Making a hyperboloid out of skewers and rubber bands

George Hart, of the Museum of Mathematics, writes a weekly column at Make Magazine called “Math Monday.” A few weeks ago he showed how to make a hyperboloid of one sheet out of 32 shish kabob skewers and 176 hair rubber bands. (Here is a direct link to the instructions.) We just finished talking about…

Perelman to be awarded the Clay Millennium Prize

The epilogue of my book is devoted to the Poincar√© conjecture, the famously challenging 98-year old topological puzzler that was proved in 2002 by Grisha Perelman. Perelman was awarded the Fields Medal in 2006 for this accomplishment, but he declined to accept the award. Today the Clay Mathematics Institute issued a press release that begins:…

A card trick that will probably amaze your friends (solution)

Warning! Spoiler alert! This post contains the secret behind the card trick that I described in my last post. Read that post before reading this one. First the bad news: this card trick is not fool-proof; it is a probabilistic card trick. The good news is that in my experience, it has a high probability…

A card trick that will probably amaze your friends

Here’s a neat card trick that I learned a few years ago. I can’t remember where I read about it. If anyone knows the source of trick, please post it in the comments. [Update: I now know more about the origin of this trick. I’ll write more in my follow-up post.] Thoroughly shuffle an ordinary…

An application of graph theory to architecture

Several years ago I came across a fascinating application of graph theory to architecture. It is in the 1983 book Incidence and symmetry in design and architecture, by Jenny A. Baglivo and Jack E. Graver. I don’t know if it is well known among experts in the field, but I’ve never seen it elsewhere. So…

Readers’ response: Euler’s greatest hits

My friend Gene Chase is teaching a history of mathematics class at Messiah College this semester. He asked me if I was interested in giving a visiting lecture in his class in a few weeks. The topic: Leonhard Euler. He said that I could talk about whatever I wanted. Wow, the possibilities! So I was…

Polya on Euler

One of my computer science colleagues sent me this quote from Polya about Euler.¬†This is usually something I’d to post on Twitter, but it is too long. So I thought I’d reproduce it here. …among old mathematicians, I was most influenced by Euler and mostly because Euler did something that no other great mathematician of…