An Etymological Dictionary of Astronomy and Astrophysics

The density corresponding to a → Planck mass in a cubic region of edge length given by the
→ Planck length: ρ_P = c⁵/(ħG²) ≅ 5.16 x 10⁹³ g cm^-3, where c is the → speed of light, ħ is the → reduced Planck’s constant, and G is the → gravitational constant.

See also: → Planck; → density.