Time ‐ From Earth Rotation to Atomic Physics

Filling the need for a book that conveys the current technology as well as the underlying history and physical background, this book tells physicists and engineers how to measure time to the precision required for modern-day use. The authors draw on their longstanding research experience with timekeeping and high-precision measurement to cover the use of satellites in measuring earth movement variation and the influence of the moon, while also dwelling on such topics as timekeeping aboard satellites and time transfer. Indispensable for high-precision measurements of processes in astrophysics, and relevant for measurement, navigation and communication, this monograph can be equally used as a course book or as accompanying work at advanced undergraduate or graduate level. TIME – From Earth Rotation to Atomic Physics......Page 5 Contents......Page 9 Preface......Page 17 Acronyms......Page 19 1.2 Characterizing Time......Page 25 1.3 Calendars......Page 26 1.4 Astronomical Observations......Page 27 1.5 Timekeeping......Page 28 1.6 Time Epochs......Page 29 1.7 Time Transfer......Page 30 1.9 Beginning the Twentieth Century......Page 31 References......Page 32 2.2 Mean Solar Time......Page 33 2.4 Sidereal Time......Page 35 2.5 Washington Conference of 1884......Page 36 2.6 Newcomb’s Theory of the Sun......Page 37 2.7 Universal Time......Page 38 2.8 Coordinated Universal Time (UTC)......Page 40 2.9 Greenwich Mean Time (GMT)......Page 41 2.10 Tropical Year......Page 42 2.12 Reference System......Page 43 2.14 Daylight Saving Time......Page 44 References......Page 46 3.2 Before Kepler and Newton......Page 47 3.3 Kepler and Newton......Page 50 3.4 Tables, General Theories, and Ephemerides......Page 51 3.5 Lunar Theories......Page 53 3.6 The Advent of Computers......Page 56 3.8 Observational Data......Page 57 3.9 Dynamical Reference Frame......Page 58 3.10 Time Arguments......Page 59 3.12 Artificial Satellite Theories......Page 60 References......Page 61 4.1 Pre 19th Century......Page 65 4.2 Secular Variation......Page 66 4.3 Irregular Variations in the Earth’s Rotation......Page 68 4.4 Early Explanations for the Variable Rotation......Page 76 4.5 Current Understanding of the Earth’s Variable Rotation......Page 77 4.6 Consequences......Page 79 References......Page 81 5.1 Earth Orientation......Page 85 5.1.1 Precession/Nutation......Page 89 5.1.2 Polar Motion......Page 90 5.1.3 UT1......Page 92 5.2.1 Precession Nutation......Page 93 5.2.2.2 Decadal Variations......Page 94 5.2.2.4 Other Variations......Page 95 5.3 Transforming Between Reference Frames......Page 96 5.4 Determination of Earth Orientation......Page 99 5.5 Earth Orientation Data......Page 100 References......Page 101 6.1 Need for a Uniform Time Scale......Page 103 6.2 Danjon Proposal......Page 104 6.3 Clemence’s Proposal......Page 105 6.4 Adoption and Definition......Page 107 6.5 Observational Determination......Page 108 6.6 The Ephemeris Second and Atomic Time......Page 110 6.7 Historical DT......Page 111 6.8 Problems with Ephemeris Time......Page 114 6.9 Relativity......Page 115 6.10 Dynamical Time Scales......Page 116 References......Page 117 7.2 Special Relativity......Page 119 7.3 Lorentz Transformations......Page 121 7.4 Coordinate and Proper Time......Page 122 7.5 Minkowski Diagrams......Page 123 7.6 Time in Special Relativity......Page 126 7.7.1 Metrics in General Relativity......Page 127 7.7.2 The Equivalence Principle......Page 128 7.8 IAU Resolutions......Page 129 7.10 Relativistic Effects in Time Transfer......Page 135 References......Page 136 8.1 Replacing Ephemeris Time......Page 137 8.2 Terrestrial Dynamical Time (TDT) and Barycentric Dynamical Time (TDB)......Page 138 8.3 Problems with TDT and TDB......Page 140 8.4 New Reference System......Page 141 8.5 New Time Scales......Page 142 8.5.2 Terrestrial Time......Page 143 8.5.4 Barycentric Coordinate Time......Page 144 8.5.6 TDB Redefined......Page 146 8.6 DT and Ephemeris Time Revised......Page 148 8.7 Relationships Among Coordinate Time Scales......Page 149 References......Page 150 9.2 Keeping Time in Antiquity......Page 153 9.2.1 Clepsydrae and Water ‘Clocks’......Page 154 9.2.2 Other Timekeeping Devices......Page 155 9.3 The First Mechanical Clocks......Page 156 9.4.1 Galileo......Page 157 9.4.2 Huygens......Page 158 9.4.3 Pendulum Clock Developments......Page 160 9.4.4 Chronometers......Page 162 9.5 Quartz Crystal Clocks......Page 163 9.6.1 Quality (Q) Factor......Page 166 9.6.3 Accuracy......Page 167 9.6.4 Stability......Page 168 References......Page 173 10.1 Beyond Quartz-Crystal Oscillators......Page 175 10.2 Physics of Atomic Clocks......Page 176 10.3 General Structure of Atomic Clocks......Page 178 10.4 Development of Atomic Clocks......Page 181 10.4.1 Cesium......Page 182 10.4.1.1 Calibration of the Cesium Frequency......Page 184 10.4.1.2 Cesium Beam Tubes......Page 186 10.4.1.3 Cesium Fountains......Page 190 10.4.2 Hydrogen......Page 193 10.4.2.1 Active Hydrogen Maser......Page 194 10.4.2.2 Passive Hydrogen Masers......Page 195 10.4.3.1 Rubidium Cells......Page 196 10.4.3.3 Double-bulb Rubidium Maser......Page 197 10.5 Stored Ion Clocks......Page 198 10.5.1 Mercury......Page 199 10.6 Characterizing Atomic