Rest in Peace, Alexander Bogomolny @CutTheKnotMath
He was of the few saints you meet in life: He gave more, much more than he took.
— Nassim Nicholas Taleb (@nntaleb) July 8, 2018
Alexander Bogomolny was a mathematician and educator well known for his website Cut the Knot, which offered interactive mathematical miscellany and puzzles. You can learn more about him, education and antisemitism in the USSR, his mathematics research and his approach to Cut the Knot in this interview from 2014.
The purpose of the website is educational, with a large index of mathematical topics to explore. In its manifesto, Bogomolny rails against the problem that it has “become an acceptable norm to confess a dislike and misunderstanding of Mathematics as a whole”, concluding that a lack of awareness of the beauty of mathematics is a contributing factor (cf. the utility of mathematics): “judging Mathematics by its pragmatic value is like judging symphony by the weight of its score.” So he invites visitors to the website to make a selection from the miscellany, saying “Learning starts from wondering, and another purpose of this site is to serve as a resource for things, simple but curious, related to Mathematics”.
In making such a selection, where should you start? I’ve used various pages on the site over the years when I’ve been looking for an interesting topic or a clear explanation of something I’m investigating. Just a couple of weeks ago, I was telling a colleague about this page linking the Towers of Hanoi puzzle to the Sierpinski Gasket, a fun result. I suggest you visit the site, pick something that interests you, and dive in. For example, there are a series of articles written as a Cut the Knot column over several years, there are various collections, such as eye openers and impossible things, or you just can just browse through the vast collection of topics on the homepage.