Let’s quickly recollect the main points of the two earlier columns in this series. Gravity appears extravagantly feeble on atomic and laboratory scales, ultimately because the proton’s mass m p is much smaller than the Planck mass , where ℏ is Planck’s quantum of action, c is the speed of light, and G N is Newton’s gravitational constant. Numerically, m p/M planck ≈ 10−18. If we aspire, in line with Planck’s original vision and with modern ambitions for the unification of physics, to use the natural (Planck) system of units constructed from c, ℏ, and G N (see “Scaling Mount Planck I: A View from the Bottom,” Physics Today, Physics Today 0031-9228 54 6 2001 12 https://doi.org/10.1063/1.1387576 June 2001, page 12 ), and if we agree that the proton is...