Planck mass

The Planck mass is a fundamental unit of mass in physics derived from natural constants, representing a scale where quantum mechanics and gravity are equally significant. It’s approximately 22 micrograms—about the mass of a tiny grain of dust—serving as a theoretical boundary beyond which our current understanding of physics—involving both quantum mechanics and gravity—breaks down. Essentially, it marks the scale at which the effects of quantum gravity become dominant, helping physicists explore unified theories of nature's forces.