# Planck Time

on . Posted in Relativity

Planck time, abbreviated as $$t_p$$, is a fundamental unit in the system of Planck units.  It is based on the speed of light, the energies needed to smash particles in the universe at a time equal to the Planck length and universal gravitational constant divided by the speed of light.  It is a useful unit in theoretical physics.

• $$\large{ t_p = 5.391, 247 \;x\;10^{-44}\;s }$$

## Planck Time Formula

$$\large{ t_p = \sqrt{ \frac{ h\;G } { c^5 } } }$$
Symbol English Metric
$$\large{ t_p }$$ = Planck time $$\large{sec}$$ $$\large{s}$$
$$\large{ G }$$ = gravitational constant $$\large{\frac{lbf-ft^2}{lbm^2}}$$  $$\large{\frac{N - m^2}{kg^2}}$$
$$\large{ h }$$ = Planck constant $$\large{\frac{lbf-ft}{sec}}$$ $$\large{J-s}$$
$$\large{ c }$$ = speed of light in vacuum  $$\large{\frac{ft}{sec}}$$  $$\large{\frac{m}{s}}$$

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