In gravitational lensing, the square of this quantity is inversely proportional to the Einstein radius.
In gravitational lensing, the square of this quantity is inversely proportional to the Einstein radius. When expressed in cgs units, the fine structure constant is inversely proportional to this quantity and h-bar. In a recent project called OPERA, scientists working with (*) neutrino oscillations at CERN made claims challenging this quantity. Tachyons theoretically exceed this value, and Albert Michelson and Galileo both worked with measuring it. For 10 points, identify this quantity whose square yields energy when multiplied by mass, an upper bound on velocity roughly equal to 3 times ten to the power of 8 meters per second.
In gravitational lensing, the square of this quantity is inversely proportional to the Einstein radius.
{speed of light} [accept {c} before mentioned]