Contributor(s): Gideon Rachman | In this lecture to mark the publication of his new book Zero-Sum World: Power and Prosperity in the Age of Anxiety, Gideon Rachman argues that the global economic crisis has changed the logic of international relations and ushered in a new and more dangerous era. This will be characterised by rising tensions between America and China and a failure to deal effectively with global problems such as climate change and nuclear proliferation. Gideon Rachman is the chief foreign affairs commentator for the Financial Times.