Cory Doctorow, Boing Boing, Why the sum of all positive integers is -1/12, here.
Here’s a brain-meltingly cool proof of the bizarre mathematical truth that the sum of all positive integers (1 + 2 + 3 + 4 + 5….) is -1/12. This is not only provably true, it’s also foundational to certain testable elements of physics. In other words: not just a logical curiosity, but also the bedrock of real-world, useful stuff.