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The fine structure constant: a review of measurement results and possible space-time variations
https://doi.org/10.32446/0368-1025it.2025-2-5-12
Abstract
A brief description of the main methods for determining the fine structure constant is given. It is shown that the exact value of the fine structure constant is important for the new International System of Units and for fundamental metrology. Recent measurement results and theoretical calculations of the fine structure constant, as well as its possible space-time variations, are presented. The results of laboratory experiments on the search for long-term variations of the fine structure constant are presented. The astrophysical and cosmological observational data on possible variability of the fine structure constant are presented. The possibility of slightly lower values of the fine structure constant in the remote past as compared to its modern value, as well as the existence of unresolved problems related to possible space-time variations of the fine structure constant and the spread of the results of its precise laboratory measurements, are noted. Despite the absence of experimentally confirmed long-term variations of the fine structure constant at a high level of accuracy, possible practical applications of the results are noted, namely, the construction of an optical frequency standard with high stability and frequency reproduction accuracy based on the ytterbium-171 ion and a laser frequency synthesizer which may replace the caesium frequency standard.
Keywords
redefinition of measurement units,
fine structure constant,
anomalous magnetic moment of the electron,
space-time variations
Supporting agencies: All authors contribu te d to the study’s conception and design. Material preparation, data collection and analysis were performed by all authors. All authors read and approved the final manuscript
About the Authors
K. A. Bronnikov
Research Center for Applied Metrology – Rostest
Russian Federation
Russian Federation
Kirill A. Bronnikov
Moscow
V. D. Ivashchuk
Research Center for Applied Metrology – Rostest
Russian Federation
Russian Federation
Vladimir D. Ivashchuk
Moscow
V. V. Khruschov
Research Center for Applied Metrology – Rostest
Russian Federation
Russian Federation
Viacheslav V. Khruschov
Moscow
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Bronnikov K.A., Ivashchuk V.D., Khruschov V.V. The fine structure constant: a review of measurement results and possible space-time variations. Izmeritel`naya Tekhnika. 2025;74(2):5-16. (In Russ.) https://doi.org/10.32446/0368-1025it.2025-2-5-12
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