noun

• A fundamental and dimensionless physical constant, equal to approximately 1/137, which occurs in expressions describing the fine structure of atomic spectra.

  ‘Some of these constants, such as the fine-structure constant, are dimensionless and are not expressed in terms of units.’

  More example sentences

  • ‘The researchers concluded that the fine-structure constant might well be constant, and that the variation seen in the prior work was highly unlikely.’
  • ‘Even atomic clocks can detect drifts in the fine-structure constant only over days or, at most, years.’
  • ‘As already noted, the fine-structure constant controls the spectral patterns made by elements.’
  • ‘This is interesting, because there are claims that the fine-structure constant, which determines the strength of the electromagnetic interaction, has actually been experimentally observed to be varying with time.’