Chapter 9: Fundamental Physics

Section 6: The Nature of Space

Planck length

Even in existing particle physics it is generally assumed that the traditional simple continuum description of space must break down at least below about the Planck length Sqrt[ \[HBar] G/c^3] 2 × 10^-35 meters—since at this scale dimensional analysis suggests that quantum effects should be comparable in magnitude to gravitational ones.

From Stephen Wolfram: A New Kind of Science [citation]