The thing about superhero movies is that there has to be a suspension of disbelief when it comes to certain premises behind the movie — no, gamma rays would not turn a guy into a huge green monster. We all know that; let’s move on.
Once those premises are set up and once the directors have a universe to work with, they need to stay with the reality and physics of that universe. The new Avengers movie does this surprisingly well, better than most other comic book movies I’ve seen.
That wasn’t always the case. In the old Superman movies, it was a relatively common occurrence for love interest Lois Lane to go tumbling out the window of a high-rise building and Superman to swoop up and catch her.
From a physics standpoint, there’s a very big problem with doing that. Technically, it’s not the fall that kills you — it’s when you hit the ground. That’s because the force you feel on your body is due to your speed changing from 120 miles per hour from the fall to zero miles per hour in less than a second (deceleration).
Now let’s go back to Superman and Lois Lane. Lois Lane is hurtling toward the ground faster than a person today would drive their car on the freeway. Superman flies up to her, reaches out his arms and catches her just before she splats into the pavement below.
The problem? Lois Lane is still decelerating from about 100 miles per hour to 0 miles per hour in about a second. Since he is the Man of Steel and presumably doesn’t have huge mounds of cushiony fat in his arms, this force would still probably kill her. There’s nothing special about hitting pavement that will kill a person more than anything else that will take your speed from 100 mph to 0 mph.
Compare that to a scene in the recent Avengers movie. Toward the end of the movie, the Incredible Hulk is hanging off the windows near the top of a building and must catch [name redacted], who is in a freefall toward the ground. The Hulk reaches up, grabs the person, then continues going down, but more slowly.
Why? Well, going from 100 mph to 0 mph in less than a second may be deadly, but decelerating that same amount in 10 seconds would impart a lower force (slower deceleration means smaller force). The Hulk and [name redacted] still hit the ground fairly hard, but much softer than if [name redacted] had hit the ground without help. Thus, this impact was actually survivable.
This seems like a lot of nitpicking for a movie featuring a genius in a flying metal suit and a World War II super soldier being frozen for decades, but it’s actually important to decide which plot points have to have a suspension of disbelief and at which points we have to say, “That’s just ridiculous.”
The fact is that we can’t suspend our disbelief for all of it. Maybe most people don’t think through the physics to the extent that I’ve written here, but there’s still a subconscious doubt in our mind. These doubts can distract from the story, which can make it less effective.
There were a few small things in The Avengers I could nitpick. For example, Scarlett Johansson’s character (Black Widow) is tied to a chair and manages to break it apart by getting to her feet and body-slamming the chair into the ground. The only way for that to work is if either Johansson actually weighed the same as a wrestler or if the chair was made of balsa wood.
Then again, sometimes the audience just wants to watch an awesome fight scene and/or explosion. That’s fine, too. Everyone has a different threshold for believability.
However, directors should keep in mind that breaking the laws of physics too much can distract not only from the story, but even the best choreographed fight scene. Good job on The Avengers for keeping this at least somewhat in mind.
AMY STEWART can be reached at science@theaggie.org.
