Splitting The Second: The Story of Atomic TimeCRC Press, 1 jan 2000 - 199 pagina's Until the 1950s timekeeping was based on the apparent motion of the Sun that in turn reflected the rotation of the Earth on its axis. But the Earth does not turn smoothly. By the 1940s it was clear that the length of the day fluctuated unpredictably and with it the length of the second. Astronomers wanted to redefine the second in terms of the moti |
Inhoudsopgave
1 Astronomers Time | 1 |
2 Physicists Time | 25 |
3 Atomic Time | 53 |
4 World Time | 69 |
5 The Leap Second | 95 |
6 Time Transfer | 115 |
7 Uses of Accurate Time | 141 |
8 The Future of Time | 161 |
Appendix | 183 |
Glossary of Abbreviations | 189 |
Back Cover | 192 |
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accuracy accurate ammonia Anne’s astronomers atomic clock BIPM broadcast caesium atoms caesium beam standard caesium clock caesium fountain caesium standard caesium transition cavity centimetres centres CGPM Chapter Coordinated Universal correct defined difference disseminated Earth Earth’s rotation electron emitted Ephemeris Essen Figure flipped frequency standards GLONASS gravitational shift Greenwich hyperfine IERS International kilogram kilometres laser leap seconds length light Louis Essen magnetic mean solar day measure megahertz meridian microseconds microwaves million milliseconds molecules Moon moving nanometres nanoseconds National Naval Observatory NIST noon observations operated optical orbit oscillator Paris Paris Observatory pendulum photons physicists planets position precise predicted primary standards pulsar pulses quartz-crystal clocks radio Royal Greenwich Observatory Sagnac effect satellites sidereal signals slow speed stable standards laboratory stars stations telescope ticks tidal drag transfer transition frequency units USNO version of UTC wavelength waves Website world timekeeping