# Pi fleece provides warmth, irrationality

Thinkgeek's Pi Fleece keeps you warm and irrational with the first 413 digits of Pi in machine-washable fleece, measuring 45"x64".

Thinkgeek's Pi Fleece keeps you warm and irrational with the first 413 digits of Pi in machine-washable fleece, measuring 45"x64".

Samuel Hansen's fantastic math podcast is everything a technical program should be deep but accessible, thoughtful but funny, and free for all; the new season is on Kickstarter for a few more hours! I put in $35.

Just in time for you to get the most out of "The Fault in Our Stars," the incomparable, fast-talking mathblogger Vi Hart's latest video is a sparkling-clear explanation of one of my favorite math-ideas: the relative size of different infinities. If that's not enough for you, have a listen to this episode of the Math for Primates podcast.

Chris Mooney of the Inquiring Minds podcast interviewed Jordan Ellenberg about his book How Not to Be Wrong: The Power of Mathematical Thinking, and in a fascinating accompanying post, Mooney investigates whether mathematics are "liberal." His argument is that liberal thought is characterized by "wishy washy" uncertainty and that math professors tend to vote left:

Brooke Powers assigned her middle-school math class a probability exercise with no single correct answer and was monumentally frustrated by her kids' inability to accept the idea of a problem without a canonical solution. After a long and productive wrangle with her kids about how critical thinking works and why divergent problem-solving is much more important than mechanically calculating an answer that you could just get out of a computer, she salvaged the exercise and made something genuinely wonderful out of it.

I've been writing about Thomas Piketty's magisterial economics bestseller Capital in the Twenty First Century for some time now (previously), and have been taking a close interest in criticisms of his work, especially the Financial Times's critique of his methods and his long, detailed response. I freely admit that I lack the stats and economics background to make sense of this highly technical part of the debate, but I think that Wonkblog's analysis looks sound, as does the More or Less play-by-play (MP3).

Here's Randall Munroe's TED talk about his What If? series, in which he answers big, weird questions about baseballs travelling at the speed of light and such, which is also the subject of a hotly anticipated forthcoming book. The talk is a mix of war-stories and insight into what makes Munroe (who is a fascinating dude) tick.

Anton Purisma has launched a civil rights suit against an airport Au Bon Pain restaurant; he's asking for $2,000,000,000,
000,000,000,000,000,000,000,000,000. That would be two undecillion dollars.

In a stirring editorial in the New Scientist, University of Edinburgh mathematician Tom Leinster calls on the world's mathematicians to boycott working for the NSA, which describes itself as the "largest employer of mathematicians in the US" and which may the world's number one employer of mathematicians. Leinster suggests that mathematicians could refuse to work for the NSA, that university heads could refuse to grant professors leave to work at NSA or GCHQ, that national mathematical societies could refuse NSA job-posting ads, and even "expel members who work for agencies of mass surveillance."

Writing in the Financial Times, Tim Harford (The Undercover Economist Strikes Back, Adapt, etc) offers a nuanced, but ultimately damning critique of Big Data and its promises. Harford's point is that Big Data's premise is that sampling bias can be overcome by simply sampling *everything*, but the actual data-sets that make up Big Data are anything but comprehensive, and are even more prone to the statistical errors that haunt regular analytic science.

What's more, much of Big Data is "theory free" -- the correlation is observable and repeatable, so it is assumed to be real, even if you don't know why it exists -- but theory-free conclusions are brittle: "If you have no idea what is behind a correlation, you have no idea what might cause that correlation to break down." Harford builds on recent critiques of Google Flu (the poster child for Big Data) and goes further. This is your must-read for today.

Chapter nine of Homeland opens with about 400 digits of Pi. When Wil Wheaton read the chapter, he soldiered through it, reading out Pi for a whopping four minutes! Here's the raw studio audio (MP3) of Wil and director Gabrielle De Cuir playing numbers station.

There's less than a week left during which you can get the independently produced Homeland audiobook through the Humble Ebook Bundle!

Math-doodling manic talking charming vlogger Vi Hart has updated her classic anti-Pi rant with a new poop-on-Pi video called "Happy Pi Day? NOPE," in which she explains why we should be wowed by numbers like 4 and 5 and completely blase about Pi and its cohort.

Tomorrow, 3/14, is Pi Day in the USA (it will not be Pi Day in the rest of the world until the Martian Emperor subjugates us all to his sinister 14-month calendar). In celebration, Thingiverse user Thor4231 posted this great Eggbot design, ready to be automatically sharpied onto your favorite ovum by means of the wonderful Eggbot printer.

Maria Droujkova writes, "Last week, The Atlantic published my interview called 5-Year-Olds Can Learn Calculus. I have been following the discussions on blogs, forums, and news sites. The themes that emerge from discussions make me cautiously optimistic. Many grown-ups believe that young math will finally give them a second chance at making sense of algebra and calculus. Others look for the balance between conceptual understanding and the fluency at manipulating numbers. Even if 5-year-olds understand calculus, what would they use it for?

XKCD creator Randall Munroe has announced that Houghton Mifflin will collect his amazing What If? science columns into a book called What If?: Serious Scientific Answers to Absurd Hypothetical Questions, to be published in September 2014. It will include in-depth answers to questions that he hasn't yet answered online, as well as expanded and updated versions of his previous columns.

