Time Machine Tales (eBook)

Also By Paul J. Nahin 6
Frontispiece: The Pioneers of Time Travel 7
A Note on the Story Citations and Science Fiction History 8
Some First Words 10
For Further Discussion 20
Acknowledgements 24
Introduction 26
That Useless Time Machine 36
A Useful Time Machine 38
For Further Discussion 41
Contents 45
About the Author 47
Chapter 1: A Broad Look at Time Travel 48
1.1 Time Travel in the Fantasy and Science Fiction Literature 48
1.2 Where Are All the Time Travelers? 57
1.3 Skepticism About Tales of Time Travel 62
1.4 Troubles with (some) Time Machines 69
1.5 Quantum Gravity, Singularities, Black Holes, and Time Travel 76
1.6 Tipler´s Time Machine 85
1.7 For Further Discussion 89
Chapter 2: Philosophical Space and Time 97
2.1 Time: What Is It, and Is It Real? 97
2.2 Linear Time and the Infinity of Past and Future 107
2.3 Cause and Effect 113
2.4 Backward Causation 118
2.5 The Fourth Dimension 124
2.6 Spacetime and the Block Universe 136
2.7 Philosophical Implications of the Block Universe 146
2.8 For Further Discussion 155
Chapter 3: The Physics of Time Travel: Part I 160
3.1 The Direction of Time 160
3.2 The Arrows of Time 169
3.3 Time Dilation 184
3.4 The Lorentz Transformation 191
3.5 Spacetime Diagrams, Light Cones, Metrics, and Invariant Intervals 200
3.6 Proper Time and the Twin Paradox in Time Travel to the Future 218
3.7 For Further Discussion 226
Chapter 4: Philosophers, Physicists, and the Time Travel Paradoxes 232
4.1 Paradoxes and Their First Appearance in Science Fiction 232
4.2 Changing the Past and the Grandfather Paradox 240
4.3 Changing Versus Affecting the Past 251
4.4 Causal Loop and Bootstrap Paradoxes 259
4.5 Sexual Paradoxes 270
4.6 Splitting Universes and Time Travel 274
4.7 For Further Discussion 282
Chapter 5: Communication with the Past 290
5.1 Reversed Time 290
5.2 Multi-dimensional Time 297
5.3 Maxwell´s Equations and Sending Messages to the Past 301
5.4 Wheeler and Feynman and Their Bilking Paradox 309
5.5 Absorber Theory and Signaling the Past 314
5.6 Tachyonic Signals and the Bell Quantum Antitelephone 318
5.7 For Further Discussion 328
Chapter 6: The Physics of Time Travel: II 333
6.1 Faster-than-Light into the Past 333
6.2 Tipler´s Rotating Cylinder Time Machine 341
6.3 Thorne´s Wormhole Time Machine 345
6.4 Gott´s Cosmic String Time Machine 363
6.5 Cutting and Warping Spacetime 370
6.6 For Further Discussion 378
Appendix A: Old Friends Across Time (A Story) 382
For Further Discussion 387
Appendix B: Newton´s Gift (A Story) 389
For Further Discussion 394
Appendix C: Computer Simulation of the Entropic Gas Clock 396
Epilogue 398
Glossary 407
Index 417