Laser wavelength measurements and the speed of light

Rowley, W. R. C.; Jolliffe, B. W.; Shotton, K. C.; Wallard, Andrew; Woods, P. T.

doi:10.1007/bf00620434

Cited by 23 publications

(5 citation statements)

References 48 publications

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“…Similar kinds of frequency chains were built by T. Blaney, Gordon Edwards, David Knight and colleagues at the NPL. It was a huge pleasure to become acquainted with these NPL team members, who also furnished wavelength, frequency and speed of light numbers to the CCDM [21,22]. The NIST-Gaithersburg team had an interferometric comparison between red and IR [10], as well as nice stabilization results using isotope 129 molecular iodine.…”

Section: Observations About the Length Redefinition (By A Participant)mentioning

confidence: 99%

Learning from the time and length redefinitions, and the metre demotion

Hall

2011

Phil. Trans. R. Soc. A.

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After discussing several issues in a future redefinition of the kilogram, this paper considers the lessons that one might have learned from the analogous redefinitions of the metre and the second. The progress of length metrology was slow and steady, from seven digits reproducibility with the 1889 X-shaped metre prototype, to nine digits with Kr lamps, to 11 digits with the 1983 redefinition of the metre using the speed of light. With laser cooling, the Cs clock improved to 15, now 16, digits (and so also astronomical distance measurements could improve). Laser-cooled ions, and now atoms captured and cooled in an optical lattice, enable accuracy capability of three different optical frequency references to exceed 17 digits, i.e. better than time itself. The optical comb and related techniques vastly simplify frequency comparisons. Such progress stimulates a new satellite experiment, the STAR Mission (Space-Time Asymmetry Research). The goal is to test at the 1E-18 level frequency shifts owing to spatial anisotropy, position, gravitational potential and boost. The onboard optical clock will use stabilization to a molecular transition in I 2 or HCCH or CO 2 . The length etalons will be multiply redundant, with stability at the thermo-mechanical mirror motion limit. For a ULE glass etalon spacer (1987), I measure length creep approximately −1.5E-12/d, i.e. below 1E-14 over the 500 s satellite spin period.Keywords: choosing base units; frequency stability; optical atomic clocks; defining the speed of light; redefinition of the kilogram BackgroundWith the great progress in the international 'Avogadro project', working to make the connection between atomic mass and the International System of Units (SI) mass scales, it will ultimately be appropriate to consider a redefinition of the SI kilogram unit [1]. The existing definition, in place for more than a century, speaks in terms of the mass of a particular metallic blob being kept in Sèvres, France, by the BIPM (Bureau International des Poids et Mesures;

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Section: Observations About the Length Redefinition (By A Participant)mentioning

confidence: 99%

Learning from the time and length redefinitions, and the metre demotion

Hall

2011

Phil. Trans. R. Soc. A.

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“…Since the pioneering works of Michelson and Morley, many reports [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] have claimed the testing of the second postulate of special relativity (SR) [31]. However, all of these cases have a common factor: that light follows closed paths, and therefore they only test, directly or indirectly, the isotropy of the average round trip speed or the so-called two-way speed of light.…”

Section: Introductionmentioning

confidence: 99%

On the experimental determination of the one-way speed of light

Pérez¹

2011

Eur. J. Phys.

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In this contribution the question of the isotropy of the one-way speed of light from an experimental perspective is addressed. In particular, we analyze two experimental methods commonly used in its determination. The analysis is aimed at clarifying the view that the one-way speed of light cannot be determined by techniques in which physical entities close paths. The procedure employed here will provide epistemological tools such that physicists understand that a direct measurement of the speed not only of light but of any physical entity is by no means trivial. Our results shed light on the physics behind the experiments which may be of interest for both physicists with an elemental knowledge in special relativity and philosophers of science.

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“…This approach seems most natural in the framework of Einstein's relativity with the fixed velocity of light c in all reference frames. Excellent historical technical summaries of the development of optical frequency standards and the frequency measurements that led to the defined speed of light and eventual redefinition of the metre can be found in reviews by Petley, Rowley, Jennings and Hall, who were some of the principals involved in these important measurements [20,25,34,63]. With the redefinition of the metre, the international standards bodies (the CGPM/CIPM) prescribe three basic methods for 'realizing' the SI metre.…”

Section: The Velocity Of Light and Metre From Optical Frequency Refermentioning

confidence: 99%

Optical frequency/wavelength references

Hollberg¹,

Oates²,

Wilpers³

et al. 2005

J. Phys. B: At. Mol. Opt. Phys.

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For more than 100 years, optical atomic/molecular frequency references have played important roles in science and technology, and provide standards enabling precision measurements. Frequency-stable optical sources have been central to experimental tests of Einstein's relativity, and also serve to realize our base unit of length. The technology has evolved from atomic discharge lamps and interferometry, to narrow atomic resonances in laser-cooled atoms that are probed by frequency-stabilized cw lasers that in turn control optical frequency synthesizers (combs) based on ultra-fast mode-locked lasers. Recent technological advances have improved the performance of optical frequency references by almost four orders of magnitude in the last eight years. This has stimulated new enthusiasm for the development of optical atomic clocks, and allows new probes into nature, such as searches for time variation of fundamental constants and precision spectroscopy.

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Laser wavelength measurements and the speed of light

Cited by 23 publications

References 48 publications

Learning from the time and length redefinitions, and the metre demotion

Learning from the time and length redefinitions, and the metre demotion

On the experimental determination of the one-way speed of light

Optical frequency/wavelength references

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