The University of Edinburgh is the top 20 universities in the world, and famous alumni include Darwin (Darwin studied medicine at Edinburgh University and later studied theology at Cambridge University), Maxwell, a famous physicist who proved that light is an electromagnetic wave, Adam Smith, the father of economics, The great philosopher David Hume, the writer Conan Doyle (the author of Sherlock Holmes), Bell, who invented the phone, and the Chinese genius Gu Hongming, known as the "Qing Dynasty monster."