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:
“A solitary traveler whom we saw perambulating in the distance loomed like a giant. He appeared to walk slouchingly, as if held up from above by straps under his shoulders, as much as supported by the plain below. Men and boys would have appeared alike at a little distance, there being no object by which to measure them. Indeed, to an inlander, the Cape landscape is a constant mirage.”
—Henry David Thoreau (1817–1862)