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In physics, the Planck mass, denoted by ''m''P, is the unit of mass in the system of natural units known as Planck units. It is defined so that : ≈ = = = ,〔CODATA 2010: (value in GeV ), (value in kg )〕 where ''c'' is the speed of light in a vacuum, ''G'' is the gravitational constant, and ''ħ'' is the reduced Planck constant. Particle physicists and cosmologists often use an alternative normalization with the reduced Planck mass, which is : ≈ = 2.435 × 1018 GeV/c2. The factor of simplifies a number of equations in general relativity. ==Significance== The Planck mass is nature’s maximum allowed mass for point-masses (quanta) – in other words, a mass capable of holding a single elementary charge. If two quanta of the Planck mass or greater met, they could spontaneously form a black hole whose Schwarzschild radius equals their Compton wavelength. Once such a hole formed, other particles would fall in, and the black hole would experience runaway, explosive growth (assuming it did not evaporate via Hawking radiation). Nature’s stable point-mass particles, such as electrons and quarks, are many, many orders of magnitude lighter than the Planck mass and cannot form black holes in this manner. On the other hand, extended objects (as opposed to point-masses) can have any mass. Unlike all other Planck base units and most Planck derived units, the Planck mass has a scale more or less conceivable to humans. It is traditionally said to be about the mass of a flea, but more accurately it is about the mass of a flea egg. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Planck mass」の詳細全文を読む スポンサード リンク
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