Where do Superman’s superpowers come from?
In every issue of Superman, the superhero is shown leaping over a massive skyscraper, more than 40 stories tall—that is, about 200 meters high. Is it possible for a human to do the same, and how much strength would it take?
According to basic high school physics, the force a person exerts to stand upright is equal to their weight, while if they attempt a standing jump, they can jump up to one meter, exerting in this case a force 70% greater than their weight. Superman appears to have a normal physique, and his weight does not seem to exceed 100 kilograms; therefore, for each jump, he would need a force equal to 170 kilograms.
Based on the law of mechanical energy, to reach a height of 200 meters in a single jump, one would need to launch off the ground at a speed of approximately 230 kilometers per hour—a speed that even the fastest cars struggle to reach.
Even more difficult is reaching that speed within 1/4 of a second—the time from the moment he begins to exert force until his feet leave the ground. According to Newton’s second law, in order for Superman to make a jump with such acceleration, he must exert a force equivalent to a weight of two and a half tons.
Based on these figures, Superman would have to weigh about 1.5 tons to be able to exert that much force. But, as we said, he doesn’t appear to weigh more than 100 kilograms. Superman’s hidden superpower lies in the fact that our weight can be relative. Like any object, the human body is made of a certain material called mass, which remains the same whether we’re on Earth or the Moon. However, when we step on a scale, we aren’t actually measuring our mass but our weight—that is, the force that Earth exerts on every object on its surface.
Any two objects that have mass exert a force on each other. What Newton realized when the apple fell on his head is that this force is greater the larger the masses of the two objects are—that is, the Earth and Superman in our case.
Let’s assume that we can travel between planets, going from one planet to another. No matter which planet we’re on, our mass will be the same; we’re made of the same amount of matter. However, the mass of each planet is not the same, so on each planet we will have a different weight. For example, the Moon’s mass is about 6 times smaller than Earth’s. So, our weight on the Moon is 6 times smaller. A person who weighs 80 kilograms on Earth would weigh just 14 on the Moon! However, each of us who has grown up on Earth is accustomed to and possesses the necessary physical strength to support our weight on Earth (let’s say 80 kilograms). So, when they move to the Moon, that 14-kilogram weight will seem like a piece of cake.
In fact, the Apollo 11 astronauts who were the first to set foot on the Moon were able to make jumps six times longer than on Earth. And if 40 stories sounds excessive, an astronaut on the Moon could easily jump over a two-story building. So, to the hypothetical inhabitants of the Moon, this astronaut would be a Superman, a superhero. The planet Krypton, where Superman was born, has a greater mass than Earth. So, Superman, trained and strengthened on a planet where you need immense strength just to lift your own weight, comes to Earth, and there everything seems like child’s play to him.
But how much greater in mass must the planet Krypton be than Earth? We said that Superman, who weighs 100 kilograms on Earth, would have to be accustomed to lifting his own weight even if he weighed one and a half tons (1,500 kilograms). This means that the planet Krypton must have 15 times the mass of Earth. And if we assume that Krypton is roughly the same size (volume) as Earth, the material it is made of must be 15 times denser than Earth’s material. In the language of physics, this means that Krypton has 15 times the density of Earth.
In the early Superman episodes, it is mentioned that the planet Krypton is three million light-years away from Earth. For the creators of Superman (Jerry Siegel and Joe Shuster), in the early 1940s, it was unthinkable that humans could ever learn what happens at such distances from Earth. And yet! Today’s astrophysicists, with the help of state-of-the-art telescopes, can study celestial bodies located up to 10 billion light-years away—far farther than Superman’s creators could have imagined. And what is the conclusion? That the planet Krypton exists? That we might one day meet Superman? No one knows… What is certain is that science fiction seems very small in the face of modern scientific discoveries.
Bibliography
– The Physics of Superheroes- James Kakalios
