Fine-structure Constant

In physics, the fine-structure constant (usually denoted α, the small Greek letter alpha) is a fundamental physical constant, namely the coupling constant characterizing the strength of the electromagnetic interaction. Being a dimensionless quantity, it has constant numerical value in all systems of units. Arnold Sommerfeld introduced the fine-structure constant in 1916.

The current recommended value of α is 7.2973525698(24)×10−3 = 1/137.035999074(44).

Read more about Fine-structure Constant:  Definition, Measurement, Erroneous 2006 Recommended Value, Physical Interpretations, History, Is The Fine-structure Constant Actually Constant?, Anthropic Explanation, Numerological Explanations, Quotes

Famous quotes containing the word constant:

    Sigh no more, ladies, sigh no more,
    Men were deceivers ever,
    One foot in sea and one on shore,
    To one thing constant never:
    Then sigh not so, but let them go,
    And be you blithe and bonny,
    Converting all your sounds of woe
    Into Hey nonny, nonny.
    William Shakespeare (1564–1616)