmospheres different from the one in which it evolved. Inventive? Definitely. But also firmly rooted in our understanding of the Universe’s physical laws.
“It all starts with the science,” he adds. “Everything works around that.”
Not your grandfather’s two-legged aliens
The best hard sci-fi is engaging and immersive, not in spite of its commitment to scientific credibility but precisely because of it. The less a story asks you to suspend your belief, the more compelling the obstacles become, and every victory feels earned.
In many space stories, characters can steer a spaceship or perform an extravehicular activity (aka “spacewalking”) as easily as they brush their teeth or tie their shoelaces. But in hard sci-fi stories like Weir’s, where dangers and complications aren’t easily brushed aside, such activities are filled with suspense. For amnesiac Grace, even using his spaceship’s user interface is a puzzle to solve.
This also allows hard sci-fi writers to breathe new life into tired tropes. Science fiction is littered with aliens that are basically Los Angeles natives with prismatic skin conditions. They breathe oxygen, are bipedal, and speak English courtesy of their universal translators. Hard sci-fi, meanwhile, leans into the fact that life evolving on other planets, under different conditions, and across different stretches of time will almost certainly take on forms so different from ours that comprehending them would be like imagining a new color.
“I didn’t want [my alien] to be comfortable in our atmosphere or to look like a human with forehead bumps,” Weir says of Grace’s alien companion. (Yes, he runs into a sentient alien, and it’s one of the best parts of the book.) “I wanted an absolutely alien alien.”
Of course, scientific credibility isn’t worth much if the story doesn’t keep readers engaged. On that level, Project Hail Mary reads like a mystery thriller. Like Sherlock Holmes or Benoit Blanc, Grace relies on reasoning to uncover the truth — only, in his case, billions of lives depend on his deductions. On another level, the novel almost resembles a philosophical treatise celebrating the power of human reason. Yes, Grace uses a variety of gadgets and gizmos to save Earth, but ultimately it’s his own brainpower that does most of the heavy lifting. Aristotle would surely approve.
But while hard sci-fi may place more emphasis on its internal logic, coherence and consistency are important to any story — no matter the genre. When the fantasy TV show Game of Thrones approached its grand finale in 2019, many fans took issue with how the story began ignoring its own parameters and precepts. Journeys that used to take entire seasons were being covered in single episodes, characters survived predicaments that once meant surefire death, and previously relevant factors like supplies, infrastructure, and alliances no longer mattered.
The lesson is that without internal logic, any story will lose its believability and, with it, its appeal.
“As a reader, the only thing that matters to me is consistency,” Weir says. “If a story has a spaceship that can go faster than the speed of light, it shouldn’t take you a week to get from Earth to Mars.”