Emoji Differential Equations: Dreidels as Euler Angles

Here is my latest set of emoji differential equations.

And in case you want a holiday-themed system of emoji differential equations, here are ones for unsteady precession of a dreidel.

Enjoy the holidays!

Euler angles: https://t.co/xk2jDceXZ8 pic.twitter.com/j0wV2u2AUX

— Mason Porter (@masonporter) December 25, 2019

The Physics of Paper Springs!

There is a new paper in Physical Review E about the physics of paper springs (i.e., springs that one constructs by folding paper). I used to do that as a kid, and I think it's really cool that there is now a scientific article about it!

The physics of a paper spring https://t.co/5yMjj4uXuM pic.twitter.com/zilPHpOGeS

— Steven Strogatz (@stevenstrogatz) July 18, 2019

Tales from the ArXiv: Centenary of Emmy Noether's Invariante Variationsprobleme

This article commemorates the centenary of Emmy Noether's article Invariante Variationsprobleme.

Title: On the Wonderfulness of Noether's Theorems, 100 Years Later, and Routh Reduction

Author: Raphaël Leone

Abstract: This paper is written in honour of the centenary of Emmy Amalie Noether's famous article entitled Invariante Variationsprobleme. It firstly aims to give an exposition of what we believe to be the most significant and elegant issues regarding her theorems, through the lens of classical mechanics. Despite the limitation to this field, we try to illustrate the key ideas of her work in a rather complete and pedagogical manner which, we hope, presents some original aspects. The notion of symmetry coming naturally with the idea of simplification, the last part is devoted to the interplay between Noether point symmetries and the reduction procedure introduced by Edward John Routh in 1877.

"The Mechanical Universe" Videos Now on YouTube

The videos of The Mechanical Universe are now on YouTube. This gives me flashbacks to my Physics 1a with David Goodstein at Caltech. (My physics teacher in high school showed us many of these videos, and then I had an odd sense of deja vu when I had Goodstein as a lecturer in the fall term of my frosh year at Caltech.)

(Tip of the cap to Guillermo Valle Pérez.)

"Why Do Most Office Chairs Have 5 Wheels?"

I have occasionally wondered about this question (with some recent inspiration after constructing such a chair that I bought at Ikea), and thankfully googling quickly picked up a good answer (and a nice physics problem to assign to undergraduates).

Tales from the ArXiv: "Dreidel Fairness Study"

There's a new paper on the arXiv preprint server called Dreidel Fairness Study.

I am amused by the following line from the abstract: "Although an unfair dreidel does not necessarily make the game itself unfair, it is conjectured that hundreds of pounds of chocolate have been distributed during Chanukah under false pretenses."

Also, the abstract mentions a dreidel with the face of Santa Claus on it. I guess they're mixing metaphors?

P.S. Somewhere in my parents' home lie my massive collection of dreidels. I can do a spiffy job of spinning them both in the standard fashion and upside-down.

Naming a Dimensionless Parameter

The June 2016 issue of Physics Today includes a 'Quick Study' on why it is hard to separate two interleaved books.

The phenomenon involves a dimensionless parameter that is now called the "Hercules Number", a term that I invented in a blog entry for the Improbable Research blog. I wrote the line "Restagno and colleagues also fit the data to a curve of force versus a dimensionless amplification parameter –– following the continuum-mechanics tradition of using cute names for dimensionless parameters, let’s call it the "Hercules number" –– that depends on the number of pages, the page thickness, and the size of the overlap region between the books." (I was motivated in part by the "Repunzel number" that Ray Goldstein and his collaborators named in their study of the physics of ponytails.)

The researchers really liked the term "Hercules Number", so they decided to adopt it and use it in their subsequent papers (which I appreciate).

I continue to try to contribute to physics and mathematics with my wit and snark.

Update (6/14/16): I was asked to write about this for the Improbable Research blog.

The Impressive Strength of Interleaved Phonebooks

My latest entry for the Improbable Research blog concerns the impressive strength of interleaved phonebooks.

I managed to miss the blog entry about this that appeared in August. Oops! But at least I coined the phrase "Hercules number".

Origin of the Term "Phase Space"

I just read a fascinating article in the April issue of Physics Today on the origin of the term "phase space". Highly recommended.

Mechanical Properties of Ice Cream

Does anybody know why ice cream sometimes gets chewy when it gets old (you know, when a lot of crystals settle inside the container)? Surely somebody has studied the mechanical properties of aging ice cream...?