A

David

Darling

Planck time

In quantum mechanics, the Planck time is the shortest meaningful period of time; any two events that are separated by less than this amount of time can be considered simultaneous. It has the value 5.390 × 10-44 second. Related to this is the Planck length of 6.160 × 10-33 centimeter, which is the distance that light can travel in the Planck time.