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Planck mass
From Wikipedia, the free encyclopedia
The Planck mass is the unit of mass, denoted by mP, in the system of natural units known as Planck units. It is the mass for which the Schwarzschild radius is equal to the Compton length divided by π.
≈ 1.2209 × 1019 GeV/c2 = 2.176 × 10-8 kg
The 2002 CODATA-recommended value for the Planck mass is 2.176 45(16) × 10-8 kg, where the part in parentheses indicates the uncertainty in the last digits shown — that is, a value of 2.17645 × 10-8 kg ± 0.00016 × 10-8 kg.
Particle physicists and cosmologists often use the reduced Planck mass, which is
≈ 4.340 µg.
Adding the 8π simplifies several equations in gravity.
Unlike most of the other Planck units, the Planck mass is on a scale more or less conceivable to humans, as the body mass of a flea is roughly 4000 to 5000 mP.
The Planck mass is the mass of a black hole whose Schwarzschild radius multiplied by π equals its Compton wavelength. The radius of such a black hole is roughly the Planck length, which is believed to be the length scale at which both general relativity and quantum mechanics simultaneously become important.
| Planck's natural units |
| Base Planck units: Planck time | Planck length | Planck mass | Planck charge | Planck temperature |
| Derived Planck units: Planck energy | Planck force | Planck power | Planck density | Planck angular frequency | Planck pressure | Planck current | Planck voltage | Planck impedance | Planck momentum |
 |
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