tingilinde

orphan annie, captain midnight and cryptography

Matt Blaze takes a dive into cryptography for kids in the 30s and 40s.

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The main qualification for membership in (and issuance of a decoder for) Radio Orphan Annie's Secret Society and Captain Midnight's Secret Squadron involved drinking Ovaltine, a malted milk flavoring containing the vitamins and nutrients then understood to be needed by growing secret operatives, or at least to be profitable for its manufacturer (which sponsored the broadcasts). Proof of sufficient Ovaltine consumption was established by mailing in labels from Ovaltine packages. New pins and badges were issued annually, requiring additional labels to be sent in each year. (The devices are sometimes described as decoder rings, but in fact they took the form of pins, badges, and the occasional whistle or signal mirror.)

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this is beautiful

There's a bot that posts random three body problem simulations..  

Here's the best I've seen to date.  

 

lobachevsky

Yesterday was the birthday of the mathematician Lobachevsky.  I first heard of him in a Tom Lehrer song, later learning he was a great mathematician.  Lehrer later said he didn't want to slight him, but the name just worked out for a song.  The song is a lot of fun.

remembering ron graham

Folks with a connection to Bell Labs and/or math will enjoy these remembrances.

 

 

innumeracy and covid

Americans are bad at math - really bad.

 

 

an intro to holomorphic dynamics

Lovely examples from 3Blue1Brown

 

the old math behind a hot card game

The math behind Spot It!

a tip of the hat to Greg

the roots of unity

A simple and well-written introduction to solutions of polynomial equations.

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If you’ve ever taken an algebra or physics class, then you’ve met a parabola, the simple curve that can model how a ball flies through the air. The most important part of a parabola is the vertex — its highest or lowest point — and there are many mathematical techniques for finding it. You can try vertex form, or the axis of symmetry, or even calculus.

But last week one of my students located the vertex of a parabola in a particularly elegant way. “The vertex is at x = 4,” she said, “because the roots are x = 1 and x = 7, and the roots are symmetric about the vertex.” She used the fact that the parabola is the graph of a quadratic polynomial, and that the roots of that polynomial — the values where it becomes 0 — have a certain structure she could take advantage of.

There is a structure to the roots of every polynomial, and mathematicians study these structures and look for opportunities to capitalize on them, just as my student did with her parabola. And when it comes to the roots of polynomials, none have more structure than the “roots of unity.”

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blind mathematicians

The mind is flexible and finds a way 

 

a beautiful numberphile

just watch