The superhero genre isn’t exactly known for adhering to the laws of physics or other scientific principles, whether it’s making time travel possible in Avengers: Endgame or slinging from buildings on spiderwebs in Spider-Man: No Way Home.
But is it actually plausible for the Man of Steel to be super strong based on how gravity works? Further, could humans actually become real-life Supermen — either through human enhancement technology or by traveling to another planet?
We interviewed the experts to get their take on the science behind Superman’s super strength. Let’s dive in.
“Nothing about Superman makes any sense,” planetary scientist Paul Byrne tells Inverse.
Reel Science is an Inverse series that reveals the real (and fake) science behind your favorite movies and TV.
Is it realistic for Superman to be super strong on Earth?
In the Superman comics, Kal-El / Clark Kent draws energy from the Sun — but his super-strength comes from Earth’s gravity compared to his home planet.
The planet where Superman was born, Krypton, is much larger than Earth and exerts a larger gravitational force. In Earth’s lower gravity — known as 1g — Superman is able to do super-human feats like bending steel because the force of gravity doesn’t affect him as much.
Unfortunately, planetary scientists don’t think gravity is a very plausible explanation for super strength.
“Gravity would have no effect on that at all,” Byrne says.
Byrne compares Superman’s situation to astronauts going to the moon, which has 16 percent of the gravity of Earth, so a human on the moon would weigh only one-sixth of their weight on Earth.
“It is true that if you were on a planetary body with less gravity on Earth, you would be able to jump higher. There's less stuff you’re pushing against in terms of the downward pull of gravity,” Byrne says.
But while your weight changes, your mass does not. Weight changes on different planets because it takes into account how much force gravity exerts on the body, but mass is simply the amount of matter in your body. Even though you might be able to lift things slightly easier, you’re not actually super strong on another planet — certainly not to the point where it’s plausible Superman could bend steel simply due to Earth’s lower gravity.
“The steel is going to have the same strength on the Moon or a deep space as it does on Earth. So there's not gonna be any benefit,” Bryne says. “Even if Krypton somehow had six times the surface gravitational acceleration.”
Can humans achieve super strength by traveling to another planet?
Along the same lines, Internet denizens have proposed that humans could travel to a smaller planet with lower gravity and build muscle to become super strong like Superman, but that’s total nonsense, physicists say.
“To survive on another planet, you would have to become stronger — you couldn't even move around. But you're not just gonna go there and become strong,” Richard Muller, an emeritus professor of physics at the University of California, Berkeley, tells Inverse.
Byrne says we have a good example of a smaller planetary body with lower gravity — the Moon — and yet no astronaut has achieved super strength simply by stepping on the lunar surface.
In fact, we need Earth’s 1g gravity to stay healthy, and going to a place with lower gravity would likely make you weaker — not stronger.
“It turns out that our bodies are musculature and our bones need gravity,” Byrne says.
Byrne explains how astronauts have to work out for hours a day to offset the effects of lower gravity on bone density and muscle mass. The effect of lower or zero gravity on the body would make long space flights to Mars potentially difficult in the future.
“So there's a real problem with having humans in lower than 1G gravity field for longer than a short amount of time — presuming the same would apply for Superman,” Byrne says.
So, if interstellar travel won’t help us become super strong, what can we do while we’re still on Earth?
Can humans become super strong on Earth?
Arguably, you already have the potential to become super strong. As bioengineering professor Michael Regnier told NBC News, the average human can lift six to seven times their body weight, helping explain how people are suddenly able to lift cars to save other people in accidents.
But even if we tap into our full potential through strength training, we’re still nowhere close to achieving Superman’s steel-bending capabilities.
Yet it’s possible we could overcome our body’s natural limits through robotic arms and legs that could make us stronger than would be naturally possible. That sounds like something out of a futuristic sci-fi novel, but it’s closer to our reality than you might think.
“Robotic limbs certainly have the potential to be stronger than human limbs,” Philip Brey, professor of philosophy and ethics of technology at the University of Twente, tells Inverse.
Robert Gaunt, associate professor of the University of Pittsburgh’s Rehab Neural Engineering Labs, tells Inverse that robotics is already helping individuals regain the use of limbs, partly through brain-computer interfaces (BCI), which connect the brain to external devices.
“In the end, a brain-computer interface cannot make a person naturally stronger, like Superman, but it could theoretically be used to control a suit, like Iron Man,” Gaunt explains.
“Never before have we been so close to creating technologies that can successfully increase the natural strength, speed, and stamina of a person,” Tommaso Lenzi, an associate professor of mechanical engineering at the University of Utah, tells Inverse.
Lenzi says there are already robotic exoskeletons that increase strength ten-fold, which are mostly being considered for military applications. But these exoskeletons are still too heavy and use too much power to be deployed realistically — yet.
“The building blocks are there–motors, battery, transmission systems, microprocessors are already capable to do it,” Lenzi adds. “We just don’t yet know how to combine these building blocks so that they work as an extension of the human body.”
For now, super strength still seems to elude us, but future technological developments could bring you one step closer to being a real-life Superman.
Several movies in the Superman franchise, like Man of Steel and Superman: The Movie, are streaming now on HBO Max.