The five parts of this essay are held together by the common theme of unification. Each section focuses on a particular theoretical development and is written in the voice of a scientist living at the time, reflecting on the discoveries of his or her age, what they mean, how they demand a changed worldview, and what might potentially lie in the future. The first section is written as a letter from a young British student at Cambridge, to his sister. He describes to her the wonders of Maxwell 's equations and what they mean, but in terms that his sister, who is an aspiring painter, would be able to relate to. The second section, about relativity, is written by a layman. A New York school teacher who admires Einstein has gone to Battery Park to join the crowds welcoming the Nobel Laureate to America. Whilst waiting for the ship, he thinks about the theories that made this man an international celebrity. The third section is based on the reflections of a young European researcher in Copenhagen in the early 1930's. He sees the greats of quantum mechanics walk the corridors and learns from their conversations, whether directed at him, or overheard. The basic developments are mentioned, including Heisenberg 's uncertainty principle, Pauli 's exclusion principle, Schrodinger 's equation and wave-particle duality. The fourth section is set in the early 1980's. A third-world scientist, early in his career, is visiting the International Center for Theoretical Physics at Trieste, Italy. In a letter to his young children, he talks about particle physics, introduces the Standard Model, and ruminates on how essential collaboration and a conducive atmosphere are for research. The last scientist is a female graduate student at Harvard in the present day. She is beginning to study string theory and is fascinated by the promise of ultimate unification. After a brief review of string theory “ and a mention of the LHC ” she addresses the question of whether or not she thinks this might be physics' last word.
