*#166 in a glorious series*

It is my honor this month to host an ancient and venerable tradition. It dates to a time before Apple had ever sold an iPhone, before Marvel ever made a superhero film, before Big Bang Theory ever aired a vaguely sexist joke. An event older than civilization itself.

Welcome to the 166th Carnival of Mathematics!

What follows is a thrilling, non-exhaustive compendium of cool mathematical writing that happened on the internet last month. Enjoy. Share. Viva la math.

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Thursday, January 3rd was **Thirdsday**, a holiday discovered/invented by Jim Propp, and which won’t return again until 2030:

We at Thirdsday HQ think that Thirdsday is better than Pi Day for a whole bunch of reasons. For one thing, 1/3 turns up a lot more than π and is much more useful in most people’s daily lives. Also, 1/3 doesn’t snootily insist on having its own special symbol, and its decimal expansion is a lot easier to remember.

Most importantly, Pi Day comes around too often. It seems that you’ve barely finished writing thank-you notes for the presents you got last Pi Day before it’s time to start start doing your Pi Day shopping all over again. Whereas Thirdsday gives you a chance to recover before the next Thirdsday rolls around.

Further coverage from Evelyn Lamb, Matt Parker and Zoe Griffiths, Bill Gasarch, and yours truly.

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YouTube champion Grant Sanderson of 3Blue1Brown blew minds across the world with this stunning puzzle on January 13th:

The explanation – which is, if possible, even more thrilling, landed a week later; watch it here.

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On January 11th, mathematics lost one of its leaders: Sir Michael Atiyah. From the *New York Times* obituary by Julie Rehmeyer:

“He could hypnotize you into believing you understood something,” said Graeme Segal, a former student of his and now an emeritus fellow in mathematics at Oxford. “He would make you think that everything was possible, and there were all these wonderful ideas, and you could put them together and do something with them.”

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While you’re mourning, it’s worth reading Terry Tao’s tribute to his advisor, the legendary harmonic analyst Elias Stein, who passed away in December:

Eli’s lectures were always masterpieces of clarity. In one hour, he would set up a theorem, motivate it, explain the strategy, and execute it flawlessly; even after twenty years of teaching my own classes, I have yet to figure out his secret…

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The podcast **My Favorite Theorem**, hosted by Evelyn Lamb and Kevin Knudson, posted two new episodes. First, Skip Girabaldi rhapsodized on the unknowability of the number line (a favorite theme of mine, too).

And second, Nira Chamberlain – a.k.a. the World’s Most Interesting Mathematician – discussed the chaos of weather:

Over in the United Kingdom, we had an interesting case in 1987 where the French meteorology office says, “By the way, people in the north of France, they should be aware that there’s going to be a hurricane approaching.” While the British meteorologic office was saying, “Oh, there’s no way that there’s going to be a hurricane. There’s no hurricane.”… And guess what? The French were right and a hurricane hit the United Kingdom.

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Iona shared this review of Ian Stewart’s *Taming the Infinite*.

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Math educator Bill Shillito highlighted recent mathematical failures on the TV show *Jeopardy!*:

[A] contestant buzzed in and said: “What is ‘finite’?”

Alex Trebek notified the contestant that they were correct.

Meanwhile, I was speechless because I knew they weren’t.

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The author of the blog **Comfortably Numbered** was prompted to a mathematical investigation by a billboard advertising the “closest casino to anywhere in L.A.”:

This is a fascinating claim…. that

whereveryou are in LA, the closest casino is the one advertised on the billboard. (This is confusingly distinct from the claim that the casino… minimizes the distance to the nearest bit of LA soil…. practically speaking this latter claim is useless because any casinowithinLA trivially has the minimal distance of zero…)The question is this: what region does the billboard’s claim imply is devoid of casinos?

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Daniel Woodhouse, in a humor piece for McSweeney’s, made a bold proposal for the mathematical community:

There is no escaping the widespread dissatisfaction within modern academia…. Those joining the ranks can look forward to bleak job prospects, excessive teaching loads, and writing stupefying grant proposals…. Within the sphere of pure mathematics — the oldest and most successful of humanity’s intellectual endeavors — I believe our best chance at preserving the integrity and dignity of our tradition is to return to our Pythagorean roots. We should become a cult.

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Way back in 2010, a mathematician named Ben Tilly made an extraordinary claim about how mathematicians eat corn:

Back when I was in grad school there was a department lunch with corn on the cob. Partway through the meal one of the analysts looked around the room and remarked, “That’s odd, all of the analysts are eating corn one way and the algebraists are eating corn another!” Everyone looked around. In fact everyone was eating the corn in one of two ways. One way was to munch over the length of the corn in a straight line, back up, turn slightly, and do another row across. Kind of like how an old typewriter goes. The other way was to go around in a spiral. All of the analysts were eating in spirals, and the algebraists in rows.

It has floated around math circles ever since, somewhere on the epistemic continuum between “urban legend” and “common sense.” This month, Scott Alexander of slatestarcodex finally put Tilly’s hypothesis to an empirical test, with, alas, disappointing results:

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Mathematician Elias Worth explains an impressive statistical achievement from WWII:

In the year 1942 the world was at war. The Allied forces tried to defeat Germany. In order to do so, they were grateful for every single piece of information that they could get their hands on. The Allies were particularly interested in the number of tanks produced in Germany in a given month….

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Applied mathematician Tamás Görbe is spreading mathematical beauty with 50 Famous Curves on Twitter:

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Ari Rubinsztejn offered an introduction to shooting methods:

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Greg Evans dug into some surprising pizza-scaling mathematics:

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Pat Ashforth detailed the journey of creating a magician’s chain.

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And finally, Singapore math educator Yan Kow Cheong explores the connections between our beleaguered subject and a very smelly fruit: the Durian.

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That’s it for the January 2019 Carnival! You can read more, as always, at the Aperiodical, and next month’s will appear at Tom Rocks Math.

Sir Michael Atiyah was the mathematics don at one of the Oxford colleges when I was an undergraduate there (Keble). The undergraduates were particularly amazed at Atiyah’s curved blackboard and that he drew his diagrams in sand. (apocryphal ???)

This kind of post is great way to know good books, podcasts and twitter accounts!