Planck momentum

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Planck Momentum is the unit of momentum, denoted by $m P c$ , in the system of natural units known as Planck units.

$m_P c = \frac{\hbar}{l_P} = \sqrt{\frac{\hbar c^3}{G}} \approx$ 6.52485 kg m/s

where

$l P$ is the Planck length
$\hbar$ is the reduced Planck's constant
$c$ is the speed of light in a vacuum
$G$ is the gravitational constant

In SI units Planck momentum is approximately 6.5 kg m/s. It is the momentum of an object with Planck mass moving at the speed of light, usually associated with the momentum of primordial photons in some prevailing Big Bang models. Unlike most of the other Planck units, Planck momentum occurs on a human scale. By comparison, running with a five-pound object (10⁸×Planck mass) at an average running speed (10^-8×speed of light in a vacuum) would give the object Planck momentum. A 70 kg human walking at an average speed of 1 m/s would have a momentum of about 10.7 $m P c$ .