Universal constants like G and Planck's constant are strictly constant across space and time
Whether universal constants such as the fine-structure constant are strictly constant remains debated, as some astrophysical quasar absorption datasets suggest spatial variations, whereas high-precision atomic clocks and other cosmological observations constrain them to be constant.
The retrieved papers show an active empirical dispute in physics: while older and some recent quasar absorption analyses (e.g., Refs 0 and 2) report spatial variations or dipole signatures in alpha, numerous other high-precision laboratory atomic clock studies, cluster observations, and JWST high-redshift galaxy measurements (e.g., Refs 1, 5, and 10) find no evidence of variation and tightly constrain any potential drift. This mixed body of literature establishes a contested balance verdict.
The evidence we hold leans evenly split
How this was weighed
official record 3x · fact-check 2x · hedged 1x · crowd & reference 1x
- Indications of a spatial variation of the fine structure con · peer-reviewed · supports · weight 2 · 2010
- Spatial variation in the fine-structure constant – new resul · peer-reviewed · supports · weight 2 · 2012
- Frequency ratio of two optical clock transitions in 171Yb+ a · peer-reviewed · refutes · weight 2 · 2014
- Constraints on the variation of fine structure constant from · peer-reviewed · refutes · weight 1.3 · 2020
- Constraints on the Variation of the Fine-structure Constant · peer-reviewed · refutes · weight 1.05 · 2024
J. Webb, J. King, M. Murphy, V. Flambaum, R. Carswell, M. Bainbridge. Indications of a spatial variation of the fine structure constant.. 2010. https://doi.org/10.1103/PhysRevLett.107.191101
Quasar absorption line data from Keck and VLT indicate spatial variations of the fine-structure constant consistent with a dipole model.
R. Godun, P. Nisbet-Jones, J. M. Jones, S. King, L. A. M. Johnson, H. Margolis, K. Szymaniec, S. Lea, K. Bongs, P. Gill. Frequency ratio of two optical clock transitions in 171Yb+ and constraints on the time variation of fundamental constants.. 2014. https://doi.org/10.1103/PhysRevLett.113.210801
High-precision atomic clock measurements constrain temporal variations of fundamental constants to near-zero levels.
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J. King, J. Webb, M. Murphy, V. Flambaum, R. Carswell, M. Bainbridge, Michael R. Wilczynska, F. Koch. Spatial variation in the fine-structure constant – new results from VLT/UVES. 2012. https://doi.org/10.1111/j.1365-2966.2012.20852.x
Combined VLT and Keck samples suggest an apparent spatial variation of the fine-structure constant across the sky.
K. Bora, S. Desai. Constraints on the variation of fine structure constant from joint SPT-SZ and XMM-Newton observations. 2020. https://doi.org/10.1088/1475-7516/2021/02/012
Cluster observations from SPT-SZ and XMM-Newton find no evidence of spatial or logarithmic redshift variation in the fine-structure constant.
Linhua Jiang, Shuqi Fu, Feige Wang, S. Bosman, Zheng Cai, H. Jun, Zhiwei Pan, F. Sun, Jinyi Yang, Huanian Zhang. Constraints on the Variation of the Fine-structure Constant at 3 < z < 10 with JWST Emission-line Galaxies. 2024. https://doi.org/10.3847/1538-4357/adad5b
JWST emission-line galaxy spectra at high redshifts show no significant spacetime variation in the fine-structure constant.
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