The distance (ℏG/c 3)½ (where G is the constant of gravitation), equal to 1.616 × 10−35 metre, which represents the length at which classical concepts of space–time cease to be valid.
Origin
1960s.
Definition of Planck length in US English:
Planck length
noun
Physics
The distance (ℏG/c 3)½ (where G is the constant of gravitation), equal to 1.616 × 10−35 metre, which represents the length at which classical concepts of space–time cease to be valid.