Arrow's theorem
Adam Smith is often thought of as the father of modern economics. In his book "An Inquiry into the Nature and Causes of the Wealth of Nations" Smith decribed the "invisible hand" mechanism by which he felt economic society operated. Modern game theory has much to add to Smith's description.
How long will you live? How should you write down numbers? Who's your ideal partner? How good is our voting system? And what is a differential equation? These are difficult and momentous questions. This issue of Plus has some answers, along with a tour of digital art and the usual range of podcasts, news and reviews.
