Why does a flat pizza slice flop over unless you bend it into a curve? Thank Gaussian curvature, the 19th century mathematical principle that underpins everything from corrugated cardboard to eggshells to Pringles chips.

# Rational numbers are impossible!

# Online Isaac Newton manuscripts workshop

# Vi Hart on the relative sizes of infinities

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.

# Mathematics as the basis for leftist reasoning

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:

# Critical thinking vs education: Teaching kids math without "correct" answers

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.

# Piketty's methods: parsing wealth inequality data and its critique

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).

# XKCD: the TED talk

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.

## Largest-ever damages sought —

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. — Cory • 25# Mathematicians: refuse to work for the NSA!

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."

# Big Data has big problems

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.

# In which I make Wil Wheaton read out Pi for four minutes

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!

# Vi Hart's updated poop-on-Pi video

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.

# Eggbot design: Pi Egg for Pi Day

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.

# Thoughts on teaching calculus to five-year-olds

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?