What's the science behind Gru's freeze ray in Despicable Me? Is such a device possible? Ask Science investigates.
A few nights ago, my children and I were watching one of our favorite movies, Despicable Me. The main character's favorite weapon to use against his opponents is the freeze ray. Whether he uses it against rival villains or the people in front of him in the checkout line, the freeze ray creates an instant block of ice around the target. As we watched, I started to wonder: What might the science behind a freeze ray be? Let's take a look..
Forecast Calls for Extreme Lows...
The first thing we have to consider is just how cold the air would have to be in order to freeze instantly. Earth's atmosphere is made up of about 78% nitrogen, about 21% oxygen, with the remaining 1% being other stuff. Since most of the atmosphere is nitrogen, let's concentrate on freezing that. Most people are familiar with liquid nitrogen, which is nitrogen that has been cooled so much it has turned from a gas to a liquid. If you cool nitrogen even further, you can turn it into a solid.
While water becomes a liquid at 100 degrees Celsius, nitrogen becomes a liquid at around -196 degrees Celsius; and while water freezes at 0 degrees Celsius, nitrogen freezes at around -200 degrees Celsius.
So we've got 2 possibilities for the freeze ray:
- The freeze ray makes the air cool down to -200 degrees Celsius, freezing the air around the person.
- The freeze ray makes the air cool down to 0 degrees Celsius, freezing the water vapor in the air around the person.
Since the extremely low temperatures of the first option would probably kill the target, and since nobody in the movie seemed to suffer any ill-effects from the freeze ray, let's take a look at option 2.