- Planck mass
The Planck mass is the unit of
mass , denoted by "m"P, in the system ofnatural units known asPlanck units . Named afterMax Planck , it is the mass for which theSchwarzschild radius is equal to theCompton length divided by π.:m_P = sqrtfrac{hbar c}{G} ≈ 1.2209 × 1019GeV /c2 = 2.176 × 10-8 kgThe2002 CODATA -recommended value for the Planck mass is 2.17645(16) × 10-8 kg, where the part in parentheses indicates theuncertainty 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:sqrtfrac{hbar{}c}{8pi G} ≈ 4.340 µg = 2.43 × 1018
GeV /c2.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 tohuman s, as the body mass of aflea is roughly 4000 to 5000 "m"P.ignificance
The Planck mass is an idealized mass that is thought to have special significance for
quantum gravity when General Relativity and the fundamentals of quantum physics become mutually important to describe mechanics.See also
*
Planck unit
*Planck length
*Planck particle
*Orders of magnitude (mass) External links
* [http://physics.nist.gov/cuu/Constants/index.html The NIST Reference on Constants, Units, and Uncertainty]
Wikimedia Foundation. 2010.