Frequency of Cesium in Terms of Ephemeris Time

Markowitz, Wm.; Hall, R. G.; Essen, L.; Parry, J. V. L.

doi:10.1103/physrevlett.1.105

Cited by 181 publications

(52 citation statements)

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“…Regime 1) One might argue for the interaction term J to be quantitatively negligible as regards the observed l-physics, as both a small interaction term and an averaged quantity. Regime 2) Instead keeping this interaction term, then (60) has not only a time provided by the h-subsystem but also a time-dependent imprint on the l-subsystem's physics due to the h-subsystem's physics. I.e.…”

Section: Some Simple L-tdse Regimesmentioning

confidence: 99%

Machian classical and semiclassical emergent time

Anderson¹

2013

Class. Quantum Grav.

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Classical and semiclassical schemes are presented that are timeless at the primary level and recover time from Mach's 'time is to be abstracted from change' principle at the emergent secondary level. The semiclassical scheme is a Machian variant of the Semiclassical Approach to the Problem of Time in Quantum Gravity. The classical scheme is Barbour's, cast here explicitly as the classical precursor of the Semiclassical Approach. Thus the two schemes have been married up, as equally-Machian and necessarily distinct, since the latter's timestandard is abstracted in part from quantum change. I provide perturbative schemes for these in which the timefunction is to be determined rather than assumed. This paper is useful modelling as regards the Halliwell-Hawking arena for the quantum origin of the inhomogeneous cosmological fluctuations.

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Section: Some Simple L-tdse Regimesmentioning

confidence: 99%

Machian classical and semiclassical emergent time

Anderson¹

2013

Class. Quantum Grav.

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“…Therefore, the values of c 0 and Δ( 133 Cs) hfs can be compatible with each other only within the uncertainty associated to them before stipulation, c 0 = 299 792 458.0(1.3) m s −1 [8] and Δ( 133 Cs) hfs = 9 192 631 770 (20) Hz [9]. This means that not necessarily the value 299 792 458 m s −1 corresponds exactly to the value 9 192 631 770 Hz, since these are only the first moments (expected values) of two probability distributions, whose second moments (standard uncertainties) are reported in parentheses: not necessarily the stipulated values using the expected values are consistent with each other to their last digit.…”

Section: Propagation Of Stipulationsmentioning

confidence: 99%

Rounding, stipulation and notation issues in measurement

Pavese¹

2013

Int. J. Metrol. Qual. Eng.

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“…It was desirable that the caesium frequency be coherent with this future definition (adopted in 1960), rather than with the current second based on the rotation of the Earth, which was longer by approximately 2 × 10 −8 . These considerations let us adopt the value proposed by Markowitz et al [2]: 9192631770 Hz, when referred to the second of Ephemeris Time, a value retained in 1967, for the atomic definition of the second, that is still in use. Let us observe that, in contrast with the usage, the re-definition of a basic unit in 1960 introduced a deliberate step in its size.…”

Section: The Genesis Of Atomic Time Scalesmentioning

confidence: 99%

Time scales in the context of general relativity

Guinot

2011

Phil. Trans. R. Soc. A.

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Towards 1967, the accuracy of caesium frequency standards reached such a level that the relativistic effect could not be ignored anymore. Corrections began to be applied for the gravitational frequency shift and for distant time comparisons. However, these corrections were not applied to an explicit theoretical framework. Only in 1991 did the International Astronomical Union provide metrics (then improved in 2000) for a definition of spacetime coordinates in reference systems centred at the barycentre of the Solar System and at the centre of mass of the Earth. In these systems, the temporal coordinates (coordinate times) can be realized on the basis of one of them, the International Atomic Time (TAI), which is itself a realized time scale. The definition and the role of TAI in this context will be recalled. There remain controversies regarding the name to be given to the unit of coordinate times and to other quantities appearing in the theory. However, the idea that astrometry and celestial mechanics should adopt the usual metrological rules is progressing, together with the use of the International System of Units, among astronomers.

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Frequency of Cesium in Terms of Ephemeris Time

Cited by 181 publications

References 2 publications

Machian classical and semiclassical emergent time

Machian classical and semiclassical emergent time

Rounding, stipulation and notation issues in measurement

Time scales in the context of general relativity

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