This puzzle comes from mathematical physicist John Baez. That’s John, not Joan (she is not a mathematical physicist, as far as I know), though they are in fact first cousins.
You don’t normally expect that a physicist with a Ph.D. from MIT would create a puzzle accessible to the general reader, but that’s what we have here—at least the puzzle itself is accessible, even though the proof isn’t. Science journalist Siobhan Roberts wrote about it recently in the New York Times, so check out her article: if you pause after the puzzle is stated, you can try it yourself. Along the way you can learn some interesting tidbits about problem-solving processes, about plastic numbers (you can look it up), and about a fascinating mix of computer science, social media, geometry, algebra, and number theory.
Thanks to my friend and colleague Brian Harvey for pointing me to this article!
Categories: Math, Teaching & Learning, Technology