he entered the University of Warsaw, and became a Doctor of Physics in 1938. He held the position of Research Fellow in the Radiological Laboratory of the Scientific Society of Warsaw, of which Wertenstein was the director, and became assistant Director of the Atomic Physics Institute of the Free University of Poland in 1938. Marriage and early physics work During this period, Rotblat married a literature student, Tola Gryn, whom he had met at a student summer camp in 1930. Before the outbreak of World War II, he conducted experiments that showed that in the fission process, neutrons were emitted. In early 1939, he envisaged that a large number of fissions could occur and if this happened within a sufficiently short time, then considerable amounts of energy could be released. He went on to calculate that this process could occur in less than a microsecond, and as a consequence would result in an explosion. In 1939, through Wertenstein's connections, Rotblat was invited to study in Paris and at the University of Liverpool under James Chadwick, winner of the 1932 Nobel Prize for discovering the neutron. Chadwick was building a particle accelerator called a "cyclotron" to study fundamental nuclear reactions, and Rotblat wanted to build a similar machine in Warsaw, so he decided to join Chadwick in Liverpool. He travelled to England alone because he could not afford to support his wife there. Before long, Chadwick gave Rotblat a fellowship (the Oliver Lodge Fellowship), doubling his income, and in that summer of 1939, the young Pole returned home, intending to bring Tola back with him. When the time came to leave Warsaw in late August, however, she was ill following an operation for appendicitis, and remained behind, expecting to follow within days; however, the outbreak of war brought calamity. Tola was trapped, and desperate efforts in the ensuing months to bring her out through Denmark (with the help of Niels Bohr), Belgium, and finally Italy came to nothing, as each country in turn was closed off by the war. He never saw her again; she was murdered in the Holocaust at the Belzec concentration camp. This affected him deeply for the rest of his life, and he never remarried. Manhattan Project While still in Poland, Rotblat had realised that nuclear fission might possibly be used to produce an atomic bomb. He first thought that he should "put the whole thing out