THE TITLE OF THIS BOOK DIFFERS by only two letters from that of a book first published in 1988. A Brif History of Time was on the London Sunday Times best-seller list for 237 weeks and has sold about one copy for every 750 men, women, and children on earth. It was a remarkable success for a book that.addressed some of the most difficult issues in modern physics. Yet those difficult issues are also the most exciting, for they address big, basic questions: What do we really know about the universe？ How do we know it？ Where did the universe come from, and where is it going？ Those questions were the essence of A Brief History of Time, and they are also the focus of this book.

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Stephen Hawking's worldwide bestseller, A Brief History of Time, was a landmark volume in scientific writing. Its author's engaging voice is one reason, and the compelling subjects he addresses is another: the nature of space and time, the role of God in creation, the history and future of the universe. But it is also true that in the years since its publication, readers have repeatedly told Professor Hawking of their great difficulty in understanding some of the book's most important concepts.

This is the origin of and the reason for A Briefer History of Time: its author's wish to make its content accessible to readers - as well as to bring it up-to-date with the latest scientific observations and findings.

Although this book is literally somewhat 'briefer', it actually expands on the great subjects of the original. Purely technical concepts, such as the mathematics of chaotic boundary conditions, are gone. Conversely,subjects of wide interest - including relativity, curved space, and quantum theory - that were difficult to follow because they were interspersed throughout the book have now been given entire chapters of their own.This reorganization has allowed the authors to expand on areas of special interest and recent progress, from the latest advances in string theory to exciting developments in the search for a complete, unified theory of all the forces of physics. Like prior editions of the book - but even more so - A Briefer History of Time will guide non-scientists everywhere in the ongoing search for the tantalizing secrets at the heart of time and space.

ACKNOWLEDGEMENTS

FOREWORD

1. Thinking About the Universe

2. Our Evolving Picture of the Universe

3. The Nature of a Scientific Theory

4. Newton's Universe

5. Relativity

6. Curved Space

7. The Expanding Universe

8. The Big Bang, Black Holes, and the Evolution of the Universe

9. Quantum Graviw

10. Wormholes and Time Travel

11. The Forces of Nature and the Unification of Physics

12. Conclusion

ALBERT EINSTEIN

GALILEO GALILEI

ISAAC NEWTON

GLOSSARY

INDEX