Does the Fine-Structure Constant Really Vary in Time?

Abstract
We discuss how laboratory experiments can be used to place constraints on possible variations of the fine-structure constant α in the observationally relevant redshift interval z0-5, within a rather general theoretical framework. We find a worst case upper limit for Δα/α of 8×10−6 for z≤5 and Δα/α of 0.9×10−6 for z≤1.6. The derived limits are at variance with the recent findings by Webb et al., who claim an observed variation of Δα/α=-2.6±0.4×10−5 at 1<z<1.6.
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