The Planck length is defined as the square root of the product of the gravitational constant, reduced Planck's constant, and the speed of light cubed, resulting in a measurement of approximately 10^-35 meters. It represents a scale where quantum mechanics and general relativity converge and is significant in theories such as string theory, where it is considered the average length of a string. Additionally, the Planck length is part of a broader framework that includes Planck energy and Planck time, which are essential in understanding the unification of natural forces. This measurement highlights the limits of our current understanding of physics at extremely small scales. The discussion emphasizes the importance of the Planck length in theoretical physics.