What If? is one of my Internet must-reads, and I look forward to each new installment, and always read it with delight.

Vi Hart, the Internet's favorite manic vlogging mathematician, has released a new video in which she teams up with math artists Andrea Hawksley and Gwen Fisher, and Gwen's sister Ruth of Sweets by Ruth. The four of them bake satisfyingly precise and geometric gingerbread polygons, then build up a variety of astounding three dimensional forms by piecing them together with icing. The video is both hunger-inspiring and brain-inspiring, and is likely to be the best thing you watch this week.

Tim sends us, "A way of encoding binary numbers into playing cards that I thought up. It usually allows many more bits than there are cards. The method can also store binary encoded letters of the English alphabet at less than 2 cards per letter on average, and has a theoretical ability to do less than 1 card per letter."

Tim isn't sure if his method of data-compression is novel or not, and neither am I. If you know of related work, please add it in the comments.

The "squared" in Pi(R)^2 means that the area of a pizza grows ~~exponentially~~ **polynomially** in relation to its diameter. As an interactive graph on Planet Money demonstrates, pizza places generally underprice their bigger pies relative to the amount of food contained in each. This is probably because energy and labor inputs account for the largest slice of the pizza-baking ahem pie, and ingredients are way down on the balance-sheet. Whatever the reason, if you're interested in getting more food for less money, larger pies are almost always a substantially better deal.

74,476 Reasons You Should Always Get The Bigger Pizza [Quoctrung Bui/Planet Money]

(*via IO9*)

Fdecomite has revisited his tessellated Escher cookie-cutters, with a new set of cutters and some new baking that he's posted to the Boing Boing Flickr pool.

Elysium Woodworks's Etsy store is full of gorgeous, laser-etched, math- and science-themed cutting boards. They're about $35, made from bamboo, and take 5-6 weeks to fabricate.

Elysium Woodworks
(*via Wil Wheaton*)

The latest installment in Randall Munroe's XKCD "What If?" series is called Paint the Earth and it is *amazing*. One of Munroe's readers wanted to know "Has humanity produced enough paint to cover the entire land area of the Earth?" and Munroe uses this as a springboard for explaining Fermi estimation, a powerful, counter-intuitive tool that has applications in many fields.

In the Boing Boing Flickr Pool the fractal-obsessed Fdecomite posts the latest iteration in a series of experiments with tessellated, Escher cookie-cutters. Bake-time expansion creates irregularities that lead to a chewy (literally) series of interlock-imperfections, which give old MC's classic a bio-organic air that rather invigorates it.

You can 3D print interlocking lizard cutters with a free model from Thingiverse. Fdecomite, if you're reading this, please post in the comments with a link to the cookie cutters you used here!

**Update:** From the comments, Fdecomite writes, "Hi, those are cookie cutters I made from aluminium foil.I also made some 3D printed Escher cookie cutters you can find in my Shapeways shop.

In Frequency, the latest XKCD cartoon, Randall Munroe has assembled a grid of animated GIFs representing various events in the universe, each keyed to blink in the frequency in which they occur in reality. As with the best of Munroe's work, it's a mix of the trenchant and the silly, and the juxtapositions are smart and provocative. There's real genius in putting "50,000 plastic bottles are produced" and "50,000 plastic bottles are recycled" next to each other, the former blinking much more often than the latter -- but the best part is "A Sagittarius named Amelia drinks a soda," just above them, mixing up the alarming and the humorous.

The other juxtapositions are just as delicious -- one birth/one death; China builds a car/Japan builds a car/Germany builds a car/US builds a car/someone else builds a car; someone buys "To Kill a Mockingbird"/someone's cat kills a mockingbird -- and so on. This being XKCD, you can be sure that Munroe has an absurdly well-thought-through process for establishing and documenting his numbers, too.

The tool-tip notes that he wanted to include pitch-drops in the chart, but "it turns out the gif format has some issues with decade-long loops."
Frequency
(*via IO9*)

Here's a brain-meltingly cool proof of the bizarre mathematical truth that the sum of all positive integers (1 + 2 + 3 + 4 + 5....) is -1/12. This is not only provably true, it's also foundational to certain testable elements of physics. In other words: not just a logical curiosity, but also the bedrock of real-world, useful stuff.

In the end of year episode (MP3) of the BBC's More or Less stats podcast, Tim Harford talks to a variety of interesting people about their "number of the year," with fascinating results.

But the crowning glory of the episode is Helen Arney's magnificent musical tribute to Mersenne 48, the largest Mersenne Prime ever calculated, which came to light in 2013. (Arney herself is going out on tour of the UK, for the delightfully named Full Frontal Nerdity tour)

I still *don't* understand it, obviously, but "the sierpinski triangle page to end most sierpinski triangle pages" has some *sweet* fractals on it! The one above clearly depicts the optimal pattern of berms and defenses to be constructed around the Waste Isolation Pilot Project in New Mexico, lest future generations wander too close to its irradiant embrace. [Oftenpaper]

Jeff Moser's "A Stick Figure Guide to the Advanced Encryption Standard (AES)" beautifully presents the history, context, and workings of one of the most important pieces of math in the modern world. AES is at the core of virtually every privacy technology you use, and it holds the promise of building an NSA-proof, unsnoopable Internet.