I’ve read scenes where characters wake up from cryosleep like they just had a really long nap, and I’ve never once stopped to wonder if that’s actually possible. (Spoiler alert: it’s complicated.)
The thing about science fiction is that we bend the rules all the time. We need faster-than-light travel for pacing. We need artificial gravity so as not to detract from the reader’s experience. Also, sometimes zero-g is the point of the book (Zero G by Dan Wells).
Writers add things that make the story work, and we trust that readers will suspend their disbelief. But every once in a while, I stumble across actual science that makes me realize some of our favorite shortcuts aren’t as fictional as I thought.
Some sci-fi tropes are pure fantasy. Others? They’re surprisingly close to reality, or at least to what scientists are actively working on. Let’s look below.
1. Cryogenic Sleep Actually Has Some Science Behind It
In almost every space opera, there’s a scene where the crew climbs into sleek pods and gets frozen for the long journey between stars. They wake up decades later, stretch a little, and get right back to saving the galaxy.
The real version is a lot messier, but it’s not entirely fiction. Scientists have been researching medical suspended animation for years, particularly for trauma patients who need their biological processes slowed down to survive. There’s also fascinating work being done with tardigrades (those nearly indestructible microscopic creatures) and how they survive extreme cold.
The problem? Ice crystals. When you freeze human tissue, the water inside cells forms sharp crystals that shred everything from the inside out. We can cool people down temporarily, and we’ve made progress with cryoprotectants (chemicals that prevent ice formation), but we’re nowhere near freezing a whole person and bringing them back good as new.
Still, the fact that we’re even trying means this trope isn’t as far-fetched as it sounds. Would you volunteer to be frozen for a hundred-year journey?
2. Faster-Than-Light Communication Is Theoretically Impossible (Sorry)
One of the most convenient lies we tell in sci-fi is that characters can talk to each other in real time across star systems. It makes the story flow better. No one wants to read dialogue with a four-year lag between question and answer (Star Trek, Star Wars,…).
Here’s where it gets interesting: quantum entanglement exists. When two particles are entangled, measuring one instantly affects the other, no matter how far apart they are. It sounds exactly like the kind of loophole we need for instant communication, right?
Except it doesn’t work that way. The universe is kind of teasing us here. You can’t actually use entanglement to send information faster than light because the results on both ends are random until you compare them (which requires normal, slower-than-light communication). It’s like having two magic coins that always land on opposite sides, but you can’t control which side your coin lands on, so you can’t send a message.
The verdict? We have something that looks like sci-fi magic, but it doesn’t do what we want it to do.
3. Generation Ships Are Totally Possible (Just Really, Really Hard)
A generation ship is exactly what it sounds like: a massive spacecraft where people are born, live, and die during a journey that takes multiple lifetimes. It’s a staple of hard science fiction, and here’s the thing: there’s no physics-breaking magic required. We could, theoretically, build one right now.
The challenges are just engineering problems on a staggering scale. You’d need:
- A closed-loop ecosystem that recycles everything perfectly for centuries
- Shielding against cosmic radiation
- A rotating structure to provide a little gravity because some human functions need gravity to work well.
- To solve the psychological effects of raising generation after generation in a confined space where no one will ever see the destination except the last group.
But it’s possible. No faster-than-light travel required, no antigravity handwaving. Just an absolutely enormous amount of work, resources, and commitment.
I think that’s why generation ship stories resonate so much. They feel real in a way that hyperdrives don’t. They’re about human endurance and sacrifice, not just cool technology.
4. Artificial Gravity Exists, But Not the Way You Think
Here’s a trope that’s in literally every space show: characters walk around ships with normal gravity, as if the floor has some kind of magic generator underneath. (The Feeler Series)
The truth is we can create artificial gravity, just not with convenient crystals or floor panels. The method is rotation. Spin a habitat fast enough, and centrifugal force pushes everything toward the outer wall, creating the sensation of gravity (Ringworld by Larry Niven). It’s the principle behind O’Neill cylinders and rotating space stations.
The catch is that for it to feel natural, the structure has to be pretty big. Too small, and you get weird effects like feeling lighter when you stand up because your head is closer to the center of rotation.
The verdict? We can fake gravity pretty convincingly, just not the sleek, effortless way most sci-fi depicts it. But I’ll keep writing it the convenient way because no one wants to read three paragraphs explaining rotational dynamics every time someone walks across a room.
5. Asteroid Fields Are Way More Boring Than Movies Suggest
This one’s quick: remember every scene where a spaceship weaves desperately through a dense field of tumbling asteroids? Pure fiction.
Real asteroid belts are mostly empty space. Like, overwhelmingly empty. You could fly through the asteroid belt between Mars and Jupiter and probably never see a single rock out your window. The distances between objects are enormous.
But I like this trope. It makes for great action sequences, and sometimes you just need your characters to dodge some space debris for tension (Star Wars).
Final Thoughts
The funny thing about science fiction is that it’s never really been about predicting the future or getting every detail right. It’s about asking “what if?” and exploring the consequences. Some of our wildest ideas turn out to have roots in real science. Others are just narrative shortcuts that keep the story moving.
What surprises me most is how often the process works in reverse: science fiction inspires real scientists. The engineers designing tomorrow’s space habitats grew up reading the same stories I did. The researchers working on suspended animation probably watched the same movies. We imagine it first, and then someone figures out how to make it real.
Even when we get it wrong, we’re contributing to a conversation about what’s possible. And honestly? That’s the part I love most about writing in this genre.
Which trope do you wish was real? Or which one surprised you by actually having science behind it? I’d love to hear what makes you think twice about the “rules” we bend in our favorite stories.