I've always thought of the circus as a kind of physics laboratory with elephants. The amazing balance of tightrope artists, the perfect timing and exact trajectories of aerialists, the feats of jugglers—they all seem to require an untheoretical mastery of the laws of inertia, angular momentum, and a lot more.
 
It turns out that there's a lively group of University of Minnesota physical scientists and local high-school science teachers who team up to create big-top-style shows that explicitly demonstrate physical laws. They're called the Physics Force. Their "performance lab" is the Minneapolis Convention Center, and they're doing their thing today (January 9) through Friday (January 11): the Physics Force Circus.
 
These crowd-pleasing physics geeks treat their audiences to routines like  "Monkey and Hunter," in which science teacher and Force member Hank Ryan is dropped from a height onto a mat just as another cast member shoots a billiard ball at him from a cannon. The way the downward-dropping Ryan catches the onward-coming projectile demonstrates how gravity and speed combine to define the path of something zooming through space.
 
The Force performers do all of this with showbiz panache, larding their explanations of the science involved with one-liners, and prompting plenty of laughter and applause from the crowd, which is full of, but by no means limited to, grade-school kids.
 
Other attractions on the bill bear intriguing titles: Hoot Tubes, Barrel Crush, Ping Pong Cannon, Human Rocket, and—surely a favorite among the youngsters in the audience—Toilet Paper the Tree. (This last is offered as a demonstration of the Bernoulli Effect, which is best known as the reason airplanes can fly, but also turns out to be a great way to launch t-p without having to throw the roll.)
 
The Physics Force Circus is free but tickets are required, and they're going fast here.