In this, the second volume in an important new series presenting core concepts across a range of critical areas of human knowledge, author Joanne Baker unravels the complexities of 20th-century scientific theory for a general readership. From Hubble's law to the Pauli exclusion principle, and from SchrOdinger's cat to Heisenberg's uncertainty principle, she explains ideas at the cutting-edge of scientific enquiry, making them comprehensible and accessible to the layperson