What happens when you see bad physics in the world? Does it make you angry? Does it make you laugh? Do you have to hold back a tidal wave of "well, actuallys" because of the overwhelming wrongness?

Some might feel that way, but I think about it a little differently. In my mind, there are different categories of incorrect physics—and I deal with each one with its own particular strategy.

Bad Phyiscs in Movies

You are watching your favorite science fiction movie—but wait! Something is wrong. There is an explosion and space and you can hear it. Next a spaceship banks during a turn—in space. Finally, a person floats weightlessly into an air lock. The door shuts and air is pumped in which makes the human fall to the ground.

Yes, these are all examples of bad physics. But do these mistakes enrage me? Usually, no. It might be difficult to believe, but in most cases I just enjoy the science fiction for the story and the action. I don't seek out movies to fill my need for more physics (I can get that from real life).

So, do I just leave this bad physics alone? No. I think the bad physics in movies offers a great opportunity. This is a chance to take that wrong idea and talk about real science. Honestly, that's one of my favorite things to do. How about an example?

Let's consider the air lock scene. It happens quite often, but I will use a moment from Wall-E. You don't need to know the plot of the movie, but in this part Wall-E (a robot) holds onto a spacecraft as it docks into a bigger spacecraft.

The airlock door shuts and all of a sudden there is gravity. Why? OK, you might argue that this massive spacecraft has some type of artificial gravity thingy. I get it. However, there is a very common idea that astronauts "float" in space because there is no air in space. No air means no gravity (this isn't the real answer). But now we can talk about gravity, orbits, apparent weight, air pressure—all in relationship to this clip. And we still get to enjoy the movie. You have to admit, Wall-E was a pretty good flick.

Oh, I should include this epic air lock scene from 2001: A Space Odyssey.

Notice how he is still weightless after the air is added. It's great.

Bad Physics in Nonfiction

There is another class of bad physics—and this one is actually bad in real life. Suppose I'm not really trying to tell a story in some way. Instead, I'm trying to show you some cool science.