Clocks......Page 201 References......Page 202 11.1 Optical Transition Frequencies......Page 205 11.2 Optical Ion Clocks......Page 207 11.4 Quantum Logic Clock......Page 208 References......Page 210 12.1 The Historical Second......Page 213 12.2 The Ephemeris Second......Page 215 12.3 The SI Second......Page 216 12.4 Adopting the SI Second......Page 219 References......Page 221 13.1 Constructing an Atomic Time Scale......Page 223 13.2 History of TAI......Page 225 13.3 Formation of TAI......Page 231 13.3.1 EAL......Page 232 13.3.2 Steering EAL with Primary Frequency Standards......Page 239 13.5 Distribution of TAI......Page 240 13.6 Relationship of TAI to Terrestrial Time......Page 242 References......Page 246 14.1 Universal Time Before 1972......Page 247 14.2 Coordinated Universal Time After 1972......Page 251 14.3 Leap Seconds......Page 253 14.5 UTC Worldwide......Page 255 14.7 The Future of UTC – Leap Seconds or Not?......Page 256 References......Page 257 15.1 The Solar System......Page 259 15.3 Pursuit of Accuracy......Page 260 15.4.1 Eclipses, Occultations, Transits......Page 261 15.4.3 Moonrises and Moonsets......Page 263 15.5 Time and Distance......Page 264 15.5.2 Radar Ranging......Page 265 15.5.4 Navigation Systems......Page 266 15.7 Proper Times at Planets......Page 270 15.8 Pulsars – An Independent Source of Time?......Page 271 References......Page 272 16.1 Historical Transfer Techniques......Page 273 16.2.1 Propagation Effects......Page 274 16.2.3 Relativistic Effects......Page 275 16.2.3.2 Nonrotating Local Inertial Reference Frame......Page 276 16.2.3.4 Electromagnetic Signals Transfer in a Nonrotating Local Inertial Reference Frame......Page 277 16.3.4 Microwave Links......Page 278 16.3.7 High-Frequency Radio Signals......Page 279 16.3.8 Low-Frequency Broadcast Radio Signals......Page 280 16.3.9 Low-Frequency Navigation Signals......Page 281 16.3.10.2 GLONASS......Page 282 16.3.12 Two-Way Satellite Time and Frequency Transfer......Page 283 References......Page 284 17.1 Terrestrial to Celestial Reference Systems......Page 287 17.2 Determination of Earth Orientation Parameters......Page 288 17.2.1 Very Long Baseline Interferometry (VLBI)......Page 289 17.2.2 Global Positioning System (GPS)......Page 294 17.2.3 Satellite Laser Ranging (SLR)......Page 296 17.2.5 Geophysical Modeling......Page 300 17.3 Earth Orientation Data......Page 303 References......Page 304 18.2 Treaty of the Meter......Page 305 18.2.2 International Committee on Weights and Measures (CIPM)......Page 306 18.3 Scientific Unions......Page 307 18.3.1 International Astronomical Union (IAU)......Page 308 18.3.2 International Union of Geodesy and Geophysics (IUGG)......Page 309 18.3.3 International Telecommunications Union (ITU)......Page 310 18.4 Service Organizations......Page 312 18.4.1 International Earth Rotation and Reference Systems Service (IERS)......Page 314 18.4.3 International Laser Ranging Service (ILRS)......Page 317 18.4.4 International GNSS (Global Navigational Satellite Service) Service (IGS)......Page 318 18.4.5 International DORIS Service (IDS)......Page 319 References......Page 320 19.2 Positioning and Navigation Services......Page 321 19.3 Communications......Page 322 19.4 Power Grid......Page 324 19.8 Summary......Page 325 Reference......Page 328 20.1 Future Needs for Time......Page 329 20.2 Modeling the Earth’s Rotation......Page 330 20.4 Future Time Scales......Page 331 20.5 Future Time Distribution......Page 332 Glossary......Page 335 Index......Page 361 "Filling the need for a book that presents the current technology as well as the underlying historical and physical background, this publication informs scientists, engineers, and those interested in the foundations of modern timekeeping how precise time and frequency are made available for modem-day use. The authors draw on their longstanding research experience with timekeeping and high-precision measurements to describe the discovery of the irregular motions of the Earth, the development of mechanical and atomic clocks, the introduction of dynamical timescales, and the development of the study of the Earth's orientation in space. Also discussed are astronomical and satellite observations used to improve solar system dynamics and Earth kinematics along with the applications of the theory of relativity to the topics of timekeeping and time transfer." --Résumé de l'éditeur Review: "Filling the need for a book that presents the current technology as well as the underlying historical and physical background, this publication informs scientists, engineers, and those interested in the foundations of modern timekeeping how precise time and frequency are made available for modem-day use. The authors draw on their longstanding research experience with timekeeping and high-precision measurements to describe the discovery of the irregular motions of the Earth, the development of mechanical and atomic clocks, the introduction of dynamical timescales, and the development of the study of the Earth's orientation in space. Also discussed are astronomical and satellite observations used to improve solar system dynamics and Earth kinematics along with the applications of the theory of relativity to the topics of timekeeping and time transfer."--Jacket