Our brains have become too small to understand math, says a rebel mathematician from Britain. Or rather, math problems have grown too big to fit inside our heads. And that means mathematicians are finally losing the power to prove things with absolute certainty. Math has been the only sure form of knowledge since the ancient Greeks, 2,500 years ago. You can't prove the sun will rise tomorrow, but you can prove two plus two equals four, always and everywhere. But suddenly, Brian Davies of King's College London is shaking the foundations of certainty. He says our brains can't grasp today's...