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Named after Max Planck, who defined it.
Etymology from Wiktionary, CC BY-SA 4.0.
Planck length
Today it means: 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: ℓ_P=√(\frac)hbar Gc³≈1.616 252(81)×10⁻³⁵ mbox m Full definition →