The Planck length is derived from three fundamental constants: the reduced Planck constant (ℏ), the gravitational constant (G), and the speed of light (c), which are all invariant regardless of the observer's frame of reference. As a result, the Planck length itself remains a universal constant. The discussion emphasizes that since these constants do not change with speed, the Planck length cannot vary based on different frames of reference. This reinforces the idea that both the Planck length and the speed of light are fundamental to our understanding of physics. The relationship between these constants highlights the consistency of physical laws across the universe.