Planck length

The Planck length is the natural unit of length, denoted by l_P. This unit was first developed by Max Planck who wished to create a system of measurement based on natural units. Although quantum mechanics and general relativity were unknown at the time that the units were proposed, it \nlater became clear that at distances of the Planck length, gravity would begin to display quantum mechanical effects, requiring a theory of quantum gravity to predict what happens. By the Heisenberg uncertainty principle of standard quantum mechanics,\nan object whose position was localizable to the Planck length would have enough\nuncertainty in momentum to generate a black hole in standard general relativity. To explain what this actually means requires a theory of quantum gravity that combines both quantum mechanics and general relativity and as yet no such widely accepted theory exists. Some theories of quantum gravity assert that the nature of space changes at the Planck length.

≈ 1.616 × 10-35 m

where:

is Dirac's constant

G is the gravitational constant c is the speed of light in vacuum

See also

\n* Natural units\n* Planck mass\n* Planck time Category:Units of length\nLength