JimPropp

The first half is a mathematically correct discussion of models of growth (exponential vs. logistic) in a fictional context. The second half uses the same scenario to show that sometimes there are more important things than being mathematically correct.

In this month's Mathematical Enchantment, a math-and-science writer named Jim Propp, inhabiting a variant of the fictional Project Hail Mary universe, confesses to his pivotal role in the impending end of all life on Earth, and kind-of sort-of apologizes. https://mathenchant.wordpress.com/2026/04/18/sorry-mary/

Learn how a stupid question led to an interesting, albeit spectacularly useless, way to estimate pi by tossing a coin many, many times, in this month's Mathematical Enchantments essay, "In Praise of Stupid Questions". https://mathenchant.wordpress.com/2026/03/12/in-praise-of-stupid-questions/

Of course, I’m not satisfied with five. Can anyone suggest a sixth source of “hexagons in the wild” here? The parking garage at Kendall Square Cinema tempted me, but it’s kind of a stretch to say it’s in-and-around Harvard Square.

“Hexagons in The Square”: five photos from five locations in and around Harvard Square. Can anyone recognize all five?

Writing in The New Yorker earlier this month, Stephen Witt said matrix multiplication is ugly. Is he right? Check out my take at https://mathenchant.wordpress.com/2025/11/21/is-matrix-multiplication-ugly/

A store called the Memory Shop just opened near me, and not a moment too soon: I really could use a few extra terabytes of RAM between my ears.

It’s used by X-ray technicians to take an X-ray that shows your fingers individually from the side, as you rest your hand on it with your fingers splayed. I doubt that this polytope has been studied, but it is definitely chiral in both the mathematical and etymology senses.

It’s made of spongy material and costs around $15.

@robinhouston@mathstodon.xyz It’s small enough and light enough to carry in one’s hand.

Riddle: What is this object used for?

(2/2) “I appreciate Stephen Witt shining a spotlight on matrices, which deserve more attention today than ever before: they play important roles in ecology, economics, physics, and now artificial intelligence ("Information Overload", November 3). But Witt errs in bringing Hardy's famous quote ("there is no permanent place in the world for ugly mathematics") into his story. Matrix algebra is the language of symmetry and transformation, and the fact that a followed by b differs from b followed by a is no surprise; to expect the two transformations to coincide is to seek symmetry in the wrong place—like judging a dog's beauty by whether its tail resembles its head. With its two-thousand-year-old roots in China, matrix algebra has secured a permanent place in mathematics, and it passes the beauty test with flying colors. In fact, matrices are commonplace in number theory, the branch of pure mathematics Hardy loved most.”

(1/2) In his article “Information Overload” from the November 3 issue of the New Yorker, Stephen Witt writes (apropos of the procedure used in computing weights for A.I.):

“… The math is unwieldy, and is especially dependent on an operation known as matrix multiplication. “Beauty is the first test: there is no permanent place in the world for ugly mathematics,“ the mathematician G. H. Hardy wrote, in 1940. But matrix multiplication, to which our civilization is now devoting so many of its marginal resources, has all the elegance of a man hammering and nail into a board. It is possessed of neither beauty or symmetry: in fact, in matrix multiplication, a times b is not the same as b times a.”

I’ve written a letter to editor about this passage; the magazine probably won’t run it, but who knows? My letter follows.

Bought one. Couldn’t finish it.