As the 21st century enters its 25th year, The Sunday Magazine's Pete Mitton speaks with a range of big thinkers about what they see as the defining features of the 2000s so far. Historians Margaret MacMillan and Anne Applebaum, political scientist Francis Fukuyama, global affairs expert Janice Stein, and more share their reflections on the century's first quarter to this point, and explore what lessons this period may hold for the next 25 years.