for National Geographic News
This month Superman Returns opens in U.S. movie theaters, and the world's oldest comic book superhero turns 68stronger, more resilient, and presumably more super than ever.
Most of us would view the Man of Steel as a purely fantastic creation. After all, he has x-ray vision, leaps tall buildings in a single bound, blows icy winds, is impervious to bulletsthe list goes on.
But while a lot of the action in Superman Returns will undoubtedly be impossible, much about the Last Son of Krypton is anchored in real science.
"Comic books get their science right more often than one would expect," said James Kakalios, a University of Minnesota physics professor.
"Of course, the hero's superpowers violate the laws of nature as we understand them, but once you grant a one-time 'miracle exception,' what follows is often surprisingly consistent with known physics," said Kakalios, who authored The Physics of Superheroes.
(Related photos and news: animals with Superman "powers".)
Consider Superman's strength.
As any fan knows, the original explanation for Big Blue's power and skyscraping leaps was gravity. He comes, the story goes, from the destroyed planet Krypton, where gravity was stronger than it is on Earth.
Under this theory, Superman on our planet is like a human astronaut bounding around on the moon, only more so. The same applies to any of his other feats of strength, Kakalios says.
The biggest problem with this idea, says Michael Dennin, a physics professor at the University of California, Irvine, is that he can also walk normallyrather than bounding around like an astronaut on the moon.
Another problem is that he remains powerful no matter how long he stays on Earth. Because weightlessness forces people to use their muscles less, "astronauts get weaker with time," Dennin says.
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