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Home > Planck mass

m_P = (c / G)^1/2 ≈ 2.1 × 10^-8 kg = 21 µg

where:

c is the speed of light

G is the gravitational constant

Unlike most of the other Planck units, the Planck mass is on an approximately human scale, being roughly the mass of some fleas. The issue is that general relativity predicts that smaller black holes can exist within an event horizon of radius less than the Planck length, while quantum mechanics predicts that the mass would probably be outside the event horizon.

See also

• Natural units
• Planck length
• Planck time

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Planck's constantPlanck's constant denoted h is a physical constant that is used to describe the sizes of quanta. It plays a central role in the theory of quantum mechanics, and is named after Max Planck, one of the founders of quantum theory. It has a value of approximat Planck's lawPlanck's law discovered by Max Planck, is the basis of the quantum theory of electromagnetism. The law states that the energy associated with electromagnetic radiation comes in indivisible packets called quanta each of which is associated with a single ph Planck temperatureThe Planck temperature named after German physicist Max Planck, is the natural unit of temperature, denoted by T. T c''5 / G 1/2 / k ≈ 1. 4 × 1032 kelvin where: c is the speed of light in a vacuum is Dirac's constant G is the gravitational constant Planck massThe Planck mass is the natural unit of mass, denoted by m. m c / G 1/2 ≈ 2. 1 × 10-8 kg 21 µg where: c is the speed of light is Dirac's constant G is the gravitational constant Unlike most of the other Planck units, the Planck mass is on an approxim Planck timeThe Planck time is the natural unit of time, denoted by t. It is considered the smallest possible measurement of time. 391 × 10-44 seconds where: is Dirac's constant G is the gravitational constant c is the speed of light in a vacuum The Planck time is th Planck's law of black body radiationIn physics, the intensity spectrum of electromagnetic radiation from a black body at temperature T is given by the Planck's law of black body radiation : where: :ν is the frequency I ν) is the amount of energy per unit time per unit surface per unit Planck units Planck energy Planck length Planck density Planck current Planck charge