Early life and education
Józef Rotblat was born on 4 November 1908, to a
Polish-Jewish family in
 in what was then
Russian Poland. He was one of seven children, two of whom died in infancy.
 His father, Zygmunt Rotblat, built up and ran a nationwide
horse-drawn carriage business, owned land and bred horses. Józef's early years were spent in what was a prosperous household but circumstances changed at the outbreak of
World War I. Borders were closed and horses requisitioned, leading to the failure of the business and poverty for their family. Despite having a religious background, by the age of ten he doubted the existence of God, and later became an agnostic.
Rotblat's parents could not afford to send him to a
gymnasium, so Rotblat received his secondary education in a
heder taught by a local rabbi. He then attended a technical school, where he studied electrical engineering, graduating with his diploma in 1923. He then worked as a
electrician in Warsaw, but had an ambition to become a physicist.
 He sat the entrance examinations of the
Free University of Poland in January 1929, and passed the physics one with ease, but was less successful in writing a paper about the
Commission of National Education, a subject about which he knew nothing. He was then interviewed by
Ludwik Wertenstein , the Dean of the Science Faculty. Wertenstein had studied in Paris under
Marie Curie and at the
Cavendish Laboratory at the
University of Cambridge under
Ernest Rutherford. Wertenstein offered Rotblat a place.
Rotblat earned a Master of Arts at the Free University in 1932. He then 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.
 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 which showed that in the
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
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; but 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 died in
the Holocaust at the
Belzec concentration camp. This affected him deeply for the rest of his life, and he never remarried.