Universal constants like G and Planck's constant are strictly constant across space and time
the verdict
CONTESTED
the evidence cuts both ways
confidence 30/100
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 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
Evidence for · 2
Indications of a spatial variation of the fine structure constant.
2010 · cited by 407
Quasar absorption line data from Keck and VLT indicate spatial variations of the fine-structure constant consistent with a dipole model.
Evidence against · 3
Frequency ratio of two optical clock transitions in 171Yb+ and constraints on the time variation of fundamental constants.
2014 · cited by 379
High-precision atomic clock measurements constrain temporal variations of fundamental constants to near-zero levels.
See more details
More for · 1
Spatial variation in the fine-structure constant – new results from VLT/UVES
2012 · cited by 225
Combined VLT and Keck samples suggest an apparent spatial variation of the fine-structure constant across the sky.
More against · 2
Constraints on the variation of fine structure constant from joint SPT-SZ and XMM-Newton observations
2020 · cited by 30
Cluster observations from SPT-SZ and XMM-Newton find no evidence of spatial or logarithmic redshift variation in the fine-structure constant.
Constraints on the Variation of the Fine-structure Constant at 3 < z < 10 with JWST Emission-line Galaxies
2024 · cited by 4
JWST emission-line galaxy spectra at high redshifts show no significant spacetime variation in the fine-structure constant.