For nearly two centuries, the Grotthuss mechanism—the way protons leap between water molecules—has been understood in broad strokes but never fully seen. An international team of researchers has now used quantum simulations powered by neural networks to resolve a long-standing debate, revealing that it is water's own local imperfections, not idealized molecular structures, that govern how protons move. The finding, published in Nature Chemistry, carries quiet but profound implications: from the batteries that store our energy to the membranes through which our cells communicate, the asymmetry