Quantum Mechanics at 100: A Triumphant Theory, Yet No One Knows Why It Works

Quantum mechanics, the most successful and important theory in modern physics, makes remarkably accurate predictions and explains phenomena ranging from lasers to the Higgs boson. Yet, for a century, physicists have struggled to agree on its fundamental principles. This article traces the origins of quantum mechanics, from Planck and Einstein's early work to the breakthroughs of Heisenberg, Born, Jordan, and Schrödinger, exploring the measurement problem, wave functions, the uncertainty principle, and the decades-long debate between Einstein and Bohr about the nature of quantum reality. Quantum entanglement further challenges our intuition and understanding of spacetime. Despite its immense success, the foundations of quantum mechanics remain shrouded in mystery, making it both fascinating and deeply challenging.