Planck length

Named after Max Planck, who defined it.

Planck length (plural Planck lengths)

1. (physics) A unit of length, believed to be the scale at which quantum gravity effects become significant, that is defined in terms of the speed of light, the gravitational constant and the reduced Planck's constant, namely: ${\displaystyle \ell _{P}={\sqrt {\frac {\hbar G}{c^{3}}}}\approx 1.616252(81)\times 10^{-35}{\mbox{ m}}}$
   • 2023 October 9, Dennis Overbye, “The Science Nobel Winners Were Short and Fast”, in The New York Times‎^[1], archived from the original on 12 October 2023:

     As Dr. Feynman noted, there are still shorter scales of time and distance to go before we reach the ultimate limits imposed by quantum physics: the Planck length, 10^-33 of a centimeter, and the Planck time, 10^-43 of a second. Both are named for the German physicist Max Planck, who made the breakthrough that led to quantum mechanics.

• Planck scale
• Planck time
• Planck unit
• superstring