史瓦西半徑
The Planck mass is the order of mass for which the Compton wavelength and the Schwarzschild radius formula_21 are the same, when their value is close to the Planck length (formula_22). The Schwarzschild radius is proportional to the mass, whereas the Compton wavelength is proportional to the inverse of the mass. The Planck mass and length are defined by: