This image illustrating the Pythagorean Theorem was created by the artist Mel Bochner. It appears on the cover of the January 2009 issue of the College Mathematics Journal. What is wrong with it? For the answer, visit the 360 blog.

# Month: January 2009

## Six degrees of separation

God Plays Dice wrote an interesting blog post asking whether Barack Obama has Erdos number. I gave a light-hearted talk about six degrees of separation / Kevin Bacon / Paul Erdos at our majors’ dinner a couple of years ago. It was fun. It is truly remarkable how tightly connected we all are. Here are some personal…

## Photos from the PUP booth at the Joint Meetings

The Princeton University Press blog has some photos from the 2009 Joint Mathematics Meeting including a few pics from my book signing—cool! Mike Cherry (author of The Addventures Plusman), Barry Tesman, me. Evelyn Sander and me

## John Stallings’ obit in NYT

The New York Times recently published an obituary for John Stallings. He passed away on November 24, 2008. John Stallings is probably most well-known for his work on the high-dimensional Poincaré conjecture. He wrote an article about his work on the theorem called “How not to prove the Poincaré conjecture.” (pdf link)

## Why do mirrors reverse right and left but not up and down?

Stand in front of a mirror and hold up your right hand. The person standing in the mirror holds up her left hand. Why is that? Why does a mirror reverse left and right? After all, it does not reverse up and down. Before we answer that question, we have to ask a more basic…

## How to use KnotPlot

As I’ve mentioned before, I’m teaching a knot theory class this semester. I’ve been playing around with KnotPlot, a powerful piece of software for drawing and working with knots. I want my students use it, but it has a somewhat unintuitive interface. So I’m trying to write up a list of easy-to-use instructions for them. The…

## Can you hear me now?

A few days ago my RSS feed switched from http://feeds.feedburner.com/wordpress/divisbyzero to http://feeds2.feedburner.com/wordpress/divisbyzero Apparently this had to do with Google’s purchase of Feedburner. They assured me that the old feed would continue to work. However, according to my stats, it looks like I’ve lost a good number of subscribers (but not all). Hmmm…. Hopefully that’s not…

## Tetragon fail

This morning I was listening to one of my radio stations on Pandora. One of the automatically-generated songs they played was by tenor saxaphonist Joe Henderson‘s group, the Joe Henderson Quartets. It was from his 1967 album Tetragon. The very mathematical title caught my eye, but so did the accompanying cover art. Obviously the art…

## 24 is the highest number

Too busy getting ready for classes to write anything. Instead I thought I’d post a little comic relief from Mr. Show. 24 is the highest number

## Calculus and sustainability

I saw a number of interesting talks while at the Joint Mathematics Meeting last week. Hopefully I’ll find the time to write about some of them here. One of the presentations that got me the most excited was the minicourse that I attended, Educating about the state of the planet and sustainability while enhancing calculus,…

## Publish or perish…?

I just received a copy of The Survival of a Mathematician: From Tenure-Track to Emeritus, by Steven Krantz, to review for MAA Reviews. I am only two pages in and I have already found something interesting (on p. xiv, to be precise). It is a hard fact that most American Ph.D. mathematicians write very few…

## Mathematician: top job

I just got back from the Joint Mathematics Meeting in Washington, DC. While I was gone the Wall Street Journal ran an article, Doing the Math to Find the Good Jobs. In it they reveal the best and worst jobs as compiled by Les Krantz, author of “Jobs Rated Almanac.” According to the study, mathematicians…