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# Planck temperature

The Planck temperature, named after German physicist Max Planck, is the unit of temperature, denoted by TP, in the system of natural units known as Planck units. It is one of the Planck units that represent a fundamental limit of quantum mechanics. The Planck temperature is the fundamental upper limit of temperature; modern science considers it nonsensical to conjecture about anything hotter, as this is the upper limit at which matter can operate. Beyond this, everything turns into energy as all subatomic particles become so excited they break down. It is the temperature of the Universe during the first instant (the first unit of Planck time) of the Big Bang according to current cosmology.

$T_P = \frac{m_P c^2}{k} = \sqrt{\frac{\hbar c^5}{G k^2}} =$ 1.41679(11) × 1032 K

where:

mP is the Planck mass

c is the speed of light in a vacuum

$\hbar$ is the reduced Planck constant (or Dirac's constant)

k is the Boltzmann constant

G is the gravitational constant

The two digits between the parentheses denote the uncertainty (standard deviation) in the last two digits of the value.