from: ~| 137 |~
"One hundred thirty-seven is the value of a number called the fine-structure constant. This constant, 137, is the way physicists describe the probability that an electron will emit or absorb a photon. Because this is the basic physical mechanism of electricity and magnetism, the fine-structure constant has its own symbol, the Greek letter a, “alpha.”
Now, alpha is nothing more, nothing less than the square of the charge of the electron divided by the speed of light times Planck’s constant. Thus this one little number contains in itself the guts of electromagnetism (the electron charge), relativity (the speed of light), and quantum mechanics (Planck’s constant). All in one number! Not only that, this number isn’t like the gravitational constant or the universal gas constant, full of meters and kilograms and degrees Celsius. Alpha is a pure, dimensionless number — little wonder that people have been fascinated."