(Note: I like Captain America. I like his shield. And I know “it’s just a comic,” this is as much a critique as it is a joke. Breathe. You’ll be fine.)
So I was sitting around thinking about Captain America today (as I often do) and I found myself kinda fixating on his shield. Now, I’m an English major and even when I was exposed to physics on a semi-regular basis my grasp of it was spotty at best, but I’m fairly sure that his shield is the worst weapon ever, by virtue of the fact that it’s the best defensive tool ever.
See, Captain America’s shield is made out of a metal called vibranium. This metal is extremely unique in that any force imparted upon it is reduced effectively to zero. I believe – but don’t quote me on this – it’s because each molecule of the metal vibrates so violently when struck that the energy dissipates imperceptibly fast. That’s some questionable science right there, but that’s not the part that I was thinking about.
The important thing to glean from that last paragraph is that no matter how hard you hit vibranium nothing happens (With the exception of a few extreme circumstances). It’s blocked Thor’s hammer. It’s blocked the Hulk. This shit is tough. There’s a reason we made a shield out of it.
But here’s the part that I alluded to in the first paragraph: Energy transfer is not a one-way street. Things don’t behave differently when they’re receiving energy or giving energy. That’s not how math works. An unstoppable force and an immovable object are the same thing viewed from different reference points; as is blocking a shot and dishing out a shot.
So what does this mean for Captain America? Well, it means that no matter how hard he throws it, that shield should never damage anybody. Realistically he should never actually be able to pick it up in the first place, but let’s focus on its offensive capability for a second. Let’s assume that he can throw it (physics says he can’t) because these vibration properties only trigger on impact force or something. Again, you can’t really be nitpicky with this kind of physics, but we’re trying to make a point here so to hell with it.
Punching and being punched are the same thing. That’s Newton’s third law. The reason punching someone hurts your hand less than their jaw is because the human face is really bad at applying directional force, unlike your fist. The cheek vibrates and the force that the face would apply to your hand goes kind of everywhere.
“Wait a second,” You’re no doubt saying, “Rapid vibration makes something less effective at imparting force on a second object? You can’t possibly mean – ?!”
Oh, but I can, hypothetical internet stranger. I certainly can.