Man of Steel was released a couple of weeks ago and I had the chance to see it. I liked it, overall. It was exciting and the action was pretty solid. But that’s not what I’m here to talk about. I want to talk about the depiction of science in the film.
I’m going to ignore both Kryptonian superpowers and their justification. That’s the buy in for superman. He’s super because yellow sun=magic. What I’m going to get into is how the physics and science of the real world would interact with that superness.
They did a few things well. For one, Superman develops a vapor cone as he crosses the sound barrier, which is nice. Also, the indestructible superbeings punch like bullets through buildings much of the time rather than making craters or explosions which I see so often.
That’s about it, really.
So let’s talk about the bad.
The first thing that really knocked me out of my suspension of disbelief was Lois Lane also being an alien of some kind. Let me elaborate. At one point, Superman is carving a tunnel through a glacier with his heat vision. That’s fine, we’ve agreed that he can do that. The thing is, that would create a pretty massive geyser of steam. Fine for superman, but Lois just walked right into that steam-filled tunnel while it was under construction without her face searing off.
Superman’s cape does what it always does and makes no sense. I’ve written about this before, so I’ll keep it short. The drag due to the cape would be huge. Also, in space, capes don’t flutter in the breeze. In fact, if Supe was in space and stopped accelerating, the cape would drift around totally freely. If he slowed down it would probably drift up and get in his face.
Another rather dubious moment came when General Zod and his crew activated the “World Engine.” It’s a teraforming device made to make earth more like Krypton. I can’t imagine why they’d want that. Earth climate is clearly much better for Kryptonians in that it makes them into gods, but regardless, it’s alien tech and it changes planets. The dubious science come from the United State’s military and the fact that they apparently have a system for monitoring the earth’s mass and gravitational waves passing through it. Not only do they have it, but apparently it’s a crucial enough system that it has fancy displays and real-time graphics interpolation. This is completely ridiculous. We’re not even completely sure that gravitational waves even exist and there is no plausible military application for monitoring them whatsoever.
They could monitor the change in mass of the earth by noting the effect on the orbits of satellites, but it would have been a pretty clever individual at Nasa to figure out they should be doing that and to tell that beardy guy with the glasses about it in the thirty seconds they had between the machine starting up and him making his conclusions.
Finally, I want to talk about is the supersnatch, the iconic mid-air rescue. That last-second grab before a falling human gets splattered on the pavement. From my recollection, Lois gets two of these rescues, and I’m happy to say that she gets treated to a gentle deceleration both times, one due to wacky gravity and the other due to genuine caution on the part of Superman. There’s a helicopter pilot that’s not so lucky, though.
By my reckoning,, the pilot fell for 4.5 seconds before being caught. Figuring out how fast he is falling at that moment takes a bit of math. Working out falling speed from first principles is a pain and requires knowledge of things like air density and exposed surface area of the falling object, however we can just approximate using the known terminal velocity of a skydiver, around 56m/s. With that we can use the following approximation.
Which yields an approximate downward velocity of 37m/s. Also, superman is moving horizontally quite fast. Based on the fact that he appears to cover about 100m in less than 2 seconds, we can put him at an average velocity of 50m/s. That’s assuming Superman doesn’t need to accelerate (It’s better for the pilot if he doesn’t.) That’s a net velocity of 62m/s or 224km/h (139mph for you imperialists).
The catch takes about two frames. At 24fps, that’s 1/12 of a second. The net acceleration on the man would be 746 m/s/s. That’s 76g. Based on rocket sled tests, a human, properly restrained, could walk away from a 36g crash. So this catch is two and a half times that and he’s only catching the pilot at two points on his body using, effectively, steel poles. Superman is not doing the pilot any favors.
Superman probably wouldn’t be too happen when he ripped that guys head off, not to mention that wouldn’t help people not be terrified of him.
I should put the disclaimer that I didn’t actually do the math to figure out if he would get a whiplash decapitation. I couldn’t find a published value for that. Consider the illustration to be an artist’s impression.
Haha. Haven’t seen the movie, but your analysis is cool.
1. The cape might flap around, based on his changes in direction. Didn’t the American flag on the moon flap and wave around for a while after they extended it, just because there was no air to stop it from flapping? Every time Sup changes directions even a tiny bit, it would create undulations in his cape. But when he stops, as you say, it ought to pile up around his head.
2. I wonder how much Earth’s gravity would have to change before some alarm went off somewhere. I’m guessing that GPS satellites would start going off course right away, and some military outfit *must* be keeping track of those. But thirty seconds …. I dunno if it would be that obvious. You’d need some pretty tight communications lasers pointing at some fast moving satellites before you’d realize there are issues.