| Acknowledgments | vii |
| INTRODUCTION An Overview: 1895-1945 | viii |
| PART ONE The Physical Sciences | 1 |
| 1. The New Atom: From X Rays to the Nucleus | 3 |
| 2. The New Universe, Part One: Einstein and Relativity | 19 |
| 3. The New Universe, Part Two: The Quantum Surprise | 37 |
| 4. New Observations of the Universe | 49 |
| 5. The Atom Split Asunder: Science and the Bomb | 59 |
| PART TWO The Life Sciences | 75 |
| 6. The Growth of Microbiology and Biochemistry | 77 |
| 7. Pursuing the Trails of Genetics and Heredity | 99 |
| 8. In Search of Ancient Humans | 113 |
| Epilogue | 131 |
| Appendix: The Scientific Method | 133 |
| Chronology | 137 |
| Glossary | 145 |
| Further Reading | 149 |
| Index | 157 |