Superman and the Physics of Flight
Superman is a hero I’ve struggled to like. Mostly due to the fact he is a nearly perfect being who can withstand every obstacle, save for a rare mineral from his home planet.
What I’ve been grappling with over the last few days is how he is able to fly. Sure, in the 1930’s when he was created, being curious about the science that would make his super powers real wasn’t a large concern. When all of H.G. Wells’ catalogue was being produced into films, the Frankenstein franchise was getting attention, and an unrelated-to-the-modern-goliath-that-is Walking Dead movie was produced, scientific accuracy wasn’t of the utmost concern to the entertainment industry.
Now, with Neil deGrasse Tyson chiming in every time someone gets science wrong in a story, some people are doing their best to get the science right in stories. Andy Weir, who wrote the epic the Martian book (and subsequent Matt Damon-starring movie), attempted to get as much of the science right in his book as he possible could. The exception being the dust storm that started the story line (which he openly admits is incorrect, but needed a starting point for the movie).
So then, how does Superman fly? Esther Inglis-Arkell, writing for Gizmodo, suggests negative mass as being the reason Superman would be capable of flying in our universe. This would require Superman to turn air molecules into negative mass in order to push his body up against the pull of gravity. This could be explained by assuming Superman’s mass is of greater density than the positive mass around him, according to general relativity, but this would violate several variants of the positive energy conditions. Also, he would likely be an immovable object…and too dense for Earth to sustain.
Also, according to Einstein’s Equivalence Principle, negative mass would repel both positive and negative mass. In fact, thanks to something called “runaway motion,” when positive mass pulls in positive and negative mass, the acceleration that occurs would push an object towards the positive-mass object. Given the mass of our planet, and the gravity that it produces, such a concept would be unlikely.
Birds are capable of escaping gravity, and thus flying, by flapping their wings and moving air faster than the air and pressure bearing down on them. Birds have strong breast muscles that help their wings move in such a way that, not only are stronger air currents produced by flapping, but it also creates thrust (air moving over and under the wing). Planes do this with their engines.
Unless Superman has something on him we’re not seeing that expels air the way wings or an engine does, this doesn’t seem likely.
While I don’t doubt Superman’s breast muscles are strong enough for him to flap his arms (because, conceptually, he has super strength), his arms aren’t wings. He also doesn’t use his cape as some type of wing system either (in fact, in the documentary Batman and Bill, Bill Finger discouraged Bob Kane from giving Batman wristbands that connected to his cape as it was impractical).
Plus, as has been demonstrated in the Because Science episode on Batman’s ability to glide using his cape, Superman’s cape would have to be monstrous. And that’s just for gliding, forget the lift off. If we’re going back to the negative mass theory, if Superman’s density is as big as it suggests, he would need one heckuva cape to do even that.
Side note: It turns out MPhys students at the University of Leicester did the math and, given Batman’s physical conditions using a cape the size it is, he could glide for a short distance (350 meters from a 150 meter height). However, the landing would equate to being hit by a car travelling 50 MPH. So, he would die.
Another possibility is that Superman, given his known speed of “faster than a speeding bullet,” travels faster than the escape velocity of Earth. That speed is 11.186 kilometers a second. That’s faster than the speed of sound and several times that of a bullet from a rifle. Assuming Superman is capable of breaking these speeds, it could be understandable how he initially gets off the surface. However, maintaining that speed once in the air remains the problem. As stated before, unless he’s got an engine built into his body we’re unaware of, it seems unlikely he could continue to remain in flight.
All things considered, and ignoring the other physics problems with his super abilities, it seems flight the way Superman does it is much more fiction than science.
