Fine-structure constant
Dimensionless number that quantifies the strength of the electromagnetic interaction / From Wikipedia, the free encyclopedia
Dear Wikiwand AI, let's keep it short by simply answering these key questions:
Can you list the top facts and stats about Fine-structure constant?
Summarize this article for a 10 year old
In physics, the fine-structure constant, also known as the Sommerfeld constant, commonly denoted by α (the Greek letter alpha), is a fundamental physical constant which quantifies the strength of the electromagnetic interaction between elementary charged particles.
Value of α |
---|
0.0072973525643(11) |
Value of α−1 |
137.035999177(21) |
It is a dimensionless quantity, independent of the system of units used, which is related to the strength of the coupling of an elementary charge e with the electromagnetic field, by the formula 4πε0ħcα = e2. Its numerical value is approximately 0.0072973525643 ≃ 1/137.035999177, with a relative uncertainty of 1.6×10−10.[1]
The constant was named by Arnold Sommerfeld, who introduced it in 1916[2] when extending the Bohr model of the atom. α quantified the gap in the fine structure of the spectral lines of the hydrogen atom, which had been measured precisely by Michelson and Morley in 1887.[lower-alpha 1]
Why the constant should have this value is not understood,[3] but there are a number of ways to measure its value.