### 42

#### Posted by John Baez

In *The Hitchhiker’s Guide to the Galaxy*, the number 42 was revealed to be the Answer to the Ultimate Question of Life, the Universe, and Everything. But we never learned what the question was!

That’s what I’ll explain this Saturday in Montreal.

My talk is part of the Canadian Mathematical Society winter meeting. But it’s open to the public, and I’ll keep the math simple and fun. So, come along and bring your kids!

It’s from 6 to 7 pm on December 5th at the Hyatt Regency Montreal, at 1255 Jeanne-Mance. It’s in “Rooms Soprano A & B”, but I won’t be singing — they must have confused me with my cousin Joan.

If you can’t come to the talk, you can still see the slides here:

If you don’t already know the joke, watch the movie clip first!

Earlier that day I’ll be at Prakash Panangaden’s session on Logic, Category Theory and Computation, and I’ll give a talk there at 10 am, right after André Joyal’s hour-long talk on “Simplicial Tribes for Homotopy Type Theory”. His abstract says “A tribe is a categorical model of homotopy type theory. We would like to show that the category of tribes has the structure of a fibration category, but path objects are missing. To correct this, we introduce the notion of simplicial tribes.”

This session is in Pavillion Kennedy of UQAM on the third floor in room PK-3605. My talk will be on categories in control theory, and the slides are here:

## Re: 42

Here is something that could be related, 42^2 + 56^2 = 70^2 ?