| Cosmology | 513 |
| 17.1Observations of the Universe | 514 |
| Distribution of Galaxies | 514 |
| Motion of Galaxies | 515 |
| Age of the Universe | 516 |
| Extending Our Reach: Estimating the Age of the Universe | 516 |
| Re-Modeling: Age Discrepancy | 517 |
| The Cosmic Horizon | 518 |
| The Size of the Universe | 518 |
| Are We at the Center of the Universe? | 519 |
| Olbers' Paradox | 519 |
| The Cosmic Microwave Background | 521 |
| Composition of the Oldest Stars | 522 |
| Conclusions Deduced from the Basic Observations of the Universe | 523 |
| 17.2Evolution of the Universe: Open or Closed? | 524 |
| The Density of the Universe | 525 |
| A Cosmological Repulsion? | 526 |
| 17.3The Shape of the Universe | 527 |
| 17.4The Origin of the Universe | 528 |
| Radiation, Matter, and Antimatter in the Early Universe | 529 |
| History of Matter and Radiation in the Early Universe | 530 |
| The Formation of Galaxies | 531 |
| 17.5The Inflationary Universe | 532 |
| Extending Our Imagination: Grand Unified Theories | 533 |