A unit of time in an absolute system of units devised by Max Planck, about
5.391 24 × 10⁻⁴⁴ second. Symbol, *t*_{P}. Algebraically, it is

where * c* = the speed of light, *
G* = Newtonian gravitational constant, and
*ħ* = the reduced Planck's constant.

From the equations, you can see that a velocity of 1 Planck length per Planck time is the speed of light.

Copyright © 2009 Sizes, Inc. All rights reserved.

Last revised: 28 September 2011.