ABSTRACT
This chapter discusses how nationalism infected society in the beginning of the 20th century, not sparing physicists. How the “great” war, World War I, severed many precious links between German and essentially all other scientists. How ideology polluted physics and caused an unprecedented brain drain in Europe during Nazi reign. It covers the concentrated efforts on the nuclear bomb on both sides of the Atlantic during the early 1940s. The chapter looks into the complicated relation between Heisenberg and Bohr during the German occupation of Denmark. Then the chapter briefly discusses how cold war affected physics and physicists. Bigotry, nationalism, racism and other non-scientific intrusions into science of course did not suddenly appear in 1914 out of nothing. Scientists are not living in a political vacuum, they are citizens and often engage in the political and social questions of their time.
