The Reason Kryptonite Hurts Superman, According To Science
If you wanted to start a discussion about the most powerful comic book characters of all time, the Mount Rushmore of power would almost definitely include Superman. The Man of Steel has been the pinnacle of strength in the DC Universe for nearly a century, with his super strength, super speed, heat vision, cooling breath, and flight. His ability to leap tall buildings in a single bound and move faster than a speeding bullet has made him the bane of criminals' existence in every issue of his iconic run.
Of course, invulnerability can get a little boring for readers as there don't seem to be any stakes if the hero cannot be bested. Surprisingly, writers introduced kryptonite, a remnant of his destroyed planet that can weaken him to the point of killing him. Astonishingly, science explains that it is based on a real-life mineral, and the effects Superman feels around the element are similar to that of radiation poisoning that humans suffer as well. While it is devastating for Superman to be exposed, the result of this plot device allowed for his most dangerous nemesis.
Lex Luthor is a brilliant and sinister villain, but at the end of the day, he is a human and is no match for the mighty Man of Steel. The existence of kryptonite evens the playing field. With Superman feeling the effects of radiation poisoning, Luthor is able to attack him in many ways, essentially making it more of a human vs. human battle. Luthor is also the main source for the argument that kryptonite's effects on Superman are similar to those of radiation on real-life people, as the prolonged exposure caused the villain to develop cancer as a result.
Kryptonite is rooted in real-life science
Anytime Lex Luthor presents kryptonite or another villain like Metallo (who has a heart of kryptonite), Superman is almost immediately affected by the mineral and weakened to the point of defeat. While it is always a suitable plot device to get readers to fear for the life of their hero, there is a scientific reason behind it. In the comics, Superman gets his strength from the yellow sun, which means his cells absorb the sun's radiation differently than we do. But kryptonite may just interrupt that process.
Scientific American states, "Radioactive materials emit radiation in the form of particles and energy. This can be anything from whole helium nuclei to gamma rays. If gamma rays were emitted by Kryptonite, they would ionize Superman's cells. By knocking electrons and atoms around in his body, this process of ionization would wreak havoc and disrupt normal cell sun-gathering." That same article outlines how creators Jerry Siegel and Joe Shuster named Superman's home planet after a real-life gas discovered in 1898, linking the character to scientific fact.
Superman is a fictional character, and many of his attributes defy science. His superpowers go beyond what mere humans can do. Yet, his most dangerous adversary is something that is not only a stark contrast to himself, but the way that he becomes his equal is also very rooted in science. Radiation is something that all humans are susceptible to; it would make sense that a brilliant villain like Luthor would think of that very thing when attempting to take down the last son of Krypton.
Green isn't the only color
Green kryptonite is deadly to the Man of Steel and his cousin, Kara Danvers, aka Supergirl, but it isn't the only one. There are numerous other colors of kryptonite that all have very different and devastating effects on Kryptonians. Some of them are dangerous and deadly, and some of them are just weird to the point of laughable.
While the red version of the mineral can cause similar effects to green, with more intense mood swings and even mutations, blue can reverse those effects, which is why they are stored together often. Gold kryptonite strips the Kryptonians of their powers, essentially making them human. Silver causes Superman to suffer from extreme hunger and delusion, creating the same effects as Scarecrow's fear toxin; in some ways, this causes him to see his greatest fears. Black kryptonite splits a being in two; whereas Superman is a noble and honorable hero, the counterpart created by this dark mineral would be his opposite, similar to Bizzaro. White kryptonite kills all plants, and Periwinkle lets the Kryptonians lose their inhibitions, like being drunk after work.
There are also kryptonite variants that aren't named for their colors. X-Kryptonite gives animals powers. And the scariest one for regular humans, Anti-Kryptonite, has the same effects on us that green has on Superman. Reading Scientific American makes us think it is basically just a nuclear core. With all of these different versions of these dangerous rocks emitting radiation, it is a wonder why we haven't seen more of them in live action. Maybe James Gunn's "Superman: Legacy" will change that.