In 1899, Max Planck combined three constants - gravity, the speed of light, and his own constant - and got a length of 10⁻³⁵ meters. A distance so small that trying to observe it creates a black hole. Two independent proofs converge on the same number - the scale where spacetime itself stops being measurable and every quantum computing qubit, every LLM latent space, and every physics simulation on GPU clusters hits the same fundamental wall. To see smaller you need higher energy. But energy curves spacetime - push enough into a Planck-sized region and the Schwarzschild radius swallows the observation behind an event horizon. The generalized uncertainty principle confirms it from the opposite direction: delta x hits a minimum then starts growing. Both paths land on 1.6 x 10⁻³⁵ meters. To reach it you'd need a collider 4,000 light years across. String theory says the fundamental building blocks are vibrating strings at exactly this scale - and gravity falls out of the equations naturally, not added by hand. 30 minutes. Bookmark & watch today. The length where physics itself stops working.