Cats and the Conservation of Angular Momentum
How does a cat go from feet up to feet down in a falling reference frame without violating the conservation of angular momentum? (Huh?)
That’s the question posed by Destin, the engineer who goes by that name on the YouTube channel Smarter Every Day.
I couldn’t completely understand the answer, but Gigi the cat is more than cute … and she always lands on her feet. That would appear to be because she understands how not to violate any of the laws of physics as she proceeds on her descent (and, possibly, because it was her ancestors who invented those laws in the first place?).
If you manage to figure out the explanation (and even if, like me, you don’t), you’re ready to move on to Lesson Two, in which Gigi teaches NASA scientists how to change the direction in which the James Webb telescope will be able to point. (The Webb telescope is the astonishing replacement to the Hubble telescope, slated for launch a few years from now.)
Gigi offers another demonstration, starting about two minutes into the video. (Try to make it through the first two minutes in order to begin to understand the genius of feline physics.) Gigi, Destin explains, is able to flip 180 degrees from rest by rotating against herself. How she does this is a matter that’s been studied by scientists galore, neuroscientists to mathematicians to astrophysicists. (Just Google “flipping cats” for some of the papers that have been written about this.)
The James Webb telescope will be using things called reaction wheels (sort of like gyros) to enable the telescope to do what Gigi does naturally.
And if (again like me) you can’t figure out what reaction wheels do or what Dean Alhorn at the Attitude Components Lab at NASA’s Marshall Space Flight Center is explaining, you’ll at least get another cameo appearance of Gigi at the end of the video.