• Luca Pacioli
• Domenico Maria Novara da Ferrara
• Nicolaus Copernicus
• Georg Joachim von Leuchen Rheticus
• Caspar Peucer
• Salomon Alberti
• Ernestus Hettenbach
• Ambrosius Rhodius
• Christoph Notnagel
• Johann Andreas Quenstedt
• Michael Walther, Jr.
• Johann Pasch
• Johann Andreas Planer who doesn’t have a Wikipedia page
• Christian August Hausen
• Abraham Gotthelf Kästner
• Johann Friedrich Pfaff
• Carl Friedrich Gauss
• Christian Ludwig Gerling
• Julius Plücker
• C. Felix (Christian) Klein
• William Edward Story
• Solomon Lefschetz
• Norman Earl Steenrod
• George William Whitehead, Jr.
• John Coleman Moore
• William Browder
• Sylvain Edward Cappell
• Shmuel Aaron Weinberger

There are some branches to choose among, but I think the branch starting with Pacioli is the most appropriate.

Here’s a little movie I made:

I’m grading for the first year topology course at Chicago, and one of their homework problems asked them to show that pairs of (indistinguishable!) points on a circle correspond to points on the Möbius strip; in other words, the quotient of the torus $T^2 = S^1 \times S^1$ by the $\Z/2$-action which exchanges the two $S^1$ factors is a Möbius strip.

In the above animation, you can see the identification in action: the two red points on the green circle correspond to the red dot on the Möbius strip.

I took my road test this morning—and I passed!

After all these years, I am a licensed driver. Now, where should I drive to?

Google Trends plots the search volume (or some other measure? search percentage?) for a given phrase over time. It’s ridiculously fun!

As an example, let’s look at the number of times people search for the words hot and cold. I downloaded the CSV file offered by Google trends to make the following graph:

The thick red and blue lines are the linear regressions on the number of searches for hot and cold, respectively. Behold!—people are searching more often for hot lately, and less often as of late for cold! The search volume does seem to be related to the temperature: you might notice that the search volume for cold dips under the regression line during the summer, but exceeds it during the winter.

And so, global warming is being revealed in our search habits. Maybe I should’ve titled this post “Google warming.”

The Romans (among others!) wrote in wax with a stylus; the wax was embedded in boards, which were bound together in pairs. If a Roman were to place clay between these boards, could they make a copy of their wax tablet in the clay?

It strikes me as remarkable that coins were minted so long before books were printed—though I guess the motivation behind minting coins and printing books are rather different.