Tag: Louis Poinsot

Geometry of the Motion of a Free Prolate Gyroscope (and the Power of Magnets)

How should I spin the story of the gyroscope this time? Imagine, you have a wonderfully crafted elongated ellipsoid from wood (shaped like a rugby ball). You built some apparatus that make it spin fast about its major axis. Probably you can make it spin with your bare hands – or you ask a tentacled…
Rolling Not Slipping – Story of a Twirling Ellipsoid

I can’t help it – I use the first title that pops into my mind! “Rolling, not slipping” is the punchline of a mathematical argument used in classical mechanics, in the theory of the motion of a gyroscope. But I am not going to do it justice in this blog post (apart from a math…
Poinsot’s Paper Spaceship (2025)

I’m presenting the recently completely series of artworks – and related physics blog posts – in its entirety! An ellipsoid is intersecting a sphere. Their intersection line is where the vector of angular momentum is seen to travel along – from the perspective of the spinning gyroscope. Four geometrical drawings, each based on the physics…
Geometry of the Physics of the Gyroscope – on a Coffee Mug!

Construct the Labyrinth from Which You Plan to Escape … has been the motto of the Oulipo movement, French writers and mathematicians who have boosted their creative writing by imposing arbitrary constraints. I had practiced Oulipo long before I knew the term. I just called it Search Term Poetry or Spam Poetry. I have been…
Bumblebees and Ellipsoids (Poinsot’s Paper Spaceship #3)

In the movie Ice Age, Manny the Mammoth says he is not fat – just poofy! It is just the fur! I feel the same must be true for bumblebees – they are fluffy, but not really fat! And yes, these were the things going through my mind, when I created this geometric drawing: A…
Poinsot’s Paper Spaceship #2 – Zeppelin: Unstable Rotation About the Intermediate Axis.

Subtitle: Why UFOs are more stable than zeppelins. This UFO… … tells a story of rotation. The yellow ellipsoid encapsulates the main features of a rotating rigid body: Its moments of inertia, that is: how masses are distributed in relation to three principal axes. The moment of inertia is larger, if more mass is positioned…
Poinsot’s Paper Spaceship #1 – UFO

Louis Poinsot has a crater on the moon named after him … and now, also my series of geometrical drawings. I am taking the ellipsoid and sphere to the third dimension, based on the plan laid out before. Number 1 is an oblate ellipsoid, intersecting the sphere nearly in two circles. It is a classic…
Poinsot’s Paper Spaceship #0 – The Plan

There was a time before computer-based three-dimensional visualization. There was a time before any software at all. When James Clark Maxwell sculpted thermodynamic functions with clay. When Louis Poinsot described the motion of the gyroscope in terms of three cones embracing each other, boiling down the essence of a free spinning top’s motion. Today, we…
Poinsot’s Gyroscope and the Magic of Precession.

Nobel prize winners have been fascinated by it: You can learn about the underlying mathematics. You can solve differential equations. But do you really feel why it does not fall? When gravity tries to topple a spinning top, the top escapes sideways, sort of, by precessing: The axis of rotation is changing slowly. There is…
Poinsot’s Dancing Cones

I have always loved the physics of the gyroscope. There are so many different mathematical / conceptual / geometrical ways to capture the same thing. Lots of interesting ellipsoids and cones are waiting to be drawn! Here, I am visualizing the motion of a gyroscope free of external forces, involving three cones, following Louis Poinsot.…